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Click for overall list of YEAR 2009 (mixed, earlier go by the specialty field) |
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(Year) - Authors - Title -
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Macek, P., Rejmankova, E. and Fuchs, R. Biological activities as patchiness driving forces in wetlands of northern Belize. Oikos 118(11), 1687-1694. |
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ABSTRACT
We conducted a survey of patches and confirmed their occurrence by spatial analysis. Patches were distinguished from a surrounding wetland by denser and taller vegetation, higher amount of empty snail shells and elevated soil phosphorus (P). Plants in patches had higher tissue nitrogen (N) and P content and there was also higher total N and P per m2 incorporated in plant biomass. In terms of stable isotopes, plants in patches were enriched in 15N; patch soils were depleted in 13C. Observations of focal individuals of Aramus guarauna, limpkin, a wading bird feeding almost exclusively on snails, revealed the origin of the snail shell piles frequently found in patches. An adult limpkin captured on average 18 snails daily, of these 80% were handled in patches and birds often repeatedly used the same patch. Experimental patch creation by adding chicken manure or P to 1 m2 plots resulted in higher and denser vegetation with values increasing in order: control, P, manure plots. The effect was significant at both experimental locations six months after the treatment and at one location even 40 months after the treatment. We present a simple mechanistic explanation for nutrient redistribution in wetlands and their eventual accumulation in patches. Both nutrient and isotopic differences result from animal input into patches, e.g. bird droppings or prey remnants. Foraging activity of Aramus guarauna is most likely responsible for patch formation. A positive feedback (repeated use of a suitable patch) is apparently the mechanism sustaining patches in these marsh environments.
KEYWORDS: snail pomacea-paludosa; phosphorus enrichment; tree islands; southern
everglades; florida everglades; habitat structure; apple snails;
vegetation; selection; kites |
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(2009) Madden, C.J., Rudnick, D.T., McDonald, A.A., Cunniff, K.M. and Fourqurean, J.W. Ecological indicators for assessing and communicating seagrass status and trends in Florida Bay. Ecological Indicators 9 (S68-S82). |
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ABSTRACT
A suite of seagrass indicator metrics is developed to evaluate four essential measures of seagrass community status for Florida Bay. The measures are based on several years of monitoring data using the Braun-Blanquet Cover Abundance (BBCA) scale to derive information about seagrass spatial extent, abundance, species diversity and presence of target species. As ecosystem restoration proceeds in south Florida, additional freshwater will be discharged to Florida Bay as a means to restore the bay's hydrology and salinity regime. Primary hypotheses about restoring ecological function of the keystone seagrass community are based on the premise that hydrologic restoration will increase environmental variability and reduce hypersalinity. This will create greater niche space and permit multiple seagrass species to coexist while maintaining good environmental conditions for Thalassia testudinum, the dominant climax seagrass species. Greater species diversity is considered beneficial to habitat for desired higher trophic level species such as forage fish and shrimp. it is also important to maintenance of a viable seagrass community that will avoid die-off events observed in the past. Indicator metrics are assigned values at the basin spatial scale and are aggregated to five larger zones. Three index metrics are derived by combining the four indicators through logic gates at the zone spatial scale and aggregated to derive a single bay-wide system status score standardized on the System-wide Indicator protocol. The indicators will provide a way to assess progress toward restoration goals or reveal areas of concern. Reporting for each indicator, index and overall system status score is presented in a red-yellow-green format that summarizes information in a readily accessible form for mangers, policy-makers and stakeholders in planning and implementing an adaptive management strategy.
KEYWORDS: Florida Bay; Seagrass; Status; Indicators; Thalassia; Restoration;
Comprehensive Everglades Restoration Plan
long-term trends; n-p ratios; thalassia-testudinum; tropical seagrass;
water-quality; die-off; historical trends; nutrient content; chesapeake
bay; potential role |
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(2009) Malecki-Brown, L.M. and White, J.R. Effect of Aluminum-Containing Amendments on Phosphorus Sequestration of Wastewater Treatment Wetland Soil. Soil Science Society of America Journal 73(3), 852-861. |
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ABSTRACT
Little research has been conducted on methods to restore the P removal capacity of older constructed wetlands, as P treatment capacity can decrease with time. We investigated the capacity of alum and three Al-containing alternatives (alum residual, polyaluminum chloride [PAC], and partially neutralized aluminum sulfate [PNAS]), at three rates (9, 18, and 36 g Al m(-2)) to reduce P concentrations. Water column pH of the alum treatment was significantly less than all other treatments, averaging 3.65 +/- 1.12, while PAC (4.85 +/- 0.96) and PNAS (4.21 +/- 0.93) treatments had pH values significantly less than the alum residual and controls. Soluble reactive P decreased in the water column of all the treatments (-60.41 to -2.11 mg m(-2) d(-1)). At all dosage rates, alum and PNAS were most effective at binding P, followed by PAC, while the alum residual was least effective. Significantly less P removal occurred in the 9 g Al m(-2) alum, PNAS, and PAC treatments than the higher Al dosages. Dosage was inversely related to microbial biomass and activity in the surface soil, suggesting short-term negative effects of chemical additions. Results suggest that a low-dosage Al amendment application to wetland soil can, in the short term, prevent release of P from organic soil into the water column as well as remove P from the water column. Longterm studies are needed, however, to verify P removal efficacy with time and the effects of continued applications on nutrient availability.
KEYWORDS: organic nitrogen mineralization; orlando easterly wetland; treatment
residuals; hydraulic analysis; everglades soils; salmo-gairdneri;
rainbow-trout; toxicity; sulfate; lake |
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(2009) Marchant, B.P., Newman, S., Corstanje, R., Reddy, K.R., Osborne, T.Z. and Lark, R.M. Spatial monitoring of a non-stationary soil property: phosphorus in a Florida water conservation area. European Journal of Soil Science 60(5), 757-769. |
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ABSTRACT
Ecological restoration plans in the Florida Everglades require detailed information about the status and change of the nutrient content of the soil. The soil total phosphorus (TP) content is of particular importance as the system is naturally P limited and the TP enrichment has led to changes in the wetland vegetation communities. One way to provide the relevant information is by geostatistical prediction from sampled data. However, conventional geostatistical models assume that properties being monitored are realizations of second-order stationary random functions. The assumption of second-order stationarity is not appropriate for soil TP in Water Conservation Area 1 (WCA-1) of the Florida Everglades because the mean and variance of soil TP are larger at sites adjacent to the canals which bound WCA-1 and deliver P to the system than at sites in the interior of the region. We develop a novel linear mixed-model framework for spatial monitoring of a property for which this assumption is not valid. Specifically we use this non-stationary model to map the status and change of TP within WCA-1 from surveys carried out in 1991 and 2003. We fit the parameters of the model by residual maximum likelihood (REML) and compare the effectiveness of this non-stationary model with the conventional stationary model. Conventional second-order stationary models fail to represent accurately the large uncertainty in predictions of TP adjacent to the canals. The non-stationary model predicts an invading front of P entering the interior of the region which is not evident in the predictions from the stationary model. Tests on the log-likelihood and the standardized squared prediction error of the fitted models provide further evidence in favour of the non-stationary model. The sampling intensity required to ensure a certain precision of TP predictions varies across WCA-1 with the variance of TP. Therefore we apply a spatial simulated annealing optimization algorithm to design future monitoring surveys based upon our non-stationary model which ensure that the status and change are efficiently and effectively predicted across the region.
KEYWORDS: residual maximum-likelihood; northern everglades marsh; optimization;
patterns |
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(2009) Marshall, F.E., Wingard, G.L. and Pitts, P. A Simulation of Historic Hydrology and Salinity in Everglades National Park: Coupling Paleoecologic Assemblage Data with Regression Models. Estuaries and Coasts 32(1), 37-53. |
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ABSTRACT
Restoration of Florida's Everglades requires scientifically supportable hydrologic targets. This study establishes a restoration baseline by developing a method to simulate hydrologic and salinity conditions prior to anthropogenic changes. The method couples paleoecologic data on long-term historic ecosystem conditions with statistical models derived from observed meteorologic and hydrologic data that provide seasonal and annual variation. Results indicate that pre-drainage freshwater levels and hydroperiods in major sloughs of the Everglades were about 0.15 m higher and two to four times greater, respectively, on average compared to today's values. Pre-drainage freshwater delivered to the wetlands and estuaries is estimated to be 2.5 to four times greater than the modern-day flow, and the largest deficit is during the dry season. In Florida Bay, salinity has increased between 5.3 and 20.1 with the largest differences in the areas near freshwater outflow points. These results suggest that additional freshwater flows to the Everglades are needed for restoration of the freshwater marshes of the Everglades and estuarine environment of Florida Bay, particularly near the end of the dry season.
KEYWORDS: Everglades; Paleoecology; Statistical models; Restoration targets;
Hydrology; Salinity
florida bay; fallout radionuclides; records; restoration; substrate;
trends |
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(2009) Mazzotti, F.J., Best, G.R., Brandt, L.A., Cherkiss, M.S., Jeffery, B.M. and Rice, K.G. Alligators and crocodiles as indicators for restoration of Everglades ecosystems. Ecological Indicators 9(S137-S149. |
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ABSTRACT
Alligators and crocodiles integrate biological impacts of hydrological operations, affecting them at all life stages through three key aspects of Everglades ecology: (1) food webs, (2) diversity and productivity, and (3) freshwater flow. Responses of crocodilians are directly related to suitability of environmental conditions and hydrologic change. Correlations between biological responses and environmental-conditions contribute to an understanding of species' status and trends over time. Positive or negative trends of crocodilian populations relative to hydrologic changes permit assessment of positive or negative trends in restoration. The crocodilian indicator uses monitoring parameters (performance measures) that have been shown to be both effective and efficient in tracking trends. The alligator component uses relative density (reported as an encounter rate), body condition, and occupancy rates of alligator holes; the crocodile component uses juvenile growth and hatchling survival. We hypothesize that these parameters are correlated with hydrologic conditions including depth, duration, timing, spatial extent and water quality. Salinity is a critical parameter in estuarine habitats. Assessments of parameters defined for crocodilian performance measures support these hypotheses. Alligators and crocodiles are the charismatic megafauna of the Everglades. They are both keystone and flagship species to which the public can relate. In addition, the parameters used to track trends are easy to understand. They provide answers to the following questions: How has the number of alligators or crocodiles changed? Are the animals fatter or thinner than they should be? Are the animal:3 in the places (in terms of habitat and geography) where they should be? As surely as there is no other Everglades, no other single species defines the Everglades as does the American alligator. The Everglades is the only place in the world where both alligators and crocodiles exist. Crocodilians clearly respond to changes in hydrologic parameters of management interest. These relationships are easy to communicate and mean something to managers, decision makers, and the public. Having crocodilians on the list of system-wide, general indicators provides us with one of the most powerful tools we have to communicate progress of ecosystem restoration in Greater Everglades ecosystems to diverse audiences.
KEYWORDS: Ecological indicators; Everglades restoration; Alligators; Crocodiles;
Restoration assessment
american crocodile; crocodylus-acutus; florida bay; holes |
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(2009) Mc Kay, F., Oleiro, M., Walsh, G.C., Gandolfo, D., Cuda, J.P. and Wheeler, G.S. Natural Enemies of Brazilian Peppertree (Sapindales: Anacardiaceae) from Argentina: Their Possible Use for Biological Control in the USA. Florida Entomologist 92(2), 292-303. |
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ABSTRACT
Brazilian peppertree (Schinus terebinthifolius Raddi, Anacardiaceae) is a perennial tree native to Argentina, Brazil, and Paraguay. The plant was introduced into the USA before 1900. Originally grown as an ornamental, Brazilian peppertree is now considered an noxious plant in Hawaii and Florida, where it is ranked among the most important threats to biodiversity in natural areas. Recent surveys conducted in northeastern Argentina recovered one fungus associated with distorted leaves and 36 phytophagous insects collected on Brazilian peppertree. A leaf-feeding notodontid moth, a new species of gracillariid leaf blotch miner, and a stem-boring weevil have been selected for further studies to determine their potential as biological control agents of Brazilian peppertree in the USA. The results of these surveys are summarized herein and descriptions are included of the insects that are considered most promising for biological control of this weed.
KEYWORDS: foreign exploration; classical biological control; Schinus
terebinthifolius; host range; invasive weed; Florida Everglades
megastigmus-transvaalensis hymenoptera; schinus-terebinthifolius
anacardiaceae; host-specificity tests; heteroperreyia-hubrichi; south
florida; control agent; lepidoptera; tortricidae; candidate; torymidae |
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(2009) McCormick, P., Newman, S. and Vilchek, L. Landscape responses to wetland eutrophication: loss of slough habitat in the Florida Everglades, USA. Hydrobiologia 621(105-114. |
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ABSTRACT
Much of the historical Everglades has been either lost or degraded as a result of human activities. Among the aquatic habitats that comprise the Everglades landscape mosaic, open-water sloughs support critical ecological functions and appear especially sensitive to both hydrologic and water-quality perturbations. We used a combination of remote sensing and on-the-ground sampling to document spatial changes in the extent and vegetative composition of sloughs along a phosphorus (P) gradient in the northern Everglades. Increasing levels of water and soil P were associated with a decline in slough coverage, loss of the abundant native periphyton community, and a shift in dominant macrophyte species. The characteristic slough macrophyte species Eleocharis cellulosa and Nymphaea odorata exhibited different sensitivities to P enrichment, but both species declined with enrichment as slough habitats were invaded by Typha domingensis, a species that is known to expand aggressively in response to enrichment. A limited amount of open-water habitat occurred in highly enriched areas, but these habitats were maintained largely as a result of airboat disturbance and did not contain characteristic slough vegetation. Many changes in slough coverage and composition occurred in areas where water and soil P concentrations were only marginally higher than background levels. Our findings support the need for Everglades hydrologic restoration efforts to adhere to strict water-quality standards for P to avoid further degradation of this key landscape feature.
KEYWORDS: Eleocharis; Everglades; Hydrology; Nymphaea; Periphyton; Phosphorus; Sloughs; Typha; Vegetation; Wetlands northern everglades; phosphorus enrichment; oligotrophic wetland; nutrient enrichment; restoration; vegetation; gradient; level |
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(2009) McInerney, M.J., Sieber, J.R. and Gunsalus, R.P. Syntrophy in anaerobic global carbon cycles. Current Opinion in Biotechnology 20(6), 623-632. |
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ABSTRACT
Syntrophy is an essential intermediary step in the anaerobic conversion of organic matter to methane where metabolically distinct microorganisms are tightly linked by the need to maintain the exchanged metabolites at very low concentrations. Anaerobic syntrophy is thermodynamically constrained, and is probably a prime reason why it is difficult to culture microbes as these approaches disrupt consortia. Reconstruction of artificial syntrophic consortia has allowed uncultured syntrophic metabolizers and methanogens to be optimally grown and studied biochemically. The pathways for syntrophic acetate, propionate and longer chain fatty acid metabolism are mostly understood, but key steps involved in benzoate breakdown and cyclohexane carboxylate formation are unclear. Syntrophic metabolism requires reverse electron transfer, close physical contact, and metabolic synchronization of the syntrophic partners. Genomic analyses reveal that multiple mechanisms exist for reverse electron transfer. Surprisingly, the flagellum functions were implicated in ensuring close physical proximity and synchronization of the syntrophic partners.
KEYWORDS: propionate oxidation; electron-transfer; fatty-acids; geobacter-metallireducens; methanogenic environments; cyclohexane carboxylate; benzoate degradation; florida everglades; nutrient gradient; deep subsurface |
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(2009) Merritt, K.A. and Amirbahman, A. Mercury methylation dynamics in estuarine and coastal marine environments - A critical review.
Earth-Science Reviews 96(1-2), 54-66. |
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ABSTRACT
Considerable recent research has focused on methylmercury (MeHg) cycling within estuarine and coastal marine environments. Because MeHg represents a potent neurotoxin that may magnify in marine foodwebs, it is important to understand the mechanisms and environmental variables that drive or constrain methylation dynamics in these environments. This critical review article explores the mechanisms hypothesized to influence aqueous phase and sediment solid phase MeHg concentrations and depth-specific inorganic Hg (II) (Hg-i) methylation rates (MMR) within estuarine and coastal marine environments, and discusses issues of terminology or methodology that complicate mechanism-oriented interpretation of field and laboratory data. Mechanisms discussed in this review article include: 1) the metabolic activity of sulfate reducing bacteria (SRB), the microbial group thought to dominate mercury methylation in these environments; 2) the role that Hg-i concentration and/or speciation play in defining depth-specific Hg-i methylation rates; and 3) the depth-dependent balance between MeHg production and consumption within the sedimentary environment. As discussed in this critical review article, the hypothesis of SRB community control on the Hg-i methylation rate in estuarine and coastal marine environments is broadly supported by the literature. Although Hg-i speciation, as a function of porewater inorganic sulfide and/or dissolved organic matter concentration and/or pH, may also play a role in observed variations in MMR, the nature and function of the controlling ligand(s) has not yet been adequately defined. Furthermore, although it is generally recognized that the processes responsible for MeHg production and consumption overlap spatially and/or kinetically in the sedimentary environment, and likely dictate the extent to which MeHg accumulates in the aqueous and/or sediment solid phase, this conceptual interpretation requires refinement, and would benefit greatly from the application of kinetic modeling.
KEYWORDS: mercury; methylation; estuary; marine; sediment sulfate-reducing bacteria; dissolved organic-matter; sediment pore waters; desulfovibrio-desulfuricans ls; desulfobulbus-propionicus 1pr3; penobscot river estuary; francisco bay-delta; community structure; florida everglades; monomethyl mercury |
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(2009) Miao, S.L. and Zou, C.B. Seasonal variation in seed bank composition and its interaction with nutrient enrichment in the Everglades wetlands.
Aquatic Botany 90(2), 157-164. |
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ABSTRACT
In the Florida Everglades, nutrient enrichment from agricultural outflow and the change in hydrology have collectively contributed to the expansion of cattails (Typha spp.). To assess the effectiveness of prescribed fire in controlling cattails and to predict vegetation dynamics after the fire, it is important to understand the seasonal variation of the soil seed bank and how the seed bank is affected by nutrient enrichment and fire. This paper investigates the effects of season, nutrient enrichment, and fire on soil seed bank species composition, richness, and density along a nutrient gradient in Water Conservation Area 2A (WCA 2A) of the Florida Everglades. Species richness was significantly affected by nutrient enrichment and season but not their interaction. Total seed density, however, was significantly affected by the interaction between nutrient enrichment and season. Yet, at species level, the relationship between seed density, nutrient enrichment and season varied. The highest seed density of cattail occurred in summer at highly enriched sites, but that of sawgrass occurred in fall regardless of enrichment; the seed density of water lily was very low regardless of season and nutrient enrichment, and the highest Amarathus seed density occurred at highly enriched sites year round. Moreover, germination timing differed greatly among species. While cattail seeds had a short incubation period and started to germinate 2-3 days after initiation of the germination assay, sawgrass seeds generally started to germinate 4 weeks later. Further, both the prescribed summer fire at the highly enriched site and the natural winter fire at the moderately enriched site reduced the seed density of cattail but not of sawgrass. Our results suggest that fire application for vegetation recovery in WCA 2A would benefit from explicitly considering seasonal dynamics of the seed bank.
KEYWORDS: Cattails; Cladium jamaicense; Nymphaea odorata; Sawgrass; Seedling germination assay; Species richness; Typha spp.; Water lily northern florida everglades; fire regimes; typha; restoration; marsh; water; constraints; community; sawgrass; patterns |
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(2009a) Miao, S.L., Zou, C.B. and Breshears, D.D. Vegetation Responses to Extreme Hydrological Events: Sequence Matters. American Naturalist 173(1), 113-118. |
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ABSTRACT
Extreme hydrological events such as flood and drought drive vegetation dynamics and are projected to increase in frequency in association with climate change, which could result in sequences of extreme events. However, experimental studies of vegetation responses to climate have largely focused on responses to a trend in climate or to a single extreme event but have largely overlooked the potential for complex responses to specific sequences of extreme events. Here we document, on the basis of an experiment with seedlings of three types of subtropical wetland tree species, that mortality can be amplified and growth can even be stimulated, depending on event sequence. Our findings indicate that the impacts of multiple extreme events cannot be modeled by simply summing the projected effects of individual extreme events but, rather, that models should take into account event sequences.
KEYWORDS: climate change; Everglades; extreme hydrological events; mortality; sequence climate-change; gas-exchange; forest; simulation; pacific; drought; model |
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(2009) Miller, C.L., Southworth, G., Brooks, S., Liang, L.Y. and Gu, B.H. Kinetic Controls on the Complexation between Mercury and Dissolved Organic Matter in a Contaminated Environment. Environmental Science & Technology 43(22), 8548-8553. |
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ABSTRACT
The interaction of mercury (Hg) with dissolved natural organic matter (NOM) under equilibrium conditions is the focus of many studies but the kinetic controls on Hg-NOM complexation in aquatic systems have often been overlooked, We examined the rates of Hg-NOM complexation both in a contaminated Upper East Fork Poplar Creek (UEFPC) in Oak Ridge, Tennessee, and in controlled laboratory experiments using reducible Hg (Hg-R) measurements and C-18 solid phase extraction techniques. Of the filterable Hg at the headwaters of UEFPC, >90% was present as HgR and this fraction decreased downstream but remained >29% of the filterable Hg at all sites. The presence of higher HgR concentrations than would be predicted under equilibrium conditions in UEFPC and in experiments with a NOM isolate suggests that kinetic reactions are controlling the complexation between Hg and NOM. The slow formation of Hg-NOM complexes is attributed to competitive ligand exchange among various moieties and functional groups in NOM with a range of binding strengths and configurations. This study demonstrates the need to consider the effects of Hg-NOM complexation kinetics on processes such as Hg methylation and solid phase partitioning.
KEYWORDS: reduced sulfur groups; waste-water effluent; humic substances; florida everglades; methyl mercury; natural-waters; strong hg(ii); binding; soil; constants |
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(2009) Min, J.H. and Wise, W.R. Simulating short-circuiting flow in a constructed wetland: the implications of bathymetry and vegetation effects.
Hydrological Processes 23(6), 830-841. |
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ABSTRACT
Short-circuiting flow, commonly experienced in many constructed wetlands, reduces hydraulic retention times in unit wetland cells and decreases the treatment efficiency. A two-dimensional (2-D), physically based, distributed modelling approach was used to systematically address the effects of bathymetry and vegetation on short-circuiting flow, which previously have been neglected or lumped in one-dimensional wetland flow models. In this study, a 2-D transient hydrodynamics with advection-dispersion model was developed using MIKE 21 and calibrated with bromide tracer data collected at the Orlando Easterly Wetland Cell 7. The estimated topographic difference between short-circuiting flow zone and adjacent area ranged from 0.3 to 0.8 m. A range of the Manning roughness coefficient at the short-circuiting flow zone was estimated (0.022-0.045 s m(-1/3)). Sensitivity analysis of topographical and vegetative heterogeneity deduced during model calibration shows that relic ditches or other ditch-shaped landforms and the associated sparse vegetation along the main flow direction intensify the short-circuiting pattern, considerably affecting 2-D solute transport simulation. In terms of hydraulic efficiency, this study indicates that the bathymetry effect on short-circuiting flow is more important than the vegetation effect.
KEYWORDS: constructed wetland; short-circuiting; hydraulic efficiency; hydrodynamic modeling; bathymetry; vegetation residence time distributions; through emergent vegetation; orlando easterly wetland; transient storage model; hydraulic efficiency; everglades; phosphorus; transport; ponds; performance |
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(2009) Mukherjee, A., Nair, V.D., Clark, M.W. and Reddy, K.R. Development of Indices to Predict Phosphorus Release from Wetland Soils.
Journal of Environmental Quality 38(3), 878-886. |
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ABSTRACT
The U.S. Environmental Protection Agency created the Clean Water Action Plan to develop nutrient criteria for four water body types: lakes and reservoirs, rivers and streams, estuaries, and wetlands. Significant progress has been made in open water systems. However, only areas in and around the Florida Everglades have had numeric nutrient criteria set, due to the complexity, heterogeneity and limited information available for wetlands. Our objective was to evaluate various soil tests to predict significant P release potential of soil in wetlands. A total of 630 surface soil samples (0-10 cm) were collected for this study from four southeastern states: Florida, Alabama, Georgia, and South Carolina. Soil samples were collected from the center of wetlands, the edge of the wetlands, and from adjacent uplands. The phosphorus saturation ratios (PSR), calculated using P, Fe, and Al molar concentrations from Mehlich 1 (M1-PSR), Mehlich 3 (M3-PSR), and oxalate (Ox-PSR) extractions and the amount of P extracted by different excractants were used to predict P loss potential from a soil. Total phosphorus (TP) concentration in wetland Soils, estimated as the 75th percentile of the distribution of least impacted wetland soils as an example, was approximately 550 mg kg(-1). Based on this reference background condition, procedures for obtaining threshold values for P release to the surrounding water bodies were developed and threshold values calculated: 1-P 24 mg kg, M3-P = 44 mg kg(-1), Ox-PSR = 0.079, M1-PSR 0.101, and M3-PSR = 0.067
KEYWORDS: conterminous united-states; soluble phosphorus; risk-assessment; water; phosphate; sorption; saturation; desorption; mehlich-3; sediments |
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(2009) Murie, D.J., Parkyn, D.C., Loftus, W.F. and Nico, L.G. Variable growth and longevity of yellow bullhead (Ameiurus natalis) in the Everglades of south Florida, USA. Journal of Applied Ichthyology 25(6), 740-745. |
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ABSTRACT
Yellow bullhead (Ictaluridae: Ameiurus natalis) is the most abundant ictalurid catfish in the Everglades of southern Florida, USA, and, as both prey and predator, is one of many essential components in the ecological-simulation models used in assessing restoration success in the Everglades. Little is known of its biology and life history in this southernmost portion of its native range; the present study provides the first estimates of age and growth from the Everglades. In total, 144 yellow bullheads of 97-312 mm total length (TL) were collected from canals and marshes of the Everglades between April 2000 and January 2001, and from October 2003 to February 2005. Fish were aged using cross-sections of pectoral spines and ranged from 1-12 years, with the maximum age almost twice that of any yellow bullhead previously reported. Yellow bullheads from south Florida grew relatively rapidly during their first 3 years, but after age 5 growth slowed and fish approached an asymptote of similar to 214 mm TL. Compared to other populations in the United States, yellow bullhead in the Everglades grew relatively slowly, were smaller at age overall, but survived to older ages.
KEYWORDS: pectoral spines; age; otoliths; catfish; fishes |
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(2009a Murie, D.J., Parkyn, D.C., Nico, L.G., Herod, J.J. and Loftus, W.F. Age, differential growth and mortality rates in unexploited populations of Florida gar, an apex predator in the Florida Everglades. Fisheries Management and Ecology 16(4), 315-322. |
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ABSTRACT
Florida gar, Lepisosteus platyrhincus DeKay, were sampled in two canal systems in south Florida during 2000-2001 to estimate age, growth and mortality as part of the Everglades ecosystem-restoration effort. Tamiami (C-4) and L-31W canal systems had direct connections to natural wetlands of the Everglades and harboured large Florida gar populations. Of 476 fish aged, maximum ages were 19 and 10 years for females and males, respectively. Maximum sizes were also larger for females compared with males (817 vs 602 mm total length). Overall, female Florida gar from both Tamiami and L-31W were larger at age than males from L-31W that, in turn, were larger at any given age than males from Tamiami. Females also had lower rates of annual mortality (Z = 0.21) than males from L-31W (Z = 0.31) or males from Tamiami (Z = 0.54). As a large and long-lived apex predator in the Everglades, Florida gar may structure lower trophic levels. Regional- and sex-specific population parameters for Florida gar will contribute to the simulation models designed to evaluate Everglades restoration alternatives.
KEYWORDS: age validation; branchiostegal ray; Lepisosteus platyrhincus; sexual dimorphism lepisosteus-oculatus; southern everglades; white grunt; spotted gar; variability; demography; louisiana; coast; fish |
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(2009) Ozturk, Z., Katsenovich, Y., Tansel, B., Laha, S., Moos, L. and Allen, M. Enhancement of TCE Attenuation in Soils by Natural Amendments.
Soil & Sediment Contamination 18(1), 1-13. |
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ABSTRACT
The objective of this study was to identify low-cost natural amendments that could be used as carbon sources and sustain a bioactive zone to promote biodegradation of TCE in contaminated shallow groundwater. The natural amendments were compared based on their geophysical characteristics as well as TCE adsorption capacities. The amendments studied included low-cost natural and agricultural materials such as eucalyptus tree mulch, pine bark mulch, muck from the Florida Everglades, SRS wetland peat, commercial compost, and peat humus. These natural substrates have relatively high organic fractions that can retard the movement of TCE while serving as carbon sources. Batch sorption studies were conducted to determine the sorption and retardation characteristics of the amendments for TCE. The experimental results were analyzed in relation to the geophysical characteristics of the amendments and compared with those of natural soils.
KEYWORDS: Sorption; retardation factor; bioactive barriers; Freundlich model; TCE; soil amendments trichloroethylene |
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(2009) Pinto-Torres, E. and Koptur, S. Hanging by a coastal strand: breeding system of a federally endangered morning-glory of the south-eastern Florida coast, Jacquemontia reclinata. Annals of Botany 104(7), 1301-1311. |
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ABSTRACT
Coastal development has led to extensive habitat destruction and the near extinction of the beach clustervine, Jacquemontia reclinata (Convolvulaceae), an endangered, perennial vine endemic to dune and coastal strand communities in south-eastern Florida. We examined the breeding system of this rare species, and observed visitors to its flowers, as part of a larger effort to document its status and facilitate its recovery. Reproductively mature experimental plants were grown from seed collected from wild plants in two of the largest remaining populations. Controlled hand pollinations on potted plants were conducted to determine the level of compatibility of the species and to investigate compatibility within and between populations. Seeds from the hand pollinations were planted in soil, and they were monitored individually, recording time to seed germination (cotyledon emergence). Wild plants were observed in several of the remaining populations to determine which species visited the flowers. Hand pollination and seed planting experiments indicate that J. reclinata has a mixed mating system: flowers are able to set fruit with viable seeds with self-pollen, but outcross pollen produces significantly greater fruit and seed set than self-pollen (>= 50 % for crosses vs. < 25 % for self-pollinations). Visitors included a wide array of insect species, primarily of the orders Diptera, Hymenoptera and Lepidoptera. All visitors captured and examined carried J. reclinata pollen, and usually several other types of pollen. Remnant populations of beach clustervine will have greater reproductive success not only if floral visitor populations are maintained, but also if movement of either pollen or seed takes place between populations. Restoration efforts should include provisions for the establishment and maintenance of pollinator populations.
KEYWORDS: Jacquemontia reclinata; Convolvulaceae; endangered species; floral visitors; coastal dunes; pollination; reproductive biology; Florida; Caribbean; bees; butterflies plant-pollinator interactions; everglades national-park; lake-wales ridge; reproductive success; habitat fragmentation; population-size; seed set; rare plants; forest fragmentation; insect pollinators |
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(2009) Qian, Y., Miao, S.L., Gu, B. and Li, Y.C. Effects of Burn Temperature on Ash Nutrient Forms and Availability from Cattail (Typha domingensis) and Sawgrass (Cladium jamaicense) in the Florida Everglades. Journal of Environmental Quality 38(2), 451-464. |
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ABSTRACT
Plant ash derived from fire plays an important role in nutrient balance and cycling in ecosystems. Factors that determine the composition and availability of ash nutrients include fire intensity (burn temperature and duration), plant species, habitat nutrient enrichments and leaf type (live or dead leaf). We used laboratory simulation methods to evaluate temperature effects on nutrient composition and metals in the residual ash of sawgrass (Cladium jamaicense) and cattail (Typha domingensis), particularly on post-fire phosphorus (P) availability in plant ash. Live and dead leaf samples were collected from Water Conservation Area 2A in the northern Everglades along a soil P gradient, where prescribed fire may be used to accelerate recovery of this unique ecosystem. Significant decreases in total carbon and total nitrogen were detected with increasing fire temperature. Organic matter combustion was nearly complete at temperatures >= 450 degrees C. HCl-extractable P (average, 50% of total P in the ash) and NH4Cl-extractable P (average, 33% of total P in the ash) were the predominant P fractions for laboratory-burned ash. Although a low-intensity fire could induce ail elevation of P availability, an intense fire generally resulted in decreased water-soluble P. Significant differences in nutrient compositions were observed between species, habitat nutrient status, and leaf types. More labile inorganic P remained in sawgrass ash than in cattail ash; hence, sawgrass ash has a greater potential to release available P than cattail. Fire intensity affected plant ash nutrient composition, particularly P availability, and the effects varied with plant species and leaf type. Therefore, it is important to consider fire intensity and vegetation community when using a prescribed fire for ecosystem management.
KEYWORDS: prescribed fire; soil nutrients; pine forests; tahoe basin; peat fire; wildfire; phosphorus; dynamics; ecosystems; vegetation |
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(2009a) Qian, Y., Miao, S.L., Gu, B. and Li, Y.C. Estimation of Postfire Nutrient Loss in the Florida Everglades.
Journal of Environmental Quality 38(5), 1812-1820. |
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ABSTRACT
Postfire nutrient release into ecosystem via plant ash is critical to the understanding of fire impacts on the environment. Factors determining a postfire nutrient budget are prefire nutrient content in the combustible biomass, burn temperature, and the amount of combustible biomass. Our objective was to quantitatively describe the relationships between nutrient losses (or concentrations in ash) and burning temperature in laboratory controlled combustion and to further predict nutrient losses in field fire by applying predictive models established based on laboratory data. The percentage losses of total nitrogen (TN), total carbon (TC), and material mass showed a significant linear correlation with a slope close to 1, indicating that TN or TC loss occurred predominantly through volatilization during combustion. Data obtained in laboratory experiments suggest that the losses of TN, TC, as well as the ratio of ash total phosphorus (TP) concentration to leaf TP concentration have strong relationships with burning temperature and these relationships can be quantitatively described by nonlinear equations. The potential use of these nonlinear models relating nutrient loss (or concentration) to temperature in predicting nutrient concentrations in field ash appear to be promising. During a prescribed fire in the northern Everglades, 73.1% of TP was estimated to be retained in ash while 26.9% was lost to the atmosphere, agreeing well with the distribution of TP during previously reported wild fires. The use of predictive models would greatly reduce the cost associated with measuring field ash nutrient concentrations.
KEYWORDS: vegetation fires; soil nutrients; nitrogen; phosphorus; savanna; ash;
dynamics; wildfire; environment; ecosystems |
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(2009) Qualls, R.G., Sherwood, L.J. and Richardson, C.J. Effect of natural dissolved organic carbon on phosphate removal by ferric chloride and aluminum sulfate treatment of wetland waters. Water Resources Research 45( |
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ABSTRACT
The use of wetlands for the removal of excess N and P has become widespread. Some sensitive P-limited ecosystems, however, may require additional reductions in the concentration of P entering the system. It has been proposed that the treatment of wetlands through addition of ferric chloride or aluminum sulfate can augment the natural P removal mechanisms. However, high concentrations of natural dissolved organic matter may interfere with the removal of P by metal addition. We evaluated the doses of ferric chloride and aluminum sulfate necessary to reduce total P concentrations below 0.32 mu M (10 mu g/L) in water from the Northern Everglades, and we determined the effect of various concentrations (21, 38, and 60 mg/L) of natural dissolved organic carbon (DOC) on the removal of PO4 and total P. High concentrations of natural DOC inhibited both the short-term removal of PO4 and the longer-term removal of total P from the water column. Similar results were observed using 15 mu M citric acid in an experiment to determine whether citric acid could effectively mimic the inhibition of phosphorus removal associated with natural DOC. Stoichiometry of these experiments indicates that the mechanism of natural DOC interference was not complexation of the metal ions by the DOC; we hypothesize that it could be adsorption to the terminal hydroxyl groups on a polynuclear Fe or Al colloid, effectively blocking the adsorption sites from a phosphate molecule. Also, the ability of citric acid to mimic the inhibitory effects also suggests that the results of the study are broadly applicable to wetland and other waters with high natural organic acid concentrations.
KEYWORDS: nutrient-enrichment gradient; phosphorus removal; everglades; matter; oxidation; iron(iii); kinetics; project; model |
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(2009) Rand, G.M. and Schuler, L.J. Aquatic Risk Assessment of Metals in Sediment from South Florida Canals.
Soil & Sediment Contamination 18(2), 155-172. |
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ABSTRACT
A major watershed restoration effort is underway in south Florida, yet there are significant gaps in scientific information on exposure and risks of contaminants to its natural resources. We conducted a two-tier aquatic screening-level ecological risk assessment for metals that were monitored in sediment at 32 sampling sites in south Florida freshwater canals from 1990-2002. For tier 1, the chemicals (or metals) of potential ecological concern (COPECs) were identified as arsenic, cadmium, chromium, copper, lead, nickel and zinc based on their exceedences of Florida sediment quality guidelines at 10 sites. For tier 2, we used a probabilistic risk assessment method to compare distributions of predicted pore water exposure concentrations of seven metal COPECs with distributions of species response data from laboratory toxicity tests to quantify the likelihood of risk. The overlap of pore water concentrations (90th centile for exposure) for metal COPECs and the effects distributions for arthropods (10th centile of LC50s) and all species (10th centile of chronic NOECs) were used as a measure of potential acute and chronic risks, respectively. Arsenic (25%) in the Holey Land tracts, in Broward County north of Everglades National Park (ENP), and chromium (25%) in the C-111 freshwater system, at the east boundary of ENP, were the most frequently detected COPECs in sediment. Antimony (6%), zinc (6%) and lead (5%) were the least frequently detected COPECs in sediment. The 90th centile concentrations for bulk sediment were highest for zinc (at S-178) and lead (at S-176) in the C-111system. The 90th centile concentration for pore water exposure was highest for arsenic in the Holey Land tracts and lowest for cadmium and chromium. The estimated acute 10th centile concentration for effects was lowest for copper and arthropods. The probabilities of pore water exposures of copper exceeding the estimated acute 10th centile concentration from the species sensitivity distributions (SSD) of acute toxicity data (for arthropods) were 57 and 100% for copper at S-177 and S-178 in the C-111 system, respectively. The probability of pore water exposures of copper exceeding the estimated NOEC 10th centile concentration from the SSD of chronic toxicity data (for all species) was 93 and 100% for copper at S-177 and S-178, respectively. Uncertainties in exposure and effects analysis and risk characterization are identified and discussed. The study presents a straightforward approach to estimate exposure and potential risks of metals detected in sediment from south Florida canals.
KEYWORDS: Ecological risk assessment; metals; sediment; south Florida canals acid-volatile sulfide; ecological risk; quality criteria; technical basis; toxicity; cadmium; normalizations; environment; everglades; pesticides |
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(2009) Reed, N.P. Water and land management in Florida: Old challenges in the new economy. Speach at the UF, Jan.2009. |
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ABSTRACT (none)
KEYWORDS: Lake Okeechobee; Phosphorus, phosphorus deposits; sediment phosphorus; legacy phosphorus; |
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(2009) Regalado, C.M. and Ritter, A. A Soil Water Repellency Empirical Model. Vadose Zone Journal 8(1), 136-141. |
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ABSTRACT
The contact angle (alpha) varies nonlinearly with the soil water content (theta(g)) in water-repellent soils; however, a quantitative description of such a theta(g) dependence of alpha is still lacking. Using a dimensionality reduction technique such as dynamic factor analysis (DFA), we managed to identify two common patterns within a scattered data set of a vs. theta(g) measurements performed with the molarity of an ethanol droplet test in 16 soil samples. These two common patterns, derived from the DFA, provided the basis for calibrating a proposed empirical, three-parameter, linear model that described satisfactorily (R-2 > 0.89) an additional alpha-theta(g) data set used for model validation, from 40 soil samples with organic matter contents spanning from 110 to 650 g kg(-1). This offered both scaling and a flexible quantitative description of the soil water content dependence of water repellency.
KEYWORDS: agricultural area adjacent; everglades-national-park; dynamic factor-analysis; hydraulic-properties; common trends; contact-angle; sandy soils; time-series; parameters; field |
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(2009) Rehage, J.S., Dunlop, K.L. and Loftus, W.F. Antipredator Responses by Native Mosquitofish to Non-Native Cichlids: An Examination of the Role of Prey Naivete. Ethology 115(11), 1046-1056. |
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ABSTRACT
The strong impact of non-native predators in aquatic systems is thought to relate to the evolutionary naivete of prey. Due to isolation and limited dispersal, this naivete may be relatively high in freshwater systems. In this study, we tested this notion by examining the antipredator response of native mosquitofish, Gambusia holbrooki, to two non-native predators found in the Everglades, the African jewelfish, Hemichromis letourneuxi, and the Mayan cichlid, Cichlasoma urophthalmus. We manipulated prey naivete by using two mosquitofish populations that varied in their experience with the recent invader, the African jewelfish, but had similar levels of experience with the longer-established Mayan cichlid. Specifically, we tested these predictions: (1) predator hunting modes differed between the two predators, (2) predation rates would be higher by the novel jewelfish predator, (3) particularly on the naive population living where jewelfish have not invaded yet, (4) antipredator responses would be stronger to Mayan cichlids due to greater experience and weaker and/or ineffective to jewelfish, and (5) especially weakest by the naive population. We assayed prey and predator behavior, and prey mortality in lab aquaria where both predators and prey were free-ranging. Predator hunting modes and habitat domains differed, with jewelfish being more active search predators that used slightly higher parts of the water column and less of the habitat structure relative to Mayan cichlids. In disagreement with our predictions, predation rates were similar between the two predators, antipredator responses were stronger to African jewelfish (except for predator inspections), and there was no difference in response between jewelfish-savvy and jewelfish-naive populations. These results suggest that despite the novelty of introduced predators, prey may be able to respond appropriately if non-native predator archetypes are similar enough to those of native predators, if prey rely on general antipredator responses or predation cues, and/or show neophobic responses.
KEYWORDS: sensitive predator avoidance; guppy poecilia-reticulata; community
structure; gambusia-affinis; introduced predators; behavioral-response;
trinidadian guppy; alien predators; risk-assessment; american toad |
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(2009) Reuter, M., Piller, W.E., Harzhauser, M., Kroh, A. and Berning, B. A Fossil Everglades-Type Marl Prairie and Its Paleoenvironmental Significance. Palaios 24(11-12), 747-755. |
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ABSTRACT
Located at the interface between land and sea, marl prairies are sensitive to changes in water balance and useful recorders of climate and sea-level changes. Palustrine carbonate in marl prairies precipitates in temporary, barely flooded grasslands within microbial mats. Despite the special mode of carbonate production, descriptions of the sedimentary facies are exceptional and cursory because marl prairies are so far reported only from the recent of the Everglades (Florida, USA), where they produce an unspectacular calcite mud. We present a Pleistocene Everglades-type marl prairie from coastal Tanzania as the first fossil example. The unique preservation and high productivity (two times higher than in the Everglades) of the periphyton community in this marl prairie is due to increased calcification of coccoid and filamentous cyanobacteria. The excellent preservation allows us to characterize a marl prairie facies in great detail for the first time. Facies; analyses of the sediments reveal a transition from tidal to terrestrial settings that started at ca. 44 C-14 ka in response to eustatic sea-level fall and coastal tectonic uplift. The resultant drop of the groundwater table triggered the development of the marl prairie. The decline of the marl prairie was initiated at ca. 33 C-14 ka due to the onset of the Last Glacial Aridity Maximum in equatorial East Africa.
KEYWORDS: last glacial maximum; needle-fiber calcite; sea-level; lake; stromatolites; florida; classification; madagascar; travertine; carbonates |
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(2009) Richardson, T.C., Robison, C.P., Neubauer, C.P. and Hall, G.B. Hydrologic Signature Analysis of Select Organic Hydric Soil Indicators in Northeastern Florida. Soil Science Society of America Journal 73(3), 831-840. |
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ABSTRACT
The magnitude, duration, and return intervals of surface water flooding and dewatering of the landward extent of the hydric soil indicators muck (LM), histic epipedon (LHE), and Histosol (LH) were quantitatively defined, providing a better understanding of the hydrologic conditions maintaining these hydric soil indicators. Land surface elevations were determined for the LM, LHE, and LH at 16 lakes with long-term (30-60-yr) modeled or gauged hydrologic data. The probability of flooding and dewatering of the elevations of the LM, LHE, and LH were determined from frequency analysis of hydrologic data from each lake. The resulting hydrologic signatures for the LM, LHE, and LH are composed of magnitude and return interval of 1, 30, 90, 183, 274, and 365-d duration flooding and dewatering events. As an example, the LM, LHE, and LH were flooded for 30 continuous days with average annual probabilities of 42, 65, and 77%, respectively. As a second example, the LM, LHE, and LH were dewatered for 365 continuous days with average annual probabilities of 49, 24, and 16%, respectively. Probabilities of flooding and dewatering for the LM, LHE, and LH are presented for 1, 30, 90, 183, 274, and 365-d durations. Mean hydrologic signatures reduce variability and may be considered representative of each soil characteristic. Quantitatively defining the hydrology associated with the presence of the LM, LHE, and LH as well as other soil characteristics is essential for environmental protection, assessment of hydrologic impacts, wetlands restoration, wetlands creation, and other environmental management applications.
KEYWORDS: everglades marsh; peat soils; subsidence; nutrient; carbon |
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(2009) Ritter, A., Regalado, C.M. and Munoz-Carpena, R. Temporal Common Trends of Topsoil Water Dynamics in a Humid Subtropical Forest Watershed. Vadose Zone Journal 8(2), 437-449. |
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ABSTRACT
Research oriented toward understanding the hydrologic functioning of the relict "laurisilva" evergreen forests is scarce. This study focused on the analysis of temporal changes in soil water status under such humid subtropical stands and explored to what extent hydrologic fluxes may explain topsoil water dynamics. Hydrologic fluxes (potential evapotranspiration, canopy fog water dripping, and rainwater below the canopy) were computed for a 2-yr period using in situ micrometeorological measurements in the Garajonay National Park cloud forest (Canary Islands). Time domain reflectometry (TDR) data were used to characterize soil water status at 0.15- and 0.30-m depths in plots located at 1145, 1185, 1230, and 1270 m above sea level. The resulting eight daily TDR data sets were studied with dynamic factor analysis. The variability in the soil water statustime series was simplified and successfully described (coefficient of efficiency = 0.717) with a single temporal trend dynamic factor model (DFM), representing unexplained variability common to all plots and monitoring depths. Comparison of DFMs with and without explanatory variables (i.e., hydrologic fluxes) indicates that unexplained variability in the observed data was partially reduced by the information provided by the hydrologic fluxes. The rainfall contribution to the soil surface, and to a lesser extent forest potential evapotranspiration, were necessary variables for describing temporal changes in topsoil water status; however, dripping fog water was found to be a negligible contributor. Dynamic factor analysis proved to be useful for studying the variability in multivariate hydrologic time series without the need of a priori detailed information about the underlying mechanisms governing soil water dynamics.
KEYWORDS: agricultural area adjacent; everglades-national-park; canary-islands; laurel forest; spatial variability; time-series; rainfall interception; sap flow; model; stand |
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(2009) Rivero, R.G., Grunwald, S., Binford, M.W. and Osborne, T.Z. Integrating spectral indices into prediction models of soil phosphorus in a subtropical wetland. Remote Sensing of Environment 113(11), 2389-2402. |
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ABSTRACT
Remote sensing, in combination with multivariate geostatistical methods, has the potential to improve the prediction of soil properties at landscape scales. In the Everglades region, and particularly in Water Conservation Area 2A (WCA-2A), phosphorus enrichment has drawn a lot of attention and has led to an extensive documentation of different aspects of the degradation of the system. This study presents a hybrid geospatial modeling approach to predict soil total phosphorus (TP) using remotely-sensed data and ancillary landscape properties as supporting variables. Two remote sensors, Landsat 7 Enhanced Thematic Mapper (ETM)+ and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), were used to investigate relationships between spectral data and indices and soil TR A variation of a vegetation index (Normalized Difference Vegetation Index - NDVI green) was found to be the most effective in predicting floc TP values, due to its capacity to capture small variations in chlorophyll a that are associated to TP levels in periphyton, especially in aquatic/non-impacted areas. On the other hand, NDVI, a more traditionally used vegetation index, was still a good indicator of TP variability, particularly in the soil surface layer, due to its stronger relationship with impacted areas dominated by cattail (Typha domingensis Pers.). Findings from this study indicate that: a) remote sensing can play an important role in optimizing monitoring of environmental variables, particularly below-ground properties of floc and soils: b) because of limitations about the numbers and frequency of soil samples that can be taken, the combination of remote sensing and geostatistics could represent a non-invasive and cost-effective method to monitor soil nutrient status in complex wetland systems, and c) variations of traditional remote sensing indices such as NDVI can be used to better capture the spatial variability associated with soil and periphyton TP. (C) 2009 Elsevier Inc. All rights reserved.
KEYWORDS: GIS; Remote sensing; Soil; Biogeochemistry; Everglades; WCA-2A; Prediction models; Phosphorus; Wetlands; Ecology; Ecosystem restoration conservation area 2a; florida everglades; landsat-tm; northern everglades; satellite imagery; ecosystem processes; chlorophyll content; water quality; red edge; vegetation |
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(2009) Rodda, G.H., Jarnevich, C.S. and Reed, R.N. What parts of the US mainland are climatically suitable for invasive alien pythons spreading from Everglades National Park ? Biological Invasions 11(2), 241-252. |
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ABSTRACT
The Burmese Python (Python molurus bivittatus) is now well established in southern Florida and spreading northward. The factors likely to limit this spread are unknown, but presumably include climate or are correlated with climate. We compiled monthly rainfall and temperature statistics from 149 stations located near the edge of the python's native range in Asia (Pakistan east to China and south to Indonesia). The southern and eastern native range limits extend to saltwater, leaving unresolved the species' climatic tolerances in those areas. The northern and western limits are associated with cold and aridity respectively. We plotted mean monthly rainfall against mean monthly temperature for the 149 native range weather stations to identify the climate conditions inhabited by pythons in their native range, and mapped areas of the coterminous United States with the same climate today and projected for the year 2100. We accounted for both dry-season aestivation and winter hibernation (under two scenarios of hibernation duration). The potential distribution was relatively insensitive to choice of scenario for hibernation duration. US areas climatically matched at present ranged up the coasts and across the south from Delaware to Oregon, and included most of California, Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Florida, Georgia, and South and North Carolina. By the year 2100, projected areas of potential suitable climate extend northward beyond the current limit to include parts of the states of Washington, Colorado, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, New Jersey, and New York. Thus a substantial portion of the mainland US is potentially vulnerable to this ostensibly tropical invader.
KEYWORDS: Python molurus; Burmese Python; Geographic range; Invasive species; Florida Everglades; Climate matching; Temperature; Precipitation species distributions; introduction success; thermoregulation; prediction; avifauna; surfaces; climate; system; boidae |
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(2009) Rogevich, E.C., Hoang, T.C. and Rand, G.M. Effects of Sublethal Chronic Copper Exposure on the Growth and Reproductive Success of the Florida Apple Snail (Pomacea paludosa). Archives of Environmental Contamination and Toxicology 56(3), 450-458. |
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ABSTRACT
Florida apple snails (Pomacea paludosa) were exposed to three concentrations of copper (Cu), in water (8 mu g/L, 16 mu g/L, 24 mu g/L), for one generation to examine uptake and the effects on survival, growth, and reproduction of the F-0 generation and survival, growth, and whole body Cu of the F-1 generation. During a 9-month Cu exposure, apple snails exposed to 8-16 mu g/L Cu had high Cu accumulation (whole body, foot, viscera, and shell) and significantly reduced clutch production (8-16 mu g/L) and egg hatching (16 mu g/L). Apple snails exposed to the 24 mu g/L Cu had low survival and the treatment was therefore terminated. Concentrations of minerals (Na+, K+, Mg2+, Ca2+) in tissues were maintained regardless of Cu exposure, but the distribution of Cu in the body of snails differed, depending on exposure concentrations. Higher exposure concentrations resulted in a greater percentage of Cu accumulated in the viscera of the snail. Copper exposure to the F-0 generation did not affect the survival, growth, or whole body Cu concentrations in the F-1 generation. These finding are significant, given the importance of the Florida apple snail in the Everglades food chain. Changes in the abundance of apple snail populations, as a result of Cu exposure, could ultimately affect foraging success of predators.
KEYWORDS: rainbow-trout; daphnia-magna; salmo-gairdneri; metal sequestration; maternal transfer; water hardness; acute toxicity; trace-metals; short-term; pH |
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(2009) Ruehlmann, J. and Korschens, M. Calculating the Effect of Soil Organic Matter Concentration on Soil Bulk Density.
Soil Science Society of America Journal 73(3), 876-885. |
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ABSTRACT
Soil bulk density (rho(b)) is required to estimate, evaluate, and calculate many physical soil properties and processes and is essential to convert data from weight-based to volume- and area-related data. One of the dominating factors changing rho(b) is the soil's organic matter (SOM) concentration that alters the soil's compressibility; rho(b) is an important soil structure attribute. Currently, no parameter for characterizing soil compactness giving directly comparable values for all soils is available. Therefore, our aim was to develop a general approach to calculate the effect of SOM concentration on rho(b) that would be universally valid for soils different in their genesis, compaction, and type of land use. To describe the effect of SOM on rho(b) mathematically, we used a nonlinear regression model that was parameterized and validated using published data from experiments where SOM concentration was the main rho(b)-affecting factor (long-term fertilization and proctor experiments, wetlands, reclaimed soils, and volcanic soils). To obtain a standardized parameter describing the present compaction status of a site, we introduced the standardized bulk density s rho(b). Mathematically, s rho(b) is the intercept parameter of the used nonlinear regression model, and ranged between 0.7 and 2.1 Mg m(-3) and was very simple to estimate. Another distinct advantage of this novel concept is that only one representative pair of rho(b) and SOM has to be known to calculate s rho(b) as well as the bulk densities corresponding to other SOM concentrations measured on the site. This concept might also be helpful for identifying similar universal approaches to standardize the effect of other rho(b) affecting parameters (e.g., texture, soil depth, tillage regime), however, reassessed from the SOM effect.
KEYWORDS: physical-properties; nitrogen mineralization; chemical-properties; everglades soils; water-content; forest soils; carbon pools; proctor test; new-zealand; nt contents |
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(2009) Rutchey, K. and Godin, J. Determining an appropriate minimum mapping unit in vegetation mapping for ecosystem restoration: a case study from the Everglades, USA. Landscape Ecology 24(10), 1351-1362. |
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ABSTRACT
This paper documents the analyses that were conducted with regards to investigating an appropriate Minimum Mapping Unit (MMU) to be used to capture the potential changes in vegetation patterns for a 10,924 square km restoration project being conducted in south Florida, USA. Spatial landscape and class metrics that were shown to change predictably with increasing grain size were adopted from previous studies and applied to a multi-scale analysis. Specifically, this study examines the effects of changing grain size on landscape metrics, utilizing empirical data from a real landscape encompassing 234,913 ha of south Florida's Everglades. The objective was to identify critical thresholds within landscape metrics, which can be used to provide insight in determining an appropriate MMU for vegetation mapping. Results from this study demonstrate that vegetation heterogeneity will exhibit dissimilar patterns when investigating the loss of information within landscape and class metrics, as grain size is increased. These results also support previous findings that suggest that landscape metric "scalograms" (the response curves of landscape metrics to changing grain size), are more likely to be successful for linking landscape pattern to ecological processes as both pattern and process in ecological systems often operate on multiple scales. This study also incorporates an economic cost for various grain dependant vegetation mapping scales. A final selection of the 50 x 50 m grain size for mapping vegetation was based on this study's investigation of the "scalograms", the costs, and a composite best professional judgment of seasoned scientists having extensive experience within these ecosystems.
KEYWORDS: Minimum mapping unit; Scalograms; Thresholds
landscape pattern-analysis; spatial-resolution; changing scale; indexes |
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(2009) Saha, A.K., Sternberg, L. and Miralles-Wilhelm, F. Linking water sources with foliar nutrient status in upland plant communities in the Everglades National Park, USA. Ecohydrology 2(1), 42-54. |
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ABSTRACT
Plant communities within an ecosystem can vary in water source usage and nutrient availabilities, thus permitting community coexistence and diversity. We investigated the differences in water source utilization in two ecologically important upland plant communities: tropical hardwood hammocks and pine rocklands in the predominantly flooded Everglades ecosystem. We then linked these differences with their foliar nutrient levels and photosynthetic performance as measured by delta C-13 abundance. Based on a comparison of delta O-18 of plant stem waters with those of potential water sources (nutrient-poor groundwater and nutrient-rich water in organic litter referred to as soilwater), we observed that during the wet season hammock plants relied on soilwater while in the dry season they relied on groundwater. A similar seasonal shift was observed in pineland plants, however, groundwater constituted the major part of water uptake throughout the year except for late wet season. Consistent with the nutrient concentration of different water sources used in the two communities, hammocks had a greater annual mean foliar nitrogen and phosphorus concentration at the community level over pinelands as well as a higher leaf area index. High foliar N concentration in hammock plants was associated with eventual stomatal limitation of photosynthesis. Hammock species being intolerant of flooded soils are restricted to water uptake in the shallow unsaturated soil layer in the wet season, yet access the lowered groundwater table in the dry season. This dependence on a relatively narrow annual range of water table levels should be considered in South Florida water management and Everglades restoration.
KEYWORDS: everglades; hardwood hammocks; pine rocklands; stable isotopes; water sources; foliar nutrients; ecohydrology; flood-intolerant vegetation florida everglades; mineral-nutrition; carbon-isotope; leaf nitrogen; soil nutrient; tree islands; wild plants; rain-forest; vegetation; responses |
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(2009) Schofield, P.J., Loftus, W.F. and Fontaine, J.A. Salinity effects on behavioural response to hypoxia in the non-native Mayan cichlid Cichlasoma urophthalmus from Florida Everglades wetlands. Journal of Fish Biology 74(6), 1245-1258. |
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ABSTRACT
This study quantified the hypoxia tolerance of the Mayan cichlid Cichlasoma urophthalmus over a range of salinities. The species was very tolerant of hypoxia, using aquatic surface respiration (ASR) and buccal bubble holding when oxygen tensions dropped to < 20 mmHg (c. 1.0 mg l(-1)) and 6 mmHg, respectively. Salinity had little effect on the hypoxia tolerance of C. urophthalmus, except that bubble holding was more frequent at the higher salinities tested. Levels of aggression were greatest at the highest salinity. The ASR thresholds of C. urophthalmus were similar to native centrarchid sunfishes from the Everglades, however, aggression levels for C. uropthalmus were markedly higher.
KEYWORDS: aquatic surface respiration; Cichlidae; dissolved oxygen; ecophysiology; non-indigenous aquatic surface respiration; poecilia-reticulata; southern florida; reproductive-biology; metabolic-rate; growth; tolerance; oxygen; fish; temperature |
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(2009a) Schofield, P.J. and Nico, L.G. Salinity tolerance of non-native Asian swamp eels (Teleostei: Synbranchidae) in Florida, USA: comparison of three populations and implications for dispersal. Environmental Biology of Fishes 85(1), 51-59. |
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ABSTRACT
Three populations of non-native Asian swamp eels are established in peninsular Florida (USA), and comprise two different genetic lineages. To assess potential for these fish to penetrate estuarine habitats or use coastal waters as dispersal routes, we determined their salinity tolerances. Swamp eels from the three Florida populations were tested by gradual (chronic) salinity increases; additionally, individuals from the Miami population were tested by abrupt (acute) salinity increases. Results showed significant tolerance by all populations to mesohaline waters: Mean survival time at 14 ppt was 63 days. The Homestead population, a genetically distinct lineage, exhibited greater tolerance to higher salinity than Tampa and Miami populations. Acute experiments indicated that swamp eels were capable of tolerating abrupt shifts from 0 to 16 ppt, with little mortality over 10 days. The broad salinity tolerance demonstrated by these experiments provides evidence that swamp eels are physiologically capable of infiltrating estuarine environments and using coastal waters to invade new freshwater systems.
KEYWORDS: Ecophysiology; Monopterus; Nonindigenous species; Osmoregulation; Synbranchidae cichlasoma-urophthalmus; fish assemblages; everglades; waters |
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(2009) Scully, B.T., Nagata, R.T., Cherry, R.H., Trenholm, L.E. and Unruh, J.B. Registration of 'Pristine' Zoysiagrass. Journal of Plant Registrations 3(1), 65-68. |
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ABSTRACT
'Pristine' (Reg. No. CV-251, PI 652481) zoysiagrass [Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr.] was developed by the Florida Agricultural Experiment Station at the Everglades Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Belle Glade, FL, and initially approved for release in 2005. This zoysiagrass variety originated as an open-pollinated progeny from 'Emerald' and tested in Florida under experimental designation BA-305. Pristine was selected for improved agronomic and horticultural traits, including reduced production of seed heads, finer leaf texture, darker leaf color, and a faster rate of ground coverage and crop establishment in southern Florida. In comparison to the standard variety Emerald, Pristine exhibited a 46% average annual reduction in seed-head production and generally produced seed heads with an attenuated morphology. It also produced darker green leaves that were 21% shorter and 19% narrower than Emerald, which visually conferred upon Pristine a more refined canopy structure and texture. In addition, ground coverage and crop establishment was significantly faster for Pristine at two of the three test sites. Pristine is primarily intended for use in the Florida specialty market for zoysiagrass.
KEYWORDS: zoysiagrass, |
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(2009) Shenker, J.M. Effects of Climate Change on Fishery Species in Florida. In Sustainability 2009: The Next Horizon, (ed.),
AMER INST PHYSICS, Melville, 39-47. |
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ABSTRACT
Recreational and commercial fishery species in Florida and elsewhere are under serious stress from overfishing and many types of habitat and water quality degradation. Climate change may add to that stress by affecting an array of biological processes, although the range of some subtropical and tropical species may expand northward in the state. It is expected to trigger sea level rise and changes in hurricanes and precipitation levels in Florida and elsewhere. Perhaps the most significant impacts of climate change on fishery species will also associated with changes in seagrasses and mangroves that function as Essential Nursery Habitats. Seagrasses in estuarine and coastal areas are limited by water depth and light penetration. Increases in sea level and in precipitation-induced turbidity may restrict the extent of seagrass habitats and their role in fishery production. Expanded efforts to reduce nutrient and sediment loading into seagrass habitats may help minimize the potential loss of a valuable fish nursery habitat. Mangroves have also been affected by human activities, and are the subject of restoration efforts in many areas. Potential sea level rise may cause an expansion of mangrove habitats in the Everglades, at the expense of freshwater habitats. This potential tradeoff of habitats should be considered by the water flow and habitat restoration programs in the Everglades.
KEYWORDS: Climate Change; Fisheries; Mangroves; Seagrasses; Sea-Level Rise early-life-history; seagrass meadows; sciaenops-ocellatus; cynoscion-nebulosus; rookery bay; tampa bay; red drum; mangrove; populations; ecosystems |
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(2009) Simoneit, B.R.T., Xu, Y.P., Neto, R.R., Cloutier, J.B. and Jaffe, R. Photochemical alteration of 3-oxygenated triterpenoids: Implications for the origin of 3,4-seco-triterpenoids in sediments. Chemosphere 74(4), 543-550. |
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ABSTRACT
The reactivity of higher plant derived 3-oxy-triterpenoids to sunlight was investigated using a series of pure reference standards both under simulated and real solar exposure. The majority of the exposed compounds showed reactivity to light, particularly to simulated sunlight and among others generated seco-derivatives. While photochemical processes have been suggested for the formation of such compounds, their abundances in some sediments have often been assumed to be the result of diagenetic reworking of parent triterpenoids. Analyses of mangrove leaf waxes, an important known source of taraxerol in coastal ecosystems, showed the presence of the 3,4-seco-derivative dihydrolacunosic acid. which could represent an important biotic source for des-A-triterpenoid precursors to such sediments, and is unrelated to aquatic organic matter diagenesis.
KEYWORDS: seco-Triterpenoids; Taraxerol; Dihydrolacunosic acid; Everglades national park; Mangroves; Lipids organic-matter; surface sediments; early diagenesis; leaf wax; lake; geochemistry; terpenoids; transport; friedelin; marker |
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(2009) Smith, S.M., Leeds, J.A., McCormick, P.V., Garrett, P.B. and Darwish, M. Sawgrass (Cladium jamaicense) responses as early indicators of low-level phosphorus enrichment in the Florida Everglades. Wetlands Ecology and Management 17(4), 291-302. |
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ABSTRACT
Anthropogenic phosphorus (P) inputs to the Florida Everglades have produced dramatic changes in the wetland vegetation of this otherwise oligotrophic system. While the proliferation of undesirable plant species in response to enrichment has been well documented, nutrient-related changes in the physiological and morphological attributes of existing vegetation, prior to any shifts in species composition or changes in the spatial extent of certain taxa, have yet to be adequately characterized. In this experiment, three sawgrass-dominated areas were enriched with P for 3 years at rates of 0.4 g P/m(2)/year (HP), 0.1 g P/m(2)/year (LP), or 0 g P/m(2)/year (controls) to assess potential impacts of P-enriched discharges from stormwater treatment areas into the Everglades. Elevated concentrations of TP in rhizomes and leaves and reduced ratios of leaf N:P were detected in HP plants within similar to 1 year at most sites. Live leaf densities, plant heights, and plant densities of the HP groups were generally higher than LP and control groups after 2 years, a pattern that was evident even after major fire events. Total aboveground biomass was significantly elevated in both HP and LP treatments at two of the three sites after 3 years. No change in species composition was detected during the study. Planned hydrologic restoration measures will increase P loads into parts of the Everglades that have not previously experienced anthropogenic P enrichment. Monitoring native vegetation such as sawgrass can be a sensitive and relatively robust means of detecting unintended P enrichment in these areas prior to shifts in vegetation community composition or changes in area cover of key species.
KEYWORDS: Ecological indicators; Everglades; Phosphorus; Plant morphology;
Sawgrass; Vegetation community; Wetlands
nutrient enrichment; restoration strategies; plant-communities;
delaware bay; wetland; marsh; nitrogen; fire; usa; additions |
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(2009a) Smith, T.J., Anderson, G.H., Balentine, K., Tiling, G., Ward, G.A. and Whelan, K.R.T. Cumulative Impacts of Hurricanes on Florida Mangrove Ecosystems: Sediment Deposition, Storm Surges and Vegetation. Wetlands 29(1), 24-34. |
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ABSTRACT
Hurricanes have shaped the structure of mangrove forests ill the Everglades via wind damage, storm Surges and sediment deposition. Immediate effects include changes to stern size-frequency distributions and to species relative abundance and density. Long-term impacts to mangroves are poorly Understood at present. We examine impacts of Hurricane Wilma oil mangroves and compare the results to findings from three previous storms (Labor Day, Donna, Andrew). Surges during Wilma destroyed 1,250 ha of mangroves and set back recovery that started following Andrew. Data from permanent plots affected by Andrew and Wilma showed no differences among species or between hurricanes for % stern mortality or % basal area lost. Hurricane damage was related to hydro-geomorphic type of forest. Basin mangroves suffered significantly more damage than riverine or island mangroves. The hurricane by forest type interaction was highly significant. Andrew did slightly more damage to island mangroves. Wilma did significantly more damage to basin forests. This is most likely a result of the larger and more spatially extensive storm surge produced by Wilma. Forest damage was not related to amount. of sediment deposited. Analyses of reports from Donna and the Labor Day storm indicate that sonic sites have recovered following catastrophic disturbance. Other sites have been permanently converted into a different ecosystem, namely intertidal mudflats. Our results indicate that mangroves are not in a steady state as has been recently claimed.
KEYWORDS: basal area; ecosystem change; Hurricane Andrew; Hurricane Donna; Hurricane Wilma; Labor Day Storm; mortality; persistence; stability; steady state bay; forest; reanalysis; everglades; recovery; season; damage; level; state; model |
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(2009) Stevens, J.T. and Beckage, B. Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper (Schinus terebinthifolius).
New Phytologist 184(2), 365-375. |
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ABSTRACT
Fire disturbance can mediate the invasion of ecological communities by nonnative species. Nonnative plants that modify existing fire regimes may initiate a positive feedback that can facilitate their continued invasion. Fire-sensitive plants may successfully invade pyrogenic landscapes if they can inhibit fire in the landscape. Here, we investigated whether the invasive shrub Brazilian pepper (Schinus terebinthifolius) can initiate a fire-suppression feedback in a fire-dependent pine savanna ecosystem in the southeastern USA. We found that prescribed burns caused significant (30-45%) mortality of Brazilian pepper at low densities and that savannas with more frequent fires contained less Brazilian pepper. However, high densities of Brazilian pepper reduced fire temperature by up to 200 degrees C, and experienced as much as 80% lower mortality. A cellular automaton model was used to demonstrate that frequent fire may control low-density populations, but that Brazilian pepper may reach a sufficient density during fire-free periods to initiate a positive feedback that reduces the frequency of fire and converts the savanna to an invasive-dominated forest.
KEYWORDS: Brazilian pepper; cellular automata; disturbance regime; Everglades; fire suppression; pine rockland savanna everglades-national-park; exotic plant invasion; biological invasions; prescribed fire; south florida; regimes; disturbance; usa; communities; ecosystems |
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(2009) Thomas, C.R., Miao, S.L. and Sindhoj, E. Environmental Factors Affecting Temporal and Spatial Patterns of Soil Redox Potential in Florida Everglades Wetlands. Wetlands 29(4), 1133-1145. |
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ABSTRACT
Redox potential impacts wetland ecosystem functions and processes. This Study assessed the temporal and spatial patterns and variability of soil redox potential in relation to: 1) hydrology, 2) soil phosphorus (P) enrichment, and 3) dominant vegetation community in an Everglades wetland. Probes installed for 2-week periods required 8 to 10 days for measurements to stabilize, considerably longer than what has been reported in the literature. Probes installed for I year yielded more stable measurements and were more useful for ecological analysis. Redox temporal patterns were related to water table fluctuation with redox increasing exponentially as the water table decreased front 5 cm above marsh surface. Large-scale spatial redox patterns were found in relation to P enrichment with higher average redox Occurring in moderately-enriched regions (-134 mV) than in highly-enriched or unenriched regions (-185 mV for both). Vegetation community had no effect on redox status. Water level change was the primary driver of small-scale spatial variability (soil profile) with redox measurements varying more near the marsh surface during low water conditions. The degree of redox response to water table fluctuation decreased with increasing soil depth. These findings are important in understanding how altering hydrology can affect soil processes and ecosystem function.
KEYWORDS: cattail; microbial processes; phosphorus; sawgrass; scale; water depth cladium-jamaicense; typha-domingensis; marsh; decomposition; variability; dynamics; growth; pH |
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(2009) Tipping, P.W., Martin, M.R., Nimmo, K.R., Pierce, R.M., Smart, M.D., White, E., Madeira, P.T. and Center, T.D. Invasion of a West Everglades wetland by Melaleuca quinquenervia countered by classical biological control. Biological Control 48(1), 73-78. |
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ABSTRACT
The population dynamics of Melaleuca quinquenervia were monitored over a 5-year period in a cypresspine wetland while subjected to two levels of herbivory. The trees had been recruited during 1998-1999 after a destructive crown fire. Half of 26 experimental plots were sprayed every 4-6 weeks with an insecticide to reduce herbivory by the biological control agents Oxyops vitiosa and Boreioglycaspis melaleucae. After only 1-year melaleuca density increased by 26% in sprayed plots and by 7% in unsprayed plots. However, over the entire 5-year period melaleuca density increased in sprayed plots by 0.1% while decreasing by 47.9% in unsprayed plots when compared to initial densities. Annual mortality of melaleuca never exceeded 6% in any year in sprayed plots but ranged from 11% to 25% in unsprayed plots. There was a significant year by treatment interaction indicating the importance of the environment on tree mortality. Limited seed production occurred on sprayed trees but never on unsprayed trees. Mean tree height increased by 19.6% in sprayed plots while declining by 30.6% in unsprayed plots. Coverage by native vegetation did not increase with decreasing melaleuca density. This is the first study with controls that quantifies the population level regulation of melaleuca by introduced biological control agents and corroborates other correlative studies that documented significant changes in melaleuca communities after the introduction and establishment of biological control agents.
KEYWORDS: Weed biological control; Melaleuca; Florida Everglades; Community level impacts oxyops-vitiosa coleoptera; enemy release hypothesis; control agent; south florida; field colonization; australian weevil; cav. blake,s.t.; host-range; acephate; plant |
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(2009) Tonini, M., Tuia, D. and Ratle, F. Detection of clusters using space-time scan statistics. International Journal of Wildland Fire 18(7), 830-836. |
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ABSTRACT
This paper aims at detecting spatio-temporal clustering in fire sequences using space-time scan statistics, a powerful statistical framework for the analysis of point processes. The methodology is applied to active fire detection in the state of Florida (US) identified by MODIS (Moderate Resolution Imaging Spectroradiometer) during the period 2003-06. Results of the present study show that statistically significant clusters can be detected and localized in specific areas and periods of the year. Three out of the five most likely clusters detected for the entire frame period are localized in the north of the state, and they cover forest areas; the other two clusters cover a large zone in the south, corresponding to agricultural land and the prairies in the Everglades. In order to analyze if the wildfires recur each year during the same period, the analyses have been performed separately for the 4 years: it emerges that clusters of forest fires are more frequent in hot seasons (spring and summer), while in the southern areas, they are widely present during the whole year. The recognition of overdensities of events and the ability to locate them in space and in time can help in supporting fire management and focussing on prevention measures.
KEYWORDS: Florida; MODIS active fires forest-fire sequences; united-states; patterns; disease; points; cancer; modis |
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(2009) Toth, L.A. and Galloway, J.P. Clonal Expansion of Cattail (Typha domingensis) in Everglades Stormwater Treatment Areas: Implications for Alternative Management Strategies. Journal of Aquatic Plant Management 47(151-155. |
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ABSTRACT (n/a)
KEYWORDS: submerged aquatic vegetation; northern everglades; cladium-jamaicense; phosphorus removal; florida everglades; nutrient-removal; wetland; restoration; ecosystem; growth |
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(2009) Trexler, J.C. and Goss, C.W. Aquatic fauna as indicators for Everglades restoration: Applying dynamic targets in assessments.
Ecological Indicators 9(S108-S119. |
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ABSTRACT
A major goal of the Comprehensive Everglades Restoration Plan (CERP) is to recover historical (pre-drainage) wading bird rookeries and reverse marked decreases in wading bird nesting success in Everglades National Park. To assess efforts to restore wading birds, a trophic hypothesis was developed that proposes seasonal concentrations of small-fish and crustaceans (i.e., wading bird prey) were a key factor to historical wading bird success. Drainage of the Everglades has diminished these seasonal concentrations, leading to a decline in wading bird nesting and displacing them from their historical nesting locations. The trophic hypothesis predicts that restoring historical hydrological patterns to pre-drainage conditions will recover the timing and location of seasonally concentrated prey, ultimately restoring wading bird nesting and foraging to the southern Everglades. We identified a set of indicators using small-fish and crustaceans that can be predicted from hydrological targets and used to assess management success in regaining suitable wading bird foraging habitat. Small-fish and crustaceans are key components of the Everglades food web and are sensitive to hydrological management, track hydrological history with little time lag, and can be studied at the landscape scale. The seasonal hydrological variation of the Everglades that creates prey concentrations presents a challenge to interpreting monitoring data. To account for the variable hydrology of the Everglades in our assessment, we developed dynamic hydrological targets that respond to changes in prevailing regional rainfall. We also derived statistical relationships between density and hydrological drivers for species representing four different life-history responses to drought. Finally, we use these statistical relationships and hydrological targets to set restoration targets for prey density. We also describe a report-card methodology to communicate the results of model-based assessments for communication to a broad audience.
KEYWORDS: Crayfish; Ecological targets; Fish; Life history; Statistical models; Status and trends florida-everglades; community structure; sampling characteristics; spatiotemporal patterns; oligotrophic wetland; phosphorus gradient; periphyton mats; fishes; ecosystem; marshes |
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(2009) Troxler, T.G. and Richards, J.H. delta C-13, delta N-15, carbon, nitrogen and phosphorus as indicators of plant ecophysiology and organic matter pathways in Everglades deep slough, Florida, USA. Aquatic Botany 91(3), 157-165. |
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ABSTRACT
Historically, the Florida Everglades was characterized by a corrugated landscape of shorter hydroperiod, elevated sawgrass (Cladium jamaicense) ridges and longer hydroperiod, deep water slough communities. Drainage and compartmentalization of the Everglades have fundamentally altered this pattern, and sawgrass ridge communities have expanded at the expense of deep water slough communities throughout much of the landscape. In this study we provide a simple isotopic and nutrient characterization of major components of the slough ecosystem to elucidate physiological and nutrient differences among species and to suggest pathways for organic matter decomposition that contribute to peat development in deep water sloughs. We examined carbon (C) and nitrogen (N) isotopes and C, N and phosphorus (P) concentrations of the floating-leaved macrophytes Nymphaea odorata and Nymphoides aquatica, the emergent macrophyte Eleocharis elongata, and the submerged species Utricularia foliosa and Utricularia purpurea, as well as soil and flocculent material from the southern Water Conservation Area 3-A. Flocculent material and soils had the highest N content (4.5 +/- 0.2%) and U.foliosa and N. odorata had the highest P content (0.13 +/- 0.01% to 0.12 +/- 0.01%). The range for delta N-15 average +/- SE values was 5.81 +/- 0.29 parts per thousand (U.foliosa) to -1.84 +/- 0.63 parts per thousand (N. odorata), while the range for delta C-13 values was -23.83 +/- 0.12 parts per thousand (N. odorata) to -29.28 +/- 0.34 parts per thousand, (U. purpurea). Differences of up to 10 parts per thousand in C isotopic values of U. foliosa and N. odorata suggest fundamental physiological differences between these species. Along a degradation continuum, enrichment of C-13 and N-15 and extent of decomposition was negatively related to phosphorus concentrations. A two end-member C-13 mixing model suggested that Utricularia species were the primary organic source for flocculent materials, whereas organic matter derived from root decomposition of N. odorata contributed to the progressively enriched delta C-13 values found with depth in soils. These results illustrate the fundamentally important roles of Nymphaea and Utricularia species in ecosystem dynamics of deep water sloughs.
KEYWORDS: Isotope; N:P ratio; Nymphaea odorata; Nymphoides aquatica; Eleocharis elongata; Utricularia; Flocculent; Decomposition; Peat; Landscape geomorphology aquatic macrophytes; foliar uptake; water column; landscape; gradient; detritus; isotope; leaves; soil; fractionation |
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(2009) Utescher, T., Ivanov, D., Harzhauser, M., Bozukov, V., Ashraf, A.R., Rolf, C., Urbat, M. and Mosbrugger, V. Cyclic climate and vegetation change in the late Miocene of Western Bulgaria. Palaeogeography Palaeoclimatology Palaeoecology 272(1-2), 99-114. |
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ABSTRACT
A late Miocene paludal to lacustrine sequence from a carbonate basin in NW Bulgaria (Staniantsi Basin) is analysed displaying up to 27 rhythmically bedded sedimentary cycles. In the lower part of the sequence, the cycles consist of alternating autochthonous brown coal and marls containing diverse mollusc assemblages. The upper part of the sequence is characterized by alternating dark to light grey clays and calcareous silts. A palynomorph record comprising 163 samples is analysed by statistical means to reconstruct vegetation changes. The Coexistence Approach is used to calculate quantitative palaeoclimate records for 6 parameters. The studied section displays hierarchical cyclicity patterns. Longer-term cycles possibly related to eccentricity (period similar to 100 kyr) are present in the palynomorph record and show climate changes of warmer/wetter and cooler/drier periods in combination with frequency oscillations of thermophilous elements. Short-term cycles most probably related to precession (period similar to 21.7 kyr) are expressed by alternations of brown coal and marl/shell beds and show cyclic change in peat-forming vegetation related to oscillations of the groundwater level. As a triggering mechanism, wetter/warmer and drier/cooler climate phases related to orbital precession are probable. In addition, sections sampled at high resolution display small scale climate and vegetational variability. As is shown by the analysis ferns were an important component of the peat-forming vegetation, while outside the mire, a wetland vegetation consisting of pioneers and a mixed mesophytic forest with evergreen shrubs existed. An oligo- to mesotrophic slightly alkaline lake became repeatedly established with a diverse mollusc fauna and a dense hydrophytic vegetation with characean meadows. In the upper part of the section, a spreading of herbaceous vegetation is observed, also known from other contemporaneaous palynomorph records in Bulgaria and surrounding areas. The increase of Asteraceae in the upper part of the section, combined with a marked decrease in woody taxa, points to an opening of habitats and a decrease in mean annual precipitation. This trend is paralleled by the mollusc fauna which yields several terrestrial, partly xerophilous taxa.
KEYWORDS: Bulgaria; Late Miocene; Palynology; Palaeoclimate; Vegetation; Cyclicity ptolemais nw greece; pannonian basin; pollen record; plant fossils; servia basin; pliocene; paratethys; everglades; sediments; reconstruction |
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(2009) Variano, E.A., Ho, D.T., Engel, V.C., Schmieder, P.J. and Reid, M.C. Flow and mixing dynamics in a patterned wetland: Kilometer-scale tracer releases in the Everglades. Water Resources Research 45( |
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ABSTRACT
Surface water flow dynamics in the Florida Everglades were investigated using sulfur hexafluoride tracer releases, from which advection and dispersion were determined. Several sites were studied, each characterized by different vegetation patterns and proximity to hydrologic control structures. The measured flow directions suggest that basin-scale forcing from water management structures and operations can override the effects of local landscape features in guiding the flow. Management effects were particularly evident in two regions where the historic, natural landscape patterning has degraded. The large spatial scale over which tracer data were collected allows the dispersion rate to be determined at unprecedented spatial scales. These measurements showed much larger dispersion coefficients than reported by previous experiments at smaller scales. This finding and a measurement of the drag due to vegetation over large scales are of interest to Everglades water resource managers concerned with the transport of sediment and biologically active solutes such as phosphorus.
KEYWORDS: water gas-exchange; longitudinal dispersion; emergent vegetation; florida everglades; solute transport; turbulence; model; landscape; canopies; velocity |
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(2009) Volety, A.K., Savarese, M., Tolley, S.G., Arnold, W.S., Sime, P., Goodman, P., Chamberlain, R.H. and Doering, P.H. Eastern oysters (Crassostrea virginica) as an indicator for restoration of Everglades Ecosystems. Ecological Indicators 9(S120-S136. |
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ABSTRACT
The Comprehensive Everglades Restoration Plan (CERP) attempts to restore hydrology in the Northern and Southern Estuaries of Florida. Reefs of the Eastern oyster Crassostrea virginica are a dominant feature of the estuaries along the Southwest Florida coast. Oysters are benthic, sessile, filter-feeding organisms that provide ecosystem services by filtering the water column and providing food, shelter and habitat for associated organisms. As such, the species is an excellent sentinel organism for examining the impacts of restoration on estuarine ecosystems. The implementation of CERP attempts to improve: the hydrology and spatial and structural characteristics of oyster reefs, the recruitment and survivorship of C. virginica, and the reef-associated communities of organisms. This project links biological responses and environmental conditions relative to hydrological changes as a means of assessing positive or negative trends in oyster responses and population trends. Using oyster responses, we have developed a communication tool (i.e., Stoplight Report Card) based on CERP performance measures that can distinguish between responses to restoration and natural patterns. The Stoplight Report Card system is a communication tool that uses Monitoring and Assessment Program (MAP) performance measures to grade an estuary's response to changes brought about by anthropogenic input or restoration activities. The Stoplight Report Card consists of both a suitability index score for each organism metric as well as a trend score (- decreasing trend, +/- no change in trend, and + increasing trend). Based on these two measures, a component score (e.g., living density) is calculated by averaging the suitability index score and the trend score. The final index score is obtained by taking the geometric score of each component, which is then translated into a stoplight color for success (green), caution (yellow), or failure (red). Based on the data available for oyster populations and the responses of oysters in the Caloosahatchee Estuary, the system is currently at stage "caution." This communication tool instantly conveys the status of the indicator and the suitability, while trend curves provide information on progress towards reaching a target. Furthermore, the tool has the advantage of being able to be applied regionally, by species, and collectively, in concert with other species, system-wide.
KEYWORDS: Ecological indicators; Everglades Restoration; Oysters; Water quality; Ecosystem health conceptual ecological model; perkinsus-marinus disease; suitability index model; gulf-of-mexico; caloosahatchee-estuary; southwest florida; american oyster; habitat use; salinity; river |
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(2009) Wang, H.Q., Walclon, M.G., Meselhe, E.A., Arceneaux, J.C., Chen, C.F. and Harwell, M.C. Surface Water Sulfate Dynamics in the Northern Florida Everglades. Journal of Environmental Quality 38(2), 734-741. |
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ABSTRACT
Sulfate contamination has been identified as a serious environmental issue in the Everglades ecosystem. However, it has received less attention compared to P enrichment. Sulfate enters the Arthur R. Marshall Loxahatchee National Wildlife Refuge (Refuge), a remnant of the historic Everglades, in pumped stormwater discharges with a mean concentration of approximately 50 mg L-1, and marsh interior concentrations at times fall below a detection limit of 0.1 mg L-1. In this research, we developed a sulfate mass balance model to examine the response of surface water sulfate in the Refuge to changes in sulfate loading and hydrological processes. Meanwhile, sulfate removal resulting from microbial sulfate reduction in the underlying sediments of the marsh was estimated from the apparent settling coefficients incorporated in the model. The model has been calibrated and validated using long-term monitoring data (1995-2006). Statistical analysis indicated that our model is capable of capturing the spatial and temporal variations in surface water sulfate concentrations across the Refuge. This modeling work emphasizes the fact that sulfate from canal discharge is impacting even the interior portions of the Refuge, supporting work by other researchers. In addition, model simulations suggest a condition of sulfate in excess of requirement for microbial sulfate reduction in the Refuge.
KEYWORDS: reduction; wetlands; sulfur; phosphorus; sediments; model; lake; usa |
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(2009) Wardwell, D. and Allen, C.R. Variability in Population Abundance is Associated with Thresholds between Scaling Regimes.
Ecology and Society 14(2), 42 (online). |
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ABSTRACT
Discontinuous structure in landscapes may result in discontinuous, aggregated species bodymass patterns, reflecting the scales of structure available to animal communities within a landscape. The edges of these body-mass aggregations reflect transitions between available scales of landscape structure. Such transitions, or scale breaks, are theoretically associated with increased biological variability. We hypothesized that variability in population abundance is greater in animal species near the edge of bodymass aggregations than it is in species that are situated in the interior of body-mass aggregations. We tested this hypothesis by examining both temporal and spatial variability in the abundance of species in the bird community of the Florida Everglades sub-ecoregion, USA. Analyses of both temporal and spatial variability in population abundance supported our hypothesis. Our results indicate that variability within complex systems may be non-random, and is heightened where transitions in scales of process and structure occur. This is the first explicit test of the hypothetical relationship between increased population variability and scale breaks.
KEYWORDS: body mass; Breeding Bird Survey; Everglades; phase transition; scale; textural discontinuity hypothesis |
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(2009) Webb, J., Miao, S.L. and Zhang, X.H. Factors and mechanisms influencing seed germination in a wetland plant sawgrass.
Plant Growth Regulation 57(3), 243-250. |
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ABSTRACT
Sawgrass (Cladium jamaicense) is the predominant plant and vegetation community in the Florida Everglades. Germination of sawgrass seeds in the laboratory or nursery has been difficult and problematic, yet little is known about the physiological mechanistic regulation of the sawgrass seed germination process. In the present study, we examined the factors and mechanisms that influence sawgrass seed germination. We found that removal of seed husk and bracts, pre-soaking with bleach (hypochlorite), breaking the seed coat, or combinations of these treatments promoted the rate and success of germination, whereas presence of seed-encasing structures or treatment with husk/bract extract inhibited germination. We further detected the presence of abscisic acid (ABA) in the husk and bract. Experiments with ABA and gibberellin biosynthesis inhibitors fluridone and tetcyclacis suggested that ABA already presented in the pre-imbibed seeds, and not derived through post-dormancy de novo synthesis, contributed to the inhibition of seed germination. Examination of bleach and mechanical treatments indicated the physical barrier presented by the seed-encasing structures provided additional mechanism for the long-term delay of seed germination. Based on the results of this study and others, we discussed the implications of sawgrass seed dormancy and germination in relation to its natural habitat and proposed a hypothesis that the protracted seed dormancy in sawgrass offered an adaptive advantage in the pre-anthropogenic Everglades environment, but may become a liability in the current man-managed Everglades water system.
KEYWORDS: Sawgrass (Cladium jamaicense); Cattail (Typha domingensis); Husks/bracts; Seed germination; Abscisic acid (ABA); Gibberellins; Wetland plant; Florida Everglades cladium-jamaicense crantz; abscisic-acid; dormancy; everglades; metabolism |
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(2009) Whelan, K.R.T., Smith, T.J., Anderson, G.H. and Ouellette, M.L. Hurricane Wilma's Impact on Overall Soil Elevation and Zones within the Soil Profile in a Mangrove Forest. Wetlands 29(1), 16-23. |
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ABSTRACT
Soil elevation affects tidal inundation period, inundation frequency, and overall hydroperiod, all of which are important ecological factors affecting species recruitment composition, and survival in wetlands. Hurricanes can dramatically affect a site's soil elevation. We assessed the impact of Hurricane Wilma (2005) on soil elevation at a mangrove forest location along the Shark River in Everglades National Park, Florida, USA. Using multiple depth surface elevation tables (SETs) and marker horizons we measured soil accretion, erosion, and soil elevation. We partitioned the effect of Hurricane Wilma's storm deposit into four constituent soil zones: surface accretion) zone, shallow zone (0-0.35 m). middle zone (0.35-4 m), and deep zone (4-6 m). We report expansion and contraction of each soil zone. Hurricane Wilma deposited 37.0 (+/- 3.0 SE) mm of material: however, the absolute soil elevation change was + 42.8 mm due to expansion in the shallow soil zone. One year post-hurricane, the soil profile had lost 10.0 mm in soil elevation, with 8.5 mm of the loss due to erosion. The remaining soil elevation loss was due to compaction from shallow subsidence. We found prolific growth of new fine rootlets (209 +/- 34 SE g m(-2)) in the storm deposited material suggesting that deposits may become more stable in the near future (i.e., erosion rate will decrease). Surficial erosion and belowground processes both played an important role ill determining the overall soil elevation. Expansion and contraction ill the shallow soil zone may be due to hydrology. and in the middle and bottom soil zones due 10 shallow subsidence. Findings thus far indicate that soil elevation has made substantial gains compared to site specific relative sea-level rise, but data trends suggest that below-round processes, which differ by soil zone. may come to dominate the long term ecological impact of storm deposit.
KEYWORDS: contraction; expansion; Florida; peat; soil swell; subsidence; wetland high-precision measurements; wetland sediment elevation; surface elevation; florida; storm; islands; erosion; growth; table; rise |
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(2009) Williams, M.R. and Savage, H.M. Identification of Culex (Melanoconion) Species of the United States Using Female Cibarial Armature (Diptera: Culicidae). Journal of Medical Entomology 46(4), 745-752. |
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ABSTRACT
Species within the subgenus Culex (Melanoconion) Theobald are the primary enzootic vectors of viruses in the Venezuelan equine encephalitis complex including Everglades virus, and probable enzootic vectors of eastern equine encephalitis and West Nile viruses. Adult females of this subgenus are often difficult or impossible to identify to species based on external morphological characters. The use of female cibarial armature allows for the identification of field-collected adult female specimens of Culex (Melanoconion). The cibarial armatures are described and illustrated for all species front the United States and a key to species using this character is presented.
KEYWORDS: Culex (Melanoconion); cibarial armature; mosquito identification equine encephalomyelitis virus; central alabama; mosquitos |
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(2009) Wilsdon, W.K. and Richards, J.H. Variation in southern Florida and Bahamian Aletris (Nartheciaceae): morphology, phenology, and putative hybridization. Journal of the Torrey Botanical Society 136(2), 192-202. |
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ABSTRACT
Variation in southern Florida and Bahamian Aletris (Nartheciaceae): morphology, phenology, and putative hybridization. J. Torrey Bot. Soc. 136: 192-202. 2009-Two species of Aletris occur in southern Florida: the yellow-flowered A. lutea and white-flowered A. bracteata. It is uncertain whether A. bracteata found in southern Florida is a distinct species or a variant of one of the other species found in the southeastern United States. Plants with intermediate flower colors are present in southern Florida populations, indicating environmental and/or genetic variation of A. bracteata or hybridization between A. bracteata and A. lutea. The morphology, phenology and habitat of flower color morphs of Aletris were examined in four populations of A. lutea and six populations of A. bracteata in southern Florida, as well as five populations of A. bracteata on Andros Island, Bahamas, the type locality for A. bracteata. Plants with intermediate flower color dominated five of the six A. bracteata populations in southern Florida. These plants were morphologically most similar to A. bracteata from the Bahamas. Although A. bracteata and A. lutea differed in flowering phenology in southern Florida, flowering times in some populations overlapped in March, allowing for hybridization. Florida A. bracteata plants were self-compatible and autogamous, but seed set for open-pollinated plants was higher than for self-pollinated or autogamously-pollinated plants. We hypothesize that A. bracteata and A. lutea are distinct species but that some hybridization between them has occurred in southern Florida.
KEYWORDS: Aletris bracteata; Aletris lutea; Andros Island; Bahamas; Big Cypress National Preserve; Everglades National Park; flower color variation; hybridization; phenology pollination |
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(2009) Wollenberg, J.L. and Peters, S.C. Mercury emission from a temperate lake during autumn turnover.
Science of the Total Environment 407(8), 2909-2918. |
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ABSTRACT
Lakes in temperate regions stratify during summer and winter months, creating distinct layers of water differentiated by their physical and chemical characteristics. When lakes mix in autumn and spring, mercury cycling may be affected by the chemical changes that occur during mixing. Sampling was conducted in Lake Lacawac, Eastern Pennsylvania, USA, throughout the autumn of 2007 to characterize changes in emission of gaseous elemental mercury (He) from the lake surface and dissolved mercury profiles in the water column during mixing. Water chemistry and weather parameters were also measured, including dissolved organic carbon (DOC), iron, and solar radiation which have been shown to interact with mercury species. Results indicate that emission of He from the lake to the atmosphere during turnover was controlled both by solar radiation and by surface water mercury concentration. As autumn turnover progressed through the months of October and November, higher mercury concentration water from the hypolimnion mixed with epilimnetic water, increasing mercury concentration in epilimnetic waters. Dissolved absorbance was significantly correlated with mercury concentrations and with iron, but DOC concentrations were essentially constant throughout the study period and did not exhibit a relationship with either dissolved mercury concentrations or emission rates. Positive correlations between dissolved mercury and iron and manganese also suggest a role for these elements in mercury transport within the lake, but iron and manganese did not demonstrate a relationship with emission rates. This research indicates that consideration of seasonal processes in lakes is important when evaluating mercury cycling in aquatic systems.
KEYWORDS: Mercury emission; Lake turnover; Dynamic flux chamber dissolved organic-carbon; gaseous mercury; florida everglades; volatile mercury; solar-radiation; waters; seawater; sulfide; phase; reservoir |
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(2009) Wright, A.L. Phosphorus sequestration in soil aggregates after long-term tillage and cropping. Soil & Tillage Research 103(2), 406-411. |
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ABSTRACT
Cultivated soils in the Everglades are being converted to their historic use as pastures or seasonally flooded prairies as parts of restoration efforts, but long-term cultivation may have altered soil P distribution and availability which may pose eutrophication hazards upon change in land use. The objectives of this study were to determine the distribution of P in soil chemical and physical fractions for contrasting long-term land management practices. The distribution of P in labile, Fe-Al bound, Ca bound, humic-fulvic acid, and residual pools in five aggregate-size fractions were measured for fields under sugarcane (Saccharum sp.) cropping for 50 years and perennial pasture for 100 years. Both land uses were characterized by a high degree of macroaggregation, as aggregates >0.25 mm contained 76 and 83% of the total soil under cultivation and pasture, respectively. Soils under sugarcane sequestered a total of 77 kg ha(-1) more P than pasture at 0-15 cm. The distribution of P in chemical fractions significantly varied between land uses as cultivation increased P sequestration in Ca-bound fractions more for sugarcane (244 kg P ha(-1)) than pasture (65 kg P ha(-1)). Pasture sequestered more P in organic pools, as storage in humic-fulvic acid and residual fractions were 26 and 25%, respectively. higher than sugarcane. Labile P was 100% higher for pasture than sugarcane, but Fe-Al bound P storage did not differ between land uses. Aggregation increased P sequestration in humic-fulvic acid and residual fractions, and P storage in organic pools increased with increasing aggregate size. In contrast, cultivation decreased aggregation and increased P accumulation in inorganic fractions. Long-term cultivation altered the distribution of soil P from organic to inorganic pools. The P stored in inorganic pools is stable under current land use, but may be unstable and pose eutrophication hazards upon onset of future land use change to the seasonally flooded prairie ecosystem.
KEYWORDS: Aggregates; Everglades; Histosol; Land use; Phosphorus fractionation everglades agricultural area; organic-matter; grassland soils; carbon; forms; accumulation; subsidence; fractions; florida; lake |
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(2009a) Wright, A.L. Soil phosphorus stocks and distribution in chemical fractions for long-term sugarcane, pasture, turfgrass, and forest systems in Florida. Nutrient Cycling in Agroecosystems 83(3), 223-231. |
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ABSTRACT
Phosphorus distribution and stability in soils of the Everglades Agricultural Area (EAA) of south Florida is important because of changing land uses. We investigated the effects of land use on P distribution in the soil profile and between chemical fractions for a histosol of the Florida Everglades. Labile, Fe-Al bound, Ca-bound, humic-fulvic acid, and residual P pools in 0-15, 15-30, and 30-45 cm depths were determined for drained soils planted to sugarcane (Saccharum sp.) for 50 yr, pasture for 100 yr, turfgrass for 60 yr, and forest for 20 yr. The P concentrations of all chemical fractions decreased with depth in the profile, indicating accumulation in surface soil resulting from oxidation and fertilization. Trends in P distribution between chemical fractions were similar between land uses. Labile P comprised less than 1% of total P. Fe-Al bound P averaged 2.9% of the total P for turfgrass and forest, but 11.4 and 9.6% for sugarcane and pasture. Increasing soil disturbance and long-term fertilization increased P allocation to inorganic fractions, as Ca-bound P contained 49% of total P for sugarcane but 28% for other land uses. Total P stocks in the soil profile (0-45 cm) averaged 1,323, 2,005, 2,294, and 2,317 kg P ha(-1) for pasture, sugarcane, turfgrass, and forest, respectively. Under current land uses P in organic fractions represents an unstable pool since the soil is prone to oxidation under drained conditions. In contrast, P sequestered in inorganic fractions is more stable under current land uses, thus sugarcane cultivation and incorporation of bedrock CaCO3 into surface soil by tillage will enhance long-term P sequestration.
KEYWORDS: Everglades Agricultural Area; Land use; Phosphorus fractionation; Phosphorus sequestration everglades agricultural area; organic phosphorus; histosols; forms; lake; accumulation; subsidence; sediments |
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(2009b) Wright, A.L. and Inglett, P.W. Soil Organic Carbon and Nitrogen and Distribution of Carbon-13 and Nitrogen-15 in Aggregates of Everglades Histosols.
Soil Science Society of America Journal 73(2), 427-433. |
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ABSTRACT
Oxidation of Histosols in the Everglades Agricultural Area (EAA) of South Florida leads to decreases in soil depth, changes in biogeochemical properties, and may limit land use Options in the future. The objectives of this study were to determine how long-term cultivation influences organic matter dynamics and C and N distribution throughout the profile Of a drained Histosol. We measured organic C and N stocks, aggregation, and the natural abundance of delta C-13 and delta N-15 in aggregates from Histosols 100 yr after drainage for two land uses: sugarcane (Saccharum officinarum L.) and prairie. Macroaggregates comprised the bulk of total soil for both land uses, averaging 81% of the total soil in fractions > 0.25 mm. Macroaggregation increased with depth and the proportion to whole soil was 65% higher at 30 to 45 cm than 0 to 15 cm. Cultivated soil averaged 13% higher organic C, but 11 lower organic N than prairie throughout the profile (0-45 cm). The majority of the organic C (76%) and N stocks (77%) was in macroaggregare fractions > 0.25 mm. The distribution of organic matter among aggregate-size fractions generally did not differ between land uses, except that organic C and N were 39 and 44%, respectively, greater For macroaggregares in prairie than cultivated soil at 0 to 15 cm. The delta N-15 decreased with depth for both land uses, indicating that organic matter was more decomposed and humified in surface soil (0-15 cm). The decrease with depth likely resulted from inundation of subsurface soils and low O-2 levels, which subsequently lowered rates of decomposition. The delta C-13 decreased with depth for Cultivated soil but increased for prairie, and was significantly higher for soil cropped to sugarcane (-25.37 parts per thousand) than prairie (-26.20 parts per thousand). Soil organic matter under Cultivation was less humified than prairie soil due to recent C inputs from Sugarcane. The 2-mm fraction had 12% lower delta N-15 than other fractions, indicating that recent organic matter inputs accumulated in macroaggregate fractions. Smaller aggregates contained higher delta N-15 and older organic matter. In contrast to most studies of mineral soils, Cultivation of Histosols increased C storage relative to prairie, with the major difference between land use being higher soil organic matter levels in the Subsurface (15-45 cm). Thus, cropping may reduce the rate of oxidation of Histosols ill Southern Florida relative to the prairie ecosystem.
KEYWORDS: agricultural area; grassland soils; natural c-13; matter; subsidence; tillage; fractionation; delta-c-13; dynamics; ratios |
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(2009c) Wright, A.L., Reddy, K.R. and Corstanje, R. Patterns of heterotrophic microbial activity in eutrophic and oligotrophic peatlands.
European Journal of Soil Biology 45(2), 131-137. |
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ABSTRACT
Nutrient enrichment of peatlands may alter patterns of heterotrophic microbial activity (HMA) and organic matter cycling. The utilization of C-substrates by heterotrophic microbial communities in response to changes in environmental conditions may serve as sensitive indicators of changes in the trophic state of wetlands. The objective of this study was to measure the response of heterotrophic microbial communities to added C-substrates in the plant detritus layer and underlying soil (0-10 cm) for eutrophic, transitional, and oligotrophic sites along a nutrient enrichment gradient in the Florida Everglades, USA. The short-term response to C-substrates (alcohols, amino acids, carboxylic acids, and polysaccharides) was measured as CO2 production. The nutrient gradient was characterized by decreasing P concentrations and microbial biomass from eutrophic to oligotrophic sites. Basal respiration was 73% higher at eutrophic than oligotrophic sites, and 41% higher in detritus than underlying soil. Heterotrophic microbial activity varied along the gradient with greater C-substrate utilization at the eutrophic site resulting from higher levels of microbial biomass and inorganic nutrients compared to the oligotrophic site. The C-substrates enhanced CO2 production at all sites suggesting that labile organic C was a limiting factor to HMA in these peatlands. Substrate-induced respiration (SIR) of detritus was 25, 45, and 42% greater for polysaccharides than other C-substrates at the eutrophic, transitional, and oligotrophic sites, respectively. Likewise, SIR at the eutrophic, transitional, and oligotrophic sites was 0, 40, and 39%, respectively, greater for detritus amended with carboxylic acids than with amino acids and alcohols. Polysaccharides dominated HMA profiles at all sites along the nutrient gradient in detritus. The transitional site was characterized by carboxylic acids and alcohols, while the HMA profile at the oligotrophic site was dominated by carboxylic acids. Patterns of HMA along the nutrient gradient provided insight into the microbial response to changes in tropic status, indicating the heterotrophic microbial community was more sensitive with increasing eutrophication.
KEYWORDS: Eutrophication; Everglades; Heterotrophic microbial activity; Peatland; Wetland northern everglades marsh; florida-everglades; wetland soils; methanogenic assemblages; spatial-distribution; nutrient enrichment; extraction method; peat soils; phosphorus; decomposition |
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(2009d) Wright, A.L., Reddy, K.R. and Newman, S. Microbial Indicators of Eutrophication in Everglades Wetlands.
Soil Science Society of America Journal 73(5), 1597-1603. |
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ABSTRACT
Nutrient loading has been implicated as a major cause of ecological changes in Everglades Wetlands. The main objective of this study was to assess changes in microbial indicators in response to nutrient loading across the Everglades landscape. Soil chemical, physical, and microbial properties were measured for nutrient-impacted and oligotrophic sites within Water Conservation Area (WCA)-1, WCA-2a, WCA-3a, and Taylor Slough of Everglades National Park. Impacts of nutrient loading were most evident by the development of gradients in floc and soil total P from peripheral to interior areas of all wetlands following the paths of surface water flow. Floc was more responsive to nutrient loading than the underlying soil. The sensitive indicators of eutrophication were floc and soil total P, microbial biomass P, and mineralized P. Total P averaged 185 and 140% greater for nutrient-impacted than oligotrophic areas for floc and soil (0-3 cm), respectively. Microbial biomass P averaged 97 and 52% higher at nutrient-impacted than oligotrophic areas for floc and soil, respectively. Mineralized P was the most sensitive indicator of eutrophication, being 689 and 135% higher at nutrient-impacted than oligotrophic areas for floc and soil, respectively. Microbial indicators in WCA-3a and Taylor Slough were more responsive to nutrient loading than in WCA-1 and WCA-2a, which received higher P loads. Delineation of nutrient-impacted and oligotrophic areas in Everglades wetlands may serve as a baseline to assess future impacts of eutrophication. The consistent pattern in the response of microbial processes to nutrient loading across the range of conditions in different Everglades wetlands demonstrates their suitability as sensitive indicators of eutrophication.
KEYWORDS: florida everglades; northern everglades; spatial-distribution; phosphorus enrichment; subtropical wetland; nutrient enrichment; extraction method; soil-phosphorus; peat accretion; water |
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(2009) Ye, R., Wright, A.L., Inglett, K., Wang, Y. and Ogram, A.V. Land-Use Effects on Soil Nutrient Cycling and Microbial Community Dynamics in the Everglades Agricultural Area, Florida, Communications in Soil Science and Plant Analysis 40(17), 2725-2742. |
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ABSTRACT
Soil subsidence has become a critical problem since the onset of drainage of the organic soils in the Everglades Agricultural Area (EAA), which may impair current land uses in the future. The objectives of this study were to characterize soil microbial community-level physiology profiles, extracellular enzymatic activities, microbial biomass, and nutrient pools for four land uses: sugarcane, turfgrass, pasture, and forest. Long-term cultivation and management significantly altered the distribution and cycling of nutrients and microbial community composition and activity in the EAA, especially for sugarcane and turf fields. The least-managed fields under pasture had the lowest microbial biomass and phosphorus (P) levels. Turf and forest had more microbial metabolic diversity than pasture or the most intensively managed sugarcane fields. Land-use changes from sugarcane cropping to turf increased microbial activity and organicmatter decomposition rates, indicating that changes from agricultural to urban land uses may further contribute to soil subsidence.
KEYWORDS: Everglades, land use, microbial community composition, nutrient cycling |
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(2009) Yin, Y., Wu, Y. and Bartell, S.M. A spatial simulation model for forest succession in the Upper Mississippi River floodplain.
Ecological Complexity 6, 494-502. |
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ABSTRACT
A Markov-chain transition model (FORSUM) and Monte Carlo simulations were used to simulate the succession patterns and predict a long-term impact of flood on the forest structure and growth in the floodplain of the Upper Mississippi River and Illinois River. Model variables, probabilities, functions, and parameters were derived from the analysis of two comprehensive field surveys conducted in this floodplain. This modeling approach describes the establishment, growth, competition, and death of individual trees for modeled species on a 10,000-ha landscape with spatial resolution of 1 ha. The succession characteristics of each Monte Carlo simulation are summed up to describe forest development and dynamics on a landscape level. FORSUM simulated the impacts of flood intensity and frequency on species composition and dynamics in the Upper Mississippi River floodplain ecosystem. The model provides a useful tool for testing hypotheses about forest succession and enables ecologists and managers to evaluate the impacts of flood disturbances and ecosystem restoration on forest succession. The simulation results suggest that the Markov-chain Monte Carlo method is an efficient tool to help organize the existing data and knowledge of forest succession into a system of quantitative predictions for the Upper Mississippi River floodplain ecosystem.
KEYWORDS: Floodplain forest succession model Markov-chain transition Monte Carlo simulation Upper Mississippi River Quercus Spatial and temporal patterns |
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(2009a) Yin, Y., Wu, Y., Bartell, S.M. and Cosgriff, R. Patterns of forest succession and impacts of flood in the Upper Mississippi River floodplain ecosystem. Ecological Complexity 6, 463-472. |
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ABSTRACT
The widespread loss of oak-hickory forests and the impacts of flood have beenmajor issues of ecological interest concerning forest succession in the Upper Mississippi River (UMR) floodplain. The data analysis from two comprehensive field surveys indicated that Quercus was one of the dominant genera in the UMR floodplain ecosystem prior to the 1993 flood and constituted 14% of the total number of trees and 28% of the total basal area. During the post-flood recovery period through 2006, Quercus demonstrated slower recovery rates in both the number of trees (4%) and basal area (17%). In the same period, Carya recovered greatly from the 1993 flood in terms of the number of trees (11%) and basal area (2%), compared to its minor status before the flood. Further analyses suggested that different species responded to the 1993 flood with varying tolerance and different succession strategies. In this study, the relation of flood-caused mortality rates and DBH, fm(d), can be expressed in negative exponential functions for each species. The results of this research also indicate that the growth functions are different for each species and might also be different between pre- and post-flood time periods. These functions indicate different survival strategies and emergent properties in responding to flood impacts. This research enhances our understanding of forest succession patterns in space and time in the UPR floodplain. And such understanding might be used to predict long-term impacts of floods on UMR floodplain forest dynamics in support of management and restoration.
KEYWORDS: Upper Mississippi River floodplain ecosystem Oak-hickory forest succession Spatial and temporal patterns |
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(2009) Zhang, L.M., Wright, L.P. and Blanchard, P. A review of current knowledge concerning dry deposition of atmospheric mercury.
Atmospheric Environment 43(37), 5853-5864. |
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ABSTRACT
The status of the current knowledge concerning the dry deposition of atmospheric mercury, including elemental gaseous mercury (Hg-0), reactive gaseous mercury (RCM), and particulate mercury (Hg-p), is reviewed. The air-surface exchange of Hg-0 is commonly bi-directional, with daytime emission and nighttime deposition over non-vegetated surfaces and vegetated surfaces with small leaf area indices under low ambient Hg-0 conditions. However, daytime deposition has also been observed, especially when the ambient Hg-0 is high. Typical dry deposition velocities (V-d) for Hg-0 are in the range of 0.1-0.4 cm s(-1) over vegetated surfaces and wetlands, but substantially smaller over non-vegetated surfaces and soils below canopies. Meteorological, biological, and soil conditions, as well as the ambient Hg-0 concentrations all play important roles in the diurnal and seasonal variations of Hg-0 air-surface exchange processes. Measurements of RGM deposition are limited and are known to have large uncertainties. Nevertheless, all of the measurements suggest that RGM can deposit very quickly onto any type of surface, with its V-d ranging from 0.5 to 6 cm s(-1). The very limited data for Hg-p suggest that its V-d values are in the range of 0.02-2 cm s(-1). A resistance approach is commonly used in mercury transport models to estimate V-d for RGM and Hgp; however, there is a wide range of complexities in the dry deposition scheme of Hg-0. Although resistance-approach based dry deposition schemes seem to be able to produce the typical V-d values for RGM and Hg-0 over different surface types, more sophisticated air-surface exchange models have been developed to handle the bi-directional exchange processes. Both existing and newly developed dry deposition schemes need further evaluation using field measurements and intercomparisons within different modelling frameworks.
KEYWORDS: Air-surface exchange; Dry deposition velocity; Measurement and modelling; Speciated mercury total gaseous mercury; relaxed eddy accumulation; elemental mercury; north-america; air/surface exchange; florida everglades; modeling framework; concentrations gem; foliar exchange; trace-elements |
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(2009) Zhong, H. and Wang, W.X. Inorganic Mercury Binding with Different Sulfur Species in Anoxic Sediments and Their Gut Juice Extractions.
Environmental Toxicology and Chemistry 28(9), 1851-1857. |
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ABSTRACT
To investigate the roles of different sulfur (S) species in controlling the partitioning and bioavailability of inorganic mercury (Hg) in anoxic sediments, we examined the differential binding of Hg with three key S species in anoxic sediment (mackinawite [FeS], pyrite [FeS2], and S2-) and then quantified their extraction by the gut juice of deposit-feeding sipunculans Sipunculus nudus. A sequential extraction method was simultaneously used to distinguish Hg sorption with different sediment components. All three S-containing sediment components could lead to a high binding of Hg in sediments, but most Hg was sorbed with FeS or FeS2 instead of formation of Hg sulfide despite the presence of S2- or humic acid. The gut juice extraction was relatively low and constant whenever FeS and FeS2 were in the sediment, indicating that both FeS and FeS2 controlled the Hg gut juice extraction and thus bioavailability. Mercury sorbed with FeS2 had higher gut juice extraction than that with FeS, while Hg sulfide was not extracted, strongly suggesting that Hg sorbed with FeS2 was more bioavailable than that with other S species. Mercury sorbed with FeS had very low bioavailability to sipunculans at a low Hg: S ratio in the sediment but was more bioavailable with increasing Hg: S ratio up to a maximum (similar to 1: 10, mole based). The present study showed that different S species (FeS, FeS2) and Hg:S ratios significantly affected the binding and bioavailability of Hg in anoxic sediments.
KEYWORDS: Anoxic sediment; Mercury mackinawite; Pyrite sulfide dissolved organic-matter; marine-sediments; geochemical controls; florida everglades; sulfide minerals; mackinawite fes; bioavailability; methylmercury; speciation; adsorption |
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(2009) Zweig, C.L. and Kitchens, W.M. Multi-state succession in wetlands: a novel use of state and transition models. Ecology 90(7), 1900-1909. |
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ABSTRACT
To investigate the roles of different sulfur (S) species in controlling the partitioning and bioavailability of inorganic mercury (Hg) in anoxic sediments, we examined the differential binding of Hg with three key S species in anoxic sediment (mackinawite [FeS], pyrite [FeS2], and S2-) and then quantified their extraction by the gut juice of deposit-feeding sipunculans Sipunculus nudus. A sequential extraction method was simultaneously used to distinguish Hg sorption with different sediment components. All three S-containing sediment components could lead to a high binding of Hg in sediments, but most Hg was sorbed with FeS or FeS2 instead of formation of Hg sulfide despite the presence of S2- or humic acid. The gut juice extraction was relatively low and constant whenever FeS and FeS2 were in the sediment, indicating that both FeS and FeS2 controlled the Hg gut juice extraction and thus bioavailability. Mercury sorbed with FeS2 had higher gut juice extraction than that with FeS, while Hg sulfide was not extracted, strongly suggesting that Hg sorbed with FeS2 was more bioavailable than that with other S species. Mercury sorbed with FeS had very low bioavailability to sipunculans at a low Hg: S ratio in the sediment but was more bioavailable with increasing Hg: S ratio up to a maximum (similar to 1: 10, mole based). The present study showed that different S species (FeS, FeS2) and Hg:S ratios significantly affected the binding and bioavailability of Hg in anoxic sediments.
KEYWORDS: alternate stable states; CART; Florida Everglades, USA; state and transition models; succession; VDDT; wetlands alternative stable states; vegetation dynamics; communities; restoration; landscape; framework; everglades; management; feedbacks; stability
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END of year 2009
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