Florida Ecosystem Research Articles

Plant invasions from a belowground nematocentric perspective

Chemical, biological and mechanical control methods are helpful in restricting the progress of invasive plants, but they may lack the full potential for the long-term goal of habitat management and restoration. Interactions and feedbacks between plant and soil microbiota represent potentially important factors regulating and facilitating the invasion process.The tree Melaleuca quinquenervia, a native of Australia, invades all types of habitats in South Florida. Thus far, the invasion has converted >200,000 ha of South Florida ecosystems to closed-canopy M. quinquenervia forests with 60–80% loss of native biodiversity. The shrub Baccharis halimifolia, a native to South Florida, is spreading in coastal Australia.We examined the impact of plant–soil biota feedbacks set in motion by the exotic plants in 2 × 2 factorial (species × location) field and microcosm experiments both within the invasive as well as natural range of both plant species using a metagenetic nematocentric approach. The results were inconsistent and did not lend themselves to simple generalizations as responses of nematode community composition patterns were specific to plant species, locations, years, and even to experimental conditions. For instance, greater diversity of plant-parasitic nematodes was confirmed for both plant species in their native ranges, but only in the field surveys (not microcosms) and only in the first year of sampling (not the second). Equally importantly, the specificity was only observed at the “near species” level allowed by the metagenetic approach and as the identification of nematodes became less resolved, i.e., as identification moved from the “near species”-level to coarser levels of taxonomic resolution, the specific responses generally diminished.

Effects of contaminated St. Lucie River saltwater sediments on an amphipod (Ampelisca abdita) and a hard-shell clam (Mercenaria mercenaria).

The St. Lucie estuary (SLE) ecosystem in South Florida has been shown to be contaminated with metals and pesticides. Our earlier studies also showed that aquatic organisms, especially benthic species in the SLE ecosystem, might be potentially at high risk from copper (Cu) exposure. The objectives of this study were to conduct studies with separate groups of organisms exposed to seven field-collected sediment samples from the St. Lucie River according to standard procedures to evaluate toxicity and tissue concentrations of Cu and zinc (Zn). Short term and longer term whole sediment acute toxicity studies were performed with Ampelisca abdita and Mercenaria mercenaria. Analysis of sediment chemical characteristics showed that Cu and Zn are of most concern because their concentrations in 86 % of the sediments were higher than the threshold effect concentrations for Florida sediment quality criteria and the National Oceanic and Atmospheric Administration Screening Quick Reference Tables (SQuiRTs) sediment values. There was no significant effect on survival of the tested organisms. However, increased Cu and Zn concentrations in the test organisms were found. Dry weight of the tested organisms was also inversely related to Cu and Zn concentrations in sediments and organisms. The effects on organism weight and Cu and Zn uptake raise concerns about the organism population dynamics of the ecosystem because benthic organisms are primary food sources in the SLE system and are continuously exposed to Cu- and Zn-contaminated sediments throughout their life cycle. The results of the present study also indicate that Cu and Zn exposures by way of sediment ingestion are important routes of exposure.

Waterbirds as indicators of ecosystem health in the coastal marine habitats of Southern Florida: 2. Conceptual ecological models

In our companion manuscript we identified 11 waterbirds as indicators of various pressures on the coastal marine ecosystems of southern Florida. Here, we identify the habitats on which these species depend and the ecological linkages that make them representative of those habitats. Through the use of conceptual ecological models (CEMs), we develop tools that can be used by managers/decision makers to evaluate the health of the various habitats in order to rectify myriad problems that are occurring or will possibly occur in the future such that the valuable ecosystem services provided by these habitats can be maximized. We also demonstrate the practical use of these tools by documenting data availability, benchmarks, and scientific needs for each species.

Interorganizational Engagement in Collaborative Environmental Management: Evidence from the South Florida Ecosystem Restoration Task Force

Collaboration is commonly used to deliver public services that reach beyond the individual capacities of independent organizations. Although much of the literature in the fields of collaborative governance has offered theoretical insights to explain how stakeholders might initially enter into collaborative processes or how the design of collaborative processes can support continued stakeholder participation over time, the literature has not effectively studied what factors might drive actors to engage one another in a particular conversation or discussion during a collaborative process, nor what factors affect whether engagement is cooperative or conflictual. We fill this gap through a more “micro-level” view of collaborative engagement in a study of the South Florida Ecosystem Restoration Task Force, a collaborative arrangement involving representatives from 14 federal, tribal, state, and local agencies, charged with advising and coordinating the efforts in South Florida to restore and recover the Florida Everglades. We use data from coded meeting minutes of discussions among the participants in the South Florida Ecosystem Restoration Program Task Force over a 5-year time frame and demonstrate that the types of issues under discussion and the actors involved in discussion can either foster or inhibit engagement and conflict during dialogue. Our results have important implications for the development of a stronger theory of collaborative engagement in interorganizational partnerships.

Navigating the complexities of dynamic ecosystem change

book reviews ISSN 1948‐6596 Navigating the complexities of dynamic ecosystem change Novel Ecosystems: Intervening in the New Ecological World Order. Richard J. Hobbs, Eric S. Higgs & Carol M. Hall (editors), 2013, Wiley–Blackwell, 380 pp. £45 (hardback) ISBN 9781118354223; http://www.wiley.com The world’s ecosystems have always been subject to dynamic change and there is every reason to expect this to continue into the future. However, many approaches to understanding ecosystem processes and managing ecosystems have tended to ignore this aspect, instead implicitly assuming historical stability. Recent concerns about climate change and its impact on ecosystems have high‐ lighted the need to be explicit about historical as well as future dynamic change in ecosystems. This has generated considerable interest in ‘novel’ or ‘no‐analogue’ ecosystems (Williams and Jackson 2007), but has raised a wide range of issues re‐ lated to how we deal with, predict, value and manage novel ecosystems. This book tries to address many of these questions, with the weight of focus on the applied implications of novel ecosystems, reflecting the predominant interests of the editors. The focus on management is one of the book’s strengths in that it tries to tackle some practical approaches for dealing with novel ecosystems in real manage‐ ment applications. As a conservation biologist, I found this enlightening and its attempt to develop practical solutions makes the book of interest to both scientific and practitioner audiences. The book arose from a series of workshops and the editors provide an interesting overview of the workshop process in Chapter 1, including a candid account of the difficulty in reaching agree‐ ment on many contentious issues in the book. De‐ spite the large number of contributors and the process through which it was written, the book is generally very well structured. It is organised into seven sections, but they largely cover the follow‐ ing four topics: novel ecosystem concepts and definitions, the characteristics of novel ecosys‐ tems, the management of novel ecosystems, and future considerations. The sections are inter‐ spersed with short case studies which are excel‐ lent illustrations of the issues in real systems, but it does tend to fragment the book a little. There is a great case study early on in the book, describing the ‘Hole‐in‐the‐Donut’ novel ecosystem in South Florida (Smith et al. 2011). This novel ecosystem was originally created through agricultural prac‐ tices, but now lies entirely with the Everglades National Park. Subsequent efforts to manage this ecosystem provide a fantastic illustration of the challenges to managing novel ecosystems that this book attempts to address. There is also a nice his‐ torical perspective on the origin of the idea of novel ecosystems. A considerable amount of space is devoted to dealing with definitions and the conceptualisa‐ tion of novel ecosystems. As you might expect, this is a contentious issue, but is dealt with thor‐ oughly by the book. The definitions that are devel‐ oped focus around the idea of categorising eco‐ systems into historical, hybrid and novel. Although these are conceptualised along a continuum of increasing dissimilarity of biotic composition and abiotic condition from historical conditions, ideas of resilience are drawn upon to distinguish hybrid (for which a return to historical state is possible through restoration) and novel (where a return to historical state is not possible). The idea that a transition to a novel ecosystemis irreversible, in some sense, means there exists a degree of per‐ manence to novel ecosystems that allows them in the future to be historical reference ecosystems themselves. However, it is not clear how this framework might deal with ecosystems that are continuously in flux, for which defining a historical reference system may be problematic. Clearly de‐ lineating among categories may also be challeng‐ ing, although this is discussed in the book. The sections on incorporating the novel ecosystem concept into management are really valuable parts of the book because I think this is where the most difficult challenges lie. A manage‐ ment framework is presented as a decision tree based around the historical / hybrid / novel classi‐ fication. The framework is explicit about defining 216 frontiers of biogeography 5.4, 2013 — © 2013 the authors; journal compilation © 2013 The International Biogeography Society

Bidirectional trophic linkages couple canopy and understorey food webs

Summary Cross‐system resource flux is a fundamental component of ecological systems. Allochthonous material flows generate trophic linkages between adjacent food webs, thereby affecting community structure and stability in recipient systems. We investigated cross‐habitat trophic linkages between canopy and understorey food webs in a terrestrial, wooded, ecosystem in South Florida, USA. The focal community consisted of three species of Anolis lizards and their prey. We described interspecific differences among Anolis species in the strength and routing of these cross‐habitat flows using stable isotope analysis, stomach content analysis and habitat use data. All three Anolis species in this study consumed different prey and occupied vertically distinct arboreal habitats. Despite these differences, carbon isotope and stomach content analysis revealed strong integration with understorey and canopy food webs for all Anolis species. Modes of resource flux contributing to the observed cross‐habitat trophic linkages included prey movement and the gravity‐driven transport of detritus. Our study shows that terrestrial systems are linked by considerable bidirectional cross‐system resource flux. Our results also suggest that considering species‐specific interactions between predator and prey is necessary to fully understand the diversity of material and energy flows between spatially separated habitats.

The effects of 11 yr ofCO2enrichment on roots in aFlorida scrub‐oak ecosystem

Uncertainty surrounds belowground plant responses to rising atmospheric CO₂ because roots are difficult to measure, requiring frequent monitoring as a result of fine root dynamics and long-term monitoring as a result of sensitivity to resource availability. We report belowground plant responses of a scrub-oak ecosystem in Florida exposed to 11 yr of elevated atmospheric CO₂ using open-top chambers. We measured fine root production, turnover and biomass using minirhizotrons, coarse root biomass using ground-penetrating radar and total root biomass using soil cores. Total root biomass was greater in elevated than in ambient plots, and the absolute difference was larger than the difference aboveground. Fine root biomass fluctuated by more than a factor of two, with no unidirectional temporal trend, whereas leaf biomass accumulated monotonically. Strong increases in fine root biomass with elevated CO₂ occurred after fire and hurricane disturbance. Leaf biomass also exhibited stronger responses following hurricanes. Responses after fire and hurricanes suggest that disturbance promotes the growth responses of plants to elevated CO₂. Increased resource availability associated with disturbance (nutrients, water, space) may facilitate greater responses of roots to elevated CO₂. The disappearance of responses in fine roots suggests limits on the capacity of root systems to respond to CO₂ enrichment.

Experimental evidence for weak effects of fire ants in a naturally invaded pine‐savanna ecosystem in north Florida

1. Fire ants naturally invade some undisturbed ecosystems of high conservation value and may negatively impact co‐occurring ants.2. Over 3 years, fire ants were added and removed from a longleaf pine savanna ecosystem that naturally supports a low density of fire ants. Impacts on co‐occurring ants were monitored using pitfall traps.3. Treatments resulted in significant differences in average fire ant abundance across all plots only in the first year of the experiment. Fire ants had little discernible impact. The abundance and species richness of co‐occurring ants in removal plots never differed from unmanipulated control plots. The abundance of co‐occurring ants was very slightly lower and ant species richness was slightly higher where Solenopsis invicta Buren colonies were added, but neither contrast was significant.4. The poor conditions in this habitat for many native ants may explain this outcome. More broadly, the impact of fire ants on ant assemblages still appears to be secondary and largely a consequence of human impacts on the environment.

Spatiotemporal Surface-Groundwater Interaction Simulation in South Florida

South Florida ecosystem is dictated by a large wetland, karst hydrogeology and extended coastal boundary with the Atlantic Ocean. The risks related to the ecosystem include: disruption of groundwater flow as a result of frequent sinkhole formation; flooding in urban areas as a result of the shallow water table; saltwater intrusion from the ocean; and excessive nutrient load to surficial water bodies and subsequently eutrophication because of the intensive utilization of wetlands for nutrient removal. Attempts to understand eco-hydrological processes primarily focus on extensive monitoring and use of distributed hydrological models. However, the relatively flat nature of the region and also the extended coastal boundary with the ocean, makes watershed-based approaches less realistic. A regional spatiotemporal groundwater level modeling approach was attempted using a Dynamic Factor Analysis (DFA) method. The daily water levels of 13 monitoring well sites from major hydrogeologic regions and different land uses were used to conduct the DFA analysis, and six dynamic factors were identified using minimum Akaike Information Criterion (AIC). Further exploratory analysis to relate the dynamic factors with physically attributable explanatory variables has helped to identify five of the major factors that govern the groundwater dynamics in south Florida. Three of the factors were attributable to the Lake Kissimmee water level in the north, Caloosahatchee River water level in the west, and Hillsboro canal in the east. The other two factors identified were the regional averaged rainfall and soil moisture. The spatiotemporal simulation involved interpolation of the loadings of the dynamic factors using an inverse distance weighted method and convoluting with the dynamic factors. The result has shown a good fit with the maximum RMSE of 0.12 m. Retrieval of rainfall, soil moisture, and surface water level from satellite imagery makes spatiotemporal modeling of the groundwater level achievable.

Phenotypic Plasticity and Integration in the Mangrove Rivulus (Kryptolebias marmoratus): A Prospectus

The mangrove rivulus (Kryptolebias marmoratus) is a small fish native to mangrove ecosystems in Florida, the Caribbean, Central America, and South America. This species is one of only two self-fertilizing, hermaphroditic vertebrates capable of producing offspring that are genetically identical to both the parent and all siblings. Long bouts of selfing result in individuals with completely homozygous genotypes, effectively allowing for the production of "clones." Rivulus is also extremely sensitive to environmental change, both during development and adulthood. Life-history traits, behavior, physiology, morphology, and even sexual phenotype are shaped to a large extent by the interaction of genes with the environment, and many of these traits appear to co-vary. True reaction norms can be generated for this species in much the same way as has been done for clonally reproducing invertebrates and plants that have contributed immensely to our understanding of the evolution of phenotypic plasticity. That is, rivulus provides the opportunity to place individuals with identical genotypes in many different environments at any point during ontogeny or adulthood. In addition, rivulus populations are characterized by high genotypic diversity, a luxury not afforded by many clonal vertebrates, which allows us to evaluate variation among genotypes in the shape of reaction norms and in patterns of covariance among traits. We provide background information on phenotypic plasticity and phenotypic integration, coupled with a description of characteristics that we feel qualify rivulus as a potentially powerful model in which to study the evolution of reaction norms and covariance among traits.

Susceptibility ofPerseaspp. and Other Lauraceae to Attack by Redbay Ambrosia Beetle,Xyleborus glabratus(Coleoptera: Curculionidae: Scolytinae)

Redbay ambrosia beetle (RAB), Xyleborus gla bratus Eichhoff (Coleoptera: Curculionidae: Sco lytinae), a native of Asia, was first discovered in the USA near Savannah, Georgia in 2002 (Haack 2001; Rabaglia et al. 2006). RAB is an effective vector of Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva (Harrington et al. 2008) that causes laurel wilt (LW), a lethal disease of several trees in the Lauraceae in the southeastern USA (Crane et al. 2008; Mayfield et al. 2008). Ambrosia beetle adults bore through the bark and into the xy lem (wood) where they lay eggs, then adults and larvae cultivate and feed on symbiotic ambrosia fungi that grow in the galleries. Native Persea (Laurales: Lauraceae) species appear to be pre ferred hosts. LW is responsible for high mortality of redbay [P borbonia (L.) Spreng.], swampbay [P palustris (Raf.) Sarg.], and sassafras [Sassa fras albidum (Nuttall) Nees] in Alabama, Flor ida, Georgia, Mississippi, North Carolina and South Carolina (Fraedrich et al. 2008; Hanula et al. 2008; Gramling 2010). As LW encroaches upon the Lake Wales Ridge ecosystem in south central Florida, silkbay (P. humilis Nash) is also showing susceptibility to LW and is dying. Addi tional species affected by LW include avocado (P. americana Mill.), spicebush [Lindera benzoin (L.) Blume], and other woody Lauraceae (Fraedrich et al. 2008) (Table 1). The susceptibility of 5 avocado cultivars of Mexican, Guatemalan or West Indian origin to RAB and LW was demonstrated by Mayfield et al. (2008). However, with more than 23 West In dian cultivars grown in Florida, it is necessary to determine their susceptibility. Moreover, as an adventive species to the North American conti nent, RAB might affect other valuable New World species. Most Persea species are of Mexican, Cen tral American, or South American origin. These Persea may have significant value in germplasm collections, some have been discovered recently, and some have resistance to diseases that afflict their commercial relative, the avocado (Skutch et l. 1992; Scora & Bergh 1992; Zentmyer & Schieber 1992). Thus, their susceptibility to RAB and LW warrants evaluation. Another member of the Lauraceae of much concern is the California bay laurel [Umbellularia californica (Hook. & Arn.) Nutt.], a dominant hardwood species of the U.S. Pacific Coast. Through inoculation experi ments, Fraedrich (2008) demonstrated that U. californica is susceptible to LW. With continued westward spread of LW, the host status of U. cali fornica needs to be confirmed. The 3 studies presented here evaluate sus ceptibility to RAB and LW in: 1) 13 West Indian avocado cultivars; 2) 10 non-commercial Persea spp., 1 Beilschmidia sp. (a genus related to Per sea), and 3) U. californica. First, no-choice ex periments were conducted to determine if RAB would bore into avocado cultivars not screened previously by Mayfield et al. (2008) and follow ing similar methodology. Avocado cultivars 'Ber necker', 'Beta', 'Brooks late', 'Choquette', 'Don nie', 'Dupuis', 'Hall', 'Loretta', 'Lula', 'Monroe', 'Simmonds', 'Tower 2' and 'Waldin' (4 plants each) were planted in 10-gallon pots in a screenhouse at he Plant Sciences Research and Education Unit, University of Florida (UF), Citra, Florida in VI 2008. Two plants of each cultivar were infested by enclosing 4 newly emerged 9 RAB (UF colony reared) within a mesh sleeve on the lower trunk. Two plants per cultivar were uninfested controls. Entrance holes and perseitol (white exudate from wounds) were monitored for 4 wk. Severity of wilt symptoms was scored using the following LW in dex: 0 = no wilt; 1 = wilt, no leaf necrosis; 2 = wilt, 10% necrosis or defoliation; 3 = wilt, 30% necrosis/ defoliation; 4 = 50% necrosis/defoliation; 5 = 75% necrosis/defoliation; 6 = 100% necrosis/defoliation

Optimizing line intercept sampling and estimation for feral swine damage levels in ecologically sensitive wetland plant communities

Ecological sampling can be labor intensive, and logistically impractical in certain environments. We optimize line intercept sampling and compare estimation methods for assessing feral swine damage within fragile wetland ecosystems in Florida. Sensitive wetland sites, and the swine damage within them, were mapped using GPS technology. Evenly spaced parallel transect lines were simulated across a digital map of each site. The length of each transect and total swine damage under each transect were measured and percent swine damage within each site was estimated by two methods. The total length method (TLM) combined all transects as a single long transect, dividing the sum of all damage lengths across all transects by the combined length of all transect lines. The equal weight method (EWM) calculated the damage proportion for each transect line and averaged these proportions across all transects. Estimation was evaluated using transect spacings of 1, 3, 5, 10, 15, and 20 m. Based on relative root mean squared error and relative bias measures, the TLM produced higher quality estimates than EWM at all transect spacings. Estimation quality decreased as transect spacing increased, especially for TLM. Estimation quality also increased as the true proportion of swine damage increased. Diminishing improvements in estimation quality as transect spacings decreased suggested 5 m as an optimal tradeoff between estimation quality and labor. An inter-transect spacing of 5 m with TLM estimation appeared an optimal starting point when designing a plan for estimating swine damage, with practical, logistical, economic considerations determining final design details.

Combining object-based texture measures with a neural network for vegetation mapping in the Everglades from hyperspectral imagery

An informative and accurate vegetation map for the Greater Everglades of South Florida is in an urgent need to assist with the Comprehensive Everglades Restoration Plan (CERP), a $10.5-billion mission to restore the south Florida ecosystem in 30+ years. In this study, we examined the capability of fine spatial resolution hyperspectral imagery collected from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) for vegetation mapping in the Everglades. In order to obtain an efficient and accurate procedure for vegetation discrimination, we developed a neural network classifier first and then combined the object-based texture measures with the classifier to examine the contribution of the spatial information for vegetation mapping. The neural network is capable of modeling the characteristics of multiple spectral and spatial signatures within a class by an internally unsupervised engine and characterizing spectral and spatial differences between classes by an externally supervised system. The designed procedure was tested in a portion of the Everglades. An object-based vegetation map was generated with an overall classification accuracy averaged 94% and a kappa value averaged 0.94 in discriminating 15 classes. The results are significantly better than those obtained from conventional classifiers such as maximum likelihood and spectral angle mapper. The study illustrates that combining object-based texture measures in the neural network classifier can significantly improve the classification. It is concluded that fine spatial resolution hyperspectral data is an effective solution to accurate vegetation mapping in the Everglades which has a rich plant community with a high degree of spatial and spectral heterogeneity.

First Report of Laurel Wilt Disease Caused by Raffaelea lauricola on Silk Bay in Florida.

Silk bay (Persea humilis Nash) is a member of the Lauraceae precinctive to the scrub forests of central and southern Florida and a sister species to the primary laurel wilt host, redbay (P. borbonia (L.) Spreng), which is generally not found in these ecosystems. In November 2011, observations of silk bay mortality near Lake Placid in Highlands County, FL, were reported to Florida Forest Service agents. A subsequent visit to roadside and homeowners' properties in the area revealed many dead and dying silkbays with characteristic laurel wilt symptoms, including wilted crowns with brown persistent foliage, frass accumulated at tree bases, sapwood with dark streaking, and ambrosia beetle entrance holes (1). Twig samples were taken and later confirmed as silk bay by the Florida Division of Plant Industry in Gainesville. Trunk samples were taken from four trees for fungal isolation. Stem sections with vascular discoloration were surface disinfested for 30 s in a 5% sodium hypochlorite solution and then plated onto cycloheximide streptomycin malt extract agar (CSMA) (1). All sapwood pieces from the four samples resulted in the same cream-buff submerged fungal growth characteristic of the laurel wilt pathogen Raffaelea lauricola T. C. Harr., Fraedrich & Aghayeva (2). DNA was extracted from a single-spore derived isolate, PL1389, and an 18S small subunit ribosomal RNA gene sequence was generated with primers NS1 and NS4, resulting in a 1,031-bp amplicon (3). A BLASTn search showed identical homology to R. lauricola strains PL159 and PL382 (GenBank Accessions No. EU257806 and JF797171, respectively, 100% similarity, e-value 0.0, and a total score of 1,982). The sequence was deposited into GenBank and assigned the accession No. JQ247569. In December 2011, a spore suspension was made by flooding a PL1389 culture plate with 2 ml of sterile water, collecting by pipette, and quantification and adjusting to 3.25 × 106 spores/ml by hemacytometer. Pathogenicity was tested on potted plants in a growth chamber experiment. Five silk bays and three redbays were drill-wounded with a 3/32" drill bit and inoculated with 20 μl of the spore suspension. Three silk bays and two redbays served as water-inoculated controls. Within 5 weeks, all inoculated plants displayed the wilt and vascular discoloration characteristic of laurel wilt disease, while all water-inoculated controls remained healthy. Sapwood samples from all plants were plated onto the same CSMA media. R. lauricola was later recovered only from the wilted plants inoculated with PL1389, while no fungal growth was recovered from the asymptomatic water-inoculated controls. Silk bay, which plays a significant role in the limited scrub ecosystems of Florida, has now become another host in the laurel wilt epidemic, with its implications upon the scrub forests yet to be seen.

Endosulfan in the atmosphere of South Florida: Transport to Everglades and Biscayne National Parks

Nutrient inputs from urban encroachment and agricultural activities have been implicated in contributing to the environmental health decline and loss of organism diversity of South Florida ecosystems. Intensive agricultural pesticide use may also challenge these ecosystems. One possible mechanism is pesticide release to the atmosphere after application. The process is enhanced in this region due to the calcareous soils, frequent rainfall, and high humidity and temperatures. This study examined the atmospheric fate of the widely-used insecticide endosulfan. Air samples were collected over a five-year period (2001–2006) at a site within the agricultural community of Homestead, Florida and at sites located in nearby Biscayne and Everglades National Parks (NPs). Mean gas phase air concentrations of α-endosulfan were 17 ± 19 ng m−3 at Homestead, 2.3 ± 3.6 ng m−3 at Everglades NP, and 0.52 ± 0.69 ng m−3 at Biscayne NP. Endosulfan emissions from agricultural areas around Homestead appeared to influence air concentration observations at the NP sites. During an intensive sampling campaign, the highest total endosulfan concentrations at the NP sites were observed on days when air parcels were predicted to move from Homestead towards the sampling locations. The α-endosulfan fraction (α/(α + β)) was used to examine the contribution of pesticide drift versus volatilization to the overall residue level. The formulated product has an α fraction of approximately 0.7, whereas volatilization is predicted to have an α fraction of ≥0.9. The median α- fraction observed during periods of high agricultural activity at Homestead and Everglades NP was 0.84 and 0.88, respectively, and during periods of low agricultural activity the median at Homestead was 0.86, indicating contributions from drift. The median α fraction at Everglades NP was 1.0 during periods of low agricultural activity, while Biscayne NP was 1.0 year round indicating air concentrations are primarily influenced by regional volatilization.

Compensatory mitigation in marine ecosystems: Which indicators for assessing the “no net loss” goal of ecosystem services and ecological functions?

Recent years have seen increasing interest in the concepts of compensation and ecosystem services. Regulation systems in the United States dealing with environmental protection (Superfund Act, Oil Pollution Act, National Environment Policy Act, Clean Water Act, Endangered Species Act, etc.) require those responsible for damage to ecosystem services to compensate for it “physically” and restore these services for the benefit of the entire population. This article, using simple indicators of compensation identified in the literature, attempts to analyze what types of ecological compensation are adopted, how performance is assessed, how standards on ecological equivalencies are adopted, and what are the costs of this compensation. To perform this analysis, compensatory measures carried out during the last ten years in the case of coastal and marine ecosystems in Florida have been addressed. The results show that: analysis criteria for the equivalencies between ecosystem services lost due to damage and ecosystem services gained due to compensatory measures are questionable; most compensation monitoring is for a relatively brief period of time and the data obtained during this period may be insufficient for assessing the net effect of the compensatory measure; the weaknesses regarding criteria for the equivalencies and the uncertainty about the relevant time-scale can be counter-balanced by increasing the area of compensation, a problematic solution at best.

Phragmites in Florida

Phragmites are a tall, perennial, wetland grasses, occurring in both fresh and brackish waters. This 3-page fact sheet discusses the three genetic lineages: native, Gulf Coast, and Eurasian; and the threat posed to Florida ecosystems by an invasion of the exotic Eurasian type. Written by W. A. Overholt, R. Diaz, M. Hanson, and D. Williams, and published by the UF Department of Entomology and Nematology, December 2011. ENY-860/IN898: Phragmites in Florida (ufl.edu)

The Herpetofauna of Lake Woodruff National Wildlife Refuge, Florida

We monitored the herpetofauna of a large conservation area in peninsular Florida from 1990 to 2010, visiting the refuge on over 2000 different days in that period and using a variety of sampling techniques. Our goals were to evaluate the species richness and abundance of herpetofauna (amphibians and reptiles) on the site. During the course of our study, we documented 72 species (22 amphibian and 50 reptile species); thus, the site has impressive species richness relative to other conservation areas in the southeastern United States. Five of the 72 species (6.9%) we found were introduced species. Continued monitoring of the diverse herpetofauna of Lake Woodruff National Wildlife Refuge could facilitate a better understanding of ongoing changes in species abundances and community assemblages occurring in the ecosystems of peninsular Florida.

Estimating the Cumulative Ecological Effect of Local Scale Landscape Changes in South Florida

Ecosystem restoration in south Florida is a state and national priority centered on the Everglades wetlands. However, urban development pressures affect the restoration potential and remaining habitat functions of the natural undeveloped areas. Land use (LU) planning often focuses at the local level, but a better understanding of the cumulative effects of small projects at the landscape level is needed to support ecosystem restoration and preservation. The South Florida Ecosystem Portfolio Model (SFL EPM) is a regional LU planning tool developed to help stakeholders visualize LU scenario evaluation and improve communication about regional effects of LU decisions. One component of the SFL EPM is ecological value (EV), which is evaluated through modeled ecological criteria related to ecosystem services using metrics for (1) biodiversity potential, (2) threatened and endangered species, (3) rare and unique habitats, (4) landscape pattern and fragmentation, (5) water quality buffer potential, and (6) ecological restoration potential. In this article, we demonstrate the calculation of EV using two case studies: (1) assessing altered EV in the Biscayne Gateway area by comparing 2004 LU to potential LU in 2025 and 2050, and (2) the cumulative impact of adding limestone mines south of Miami. Our analyses spatially convey changing regional EV resulting from conversion of local natural and agricultural areas to urban, industrial, or extractive use. Different simulated local LU scenarios may result in different alterations in calculated regional EV. These case studies demonstrate methods that may facilitate evaluation of potential future LU patterns and incorporate EV into decision making.

The effect of acclimation salinity and age on the salinity tolerance of pink shrimp postlarvae

The pink shrimp Farfantepenaeus duorarum (Burkenroad) lives in south Florida ecosystems in different salinity regimes ranging from brackish to hypersaline. In Florida Bay, the main nursery grounds, juveniles reside in 25–50 salinity; while 20 km northwest of the Bay, juveniles inhabit more estuarine salinities between 5 and 15. In this study we investigated the hypothesis that the disparate salinity regimes in which pink shrimp juveniles reside may be due to a non-genetic resistance adaptation to different acclimation salinities in their respective nursery habitats during postlarval development when the maximum tolerance to salinity occurs. To test this hypothesis and to define salinity tolerances during ontogenetic development, salinity trials were conducted with four postlarval ages (PL 15, PL 25, PL 35 and PL 55) previously acclimated in two salinities (15 and 35) and then exposed to an abrupt salinity change for 96 h at 27.5 ± 0.5 °C. Results indicated that the degree of tolerance to salinity varies with ontogenetic development. Regardless of acclimation salinity, two clearly distinguishable salinity tolerance ages were discernable. Postlarvae of age PL 35 and PL 55 exhibited significantly higher average survival than at an age of PL 15 and PL 25. This result suggests that postlarvae between 25 and 35 d old may complete development of osmoregulatory capabilities to cope with abrupt changes in salinity, which concurs with the age at which planktonic postlarvae settle on the sea-grass banks of Florida Bay. Results regarding salinity tolerances in the two acclimation salinity groups demonstrated that postlarvae acclimated in a salinity of 15 tolerated salinities 20 units lower than those acclimated in regular 35 sea water salinity. The high survival of postlarvae recorded at salinities between 2 and 15 after a long acclimation period at a salinity of 15 suggested that non-genetic resistance adaptation (acclimation) had taken place during development, supporting our hypothesis that a preconditioning salinity during postlarval development may modify the subsequent tolerance limits of juvenile stages.