South Florida Ecosystem Research Articles

Repeated Tree Inventories of Pine Forests in South Florida's Big Cypress National Preserve.

The natural forest ecosystems of South Florida, USA, support a high biodiversity of plant and animal species and provide valuable ecosystem services. However, these ecosystems remain poorly represented in global studies, primarily due to a paucity of standardized data. Here, we present previously unpublished data from 332 censuses of 54 permanent 1-ha tree inventory plots in the Racoon Point area of Big Cypress National Preserve, Florida, USA, including a total of nearly 100,000 measurements (diameter or height) of > 17,000 individual living trees and palms (with additional measurements of nearly 6000 dead pine snags) collected sporadically over a 19-year period (1993-2012). These data, which were originally collected as part of a project to investigate tree responses to different experimental burning regimes, provide unique insight into the diversity, composition, structure, and dynamics of South Florida's unique and endangered pine forest ecosystems. Data files include the species identity, size (dbh = diameter at breast height), and location of all trees ≥ 5 cm dbh in 54 individual tree plots. Additional data are provided about heights of palm trees, and the location and burn history of each plot. These data are freely available for noncommercial scientific use under a Creative Commons license; users are encouraged to cite this paper when using the data.

Population Genetic Structure of a Rare Butterfly in a Fragmented South Florida Ecosystem.

We investigated the genetic structure and diversity between populations of a rare butterfly, the Florida duskywing (Ephyriades brunnea floridensis E. Bell and W. Comstock, 1948) (Lepidoptera: Hesperiidae) across a network of South Florida pine rockland habitat fragments. Based on 81 individuals from seven populations and using multiple polymorphic microsatellite loci, our analyses support the presence of mainland Florida (peninsular) and Florida Keys (island) population groupings, with a moderate, asymmetrical gene flow connecting them, and the presence of private alleles providing unique identities to each. We additionally found that despite a prevalence in many Lepidoptera, the presence of Wolbachia was not identified in any of the samples screened. Our findings can be used to inform conservation and recovery decisions, including population monitoring, organism translocation, and priority areas for management, restoration or stepping-stone creation to help maintain the complex genetic structure of separate populations.

Understanding the ups and downs: application of hydrologic restoration measures for a large subtropical lake

Julian P II, Welch Z. 2022. Understanding the ups and downs: application of hydrologic restoration measures for a large subtropical lake. Lake Reserv Manage. 38:304–317. Hydrologic regimes in shallow lakes strongly influence the system’s function and ecology. Changes in water levels can have nonlinear, disproportionate effects in these low-gradient systems. High water levels can submerge upper elevation littoral areas, degrade benthic habitats, and redistribute sediments and nutrients throughout the lake. When water levels are low, wetland littoral areas are dried out, prompting shifts in plant communities. Lake Okeechobee, a large shallow lake, is a diverse and complex ecosystem managed for multiple purposes. Currently, water levels within the lake are managed based on the Lake Okeechobee Regulation Schedule of 2008, which is being replaced as restoration projects now are complete. The new regulation schedule, Lake Okeechobee System Operating Manual (LOSOM), updates water management rules while attempting to balance the needs of downstream systems; salinity and water quality in the Caloosahatchee and Saint Lucie estuaries; and more water for the southern Everglades. This study evaluates LOSOM relative to ecologically significant performance measures for the lake. Overall, the proposed regulation schedule is expected to cause deeper average lake levels, increased occurrence of damaging high-stage events, and reduced frequency of low-stage events. While decreases in the severity and frequency of low stages will be beneficial, increases in high stages may affect the long-term ecology of the system. As lake management shifts to optimize restoration efforts around and downstream of Lake Okeechobee, restoration projects upstream of the lake become critical to building and improving resilience in this central South Florida ecosystem.

Using mollusks as indicators of restoration in nearshore zones of south Florida's estuaries

Current south Florida ecosystem restoration efforts are focused on restoring more natural freshwater flow through the wetlands and into the estuaries to reestablish natural salinity gradients, particularly in the nearshore zones. Indicator taxa are used to monitor and assess restoration progress and the current suite of biota used for the estuaries in south Florida (Biscayne Bay, Florida Bay, and the southwest mangrove riverine system) does not include mollusks. Mollusks make excellent indicators because they are found in all south Florida environments, are relatively stationary in postlarval stages, and, therefore, do not leave a site when conditions change. Their hard shells increase the likelihood of preservation after death, thus, making it possible to assess death assemblages. In addition to these features, many mollusks can be quickly sampled in the field and assessed in the lab, so poor visibility and tidal cycles are not an issue for monitoring surveys. Here we examine 27 years of molluscan data from 887 samples from 640 visits to 167 sites in south Florida's estuaries and present a suite of taxa that could be used as indicators for restoration of the oligohaline to mesohaline (0.5 to 17.9 psu) nearshore zones. Cyrenoida floridana, Hydrobiidae, Polymesoda caroliniana, Crassostrea virginica, and additional taxa are included with suggested sampling strategies.

Setting the foundation for renewal: restoring sponge communities aids the ecological recovery of Florida Bay

AbstractCoastal ecosystems are constantly buffeted by anthropogenic forces that degrade habitats and alter ecological processes and functions; in turn, this habitat degradation diminishes the ecosystem goods and services on which humans rely. Within the last few decades, the field of restoration ecology has burgeoned into a discipline that marries scientific rigor with functional restoration practice—an idea championed by Pete Peterson and his research. Here, we describe our efforts to restore the hard‐bottom sponge communities of Florida Bay, FL (USA)—a once‐diverse subtropical lagoon severely degraded by cyanobacteria blooms—and the scientific and practical lessons learned from those efforts. Sponge community restoration yielded insights into basic sponge biology and ecology (e.g., density‐dependent growth rates) and hastened the recovery of ecological processes (e.g., rates of sedimentation, structuring of water column characteristics, soundscape productions). Because the results of our initial restoration efforts were promising, our collaboration among academic researchers, natural resource managers, and non‐governmental organizations has begun scaling up restoration efforts to re‐establish the sponge communities over large areas of degraded hard‐bottom to “jump start” the ecological recovery of Florida Bay. Though our efforts show promise for ecological recovery, restoration will require a concerted effort by scientists, resource managers, and citizens to stem the anthropogenic drivers of ecological degradation of this unique South Florida ecosystem.

Understanding the occurrence and distribution of emerging pollutants and endocrine disruptors in sensitive coastal South Florida Ecosystems

Environmental exposure risk to different xenobiotics, which can potentially alter the function of the endocrine system, remains a great health and safety concern for aquatic species and humans. Steroid hormones, pharmaceuticals and personal care products (PPCPs) have been identified as important aquatic contaminants due to their widespread occurrence in surface waters and their endocrine disrupting properties. Heavily populated areas in South Florida not served by municipal wastewater collection present an unexpected high risk of anthropogenic contaminants to nearby coastal systems through surface runoff and groundwater flow. Previous studies in South Florida have been largely concentrated on assessing the relevance of the fate and transport of inorganic nutrients, heavy metals and pesticides with regulatory criteria. Therefore, a significant gap exists in assessing occurrence, distribution and biological significance of the presence of human related organic contaminants in natural surface waters. In this study, we have developed a fast and sensitive online solid-phase extraction followed by liquid chromatography-high resolution mass spectrometry (SPE-LC-HRMS) method using a Q-Exactive system for the determination of the occurrence and distribution of selected wastewater tracers/indicators, recalcitrant PPCPs and steroid hormones in South Florida surface waters. Seasonal and spatial variations of these contaminants were monitored from 2017 to 2019. The presence of total coliforms and E. coli were also evaluated in order to further assess water quality. Correlations between hormones and anthropogenic tracers were explored to better elucidate the sources, pathways and exposure risks to these contaminants. Caffeine, sucralose, Diethyl-m-toluamide (DEET) and carbamazepine were frequently detected in the water samples, which is indicative of extensive wastewater intrusion impacting the surface water. Estrone (E1), 17-β-estradiol (E2), and 17-α-ethynylestradiol (EE2) levels found in surface water raises concern of potential endocrine disruption effects in the aquatic ecosystem. Hazard quotient has been calculated to identify areas with high ecological risks to aquatic organisms.

Untangling filamentous marine cyanobacterial diversity from the coast of South Florida with the description of Vermifilaceae fam. nov. and three new genera: Leptochromothrix gen. nov., Ophiophycus gen. nov., and Vermifilum gen. nov.

Benthic cyanobacterial mats are an integral component of aquatic communities in tropical marine waters. These mats can develop into massive nuisances at risk of expansion due to climate change. The extent of diversity occurring within these mats, still remains largely unexplored, especially in Florida. To reveal this diversity, coastal environments of South Florida were sampled and subsequently processed for isolation and systematic identification. Three new genera are proposed based on the molecular phylogeny, morphology, and ecology. These new genera are characterized by discoid cells and homocytous, unbranched filaments without sheaths. Individual genus morphological differences include either rounded bent, rounded, or conical rounded apical cells. A unique molecular fingerprint including a base pair insert within the 16S rRNA gene sequence and genetic similarities facilitates the delimitation of a novel family Vermifilaceae. Using the polyphasic approach, our research presents three new genera and four new species of marine cyanobacteria inhabiting coastal ecosystems of South Florida.

Dynamic Satellite Seascapes as a Biogeographic Framework for Understanding Phytoplankton Assemblages in the Florida Keys National Marine Sanctuary, United States

Physical, chemical, geological, and biological factors interact in marine environments to shape complex but recurrent patterns of organization of life on multiple spatial and temporal scales. These factors define biogeographic regions in surface waters that we refer to as seascapes. We characterize seascapes for the Florida Keys National Marine Sanctuary (FKNMS) and southwest Florida shelf nearshore environment using multivariate satellite and in situ measurements of Essential Ocean Variables (EOVs) and Essential Biodiversity Variables (EBVs). The study focuses on three periods that cover separate oceanographic expeditions (March 11-18, May 9-13, and September 12-19, 2016). We collected observations on bio-optical parameters (particulate and dissolved spectral absorption coefficients), phytoplankton community composition, and hydrography from a ship. Phytoplankton community composition was evaluated using 1) chemotaxonomic analysis (CHEMTAX) based on high-performance liquid chromatography (HPLC) pigment measurements, and 2) analysis of spectral phytoplankton absorption coefficients (aphy). Dynamic seascapes were derived by combining satellite time series of sea surface temperature, chlorophyll-a concentration, and normalized fluorescent line height (nFLH) using a supervised thematic classification. The seascapes identified areas of different salinity and nutrient concentrations where different phytoplankton communities were present as determined by hierarchical cluster analyses of HPLC pigments and aphy spectra. Oligotrophic, Mesotrophic and Transition seascape classes of deeper offshore waters were dominated by small phytoplankton ( 60 %). Spectral analysis of aphy indicated higher absorption levels at 492 and 550 nm wavelengths in seascapes carrying predominantly small phytoplankton than in classes dominated by larger taxa. Seascapes carrying large phytoplankton showed absorption peaks at the 673 nm wavelength. The seascape framework promises to be a tool to detect different biogeographic domains quickly, providing information about the changing environmental conditions experienced by coral reef organisms including coral, sponges, fish and higher trophic levels. The effort illustrates best practices developed under the Marine Biodiversity Observation Network (MBON) demonstration project, in collaboration with the South Florida Ecosystem Restoration Research (SFER) project managed by the Atlantic Oceanographic and Meteorological Laboratory of NOAA (AOML-NOAA).

Ciencia y gobernanza de ecosistemas con áreas naturales protegidas: el ejemplo de los Everglades (EE.UU.)

Science is key to solving the challenge of managing ecosystems for sustainable development. How do we achieve the benefits that result from the transformation and exploitation of ecosystems, and at the same time preserve ecosystem services and protected areas? In the ecosystem of the Everglades, a subtropical wetland located in South Florida (United States), an economic and environmental transformation occurred in the middle of the 20th century. Today, the Everglades Restoration Program is addressing the challenge of maintaining the benefits of the transformed ecosystem while at the same time protecting and restoring Everglades National Park. An analysis of the governance of this program highlights three important aspects of the system with respect to science. First, the primary decision-making body is the South Florida Ecosystem Restoration Task Force, a diverse group of 14 agency leads at the highest level of national, tribal, state and local government. Second, the role of science in the restoration program is written into the federal laws and regulations governing the program. Finally, all the member agencies of the Task Force employ qualified technicians and scientists whose work is to conduct, collect and synthesize scientific research. This system reduces the distance between scientists and decision makers. At the same time, the program’s governance system allows actors with less financial or political power to exercise power through their scientific results, thus achieving a balance between the economic benefits and environmental benefits of the program.

Investigating Collaborative Processes Over Time

Collaboration is commonly used to deliver public services that reach beyond the capacities of independent organizations. Much of the literature has been concerned with understanding the types of collaborative processes that are associated with successful collaboration. Yet, few scholars have studied how these design features unfold or evolve over time. We fill this gap through a study of a collaborative environmental management process—the South Florida Ecosystem Restoration Task Force—over a 10-year period. Using data coded from the Task Force’s meeting minutes, we examine three key elements of successful collaborative processes in the literature, including internal governance and administration, internal communication, and external communication. To complement our coded data, we also rely on interviews with collaborative participants and contextual information from news media and secondary sources. From our 10-year analysis, we develop propositions about the evolution of collaborative processes, which can provide a foundation for theory development and testing in other cases.

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.

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.

Oceanographic conditions in the Gulf of Mexico in July 2010, during the Deepwater Horizon oil spill

Circulation in the Gulf of Mexico (GOM) is dominated by mesoscale features that include the Loop Current (LC), Loop Current Rings (LCRs), and smaller frontal eddies. During May–June 2010, while oil was still flowing from the Macondo well following the Deepwater Horizon (DWH) platform explosion on April 20, 2010, drifter trajectories, satellite observations, and numerical simulations indicated a potential for direct connectivity between the northern Gulf and the Florida Straits via the LC system. This pathway could have potentially entrained particles, including northern GOM contaminants related to the oil spill, carrying them directly towards the coastal ecosystems of south Florida and northern Cuba. To assess this connectivity, and to evaluate the potential oil impacts on economically important GOM fisheries, an interdisciplinary shipboard survey was conducted in the eastern Gulf during July 2010. Analysis of the resulting hydrographic data confirmed that: (1) by July 2010 a large LCR had become separated from the main LC by a cyclonic eddy resulting in the loss of a direct transport mechanism from the northern GOM to the Florida Straits, leaving only indirect pathways available to potential contaminants; and (2) with the exception of four hydrographic stations occupied within 84km of the wellhead, no evidence of oil was found during the survey on the surface or within the water column. These results corroborated analysis of satellite altimetry observations of the GOM surface circulation and verified official surface oil coverage forecasts where they intersected with the survey track. This cruise sampled the LC, LCR, and frontal eddies to a depth of 2000m, with the results suggesting that any oil entrained by circulation features in prior months had either been weathered, consumed by bacteria, dispersed to undetectable levels, or was only present in unsurveyed areas. The assembled subsurface measurements represent one of only a few data sets collected across the dominant GOM mesoscale circulation features at a time when there was great concern about the potential long-range spreading of DWH related contaminants. Direct observations such as these are critical for the assessment of particle trajectory and circulation models utilized during the spill, and for the improvement of future numerical forecast products.

Marine Studies Show Potential for U.S.-Cuban Collaboration

The U.S. embargo continues to get in the way of joint research on the parallel ecosystems of Cuba and South Florida.

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.

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.

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.

A Hydrological Budget (2002–2008) for a Large Subtropical Wetland Ecosystem Indicates Marine Groundwater Discharge Accompanies Diminished Freshwater Flow

Water budget parameters are estimated for Shark River Slough (SRS), the main drainage within Everglades National Park (ENP) from 2002 to 2008. Inputs to the water budget include surface water inflows and precipitation while outputs consist of evapotranspiration, discharge to the Gulf of Mexico and seepage losses due to municipal wellfield extraction. The daily change in volume of SRS is equated to the difference between input and outputs yielding a residual term consisting of component errors and net groundwater exchange. Results predict significant net groundwater discharge to the SRS peaking in June and positively correlated with surface water salinity at the mangrove ecotone, lagging by 1 month. Precipitation, the largest input to the SRS, is offset by ET (the largest output); thereby highlighting the importance of increasing fresh water inflows into ENP for maintaining conditions in terrestrial, estuarine, and marine ecosystems of South 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.