Abstract:

Estuaries and coastal areas worldwide are rapidly changing, especially those adjacent to urban centers. Physical and ecological stresses are exacerbated by climate change (CC) and sea level rise (SLR). In this research, a salinity transport model for Biscayne Bay is presented. The model is used to estimate salinity under various scenarios of altered precipitation, increased salinity/temperature, and SLR. The simulated scenarios (based on prior studies and existing literature) assumed increases of 1.5°C in temperature, and 0.6 PSU in ocean salinity. Current precipitation was varied from −10% to +10%. SLR varied from +0.46 m to +2.18 m. The highest increase in bay salinity (worst-case scenario) occurred for 10% decrease in precipitation, and +2.18 m SLR. The lowest increase in salinity (mildest scenario) occurred for 10% increase in precipitation, and +0.46 m SLR. In the mildest scenario, a 50% increase in baseline freshwater inputs is needed to maintain currently observed Bay salinities. For the worst scenario, a 300% freshwater increase would be required. Current Everglades Restoration plans to restore the Bay salinity to “natural” conditions must consider the potential CC-induced effects simulated in this research. Present efforts may not be sufficient to even maintain current salinity conditions in Biscayne Bay. Increasing urban vegetation (urban greening), artificial groundwater recharge with treated wastewater, and decreasing water consumption, are proposed as management measures for reinforcing current and future restoration efforts.

Abstract:

Salinity in estuaries varies naturally due to tides, weather, geomorphology, freshwater flow, climate, and sea level. Before the 1950s, water management in southern Florida focused on diverting freshwater to the ocean to make historic wetlands more amenable to development and to protect human life. However, current water management activities aim to restore wetlands and estuaries while maintaining flood control and drinking water for the human population. Due to anthropogenic alteration, the spatiotemporal variability in salinity within Biscayne Bay, Florida, is a significant concern for ecosystem restoration under the Comprehensive Everglades Restoration Plan (CERP). This study aims to analyze daily seasonal salinity trends within the Bay and quantify the change in salinity per year (salinity slope). Salinity data, collected at 30 stations within the central and southern regions of Biscayne Bay over 16 years (2005–2020), were examined for trends. The nonparametric seasonal Kendall trend test, at a 0.05 significance level, was used for the analysis. Results of the trend analysis show that salinity slopes were consistently positive (indicating increasing salinity over time) in the southern portion of the study area and negative (indicating decreasing salinity over time) in the northern portion of the study area. Throughout the study region, most salinity slopes were positive in the wet season and negative in the dry season. The study results show trends in seasonal salinity, which helps in understanding changes in this region. This study will aid future management efforts within Biscayne Bay.

Abstract:

Coral cover has declined worldwide due to anthropogenic stressors that manifest on both global and local scales. Coral communities that exist in extreme conditions can provide information on how these stressors influence ecosystem structure, with implications for their persistence under future conditions. The Port of Miami is located within an urbanized environment, with active coastal development, as well as commercial shipping and recreational boating activity. Monitoring of sites throughout the Port since 2018 has revealed periodic extremes in temperature, seawater pH, and salinity, far in excess of what have been measured in most coral reef environments. Despite conditions that would kill many reef species, we have documented diverse coral communities growing on artificial substrates at these sites—reflecting remarkable tolerance to environmental stressors. Furthermore, many of the more prevalent species within these communities are now conspicuously absent or in low abundance on nearby reefs, owing to their susceptibility and exposure to stony coral tissue loss disease. Natural reef frameworks, however, are largely absent at the urban sites and while diverse fish communities are documented, it is unlikely that these communities provide the same goods and services as natural reef habitats. Regardless, the existence of these communities indicates unlikely persistence and highlights the potential for coexistence of threatened species in anthropogenic environments, provided that suitable stewardship strategies are in place.

Abstract:

Ocean acidification (OA) threatens coral reef persistence by decreasing calcification and accelerating the dissolution of reef frameworks. The carbonate chemistry of coastal areas where many reefs exist is strongly influenced by the metabolic activity of the underlying benthic community, contributing to high spatiotemporal variability. While characterizing this variability is difficult, it has important implications for the progression of OA and the persistence of the ecosystems. Here, we characterized the carbonate chemistry at 38 permanent stations located along 10 inshore-offshore transects spanning 250 km of the Florida Coral Reef (FCR), which encompass four major biogeographic regions (Biscayne Bay, Upper Keys, Middle Keys, and Lower Keys) and four shelf zones (inshore, mid-channel, offshore, and oceanic). Data have been collected since 2010, with approximately bi-monthly periodicity starting in 2015. Increasing OA, driven by increasing DIC, was detected in the mid-channel, offshore, and oceanic zones in every biogeographic region. In the inshore zone, however, increasing TA counteracted any measurable OA trend. Strong seasonal variability occurred at inshore sites and included periods of both exacerbated and mitigated OA. Seasonality was region-dependent, with greater variability in the Lower and Middle Keys. Elevated pH and aragonite saturation states (Ω_Ar) were observed in the Upper and Middle Keys, which could favor reef habitat persistence in these regions. Offshore reefs in the FCR could be more susceptible to global OA by experiencing open-ocean-like water chemistry conditions. By contrast, higher seasonal variability at inshore reefs could offer a temporary OA refuge during periods of enhanced primary production.

Abstract:

Southeast Florida (SF) is among the most vulnerable regions to sea-level rise in the United States of America. The consequences associated with sea-level rise (SLR) are already apparent, including coastal inundation and erosion. The Coral Gables Canal watershed is located in SF and can be considered representative of the effects of combined mean and extreme SLR. In this research, the effect of concurrent mean and extreme sea-level rise on coastal inundation in the Coral Gables Canal watershed is explored. A three-dimensional hydrodynamic model for Biscayne Bay and the Coral Gables Canal is presented. The model is used to estimate water surface elevations throughout the model domain, and map inundation due to an extreme water-level event (Irma Hurricane) occurring alongside mean SLR scenarios. A comparison of the inundation coverage calculated in this research to estimations made by several online tools shows that the online simulators underestimate flooding areas by 72% to 85%. This is a consequence of underpredicting maximum water surface elevations occurring under combined SLR in the Coral Gables Canal. The model predicts that under the NOAA Intermediate High SLR scenario (year 2100), 40% of the CGC watershed will be inundated (water depths > 0.6 m), and 70% of the area will be flooded with water depths greater than 1.6 m in year 2120. Under the NOAA High SLR scenario at least 70% of the Coral Gables Canal watershed would be inundated in 2100 (water depths > 1.0 m). In year 2120, 90% of inland sub-basins will be flooded (0.6 m < depths < 2.2 m). These results are significant for planning flooding/inundation risk management strategies.

Abstract:

Interdisciplinary science and environmental management involve bringing together data and expertise at multiple spatial scales. The most challenging part of merging scales is aligning the scale of inquiry with the research application. Through the Louisiana case study relating wetland loss and commercial fishing, we examine how the nature and strength of the relationship changes depending on the scale of investigation. Resulting management implications also vary because of tradeoffs in choosing the scale of inquiry. State-level fisheries managers may miss effects of wetland loss in fishing communities because they are looking at aggregate data. Scientific information must directly address the constituent scale, where managers can enact policy. The case study demonstrates why scalar considerations should be an explicit part of the planning process for both science and management.

Abstract:

Macrophyte foundation species provide both habitat structure and primary production, and loss of these habitats can alter species interactions and lead to changes in energy flow in food webs. Extensive seagrass meadows in Florida Bay have recently experienced a widespread loss of seagrass habitat due to a Thalassia testudinum mass mortality event in 2015 associated with prolonged hypersalinity and bottom-water anoxia. Using stable isotope analysis paired with Bayesian mixing models, we investigated the basal resource use of seven species of seagrass-associated consumers across Florida Bay in areas affected by the 2015 seagrass die-off. Three years after the die-off, basal resource use did not differ for species collected inside and outside the die-off affected areas. Instead, consumers showed seasonal patterns in basal resource use with seagrass the most important in the wet season (58%), while epiphytes were the most important in the dry season (44%). Additionally, intraspecific spatial variability in resource use was lower in the wet season compared to the dry season. We were unable to detect a legacy effect of a major disturbance on the basal resource use of the most common seagrass-associated consumers in Florida Bay. 

Abstract:

Microzooplankton are considered the primary consumers of phytoplankton in marine environments. Microzooplankton grazing rates on phytoplankton have been studied across the globe, but there are still large regions of the ocean that are understudied, such as sub-tropical coastal oceans. One of these regions is the coastal area around south Florida, USA. We measured microzooplankton grazing rates in two distinct environments around south Florida; the oligotrophic Florida Keys and the mesotrophic outflow from the Everglades. For 2-years from January 2018 to January 2020, we set up 55 dilution and light-dark bottle experiments at five stations to estimate the microzooplankton community grazing rate, instantaneous phytoplankton growth rate, and primary production. Our results suggest that microzooplankton are consuming a higher proportion of the primary production near the Everglades outflow compared to the Florida Keys. We also found that changes in phytoplankton growth rates are disconnected from changes in the microzooplankton grazing rates in the Florida Keys. Overall, the data from the Everglades outflow is what would be expected based on global patterns, but factors other than microzooplankton grazing are more important in controlling phytoplankton biomass in the Florida Keys. 

Abstract:

Harmful algal blooms (HABs) caused by the dinoflagellate Karenia brevis on the West Florida Shelf have become a nearly annual occurrence causing widespread ecological and economic harm. Effects range from minor respiratory irritation and localized fish kills to large-scale and long-term events causing massive mortalities to marine organisms. Reports of hypoxia on the shelf have been infrequent; however, there have been some indications that some HABs have been associated with localized hypoxia. We examined oceanographic data from 2004 to 2019 across the West Florida Shelf to determine the frequency of hypoxia and to assess its association with known HABs. Hypoxia was present in 5 of the 16 years examined and was always found shoreward of the 50-meter bathymetry line. There were 2 clusters of recurrent hypoxia: midshelf off the Big Bend coast and near the southwest Florida coast. We identified 3 hypoxic events that were characterized by multiple conductivity, temperature, and depth (CTD) casts and occurred concurrently with extreme HABs in 2005, 2014, and 2018. These HAB-hypoxia events occurred when K. brevis blooms initiated in early summer months and persisted into the fall likely driven by increased biological oxygen demand from decaying algal biomass and reduced water column ventilation due to stratification. There were also four years, 2011, 2013, 2015, and 2017, with low dissolved oxygen located near the shelf break that were likely associated with upwelling of deeper Gulf of Mexico water onto the shelf. We had difficulty in assessing the spatiotemporal extent of these events due to limited data availability and potentially unobserved hypoxia due to the inconsistent difference between the bottom of the CTD cast and the seafloor. While we cannot unequivocally explain the association between extreme HABs and hypoxia on the West Florida Shelf, there is sufficient evidence to suggest a causal linkage between them. 

Abstract:

The Soil and Water Assessment Tool (SWAT) is a watershed to river basin-scale model widely used to simulate the quality and quantity of surface water and groundwater. SWAT has been applied in a wide variety of geographical landscapes around the world. This review presents a comprehensive summary of SWAT applications for coastal watersheds. Thirty-four papers were identified as coastal applications of SWAT, which accounts for 3% of the total published studies using SWAT. The Nash–Sutcliffe efficiency was the most common evaluation criteria used to evaluate SWAT simulations. The SWAT model calibration and validation studies in the coastal watershed reported higher NSE values for monthly flow simulation (NSE up to 0.95) than daily flow simulation (NSE up to 0.89). Among all the studies, 34% of the reported NSE (flow and water quality combined) values were >0.75. The majority (58%) of flow values were reported daily, whereas the majority (81%) of water quality values were reported monthly. To account for tide-storm surge processes only two applications combined SWAT with a hydrodynamic model. SWAT may be applied more readily and successfully to coastal watersheds if a user-friendly method is developed for coupling SWAT with hydrodynamic models to simulate the tidal influence.

Abstract:

In response to calls for marine ecosystem-based management (EBM), the U.S. National Oceanic and Atmospheric Administration (NOAA) developed a multidisciplinary science support framework called integrated ecosystem assessment (IEA). The IEA framework and a national NOAA program for implementing that framework were the culmination of many efforts in the 2000s. At a recent workshop, five leaders from the early days of NOAA IEA development participated in a panel to discuss the history of the framework and program, and to provide recommendations for future work. Panelists intended IEA to be a call to action for scientists and agencies to support EBM, and they designed the framework to be adaptable, scalable, and non-prescriptive so that it could be applied to a range of issues. Panelists emphasized the complementary nature of the processes, tools, and products that make up IEA efforts, and also stressed the need to adapt the IEA approach to shifting management and governance structures. Finally, panelists offered a range of recommendations for future development of the IEA approach, including: (1) broadening the stakeholder base; (2) developing objectives and reference points in partnership with end-users; (3) increasing diversity of IEA practitioners to better reflect the communities that IEA serves; (4) increasing development of readily updatable, real-time products; (5) carefully assessing and prioritizing the demands placed on IEA practitioners; (6) increasing collaboration across disciplines and resource sectors; (7) seeking opportunities to engage with emerging governance structures; and (8) strengthening support for IEA by effectively communicating its stories.

Abstract:

The ecosystem‐based fisheries management (EBFM) framework has a solid theoretical justification and has been embraced in principle by many regions; yet, systematic implementation remains a challenge. In regions with strong governance, single‐species stock assessment and management has been successful in ending overfishing and maintaining stocks near levels that produce maximum catches. However, considering species in isolation and recognizing a limited set of management objectives leads to systemic inefficiencies, incentivizes waste and generates unintended consequences. To avoid undesirable outcomes, human values and needs must be positioned at the forefront of management, system‐level objectives must be identified, and management actions must be systematically evaluated to ensure they are contributing to those larger objectives. Such processes, when implemented transparently, will lead to reduced conflict and improved stakeholder support for governance and should greatly facilitate long‐term management. We argue here that, regardless of the management framework adopted, we inherently manage at the ecosystem level—albeit sometimes “blindly”—and that increased attention to ecosystem objectives and trade‐offs will improve management outcomes.

Abstract:

The spotted seatrout, Cynoscion nebulosus, is an important recreational sportfish in Florida Bay and spends its entire life history within the Bay (Rutherford et al., 1989). The geographic distribution of juvenile (20-100 mm standard length, 35-100 days old) C. nebulosus within the bay varies in response to salinity conditions, seagrass characteristics, and sediment types (Thayer and Chester, 1989). This and other findings clearly show that juvenile spotted seatrout are a good ecosystem indicator that is directly responsive to changes in freshwater runoff from the Everglades to Florida Bay. Plans to restore the Everglades are centered on continued increases in freshwater flows to Florida Bay in the future. These changes in freshwater flow are likely to impact sportfish populations in Florida Bay by affecting seatrout physiology and recruitment, as well as habitat, predator, and prey distributions. This report describes reference conditions that can be used as a baseline to evaluate trends in juvenile spotted seatrout populations and compares current year juvenile spotted seatrout population metrics and environmental parameters with data sets from 2004-2019. The report describes juvenile abundance, as well as compares differences in abundance throughout the bay; examines the relationship between juvenile spotted seatrout abundance to salinity and seagrass habitat to provide insight into the potential response of spotted seatrout to CERP implementation; and determines salinity preferences for other juvenile sportfish in Florida Bay. This project will help better predict juvenile sportfish responses to modifications in the timing, distribution, and quantity of freshwater inflow to Florida Bay and provide information to the adaptive management process on ecological effects in Florida Bay. Continued monitoring also provides insight on the effect of storms and other ­environmental events on sportfish distribution and abundance in Florida Bay. This project is a component of the Restoration Coordination and Verification (RECOVER) Monitoring and Assessment Plan of the Comprehensive Everglades Restoration Program (CERP).

Abstract:

The spotted seatrout, Cynoscion nebulosus, is an important recreational sportfish in Florida Bay and spends its entire life history within the bay (Rutherford et al., 1989). The geographic distribution of juvenile (20-100 mm standard length, 35-100 days old) C. nebulosus within the bay varies in response to salinity conditions, seagrass characteristics, and sediment types (Thayer and Chester, 1989). This and other findings clearly show that juvenile spotted seatrout are a good ecosystem indicator that is directly responsive to changes in freshwater runoff from the Everglades to Florida Bay. Plans to restore the Everglades are centered on continued increases in freshwater flows to Florida Bay in the future. These changes in freshwater flow are likely to impact sportfish populations in Florida Bay by affecting seatrout physiology and recruitment, as well as habitat and predator-prey distributions. This report describes reference conditions that can be used as a baseline to evaluate trends in juvenile spotted seatrout populations and compares current year juvenile spotted seatrout population metrics and environmental parameters with datasets from 2004-2018. The report describes juvenile abundance, as well as compares differences in abundance throughout the bay; examines the relationship between juvenile spotted seatrout abundance to salinity and seagrass habitat to provide insight into the potential response of spotted seatrout to Comprehensive Everglades Restoration Program (CERP) implementation; and determines salinity preferences for other juvenile sportfish in Florida Bay. This project will help better predict juvenile sportfish responses to modifications in the timing, distribution, and quantity of freshwater inflow to Florida Bay and provide information to the adaptive management process on ecological effects in Florida Bay. Continued monitoring also provides insight on the effect of storms and other ­environmental events on sportfish distribution and abundance in Florida Bay. This project is a component of the Restoration Coordination and Verification (RECOVER) Monitoring and Assessment Plan of CERP.

Abstract:

In the marine science community of practice, the concept of ecosystem-based management (EBM) is a management strategy that incorporates the entire ecosystem, including humans, into resource management decisions and is growing in its use to integrate and manage complex social and marine ecosystems. The National Oceanic and Atmospheric Administration’s (NOAA) Integrated Ecosystem Assessment (IEA) program uses a multidisciplinary framework to help advance EBM and to manage marine resources in an ecosystem context. NOAA has conducted integrated ecosystem assessment research for many years, however, 2020 was the 10-year anniversary of implementation of NOAA’s formal IEA framework around the country. This Coastal Management Journal special issue discusses the ten-plus years of IEA experiences with perspectives about and successes in the development and implementation of the NOAA IEA approach. This volume on the NOAA IEA program comprises six manuscripts ranging in content from the history and origin of IEAs in NOAA, to the development and application of IEA components to advance the tenets of EBM in coastal and marine environments.

Abstract:

Ecosystem indicators are a well-established method for tracking ecosystem conditions and trends with the purpose of informing ecosystem-based management. The selection of indicators is a key step in the management process; however, because 1) selection can be inherently subjective 2) researchers can be entrenched in the ecosystem components they routinely measure, and 3) some voices may be marginalized in a group setting, the selection, prioritization, and consensus processes can be challenging. To overcome these issues, an indicator selection process was developed herein that incorporated expert opinion both qualitatively and quantitatively. The decision matrix asked experts to provide weighted values for each selection criterion and a score of how well each potential indicator fit each criterion. The score of how well the indicators fit the criterion was multiplied by the weight given to that criterion, then summed for all criteria, resulting in an overall score of how well a potential indicator fit the criteria. The indicator scores were then ranked using all experts’ scores to develop a single best-fit list of indicators. The approach was pilot-tested to select indicators for the Florida Keys National Marine Sanctuary (FKNMS), creating a prioritized list of indicators that best reflected the condition of the FKNMS resources, ecosystem services, and pressures. Specifically, 56 indicators were found to best model the status and trends associated with 16 standard questions regarding condition of national marine sanctuaries. This process is directly transferable to other national marine sanctuaries, and also identifies data gaps. The criteria can be modified to make the selection process applicable to a wide range of ecosystem-based management applications in both marine and terrestrial ecosystems. This method provides a means of selecting indicators that minimizes the effects of group dynamics on consensus.

Abstract:

Qualitative Network Models (QNMs), Fuzzy Cognitive Maps (FCMs), and Bayesian Belief Networks (BBNs) have been proposed as methods to formalize conceptual models of social–ecological systems and project system responses to management interventions or environmental change. To explore how these different methods might influence conclusions about system dynamics, we assembled conceptual models representing three different coastal systems, adapted them to the network approaches, and evaluated outcomes under scenarios representing increased fishing effort and environmental warming. The sign of projected change was the same across the three network models for 31–60% of system variables on average. Pairwise agreement between network models was higher, ranging from 33 to 92%; average levels of similarity were comparable between network pairs. Agreement measures based on both the sign and strength of change were substantially worse for all model comparisons. These general patterns were similar across systems and scenarios. Different outcomes between models led to different inferences regarding trade-offs under the scenarios. We recommend deployment of all three methods, when feasible, to better characterize structural uncertainty and leverage insights gained under one framework to inform the others. Improvements in precision will require model refinement through data integration and model validation.

Abstract:

Seagrasses are threatened worldwide due to anthropogenic and natural disturbances disrupting the multiple feedbacks needed to maintain these ecosystems. If the disturbance is severe enough, seagrass systems may undergo a regime shift to a degraded system state that is resistant to recovery. In Florida Bay, Florida, USA, two recent, large-scale disturbances (a drought-induced seagrass die-off in 2015 and Hurricane Irma in 2017) have caused 8777 ha of seagrass beds to degrade into a turbid, unvegetated state, causing a large sediment plume. Using satellite imagery digitization and long-term seagrass cover data, we investigate the expansion of this sediment plume between 2008 and 2020 and the potential interaction of this sediment plume with seagrass recovery in two focal basins in Florida Bay affected by the die-off, Johnson and Rankin. The average size of the sediment plume increased by 37% due to the die-off and Hurricane Irma, increasing from an average of 163.5 km² before the disturbances to an average of 223.5 km². The expansion of the plume was basin-specific, expanding into Johnson after the 2015 seagrass die-off with expansive and long-lasting effects, but only expanding into Rankin after Hurricane Irma with less severe and short-term effects. Furthermore, the sediment plume was negatively correlated with seagrass cover in Johnson, but held no relationship with seagrass cover in Rankin. Thus, different disturbances can act upon seagrass ecosystems at varying scales with varying consequences. These findings highlight the importance of investigating disturbances of seagrass ecosystems at various scales to increase seagrass resilience against future extreme events.

Abstract:

Science-based natural resource management is necessary for agencies to effectively meet their goals and mandates. However, this scientific basis needs to be advanced and evolved with ecosystems experiencing unprecedented events that challenge conventional management frameworks. Effectively managing marine resources and achieving agency missions requires more than meeting independent mandates and managing individual resources as chronic stressors overwhelm conventional management frameworks. Global science organizations are transitioning to interdisciplinary and holistic research to integrate human well-being as a key outcome. The United States’ principal federal agency tasked with managing coastal and marine ecosystems is the National Oceanic and Atmospheric Administration (NOAA). NOAA’s vision is “healthy ecosystems, communities and economies that are resilient in the face of change.” NOAA adopted the Integrated Ecosystem Assessment (IEA) approach to conduct the collaborative science necessary for ecosystem-based management. IEAs have been employed for over a decade to develop science, tools, and collaborations that address complex ecosystem challenges and make progress toward NOAA’s vision. This paper demonstrates, through case studies, how scientists, stakeholders, and managers build trust and meaningful relationships from the IEA approach. These case studies further demonstrate how the IEA approach can be adapted to various geographic and management scales to build trust with partners and provide the ecosystem science, including social science, required to build resilient coastal ecosystems, communities, and economies.

Abstract:

The Gulf of Mexico NOAA Integrated Ecosystem Assessment Program seeks to provide scientific knowledge of the Florida Keys National Marine Sanctuary integrated ecosystem with the aim of supporting Ecosystem-Based Management, and transfering that knowledge to scientists and managers. The purpose of this report is to provide a broad, interdisciplinary overview of the condition and status of ecosystem and human activity components of the Florida Keys National Marine Sanctuary (FKNMS), with respect to recent and historical trends. In order to understand the status and trends of the condi­tion and current state of FKNMS, a suite of indicators, in accordance with the Sanctuary Condition Report sections and questions, was developed and vetted via qualitative and quantitative processes and is presented in this report. The public time series data available on these indicators were requested and sourced via our team of experts, and status and trend analyses were completed and graphed in order to illustrate long term and recent changes in socioeconomic and ecological conditions of the marine resources in the Florida Keys National Marine Sanctuary.

Abstract:

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 (a_phy). 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 a_phy spectra. Oligotrophic, Mesotrophic, and Transition seascape classes of deeper offshore waters were dominated by small phytoplankton (<2 μm; ∼40–60% of total cell abundance). In eutrophic, optically shallow coastal seascapes influenced by fresh water discharge, the phytoplankton was dominated by larger taxa (>60%). Spectral analysis of a_phy 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).

Abstract:

The short-term (< 6 months) effects of Hurricane Irma on water quality and phytoplankton community structure were assessed in Biscayne Bay and the adjacent coastal canals from September 2017 through January 2018. The bay experienced sharp fluctuations in daily average salinity and salinity gradients during the passage of the hurricane and significant decreases in salinity as a result of increased freshwater inflows that followed the hurricane (148.2% increase in total inflows in the first week after the hurricane compared to a week before). These decreases were most pronounced in southern and south-central parts of the bay, which experienced the largest post-hurricane increases in freshwater inflows (349.4% and 103.1% in southern and south-central parts of the bay, respectively). Storm-induced increases in inorganic nutrient concentrations stimulated phytoplankton growth in northern, north-central, and southern parts of the bay. Opportunistic phytoplankton taxonomic groups such as chlorophytes and cyanobacteria dominated the total algal biomass pool in the canals, and northern and southern parts of the bay in the weeks following the storm, but they were gradually outcompeted by diatoms in the following months. Changes in spatial-temporal phytoplankton community structure in the months following Hurricane Irma reflect recovery and return to usual seasonal patterns. The effect of Hurricane Irma on water quality and phytoplankton communities was short-lived (< 3 months), suggesting that Biscayne Bay is resilient to tropical cyclones.

Abstract:

Hurricanes are important ecological disturbances that maintain biodiversity. We investigated the short-term impacts of Hurricane Irma, a category 4 storm that passed through south Florida on September 10, 2017, on fish and macroinvertebrate communities of western and north-central Florida Bay, FL, USA. Spatiotemporal trends in physical water conditions (temperature, salinity, water depth, dissolved oxygen, chlorophyll a, and turbidity) as well as rainfall and coastal discharge were assessed to characterize hurricane-induced habitat changes. Dramatic but ephemeral changes in water depth and rainfall were observed. Longer lasting reductions of salinity regime and increases in turbidity and chlorophyll a were also observed. The prevailing hypersalinity (≥ 40 ppt) conditions, ongoing since March 2017, were abruptly ended by the storm. Hurricane Irma significantly altered fish and macroinvertebrate communities. Analysis of community spatiotemporal trends revealed spatially distinct temporal community shifts. Cluster analysis distinguished four groups among nine highly abundant species identified as exerting the most influence on pre- and post-hurricane total community differences. Reductions in relative abundance of two groups were coincident with Irma’s passage while a third group, comprised solely of pelagic, zooplanktivorous Anchoa mitchilli, exhibited rapid population growth that started 2 months after the passage of the storm. These faunal disruptions are reminiscent of a prior Florida Bay community shift that followed a similar sequence of consecutive disturbances: hypersalinity, seagrass die-off, and a category-5 hurricane. Recovery from this prior community shift cascade took many years.

Abstract:

Widespread and persistent Ecosystem Disruptive Algal Blooms dominated by marine picocyanobacteria (Synechococcus) commonly occur in the subtropical lagoonal estuary of Florida Bay (U.S.A). These blooms have been linked to a decline in natural sheet flow over the past century from upstream Everglades National Park. Remote sensing algorithms for monitoring cyanobacteria blooms are highly desired but have been mainly developed for freshwater and coastal systems with minimal bottom reflectance contributions in the past. Examination of in situ optical properties revealed that Synechococcus blooms in Florida Bay exhibit unique spectral absorption and reflectance features that form the basis for algorithm development. Using a large, multi-year match-up dataset (2002–2012; n = 682) consisting of in situ pigment concentrations and Moderate Resolution Imaging Spectroradiometer (MODIS) Rayleigh-corrected reflectance (R_rc(λ)), classification criteria for detecting cyanobacteria blooms with chlorophyll-a concentrations (Chl-a) ~5–40 mg m⁻³ were determined based on a new approach to combine the MODIS Cyanobacteria Index, CI_MODIS, and spectral shape around 488 nm, SS(488). The inclusion of SS(488) was required to prevent false positive classifications in seagrass-rich, non-bloom waters with high bottom reflectance contributions. 75% of cyanobacteria blooms were classified accurately based on this modified CI approach with <1% false positives. A strong correlation observed between cyanobacteria bloom in situ Chl-a and CI_MODIS (r² = 0.80, n = 32) then allowed cyanobacterial chlorophyll-a concentrations (Chl_CI) to be estimated. Model simulations and image-based analyses showed that this technique was insensitive to variable aerosol properties and sensor viewing geometry. Application of the approach to the entire MODIS time-series (2000–present) may help identify factors controlling blooms and system responses to ongoing management efforts aimed at restoring flow to pre-drainage conditions. The method may also provide insights for algorithm development for other lagoonal estuaries that experience similar blooms.

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Abstract:

Anthropogenic eutrophication threatens numerous aquatic ecosystems across the globe. Proactive management that prevents a system from becoming eutrophied is more effective and cheaper than restoring a eutrophic system, but detecting early warning signs and problematic nutrient sources in a relatively healthy system can be difficult. The goal of this study was to investigate if rates of change in chlorophyll a and nutrient concentrations at individual stations can be used to identify specific areas that need to be targeted for management. Biscayne Bay is a coastal embayment in southeast Florida with primarily adequate water quality that has experienced rapid human population growth over the last century. Water quality data collected at 48 stations throughout Biscayne Bay over a 20-year period (1995–2014) were examined to identify any water quality trends associated with eutrophication. Chlorophyll a and phosphate concentrations have increased throughout Biscayne Bay, which is a primary indicator of eutrophication. Moreover, chlorophyll a concentrations throughout the northern area, where circulation is restricted, and in nearshore areas of central Biscayne Bay are increasing at a higher rate compared to the rest of the Bay. This suggests increases in chlorophyll a are due to local nutrient sources from the watershed. These areas are also where recent seagrass die-offs have occurred, suggesting an urgent need for management intervention. This is in contrast with the state of Florida listing of Biscayne Bay as a medium priority impaired body of water.

Abstract:

Environmental DNA (eDNA) is the DNA suspended in the environment (e.g., water column), which includes cells, gametes, and other material derived from but not limited to shedding of tissue, scales, mucus, and fecal matter. Amplifying and sequencing marker genes (i.e., metabarcoding) from eDNA can reveal the wide range of taxa present in an ecosystem through analysis of a single water sample. Metabarcoding of eDNA provides higher resolution data than visual surveys, aiding in assessments of ecosystem health. This study conducted eDNA metabarcoding of two molecular markers (cytochrome c oxidase I (COI) and 18S ribosomal RNA (rRNA) genes) to survey eukaryotic diversity across multiple trophic levels in surface water samples collected at three sites along the coral reef tract within the Florida Keys National Marine Sanctuary (FKNMS) during four research cruises in 2015. The 18S rRNA gene sequences recovered 785 genera while the COI gene sequences recovered 115 genera, with only 33 genera shared between the two datasets, emphasizing the complementarity of these marker genes. Community composition for both genetic markers clustered by month of sample collection, suggesting that temporal variation has a larger effect on biodiversity than spatial variability in the FKNMS surface waters. Sequences from both marker genes were dominated by copepods, but each marker recovered distinct phytoplankton groups, with 18S rRNA gene sequences dominated by dinoflagellates and COI sequences dominated by coccolithophores. Although eDNA samples were collected from surface waters, many benthic species such as sponges, crustaceans, and corals were identified. These results show the utility of eDNA metabarcoding for cataloging biodiversity to establish an ecosystem baseline against which future samples can be compared in order to monitor community changes.

Abstract:

The Gulf of Mexico is an ecologically and economically important marine ecosystem that is affected by a variety of natural and anthropogenic pressures. These complex and interacting pressures, together with the dynamic environment of the Gulf, present challenges for the effective management of its resources. The recent adoption of Bayesian networks to ecology allows for the discovery and quantification of complex interactions from data after making only a few assumptions about observations of the system. In this study, we apply Bayesian network models, with different levels of structural complexity and a varying number of hidden variables to account for uncertainty when modeling ecosystem dynamics. From these models, we predict focal ecosystem components within the Gulf of Mexico. The predictive ability of the models varied with their structure. The model that performed best was parameterized through data-driven learning techniques and accounted for multiple ecosystem components’ associations and their interactions with human and natural pressures over time. Then, we altered sea surface temperature in the best performing model to explore the response of different ecosystem components to increased temperature. The magnitude and even direction of predicted responses varied by ecosystem components due to heterogeneity in driving factors and their spatial overlap. Our findings suggest that due to varying components’ sensitivity to drivers, changes in temperature will potentially lead to trade-offs in terms of population productivity. We were able to discover meaningful interactions between ecosystem components and their environment and show how sensitive these relationships are to climate perturbations, which increases our understanding of the potential future response of the system to increasing temperature. Our findings demonstrate that accounting for additional sources of variation, by incorporating multiple interactions and pressures in the model layout, has the potential for gaining deeper insights into the structure and dynamics of ecosystems.

Abstract:

A picophytoplankton bloom dominated by Synechococcus formed in September 2005 in a series of shallow lagoons between Florida Bay and Biscayne Bay and lasted until May 2008. Chlorophyll-a concentrations peaked at >20 µg L⁻¹. The bloom coincided with a massive mortality of sponges and caused massive mortality of the seagrass. However, follow-up analysis to determine if there were any long-term impacts from the bloom on the system is lacking. We used long-term water quality data (chlorophyll-a and nutrient concentrations) collected at 13 stations in the affected region over a 20-yr period to compare environmental conditions before (1995–2004) and after (2009–2014) the bloom. We found that after the bloom, baseline chlorophyll-a concentration significantly increased 45%, from 0.42 (SE 0.02) to 0.77 (SE 0.04) µg chl a L⁻¹, at the stations most impacted by the bloom. Before-After Control-Impact paired analysis suggested these changes were related to the 3-yr bloom and not a larger, regional scale shift. The increase in chlorophyll-a does not appear to be associated with additional changes in water quality, but is potentially due to a reduction in the epibenthic community (e.g., SAV and sponges). Now that the bloom has terminated and the causes of the bloom abated, the system has not returned to its original status, suggesting a lasting impact from the bloom on the ecosystem.

Abstract:

Measurements of the status and trends of key indicators for the ocean and marine life are required to inform policy and management in the context of growing human uses of marine resources, coastal development, and climate change. Two synergistic efforts identify specific priority variables for monitoring: Essential Ocean Variables (EOVs) through the Global Ocean Observing System (GOOS), and Essential Biodiversity Variables (EBVs) from the Group on Earth Observations Biodiversity Observation Network (GEO BON) (see Data Sheet 1 in Supplementary Materials for a glossary of acronyms). Both systems support reporting against internationally agreed conventions and treaties. GOOS, established under the auspices of the Intergovernmental Oceanographic Commission (IOC), plays a leading role in coordinating global monitoring of the ocean and in the definition of EOVs. GEO BON is a global biodiversity observation network that coordinates observations to enhance management of the world's biodiversity and promote both the awareness and accounting of ecosystem services. Convergence and agreement between these two efforts are required to streamline existing and new marine observation programs to advance scientific knowledge effectively and to support the sustainable use and management of ocean spaces and resources. In this context, the Marine Biodiversity Observation Network (MBON), a thematic component of GEO BON, is collaborating with GOOS, the Ocean Biogeographic Information System (OBIS), and the Integrated Marine Biosphere Research (IMBeR) project to ensure that EBVs and EOVs are complementary, representing alternative uses of a common set of scientific measurements. This work is informed by the Joint Technical Commission for Oceanography and Marine Meteorology (JCOMM), an intergovernmental body of technical experts that helps international coordination on best practices for observing, data management and services, combined with capacity development expertise. Characterizing biodiversity and understanding its drivers will require incorporation of observations from traditional and molecular taxonomy, animal tagging and tracking efforts, ocean biogeochemistry, and ocean observatory initiatives including the deep ocean and seafloor. The partnership between large-scale ocean observing and product distribution initiatives (MBON, OBIS, JCOMM, and GOOS) is an expedited, effective way to support international policy-level assessments (e.g., the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services or IPBES), along with the implementation of international development goals (e.g., the United Nations Sustainable Development Goals).

Abstract:

The aim of ecosystem-based management (EBM) is to maintain an ecosystem in a healthy, productive, and resilient condition through the implementation of policies and management measures. Although cross-sectoral planning may be led by a planning competent authority, it is up to the sector competent authority to implement the necessary management measures within their operations to achieve EBM goals and objectives. We suggest that scientific impediments to EBM are no longer significant to implement EBM operationally. Instead, we consider that approaching EBM within current policy cycle approaches would provide the necessary policymaking process step to operationalize EBM. In addition to enabling and facilitating collaboration, exchange, understanding as promoted by EBM, policymaking processes also require that policy is to be implemented through programs, measures, procedures and controls that have expected outcomes to “carry into effect” the policy objective. We are of the view that moving EBM from planning and objective setting to operational implementation is a management problem solving issues instead of a scientific one.

Abstract:

The Integrated Ecosystem Assessment (IEA) approach was designed to assimilate scientific knowledge in the ideal format for providing advice to inform marine Ecosystem-Based Management (EBM). As such, IEAs were envisioned as the cornerstone integrated science product for the US National Oceanic and Atmospheric Administration (NOAA) that would maximize efficiencies and synergies across the agency’s ecosystem science efforts. This led to the development of a NOAA IEA Program that would oversee regional implementation of the national IEA framework. As implementation proceeded, uptake by management entities was slower than anticipated, in part because EBM was not quickly embraced and applied to achieve management objectives. This slow movement to EBM in conjunction with the need to develop scientific analyses and methods to properly implement IEA resulted in the IEA process being viewed as its own endpoint. This commonly led to referring to “the IEA” when variously discussing the IEA framework, program, products, and process. Now that IEA and EBM are maturing, we need to be specific with what we are referring to when discussing IEAs, in order to develop reasonable expectations for applying IEA tools. We also now recognize the need to implement multiple IEA processes at varying geographic and complexity scales within an ecosystem to effectively meet the scientific requirements for operational EBM rather than viewing an IEA application as a single regional science product.

Abstract:

Risk assessments quantify the probability of undesirable events along with their consequences. They are used to prioritize management interventions and assess tradeoffs, serving as an essential component of ecosystem-based management (EBM). A central objective of most risk assessments for conservation and management is to characterize uncertainty and impacts associated with one or more pressures of interest. Risk assessments have been used in marine resource management to help evaluate the risk of environmental, ecological, and anthropogenic pressures on species or habitats including for data-poor fisheries management (e.g., toxicity, probability of extinction, habitat alteration impacts). Traditionally, marine risk assessments focused on singular pressure-response relationships, but recent advancements have included use of risk assessments in an EBM context, providing a method for evaluating the cumulative impacts of multiple pressures on multiple ecosystem components. Here, we describe a conceptual framework for ecosystem risk assessment (ERA), highlighting its role in operationalizing EBM, with specific attention to ocean management considerations. This framework builds on the ecotoxicological and conservation literature on risk assessment and includes recent advances that focus on risks posed by fishing to marine ecosystems. We review how examples of ERAs from the United States fit into this framework, explore the variety of analytical approaches that have been used to conduct ERAs, and assess the challenges and data gaps that remain. This review discusses future prospects for ERAs as EBM decision-support tools, their expanded role in integrated ecosystem assessments, and the development of next-generation risk assessments for coupled natural–human systems.

Abstract:

Few conceptual frameworks attempt to connect disaster-associated environmental injuries to impacts on ecosystem services (the benefits humans derive from nature) and thence to both psychological and physiological human health effects. To our knowledge, this study is one of the first, if not the first, to develop a detailed conceptual model of how degraded ecosystem services affect cumulative stress impacts on the health of individual humans and communities. Our comprehensive Disaster-Pressure State-Ecosystem Services-Response-Health model demonstrates that oil spills, hurricanes, and other disasters can change key ecosystem components resulting in reductions in individual and multiple ecosystem services that support people's livelihoods, health, and way of life. Further, the model elucidates how damage to ecosystem services produces acute, chronic, and cumulative stress in humans which increases risk of adverse psychological and physiological health outcomes. While developed and initially applied within the context of the Gulf of Mexico, it should work equally well in other geographies and for many disasters that cause impairment of ecosystem services. Use of this new tool will improve planning for responses to future disasters and help society more fully account for the costs and benefits of potential management responses. The model also can be used to help direct investments in improving response capabilities of the public health community, biomedical researchers, and environmental scientists. Finally, the model illustrates why the broad range of potential human health effects of disasters should receive equal attention to that accorded environmental damages in assessing restoration and recovery costs and time frames.

Abstract:

The circulation and exchange processes controlling transport and water renewal within the western subregion of Florida Bay, USA, are presented and compared to our previous findings for the north-central and northeast subregions of the bay. We find there is a common bank/basin flow response to wind forcing that is the primary driver of water renewal for each of the regions studied. Florida Bay is a patchwork of shallow basins surrounded by very shallow banks that are cut through with deeper channels connecting to nearby basins. We observed that, for each subregion studied, there was a net downwind basin outflow through the larger channels that was approximately balanced by a net basin inflow over the surrounding shallow banks. The resulting basin throughflows are used to estimate exchange times for renewal of western basin waters of approximately 1 month. This exchange time is sufficient to prevent hypersalinity and degradation of water quality in the western basin, in contrast to the north-central subregion, where hypersalinity development is an annual occurrence. Our results highlight the importance of wind induced water renewal in shallow coastal bays with weak to moderate tidal exchange. In addition, we have discovered a significant clockwise circulation pattern through the western basins from strong inflows of coastal waters through Flamingo Channel that turn southward through the western basins before rejoining the coastal flow toward the Florida Keys tidal passages and Atlantic coastal zone. A practical solution to control hypersalinity, sea grass die-off, and water quality degradation of Florida Bay is proposed.

Abstract:

The Gulf of Mexico is one of the most ecologically and economically valuable marine ecosystems in the world and is affected by a variety of natural and anthropogenic phenomena including climate, hurricanes, coastal development, agricultural runoff, oil spills, and fishing. These complex and interacting stressors, together with the highly dynamic nature of this ecosystem, present challenges for the effective management of its resources. We analyze a compilation of over 100 indicators representing physical, biological, and economic aspects of the Gulf of Mexico and find that an ecosystem-wide reorganization occurred in the mid-1990s. Further analysis of fishery landings composition data indicates a major shift in the late 1970s coincident with the advent of US national fisheries management policy, as well as significant shifts in the mid-1960s and the mid-1990s. These latter shifts are aligned temporally with changes in a major climate mode in the Atlantic Ocean: the Atlantic Multidecadal Oscillation (AMO). We provide an explanation for how the AMO may drive physical changes in the Gulf of Mexico, thus altering higher-level ecosystem dynamics. The hypotheses presented here should provide focus for further targeted studies, particularly in regard to whether and how management should adjust to different climate regimes or states of nature. Our study highlights the challenges in understanding the effects of climatic drivers against a background of multiple anthropogenic pressures, particularly in a system where these forces interact in complex and nonlinear ways.

Abstract:

The Florida Bay ecosystem supports a number of economically important ecosystem services, including several recreational fisheries, which may be affected by changing salinity and temperature due to climate change. In this paper, we use a combination of physical models and habitat suitability index models to quantify the effects of potential climate change scenarios on a variety of juvenile fish and lobster species in Florida Bay. The climate scenarios include alterations in sea level, evaporation and precipitation rates, coastal runoff, and water temperature. We find that the changes in habitat suitability vary in both magnitude and direction across the scenarios and species, but are on average small. Only one of the seven species we investigate (Lagodon rhomboides, i.e., pinfish) sees a sizable decrease in optimal habitat under any of the scenarios. This suggests that the estuarine fauna of Florida Bay may not be as vulnerable to climate change as other components of the ecosystem, such as those in the marine/terrestrial ecotone. However, these models are relatively simplistic, looking only at single species effects of physical drivers without considering the many interspecific interactions that may play a key role in the adjustment of the ecosystem as a whole. More complex models that capture the mechanistic links between physics and biology, as well as the complex dynamics of the estuarine food web, may be necessary to further understand the potential effects of climate change on the Florida Bay ecosystem.

Abstract:

In situ fluorometers were deployed during the Deepwater Horizon (DWH) Gulf of Mexico oil spill to track the subsea oil plume. Uncertainties regarding instrument specifications and capabilities necessitated performance testing of sensors exposed to simulated, dispersed oil plumes. Dynamic ranges of the Chelsea Technologies Group AQUAtracka, Turner Designs Cyclops, Satlantic SUNA and WET Labs, Inc. ECO, exposed to fresh and artificially weathered crude oil, were determined. Sensors were standardized against known oil volumes and total petroleum hydrocarbons and benzene-toluene-ethylbenzene-xylene measurements—both collected during spills, providing oil estimates during wave tank dilution experiments. All sensors estimated oil concentrations down to 300 ppb oil, refuting previous reports. Sensor performance results assist interpretation of DWH oil spill data and formulating future protocols.

Abstract:

Marine ecosystem based management plans are gaining popularity with natural resource managers, but examples of their successful implementation remain few. The complexity inherent in marine ecosystems presents a major obstacle to understanding how individual ecosystem pressures impact multiple ecosystem states that in turn impact the provisioning of ecosystem services. To create and implement successful ecosystem based management plans will require tools for understanding these processes. Over the past three years integrated conceptual ecosystem models of the coastal marine environment have been developed as part of the Marine and Estuarine Goal Setting for South Florida (MARES) project. Here we use these conceptual models in conjunction with a modified DPSIR model, expert opinion and matrix-based analyses to explore the direct and indirect relative impact of 12 ecosystem pressures on 11 ecosystem states and 11 ecosystem services identified through MARES. Within the South Florida coastal ecosystem the most pervasive pressures were freshwater delivery, temperature effects of climate change, and impacts of climate change on weather. For the study region the least pervasive pressures were recreational fishing, commercial fishing, and invasive species. The most at risk ecosystem states, as determined by cumulative impacts were fish and shellfish, protected species, and marine birds. By the same measure, the least at risk states were oyster reefs and inshore flats. The most at risk ecosystem services were existence of a natural system, pristine wilderness experience, and non-extractive recreation. The least impacted ecosystem services were commercial extraction, recreational fishing and climate stability. When the relative direct and indirect (i.e., including state to state interactions) impacts of ecosystem pressures were traced to individual ecosystem services, it was apparent that within the study domain a lack of freshwater delivery to coastal estuaries was the predominant pressure, and recreational fishing had the lowest relative impact on the provisioning of ecosystem services. Through this expert opinion analysis and exploration of the interaction strength among various ecosystem pressures, states, and ecosystem services, we can begin to understand the diverse manners in which ecosystem services are impacted by various pressures. In so doing we provide a tool for resource managers to understand the trade-offs among individual user groups and the possible impact on provisioning of ecosystem services that may occur when considering various management strategies.

Abstract:

Ecosystem-based management is widely regarded as a method to improve the way we manage our coastal marine resources and ecosystems. Effective ecosystem-based management relies upon synthesizing our scientific knowledge and transferring this knowledge into management actions. Integrated ecosystem assessment is a framework to conduct this scientific synthesis and transfer information to resource managers. Portions of the framework were applied to build consensus on the focal ecosystem components and processes that are characteristic of a sustainable South Florida coastal ecosystem that is producing ecosystem services at the level society desires. Consensus was developed through facilitated meetings that aimed to conceptualize the ecosystem, develop ecosystem indicators, and conduct risk analysis. Resource managers, researchers, academics, and non-governmental organizations participated in these meetings and contributed to the synthesis of science and a myriad of science communications to transfer information to decision makers and the public. A proof of concept Bayesian Belief Network was developed to explore integrating the results of this assessment into an interactive management scenario evaluation tool. The four year effort resulted in the development of a research and management coordination network in South Florida that should provide the foundation for implementing ecosystem-based resource management across multiple agencies.

Abstract:

Ecosystem-based management (EBM) has emerged as a basic approach for managing human activities in marine ecosystems, with the aim of recovering and conserving marine ecosystems and the services they deliver. Integrated ecosystem assessments (IEAs) further the transition of EBM from principle to practice by providing an efficient, transparent means of summarizing the status of ecosystem components, screening and prioritizing potential risks, and evaluating alternative management strategies against a backdrop of environmental variability. In this paper, we draw upon lessons learned from the US National Oceanic and Atmospheric Administration's IEA programme to outline steps required for IEA implementation. We provide an overview of the conceptual framework for IEAs, the practical constraints that shape the structure of individual IEAs, and the uses and outcomes of IEAs in support of EBM.

Abstract:

Enabling ecosystem-based management requires, among other things, reaching a scientifically based consensus with respect to the key characteristics of a sustainable ecosystem capable of supporting those levels of key ecosystem services desired by society. To determine and convey whether an ecosystem is in fact approaching this goal implies developing indicators that capture the status of both the natural and societal aspects of the system. That said, developing consistent and useful indicators for both societal and natural system aspects of the ecosystem requires both resolving disparate perspectives and inconsistent terminology between human dimensions and natural system scientists and keeping the number of indicators manageably few, without oversimplifying a highly complex ecosystem. To accomplish this we employed a “recursive relationship” approach that defined (and redefined) variables, indicators, and indices along a sliding hierarchy from measurable parameters to highly aggregated indices. To illustrate this approach it is applied herein to both a human dimensions index (recreational quality), and a natural sciences index (water column). This “recursive relationship” approach facilitated development of a parsimonious set of high-level indices that together constitute an ecosystem report card integrating natural system status and related societal dimensions from an ecosystem services perspective, while maintaining all of the information at lower levels necessary to inform specific management decisions.

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Abstract:

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 84 km 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 2000 m, 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 circulations models utilized during the spill, and for the improvement of future numerical forecast products.

Abstract:

Despite the importance of the West Florida Shelf (WFS) on regional ecology and local economy, systematic shelf-wide assessment of the ocean biology has not been conducted, primarily because of budgetary limitations for routine field campaigns and unknown accuracy of satellite-based data products. Here, using shipboard spectral normalized water-leaving radiance (nL_w[λ]) data and chlorophyll-a concentrations (Chl-a) collected regularly during two multiyear field programs spanning >10 years, the accuracies of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) standard data products were evaluated. The in situ data covered a wide dynamic range, with about one order of magnitude in nL_w(490) (0.47-4.01 mW cm⁻² μm⁻¹ sr⁻¹) and two orders of magnitude in Chl-a (0.07-10.6 mg m⁻³). Near-concurrent in situ and satellite nL_w(λ) data showed absolute percent differences (APD) increasing from 7–9% to 10–14% when data with elevated aerosol optical thicknesses at 865 nm (τ_a865) were included. Most of this uncertainty, however, canceled in the maximal blue-to-green reflectance band ratios traditionally used for estimating Chl-a. SeaWiFS OC4 Chl-a data showed a root mean square (RMS) uncertainty of 0.106 for log-transformed data in waters offshore of the 20-m isobath that increased to 0.255 when all data were considered. The increased likelihood for nearshore SeaWiFS Chl-a greater than 0.5 mg m⁻³ to be overestimated was shown to be caused by a variety of factors (colored dissolved organic matter [CDOM], suspended sediments, and bottom reflectance) that varied in both time and space. In the future, more sophisticated algorithms capable of taking these factors into consideration are required to improve remote determinations of Chl-a in nearshore waters of the WFS.

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There is a pressing need to integrate biophysical and human dimensions science to better inform holistic ecosystem management supporting the transition from single species or single-sector management to multi-sector ecosystem-based management. Ecosystem-based management should focus upon ecosystem services, since they reflect societal goals, values, desires, and benefits. The inclusion of ecosystem services into holistic management strategies improves management by better capturing the diversity of positive and negative human-natural interactions and making explicit the benefits to society. To facilitate this inclusion, we propose a conceptual model that merges the broadly applied Driver, Pressure, State, Impact, and Response (DPSIR) conceptual model with ecosystem services yielding a Driver, Pressure, State, Ecosystem service, and Response (EBM-DPSER) conceptual model. The impact module in traditional DPSIR models focuses attention upon negative anthropomorphic impacts on the ecosystem; by replacing impacts with ecosystem services the EBM-DPSER model incorporates not only negative, but also positive changes in the ecosystem. Responses occur as a result of changes in ecosystem services and include inter alia management actions directed at proactively altering human population or individual behavior and infrastructure to meet societal goals. The EBM-DPSER conceptual model was applied to the Florida Keys and Dry Tortugas marine ecosystem as a case study to illustrate how it can inform management decisions. This case study captures our system-level understanding and results in a more holistic representation of ecosystem and human society interactions, thus improving our ability to identify trade-offs. The EBM-DPSER model should be a useful operational tool for implementing EBM, in that it fully integrates our knowledge of all ecosystem components while focusing management attention upon those aspects of the ecosystem most important to human society and does so within a framework already familiar to resource managers.

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Abstract: The greater Everglades ecosystem, including Florida Bay, has undergone significant anthropogenic manipulation over the past century. These actions resulted in a series of ecologically undesirable events in the Everglades ecosystem, prompting passage of the Comprehensive Everglades Restoration Plan (CERP). It is necessary to understand the variability in, and relationship between, salinity and ecology to fully evaluate the potential effects of CERP on Florida Bay. A seven-year dataset on surface salinity along with eleven-year and eight-year datasets on mesozooplankton and planktivorous fish were analyzed. Overall, mean Bay-wide salinity varied from a low of 24.2 just after the passing of Hurricane Irene in October 1999 to a high of 41.8 near the end of a drought period in July 2001. Bay-wide mean salinity exhibited dramatic decreases, up to 0.5 per day, whereas increases in bay-wide salinity were slower, with a maximum rate of 0.1 per day. Meteorological phenomena, such as tropical cyclones and ENSO, dramatically altered the salinity patterns of Florida Bay on interannual time scales. There was a large degree of spatial heterogeneity in salinity between sub-regions of Florida Bay due to differing freshwater sources and geomorphology. Mesozooplankton abundance displayed interannual variability and a positive correlation with salinity. Both of these features were also closely correlated with abundance of the dominant planktivorous fish, Anchoa mitchilli, indicating the importance of top-down control. The hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance during periods of increased physiological stress. The interaction between mesozooplankton and A. mitchilli, along with its correlation to salinity, was further investigated through the development of a mechanistic model of the populations in Florida Bay. The model indicated predation alone was insufficient to control mesozooplankton populations; rather, it was necessary to incorporate density-dependence utilizing a logistic prey population. With both mechanisms the model was able to replicate the observed interannual variability pattern and positive correlation between mesozooplankton and salinity. A preliminary management scenario evaluation suggests a two to six-fold difference in A. mitchilli and mesozooplankton populations between targeted and general salinity reductions. This suggests alternative freshwater management scenarios could produce drastically different ecological consequences.

Abstract: Quantifying the relationship between mesozooplankton and water quality parameters identifies the factors that structure the mesozooplankton community and can be used to generate hypotheses regarding the mechanisms that control the mesozooplankton population and potentially the trophic network. To investigate this relationship, mesozooplankton and water quality data were collected in Florida Bay from 1994 to 2004. Three key characteristics were found in the mesozooplankton community structure: (1) there are significant differences between the four sub-regions of Florida Bay; (2) there is a break in May of 1997 with significant differences before and after this date; and (3) there is a positive correlation between mesozooplankton abundance and salinity. The latter two characteristics are closely correlated with predator abundance, indicating the importance of top-down control. Hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance despite the increased physiological stress.

Abstract: Altered freshwater inflows have affected circulation, salinity, and water quality patterns of Florida Bay, in turn altering the structure and function of this estuary. Changes in water quality and salinity and associated loss of dense turtle grass and other submerged aquatic vegetation (SAV) in Florida Bay have created a condition in the bay where sediments and nutrients have been regularly disturbed, frequently causing large and dense phytoplankton blooms. These algal and cyanobacterial blooms in turn often cause further loss of more recently established SAV, exacerbating the conditions causing the blooms. Chlorophyll a (CHLA) was selected as an indicator of water quality because it is an indicator of phytoplankton biomass, with concentrations reflecting the integrated effect of many of the water quality factors that may be altered by restoration activities. Overall, we assessed the CHLA indicator as being (1) relevant and reflecting the state of the Florida Bay ecosystem, (2) sensitive to ecosystem drivers (stressors, especially nutrient loading), (3) feasible to monitor, and (4) scientifically defensible. Distinct zones within the bay were defined according to statistical and consensual information. Threshold levels of CHLA for each zone were defined using historical data and scientific consensus. A presentation template of condition of the bay using these thresholds is shown as an example of an outreach product.

Abstract: Water quality surveys conducted in Biscayne Bay, Florida, indicated enhanced nutrient input coupled with increased runoff as a result of precipitation associated with Hurricane Katrina. Nutrient concentrations before Katrina ranged from 0.06-24.2 mM (mean 3.3 mM) for nitrate and 0.01-0.18 mM (mean 0.1 mM) for soluble reactive phosphate. Five days after Katrina, nitrate concentrations ranged from 0.87-80.0 mM (mean 17.0 mM), with a bay-wide mean increase of 5.2-fold over pre-hurricane levels. Soluble reactive phosphate concentrations ranged from 0.07-0.62 mM (mean 0.2 mM), with a bay-wide mean increase of 2-fold over pre-hurricane levels. The maximum concentrations for both nitrate and soluble reactive phosphate were found at a water quality monitoring station near the mouth of Mowry Canal, which drains an agricultural area in the southern Biscayne Bay watershed near Homestead, Florida. At this station, nitrate and soluble reactive phosphate concentrations increased 7- and 10-fold, respectively. Storm-induced fertilizer runoff from this agricultural area caused a bay-wide increase in nutrient concentrations after Hurricane Katrina. Nutrient concentrations in the bay returned to pre-hurricane levels within three months after Hurricane Katrina, showing the resiliency of the Biscayne Bay ecosystem.

Abstract: In July 1998 approximately 2.5 x 10⁸ of recently-spawned Mercenaria spp. larvae were intentionally released in the northernmost basin of the Indian River Lagoon, Florida, to characterize the initial dispersion from a point source at time scales of hours to days. Larval densities measured with a quantitative molecular method indicated ambient concentrations were enhanced by 10 larvae L^-1 near surface drifters released with the larvae. Surface distributions from samples collected near the drifters indicate that larval patches developed during the first day. Diffusive processes evaluated from dye releases yield apparent diffusivity coefficients that suggest diffusive processes could spread larvae over several km² within 2 d. Our observations suggest that high-resolution methods for mapping larvae are essential to better resolve spatial distribution evolution at time scales of hours to days, and spatial scales of tens to hundreds of meters. This capability could better define the temporal evolution of larval distributions following a mass spawning event.

Abstract: The northeast subregion of Florida Bay receives approximately 75% of the direct freshwater runoff to the bay, most of which is retained within the subregion and has little impact on the dilution of hypersalinity development in adjacent subregions. Using direct measurements of the volume transports through connecting channels and indirectly estimating the total transport to the subregion from mean sea level variability, we show that interior basin water exchanges are weak and controlled by local wind forcing. East-west winds produced seasonally averaged throughflows of 33 and 78 m³ s^-1 during the El Niño-influenced wet and dry seasons of 2002 and 2003, respectively, and resulted in a one year residence time for the northeast sub-region. The long residence time of the interior waters is due to the confining nature of the shallow banks and mangrove borders that surround the northeast subregion, as well as the lack of significant tidal exchange. Weak interbasin exchange results in the trapping of freshwater discharge from the Everglades within the northeast subregion. Development of hypersalinity within the north-central subregion of the bay has been associated with seagrass die-off and algal blooms that can cause water quality reduction in south Florida's coastal waters, including the Florida Keys reef tract. To reduce the development of hypersalinity within this region of the bay it will be necessary to divert a portion of the Everglades flow away from the northeast basin and into Whipray Basin during the dry season. Seasonal water balance estimates made for the northeast subregion and previous estimates from the north-central region indicate that groundwater inflows to Florida Bay are negligible and probably not a factor in water quality considerations.

Abstract: Challenges associated with species identification, live collection and laboratory maintenance of billfish larvae have hindered research on their physiology and behavior. In the present study, short-duration neuston net tows in the Straits of Florida yielded 19 live istiophorid billfish larvae, which were immediately placed in a shipboard vertical swimming chamber to measure their vertical movement rates. After swimming trials, larvae were transferred to the laboratory where they were identified to species, classified as to flexion stage and measured for length. Mean vertical swimming speeds of captive larval sailfish (Istiophorus platypterus) and blue marlin (Makaira nigricans) ranged from 1.0 to 7.0 cm s^-1 or 1.6 to 5.6 body lengths s^-1. These rates exceed most larval fish sinking rates reported for other species and are comparable to mean larval "cruising" speeds reported for several temperate freshwater and marine fishes; however, they appear far lower than most swimming speed estimates for reef fish larvae.

Abstract: South Florida's bays and the plants and animals that they support reflect the volume, distribution, and quality of fresh water flowing into these aquatic systems. Past changes to the quality, quantity, timing, and distribution of freshwater flow have degraded water quality and compromised estuarine community structure and function in some areas of the southern estuaries. Current water quality monitoring programs provide adequate spatial and temporal coverage throughout the southern estuaries with the possible exception of the southwest Florida shelf where the temporal variability may not be adequately captured. Chlorophyll-a was selected as an indicator of water quality because its biomass is an integrator of many of the water quality factors which may be altered by CERP. There is concern that increased freshwater flow due to CERP activities may result in more frequent, intense, and persistent phytoplankton blooms in the southern estuaries. The baseline conditions indicate that most of the southern estuaries is oligotrophic with median chlorophyll-a concentrations of less than or approximately 1 ppb. This baseline data was used as the reference condition to assess the 2006 southern estuaries data, and only the Barnes, Manatee, and Blackwater Sound subregion was found to have chlorophyll a biomass significantly higher than the baseline. This algal bloom was the result of an increase in total P in this subregion from the combined effects of highway construction and hurricane impacts, including the pre-hurricane freshwater release. This phytoplankton bloom illustrates the sensitivity of the southern estuaries to small increases in nutrient loading, because it took only a small increase in TP (> 10 ppb) to trigger this large phytoplankton bloom, which continues to persist. The ability of our methodologies to adequately detect this decline in water quality due to altered environmental conditions indicates the applicability of this technique to detect changes in water quality as a result of CERP activities. Understanding how CERP affects water quality in the southern estuaries will facilitate adaptively managing and guiding restoration efforts.

Abstract:

The salinity of Florida Bay has undergone dramatic changes over the past century. Salinity values reached their most extreme, up to 70, in the late 1980s, concurrent with ecological changes in Florida Bay including a mass seagrass die-off. In this study, surface salinity was measured at approximately monthly intervals between 1998 and 2004. The 7-year data set was analyzed to quantify the effects of precipitation, runoff, evaporation, and climatic variability on salinity in Florida Bay. Overall mean Bay-wide salinity varied from a low of 24.2 just after the passing of Hurricane Irene in October 1999 to a high of 41.8 near the end of a drought period in July 2001. Bay-wide mean salinity exhibited dramatic decreases, up to -0.5 per day, whereas increases were slower, with a maximum rate of 0.1 per day. The freshwater budget for Florida Bay was slightly negative on an annual basis with significant positive monthly values observed during the peak of the rainy season (August through October) and significant negative monthly values observed during the peak of the dry season (March through May). This resulted in a minimum mean monthly Bay-wide salinity in January and a maximum monthly mean in July. Mean salinity for the overall Bay and for each of its four sub-regions could be predicted with reasonable accuracy utilizing a mass balance box model. There was no monotonic trend in salinity over this 7-year study; however, meteorological phenomena, such as tropical cyclones and El Niño-Southern Oscillation, dramatically altered the salinity patterns of Florida Bay on interannual time scales.

Abstract:

Basic research on larval billfish biology and ecology has been hampered by difficulties with species identification, the capture of live specimens, and their survival after capture (Richards, 1974; Post et al., 1997; Serafy et al., 2003). Whereas, genetic techniques are helping to resolve the identification problems (McDowell and Graves, 2002; Hyde et al., 2005; Luthy et al., 2005), obtaining live, uninjured billfish larvae for scientific study remains a serious obstacle (Idrisi et al., 2003; Serafy et al., 2003). To date, the most successful effort to collect live istiophorid larvae, and to subsequently maintain them in captivity, was conducted by Post et al. (1997). They sampled over a 2-yr period off Miami, Florida with a circular, 1 m diameter plankton net with 1 mm mesh. By limiting their Neuston tow duration to 2 min or less, overall larval istiophorid survival immediately after collection was 30%. Building on the Post et al. (1997) work, we addressed the problem of live billfish collection by developing a new Neuston gear in which tow duration can span, uninterrupted, whatever time period desired, and while underway, its cod-end contents are both viewable and immediately collectable. The rationale behind the "continuous access Neuston observation net" (CANON) design is that the key to minimizing larval injury (due to net abrasion, turbulence, and interactions with other organisms in the cod-end) lies in reducing the time larvae spend in the collection gear. Here, we describe the components, configuration, and operation of the CANON as well as provide results of its performance relative to conventional Neuston net sampling. Possible future applications for this new gear are also described.

Abstract:

Sea surface temperature imagery, ship-based surveys, and moored current meters described the passage of a Tortugas eddy as it moved east at ca. 6 km day^-1 through the southern Straits of Florida (SSF). In mid-April 1999, the eddy SST signature extended across half the width of the Straits. While in the western SSF, the eddy center was ca. 30 km seaward of the outer reef. The upper pycnocline, the subsurface chlorophyll a maximum (SCM), and nutricline shoaled from ca. 80 m at the eddy edge to -3, although the depth-integrated concentrations (mg m^-2) were similar across the feature. Nutrient-density relationships show nitrate+nitrite, phosphate, and silicate decreased to detection limits at sigma_t <25.0; the SCM was centered near this isopycnal surface. As the Eddy passed Looe Key (81.5°W), the alongshore currents reversed to the west. During this period high-nutrient, cool waters shoaled near the bottom on the outer reef. By early May, the eddy SST signature was compressed into a thin band of cool surface waters off the middle to upper Keys. As the feature moved towards shore in the middle to upper Florida Keys, the nitrate+nitrite and chlorophyll concentrations increased in bottom waters along the outer reef. Processes such as internal tidal bores and breaking internal waves are likely responsible for delivering nutrients from Tortugas eddies to the outer reef in the middle to upper Keys.

Abstract:

Near real-time data from the MODIS satellite sensor was used to detect and trace a harmful algal bloom (HAB), or red tide, in southwest Florida coastal waters from October to December 2004. MODIS fluorescence line height (FLH in W m^-2 m^-1 sr^-1) data showed the highest correlation with near-concurrent in situ chlorophyll-a concentration (Chl in mg m^-3). For Chl ranging between 0.4 to 4 mg m^-3 the ratio between MODIS FLH and in situ Chl is about 0.1 W m^-2 m^-1 sr^-1 per mg m^-3 chlorophyll (Chl = 1.255 (FLH x 10)^0.86, r = 0.92, n = 77). In contrast, the band-ratio chlorophyll product of either MODIS or SeaWiFS in this complex coastal environment provided false information. Errors in the satellite Chl data can be both negative and positive (3-15 times higher than in situ Chl), and these data are often inconsistent either spatially or temporally due to interferences of other water constituents. The red tide that formed from November to December 2004 off southwest Florida was revealed by MODIS FLH imagery and was confirmed by field sampling to contain medium (10⁴ to 10⁵ cells L^-1) to high (>10⁵ cells L^-1) concentrations of the toxic dinoflagellate Karenia brevis. The FLH imagery also showed that the bloom started in mid-October south of Charlotte Harbor, and that it developed and moved to the south and southwest in the subsequent weeks. Despite some artifacts in the data and uncertainty caused by factors such as unknown fluorescence efficiency, our results show that the MODIS FLH data provide an unprecedented tool for research and managers to study and monitor algal blooms in coastal environments.

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Light attenuation in marine ecosystems can limit primary production and determine the species composition and abundance of primary producers. In Florida Bay, the importance of understanding the present light environment has heightened as major upstream water management restoration projects have been proposed and some are already being implemented. We analyzed a two-yearr (2001-2003) data set of the light attenuation coefficient (K_t) and its principal components (water, chromophoric dissolved organic matter [CDOM], tripton, phytoplankton) obtained at 40 stations within Florida Bay, calibrated synoptic underway data to produce high spatial resolution maps, examined the potential for light limitation, and quantified the individual effect of each component upon light attenuation. Tripton was the dominant component controlling light attenuation throughout Florida Bay, whereas the contribution of chlorophyll a and CDOM to K_t was much smaller in all regions of Florida Bay. It was possible to accurately estimate the light attenuation coefficient from component concentrations, using either a mechanistic or a statistical model with root mean square errors of 0.252 or 0.193 m^-1, respectively. Compared to other estuaries, Florida Bay had the lowest overall K_t and the greatest relative contribution from tripton. Comparing the recent data to a study of Florida Bay's light environment conducted in 1993-1994, we found that overall water clarity in the Bay increased significantly, indicated by a nearly three-fold decrease in K_t, as a result of lower tripton concentrations, although the percent contribution of each of the components to K_t is unchanged. Only the northwest corner of Florida Bay, an area comprised of approximately 8% of the Bay's total area, was found on average to have sufficient light attenuation to limit the growth of seagrasses. This is much less extensive than in 1993-1994, when seagrass growth was potentially limited by light at over 50% of the stations sampled.

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During the winter months (December to April), the southeast United States is influenced by continental air masses from the north or northwest which pass at approximately 4 to 7 d intervals. These wind events can cause suspension of bottom sediments in Florida Bay. Over a 9 d period in March 2001, we examined the effects of a wind-mixing event on the pelagic system within the northwest part of Florida Bay, where water depth is 2 to 3 m. This event caused significant suspension of bottom materials, large increases in NH₄ and PO₄, smaller increases in NO₃+NO₂ and Si(OH)₄, a decrease in microzooplankton abundance, and an increase in benthic copepods in the water column. As wind speeds declined, there was a rapid decline in PO₄ concentration, gradual declines in suspended sediment, NH₄ and Si(OH)₄, an increase in chlorophyll a (chl a) stock, an increase in phytoplankton growth and productivity, an increase in microzooplankton grazing rate, and a settling of the benthic harpacticoid community. No grazing response was apparent in the mesozooplankton community. The wind event clearly injected dissolved and particulate benthic materials into the water column, where they directly stimulated the bacterioplankton, phytoplankton and microzooplankton communities within 1 to 2 d after the event. The water column was strongly net heterotrophic at this time, suggesting a large input of dissolved organic matter from the bottom. Stimulation of the pelagic food web continued at least until we completed our study 6 d after the event. By the end of our study, the water column was net autotrophic.

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Abstract: The availability of light in marine ecosystems is of vital importance to primary producers, both benthic and pelagic, and is governed by attenuation within the water column. Light attenuation is especially important for Florida Bay because the Bay is dominated by seagrass. Light attenuation is measured as the light attenuation coefficient, Kt, which is affected by four main factors: seawater, chromophoric dissolved organic matter (CDOM), phytoplankton, and tripton (non-living particulate matter). In this study, Kt was measured in Florida Bay, along with the concentration of each of these factors during survey cruises from July 2001 to March 2002. The effect of each of the factors on Kt was quantified to produce an equation to estimate Kt from factor concentrations and identify the dominant factor(s). These surveys also consisted of a series of underway measurements that were used to estimate factor concentrations along the entire cruise track. These underway factor concentration estimates were then inserted into the equation to estimate Kt without a loss of accuracy and allowed for a high-resolution study of light-limitation on the primary producers of Florida Bay. Light-limitation of pelagic phytoplankton was of minimal importance overall, but did occur in a minute area of northwest Florida Bay. However, light-limitation of seagrass was of much greater importance with seagrass growth being inhibited throughout a large portion of northwest Florida Bay. This study indicates the importance of light attenuation in Florida Bay and highlights the need for continued monitoring to identify and predict the effects of light attenuation on Florida Bay's primary producers.

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A long liquid waveguide capillary flow cell has been successfully adapted to a gas-segmented continuous flow auto-analyzer for trace analysis of iron in water. The flow cell was made of new material, Teflon AF-2400, which has a refractive index (1.29) lower than water (1.33). Total reflection of light can be achieved provided that the incident angle at each reflection on the water/Teflon interface is greater than the critical angle. Teflon AF-2400 is superior to currently used materials in both refractivity and mechanical stability. This allows for construction of a long liquid waveguide capillary flow cell in a helical, rather than linear shape, with compact dimensions. Since the internal volume of a 2 m-long, 550 ?m ID liquid waveguide capillary flow cell is only approximately 0.5 cm³, a small sample volume is required. Utilization of this long flow cell significantly enhances the sensitivity of automated colorimetric analysis of iron by the ferrozine method, allowing for accurate determination of nanomolar concentrations of iron in natural waters. The advantages of this technique are low detection limit (0.1 nM), small sample volume (2 ml), high precision (1%), and automation for rapid analysis of a large number of samples. This technique is applicable to any gas-segmented continuous flow analysis or flow injection analysis with spectrophotometric detection.