Search Results (68)

While studies have shown that heavy metal sulfides in sediments are not bioavailable, most of them are acid-extractable (AE) and inseparable from non-sulfides in sediments. Exceptions were found recently that mercury and copper sulfides precipitated in sediments are non-AE because they are exclusively bi-sulfides. Therefore, quantifying mercury sulfide in sediments is possible for bioavailability assessment. To illustrate the application of this new approach for mercury bioavailability assessment, we quantified the distribution of mercury sulfide in sediments of the Apalachicola Bay, North Florida, USA. We extracted sediment cores and determined the total mercury, non-sulfide mercury, and sulfide mercury as well as the total sulfides, bulk density, and organic matter. The results showed that the mercury in the top 45 cm sediments were, on average, 13.3 ± 5.4 ng/cm³, of which 97.1 ± 2.5% were sulfide. The potentially bioavailable (non-sulfide) mercury was on average only 0.28 ± 0.22 ng/cm³ (2.9% of the total mercury). The total mercury and sulfide mercury were significantly correlated with the organic matter, which were dictated by the discharge pattern of the river input. This study demonstrates that aquatic sediments accumulate terrestrial mercury, and sulfidic sediments sequester most of it as sulfide. This new approach for mercury bioavailability assessment is simple yet chemically rigorous. Full article

Diatoms are the most numerous of algae and scanning electron microscopy continues to reveal ever-increasing diversity. Two new species of Hyalosira from Florida add new characters distinguishing species in this recently redefined genus: H. ornata sp. nov. from Florida Bay has consistent and elaborate ornamentation on both valves and undulate valve margins; H. sertifera sp. nov., from the Atlantic coast of Key Largo, has a thick, consistent, garland-like ring of cristae on only one valve; the former species has deep septa on all copulae except the valvocopula, the latter shallow septa or none on the copulae. Hyalosira hesperia was also found in the Atlantic sample; this is the first record outside the Mediterranean. The number of species known from SEM is now twelve, including four with septa, a diversity potentially useful in exploring outstanding questions of septum function; a key to these species is appended. Full article

As polybrominated diphenyl ethers were phased out as flame retardants and plasticizers, increasing quantities of organophosphate triesters (OPEs) have been used as replacements. Despite a surge in reports on levels and profiles of OPEs, especially in indoor environments, and the potential exposure, there are still understudied areas with no data on the levels of these chemicals. We carried out the first study investigating levels and profiles of OPEs in indoor dust from such an area, the Tampa Bay (Florida) area. ∑₁₃OPEs measured at each site ranged from 545 to 502,086 ng g⁻¹, with overall medians and means over 64 sites of 15,447 and 36,135 ng g⁻¹, respectively. Alkyl OPEs were predominant, with lesser levels of chlorinated and aryl OPEs. Median levels were highest for tris (2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPHP) at 4641 and 1046 ng g⁻¹, respectively; lower for tris(1,3–dichloro-2-propyl) phosphate (TDCIPP), tris(2-chloropropyl) phosphate (T2CPP), and tris (2-chloroisopropyl) phosphate (TCIPP) at 530, 458, and 360 ng g⁻¹, respectively; with others ranging from 2 to 85 ng g⁻¹. There were differences in levels in different microenvironments (urban versus suburban; non-residential versus residential; apartments versus single-family homes; daycares versus residences and university rooms; building age; and rooms with different floor material). Estimated daily intakes for median and higher exposure scenarios for ∑₁₃OPEs (in ng kg⁻¹ bw day⁻¹) were 12 and 552 for toddlers and 6 and 451 for adults, respectively. TBOEP accounted for 30% of total intake for toddlers and adults in a mean exposure scenario but 90% for high exposure scenario. Full article

Biscayne Bay in southeastern Florida, USA, has experienced dramatic ecological declines due to pollution. The Biscayne Bay and Southeastern Everglades Ecosystem Restoration will deliver water from a canal adjacent to coastal mangroves, intercepting pollutants before they are deposited into the estuary. Given their demonstrated capacity to filter nutrients and other contaminants from the water column, we hypothesized that mangrove wetlands also filter microplastics (“MPs”). Water and sediment samples were taken from 3 “zones”: the L-31E canal, a potential MP source; interior, dwarf mangroves; and coastal, tidal fringe mangroves. These three environments were replicated in coastal basins with and without canal culverts. MPs were expected to vary seasonally and be more abundant and larger in the dwarf zone and in low-bulk density sediments as particles settled into peat soils. In sediment, MPs were more abundant in the dry season (average 0.073 ± 0.102 (SD) MPs/g dw) before getting flushed by overland runoff resulting in greater concentrations in water during the wet season (average 0.179 ± 0.358 (SD) MPs/L). MPs were most abundant and larger in the low bulk density sediments of the dwarf zone, likely due to sheltering from fragmentation. Culvert presence had no effect, but MPs may increase as waterflows increase to planned volumes. Understanding MP dynamics enables managers to predict water quality impacts and leverage the potential ecosystem service of MP filtration by mangrove wetlands. Full article

The tropical coral Siderasterea radians is typically found in mangrove areas, seagrass beds, and environments tolerated by few other scleractinians in the Caribbean and South Florida. Siderastrea radians experience bleaching stress in Buttonwood Sound in Florida Bay during April–May, a time when the seawater is below bleaching temperatures. Stress first appears as a pink coloration due to the presence of fluorescent pigments protecting the coral tissue and algal symbionts from exposure to excessive sunlight/UV light. Surveys of S. radians in areas frequented by parrotfish showed that up to 38.5% of the corals were pink, with about a quarter of all the corals having bite marks. In areas not frequented by parrotfish, only 3.2% of the corals were pink, and none had bite marks. A seasonal analysis in parrotfish-frequented seawater showed S. radians contained among the lowest tissue biomass and density of symbiotic algae during April–May 2010–2017, often looking pink. It is hypothesized that seawater temperature is not the cause of bleaching in Buttonwood Sound during April–May but rather predation by the rainbow parrotfish Scarus guacamaia. Full article

With elevations mostly less than 2 m, the Florida Keys, an island chain stretching nearly two hundred kilometers from Biscayne Bay to Key West, Florida, is among the most vulnerable coastal regions globally. As the threats from tropical cyclones, storm surges, and sea level rise intensify, urbanized areas increasingly rely on shoreline armoring, disregarding the negative effects on coastal habitats. Living shorelines, which integrate coastal vegetation to stabilize erodible shoreline segments or enhance existing grey infrastructure, have successfully addressed some of these challenges. We present a decision framework for evaluating the suitability of different stabilization methods for existing shoreline conditions. The framework incorporates a Shoreline Relative Exposure Index (SREI) based on shoreline orientation, wind and wave exposure, shoreline slope, bathymetry, nearshore habitat, and storm surge. To refine this framework, we conducted an expert opinion survey to determine parameter weights. The results will inform decisions on using vegetated shorelines alone or with structural elements to reduce wave action, control erosion, and protect Florida Keys communities from storm damage. Implementing innovative shoreline stabilization methods is crucial as climate change and population growth are expected to exacerbate flood management challenges. Full article

Gray snapper (Lutjanus griseus) move from inshore to offshore habitats as they mature and spawn along the West Florida Shelf. The connectivity between offshore spawning sites and inshore settlement regions along the Eastern Gulf of America (formerly Gulf of Mexico, hereafter Gulf) coast is unknown, and this study therefore predicted these larval dispersal pathways. To determine larval transport, an ocean model was integrated with the Connectivity Modeling System (CMS), which is a biophysical model that allowed for the inclusion of larval behavior and updated spawning information for the gray snapper. Our larval dispersal model showed that spawning sites offshore of Tampa, in the Florida Keys, and in the Florida Middle Grounds had the highest percentages of successfully settled larvae inshore. Larvae that were spawned at the offshore Tampa Bay and offshore Southwest Florida spawning sites were mostly transported to the Tampa Bay and Southwest Florida settlement regions, showing local retention. In contrast, larvae spawned offshore in the Florida Middle Grounds were transported northwest, exclusively to the Florida Panhandle. In addition, there was no difference in the proportion of successful larval settlers between full and new moon spawning events. Since gray snapper are an important recreational fishery in the eastern Gulf, especially off the west coast of Florida, it is important to identify spawning sites that have the largest proportions of settling larvae, such as offshore Tampa Bay. Full article

Previous work examining dietary interventions high in polyphenols (i.e., antioxidant/anti-inflammatory properties) has shown cognitive benefits. In a prior investigation examining American elderberry juice consumption with inflammation and cognition in mild cognitive impairment (MCI), we found a trend toward better visuospatial construct flexibility in MCI patients who consumed elderberry relative to the placebo control. This study aims to further examine the preliminary effects of American elderberry juice on the cognitive domains in MCI using cognitive composite scores. MCI patients (N = 24; M_age = 76.33 ± 6.95) received elderberry (n = 11) or placebo (n = 13) juice for 6 months and completed cognitive tasks targeting memory, visuospatial ability, and cognitive flexibility at the baseline, 3 months, and 6 months. For the composite z-scores calculated for global cognition and each domain, multilevel models and Kenward–Roger post hoc tests examined the interaction between condition (elderberry/placebo) and time (baseline/3 months/6 months). The findings showed a significant interaction between global cognitive flexibility (p = 0.049) and elderberry juice (not the placebo) trending toward a significant decrease (better) in composite cognitive flexibility latency scores from the baseline (M = 29.89, SE = 18.12) to 6 months (M = 18.57, SE = 9.68). Preliminary findings suggest elderberry juice may provide overall cognitive flexibility benefits in MCI. These promising results provide support for prospective investigations examining the potential underlying mechanisms of elderberries that may provide cognitive benefits in MCI, possibly due to anti-inflammatory effects. Full article

Mangrove restoration efforts have increased in order to help combat their decline globally. While restoration efforts often focus on planting seedlings, underlying chronic issues, including disrupted hydrological regimes, can hinder restoration success. While improving hydrology may be more cost-effective and have higher success rates than planting seedlings alone, hydrological restoration success in this form is poorly understood. Restoration assessments can employ a functional equivalency approach, comparing restoration areas over time with natural, reference forests in order to quantify the relative effectiveness of different restoration approaches. Here, we employ the use of baseline community ecology metrics along with stable isotopes to track changes in the community and trophic structure and enable time estimates for establishing mangrove functional equivalency. We examined a mangrove system impacted by road construction and recently targeted for hydrological restoration within the Rookery Bay National Estuarine Research Reserve, Florida, USA. Samples were collected along a gradient of degradation, from a heavily degraded zone, with mostly dead trees, to a transition zone, with a high number of saplings, to a full canopy zone, with mature trees, and into a reference zone with dense, mature mangrove trees. The transition, full canopy, and reference zones were dominated by annelids, gastropods, isopods, and fiddler crabs. Diversity was lower in the dead zone; these taxa were enriched in ¹³C relative to those found in all the other zones, indicating a shift in the dominant carbon source from mangrove detritus (reference zone) to algae (dead zone). Community-wide isotope niche metrics also distinguished zones, likely reflecting dominant primary food resources (baseline organic matter) present. Our results suggest that stable isotope niche metrics provide a useful tool for tracking mangrove degradation gradients. These baseline data provide critical information on the ecosystem functioning in mangrove habitats following hydrological restoration. Full article

This study investigated how nitrogen and dissolved organic matter (DOM) from stormwater runoff and rainfall support the growth of Karenia brevis and Pyrodinium bahamense. Excitation–emission matrix spectroscopy coupled with parallel factor analysis tracked changes in the optical properties of DOM in each bioassay, revealing greater reactivity of terrestrial humic-like DOM. Significant increases in cell yield and specific growth rates were observed upon additions of runoff for both species, with significant increases in specific growth rates upon the addition of a 2 in simulated rain event for P. bahamense only. By hour 48, 100% of the dissolved organic nitrogen (DON) in each treatment was utilized by P. bahamense, and by hour 72, over 50% of the DON was utilized by K. brevis. The percentage of bioavailable dissolved organic carbon (DOC) was greater for P. bahamense compared to K. brevis, suggesting a greater affinity for DOC compounds by P. bahamense. However, the bioavailability of DOM for each species could be owed to distinct chemical characteristics of labile DOM conveyed from each site. This study demonstrates that stormwater runoff and rainfall are both sources of labile DOM and DON for K. brevis and P. bahamense, which has implications for blooms of these species in Tampa Bay waters. Full article

West Nile virus (WNV) is an arbovirus spread primarily by Culex mosquitoes, with humans being a dead-end host. WNV was introduced to Florida in 2001, with 467 confirmed cases since. It is estimated that 80 percent of cases are asymptomatic, with mild cases presenting as a non-specific flu-like illness. Currently, detection of WNV in humans occurs primarily in healthcare settings via RT-PCR or CSF IgM when patients present with severe manifestations of disease including fever, meningitis, encephalitis, or acute flaccid paralysis. Given the short window of detectable viremia and requirement for CSF sampling, most WNV infections never receive an official diagnosis. This study utilized enzyme-linked immunosorbent assay (ELISA) to detect WNV IgG antibodies in 250 patient serum and plasma samples collected at Tampa General Hospital during 2020 and 2021. Plaque reduction neutralization tests were used to confirm ELISA results. Out of the 250 patients included in this study, 18.8% of them were IgG positive, consistent with previous WNV exposure. There was no relationship between WNV exposure and age or sex. Full article

Bottlenose dolphins (Tursiops spp.) inhabit bays, sounds, and estuaries (BSEs) throughout the southeast region of the U.S.A. and are sentinel species for human and ecosystem-level health. Dolphins are vulnerable to the bioaccumulation of contaminants through the coastal food chain because they are high-level predators. Currently, there is limited information on the spatial dynamics of mercury accumulation in these dolphins. Total mercury (THg) was measured in dolphin skin from multiple populations across the U.S. Southeast Atlantic and Gulf of Mexico coasts, and the influence of geographic origin, sex, and age class was investigated. Mercury varied significantly among sampling sites and was greatest in dolphins in St. Joseph Bay, Florida Everglades, and Choctawhatchee Bay (14,193 ng/g ± 2196 ng/g, 10,916 ng/g ± 1532 ng/g, and 7333 ng/g ± 1405 ng/g wet mass (wm), respectively) and lowest in dolphins in Charleston and Skidaway River Estuary (509 ng/g ± 32.1 ng/g and 530 ng/g ± 58.4 ng/g wm, respectively). Spatial mercury patterns were consistent regardless of sex or age class. Bottlenose dolphin mercury exposure can effectively represent regional trends and reflect large-scale atmospheric mercury input and local biogeochemical processes. As a sentinel species, the bottlenose dolphin data presented here can direct future studies to evaluate mercury exposure to human residents in St. Joseph Bay, Choctawhatchee Bay, and Florida Coastal Everglades, as well as additional sites with similar geographical, oceanographic, or anthropogenic parameters. These data may also inform state and federal authorities that establish fish consumption advisories to determine if residents in these locales are at heightened risk for mercury toxicity. Full article

Florida Bay, a large and shallow estuary, serves as a vital habitat for a diverse range of marine species and holds significant environmental, commercial, and recreational value. The salinity structure of the bay plays a key role in the bay’s ecosystem. Florida Bay receives 45% of its freshwater directly from rainfall, the largest source of freshwater, while the Taylor River is the second largest source. A hydrodynamic model was applied to determine if doubling the Taylor River flow, as currently planned, is adequate to meet salinity performance measures and protect the bay’s ecosystem health. Model-predicted salinity indicated that rainfall caused the largest reduction (10–15 ppt) followed by Taylor River discharges, and none of the predicted salinity scenario means exceeded 38 ppt. The salinity restoration target was achieved more than 70% of the time, by doubling the Taylor River freshwater discharges, only for the existing bay conditions. To protect Florida Bay’s ecosystem health and counterbalance saltwater intrusion in the Everglades wetlands, caused by future sea-level rise, additional freshwater sources needs to be identified. Yet, the question becomes, do we have enough available freshwater sources to achieve the restoration target and protect the bay’s ecosystem health now and for future sea-level rise? Full article

This investigation evaluated two fundamental assumptions of wetland inundation models designed to emulate landscape evolution and resiliency under conditions of sea level rise: that they can (1) migrate landward at the same rate as the transgressing shoreline and (2) immediately replace the plant community into which they are onlapping. Rates of wetland (e.g., marsh, mangrove) migration were culled from 11 study areas located in five regions of focus: Delaware Bay, Chesapeake Bay, Pamlico Sound, South Florida, and Northwest Florida. The average rate of marsh migration (n = 14) was 3.7 m yr⁻¹. The average rate of South Florida mangrove migration (n = 4) was 38.0 m yr⁻¹. The average rate of upland forest retreat (n = 4) was 3.4 m yr⁻¹. Theoretical rates of shoreline transgression were calculated using site-specific landscape slope and scenario-based NOAA sea level rise elevations in 2050. Rates of shoreline transgression over the marsh landscape averaged 94 m yr⁻¹. The average rate of shoreline transgression in the mangrove-dominated areas of South Florida was 153.2 m yr⁻¹. The calculated rates of shoreline transgression were much faster than the observed horizontal marsh migration, and by 2050, the offset or gap between them averaged 2700 m and ranged between 292 and 5531 m. In South Florida, the gap average was 3516 m and ranged between 2766 m and 4563 m. At sites where both horizontal marsh migration and forest retreat rates were available, the distance or gap between them in 2050 averaged 47 m. Therefore, the results of this study are inconsistent with the two fundamental assumptions of many wetland inundation models and suggest that they may overestimate their resilience under conditions of 21st century accelerating sea level rise. Full article

Florida Bay, a large and shallow estuary, serves as a vital habitat for a diverse range of marine species and holds significant environmental, commercial, and recreational value. The Florida Bay ecosystem is under extensive stress due to decades of increased nutrient loads. Based on the Environmental Fluid Dynamics Code (EFDC), a hydrodynamic model was developed in this study. The model was calibrated with a comprehensive dataset, including measurements over 7 years from 34 tidal stations, 42 current stations, and 14 temperature and salinity stations. Key findings include the following: (1) the bay exhibits a shift in the tidal regime, transitioning from macro-tidal in the western region to micro-tidal in the central and eastern/northeast regions; (2) local winds and the subtidal variations from the coastal ocean are the primary drivers for the hydrodynamic processes in the eastern and central regions; (3) salinity changes in the bay are primarily controlled by three processes: the net supply of freshwater, the processes that drive mixing within the estuary (e.g., wind, topography, currents), and the exchange of salinity with the coastal ocean. This hydrodynamic model is essential for providing a comprehensive tool to address environmental challenges and sustain the bay’s ecosystem health. Full article