Mosquito Lagoon Research Articles

Ecological Shifts: Plant Establishment in an Animal-Based Ecosystem

Shifts from saltmarsh to mangroves are well-documented at mangrove poleward boundaries. A regime shift from intertidal oyster (Crassostrea virginica) reefs to mangrove islands has recently been documented in transitional phases in Florida, USA. To understand the local drivers of an oyster/mangrove regime shift and potential tipping points leading to a permanent mangrove state, we tracked all mangrove propagules (n = 1681) across 15 intertidal oyster reefs with or without adult mangroves for 15 months in Mosquito Lagoon, FL. While no propagule bottleneck was observed, few (3.2%) mangrove propagules/seedlings survived on reefs with no prior encroachment, compared to 11.3% and 16.1% on reefs with established older (pre-1943) or newer (1943 to present) adult mangrove stands, respectively. In total, 90.6% of the arriving propagules were from the red mangrove Rhizophora mangle; 13.2% of these were alive at the end of this study. Survival was <1% for black (Avicenna germinans) and 0% for white (Laguncularia racemosa) mangroves. Factors that promoted red mangrove success included close proximity (≤0.3 m) to adult mangroves, especially black mangroves; partial, upright burial of propagules in sediment; and arrival on reefs after annual high-water season. Additionally, once reefs had 50% mangrove cover, the density of red mangrove seedlings increased from 0.04 to 0.46 individuals m−2. Although climate change has alleviated the impact of extreme freezes on mangroves, local factors determine whether the regime shift will be complete and permanent; positive feedback loops associated with established mangroves suggest mangrove recruitment on intertidal oyster reefs will continue to increase.

Monitoring an Ecosystem in Crisis: Measuring Seagrass Meadow Loss Using Deep Learning in Mosquito Lagoon, Florida

Monitoring an Ecosystem in Crisis: Measuring Seagrass Meadow Loss Using Deep Learning in Mosquito Lagoon, Florida

Groundwater nutrient loading into the northern Indian River lagoon: measurements and modeling

The Indian River Lagoon System (IRLS) has been impacted by the surrounding development, leading to excessive nutrient loads that have resulted in frequent and prolonged phytoplankton blooms in the northern reaches. Our study focused on estimating terrestrial groundwater discharge (TGD) and associated nutrient loads by combining field measurements and hydrogeologic modeling at four transects: Eau Gallie (EGT), River Walk (RWT), Banana River (BRT), and Mosquito Lagoon (MLT) across the IRLS. Multiple monitoring stations were installed to collect groundwater and surface water levels, salinity, and nutrient concentrations during 2014-2015. Samples were analyzed for dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). Numerical modeling was accomplished using SEAWAT to simulate TGD rates, whereas nutrient loads were calculated by multiplying simulated TGD by measured concentrations. TGD rates and nutrient loads were also estimated specifically for the “near-shore zone” along each transect. The effect of recharge from underlying Hawthorn Formation was also evaluated by incorporating estimated recharge rates into the models. Porewater and lagoon water samples showed that ammonium predominated over (NO2+NO3) and PO4 at all sites, resulting in DIN/DIP ratio surpassing the Redfield ratio. Low nitrite/nitrate, coupled with elevated ammonium concentrations at RWT, BRT, and MLT, may be attributed to biogeochemical transformations catalyzed by mangroves and wetlands. Simulated TGD showed mild temporal but significant spatial variation, especially between EGT and RWT compared to BRT and MLT. The highest average TGD of 0.73 and 0.77 m3/d.m occurred at RWT and EGT, respectively, whereas the lowest rates were predicted at BRT and MLT. The highest estimated average DIN loads of 507 and 428 g/yr.m were received at EGT and RWT, respectively, whereas MLT and BRT exhibited lower loads. The DIP loads were remarkably lower than the DIN loads and were significantly different in space and time between sites. Elevated DIN combined with reduced DIP resulted in DIN/DIP exceeding the Redfield ratio, thereby encouraging the blooming of harmful algae. Although the majority of seepage occurs through the near-shore zone, small amounts are received along the entire transect at all sites. The Hawthorn Formation does not contribute significant recharge to the aquifer at the transect locations.

Documenting Loss and Fragmentation of Intertidal Oyster (Crassostrea virginica) Reefs in a Subtropical Estuary

Intertidal reefs of Crassostrea virginica (eastern oyster) provide ecologically valuable habitat in estuaries along the Atlantic coast of North America. In Mosquito Lagoon, a shallow-water estuary on the east coast of central Florida, USA, historical aerial imagery was used to document a 24% decline in the live C. virginica reef area between 1943 and 2009. Using 2021 imagery, every living and dead reef in the same region was manually digitized to identify changes during the intervening 12 years. Positive impacts of C. virginica reef restoration that took place between 2007 and 2021 were also digitized to quantify long-term restoration impact. Natural, live C. virginica reef coverage throughout the system was found to have decreased by 50.6% between 2009 and 2021 and, thus, 62.6% between 1943 and 2021. This was attributed to reef fragmentation, reef footprint loss, boating activity, and mangrove expansion. Of the 2542 live reefs identified using 2009 imagery, 219 reefs fragmented, 988 reefs no longer had an identifiable footprint, and 598 reefs contained visible mangroves with non-continuous canopies. Conservatively, 63.6% of directly restored reef area was classified as living reef in 2021, and 74.5% of restoration projects were more than 50% live reef. Dead reef area decreased by 57.9% throughout the system. Understanding changes in C. virginica reef acreage, reef numbers, and mangrove expansion is essential for resource management, restoration practices, and tracking climate change impacts on publicly protected estuaries.

Short-term changes in the underwater soundscape of Mosquito Lagoon after Hurricane Ian

During late September 2022, Hurricane Ian passed over the east coast of Florida and Mosquito Lagoon. This 4740-acre body of water is part of a larger estuary system sandwiched between the mainland and narrow barrier islands. Two-thirds of the lagoon is located within Canaveral National Seashore, which helps maintain a balance between protecting its rich biodiversity and allowing access for recreational boating. As part of a previously planned study, we deployed two HydroMoths in Mosquito Lagoon to capture the underwater soundscape for two months from September 24 to November 19. Our sampling protocol recorded 5 min of continuous sound at the top and bottom of every hour, with the idea that we could begin to explore diurnal and lunar cycles. When Hurricane Ian's path took it directly over our recorders, we were given an unplanned opportunity to document how the underwater soundscape would respond. The most striking change came from the oyster toadfish (Opsanus tau). Calls from males of this species are a prominent part of the underwater soundscape in Mosquito Lagoon during their breeding season. In the days immediately following Hurricane Ian, they lowered the fundamental frequency of their calls leading to an audible change in pitch.

Organic carbon dynamics and microbial community response to oyster reef restoration

AbstractOyster reefs are often touted for their contribution to water quality improvement, shoreline protection, and habitat creation, but few studies highlight another significant ecosystem service: organic carbon (OC) storage and cycling. Although oyster reefs may not fall within the definition of “blue carbon” as a vegetated coastal ecosystem, they may store as much carbon (C) as other well‐studied coastal C sinks (e.g., mangroves, salt marshes, and sea grasses), providing an additional justification for restoration activities. Leveraging ongoing Crassostrea virginica reef restoration in Mosquito Lagoon, Florida (USA), this study employed a Before‐After‐Control‐Impact sampling design to evaluate short‐term (1 yr) changes in sediment OC storage and flux, microbial activity, and microbial community composition on degraded, natural, and restored oyster reefs. Restored reefs exhibited the greatest change in OC cycling within the study year, with increases in dissolved OC (31%), particulate OC (97%), CO2 flux (707%), and β‐glucosidase enzyme activity (467%), resulting in the highest total C and OC concentrations of the three reef types. Results demonstrate that sediment microbial community abundances are resilient and easily reinvigorated through reef restoration, while enzyme assays suggest sediment microbial activity on restored reefs may be limited by labile C availability. Overall, this study suggests restoration and oyster presence can rapidly enhance OC storage and can help offset the C flux from high calcification rates on young oyster reefs, providing an additional ecosystem service to support the importance of restoration activities.

Impact of Oyster (Crassostrea virginica) Reef Restoration on Benthic Invertebrates and Coastal Birds in a Subtropical Estuary

In order to mitigate the degradation of eastern oyster (Crassostrea virginica) reefs in Mosquito Lagoon (ML) along the east coast of central Florida, oyster reef restoration efforts have been in place for over 14 years. These restored reefs are successful in terms of universal oyster metrics (i.e., density, shell height, reef height) and are similar to natural reefs. However, little is known about the impact of this restoration on bird populations. ML provides a habitat for many bird species, including several listed as “threatened” by the Florida Fish and Wildlife Conservation Commission. Many of these birds rely on oyster reefs for foraging and loafing habitats. As benthic invertebrates serve as an important food source for coastal birds, we monitored the abundances and diversity of these organisms on live, restored, and dead reefs. We collected sediment samples from the reef sites pre-restoration, and one month, six months, one year, two years, and three years post-restoration. We counted benthic invertebrates present in the sediment samples, and sorted them by taxa (polychaetes, amphipods, isopods, gastropods, bivalves, decapods). Benthic invertebrate abundances on restored reefs became similar to live reefs over time (species composition, density), indicating that the prey base on restored reefs was similar to that of live reefs within 6 months. A second objective of this study was to determine if restored oyster reefs reach the same abundances, foraging behaviors, and diversity of bird species on natural, live reefs. We conducted monthly bird surveys to assess bird utilization of live, restored, and dead reefs. After three years, the abundances, behaviors, and assemblages of birds on restored reefs were similar to live reefs.

A Resident Fish Guild as a Higher Trophic Level Indicator of Oyster Reef Restoration Success

Eastern oysters (Crassostrea virginica) are critical foundation species in estuarine waters, but due to a combination of natural and anthropogenic pressures, oyster abundance has declined. Restoring oyster reefs and monitoring restoration success often focuses on oyster metrics, but relatively infrequently, responses of higher trophic level species and the production of related ecosystem services are accounted for. To address this, we compare the response of a resident reef fish guild (gobies, blennies, toadfish) to standard metrics of oyster restoration success. Using lift nets and seines, natural and restored reefs were monitored over a two-year period within Mosquito Lagoon, Florida, USA. Standard metrics are indicative of restoration success; live oyster density and reef thickness increased in restored reefs after 12 and 24 months. Combined, live oyster density and reef thickness were the best predictors of annual resident reef fish abundance compared to water quality metrics. These results suggest that the benefits of restoring oyster reef habitat are conferred to broader components of the food web, with benefits accruing to reef resident fishes that are a key trophic linkage between lower trophic level foundation species and higher trophic level predators inhabiting coastal ecosystems.

Soft-Sediment Communities of the Northern Indian River Lagoon, FL, United States

Understanding the structure and function of infaunal communities is useful in determining the biodiversity and ecosystem function of shallow estuaries. We conducted a survey of infaunal communities within three separate water basins [Mosquito Lagoon (ML), Indian River (IR), and Banana River (BR)] in the larger Northern Indian River Lagoon, FL, United States to establish a database of infaunal community structure and function. Twenty-seven sites were sampled quarterly from 2014 to 2016. Analysis of all samples determined that basin, season, and sediment composition were the primary drivers of macrobenthic community composition. Diversity was highest in the ML, and lower in spring compared to other seasons. The occurrence of a brown tide (Aureoumbra lagunensis) in 2016 allowed a comparison of winter and spring communities before (2015) and during (2016) a bloom event. Community composition and diversity at the BR sites were the most affected by the bloom event with the lowest diversity and abundances during the bloom. Diversity in the IR was also lower during the bloom, while the ML was unaffected by the bloom. Species of all feeding groups were affected by the bloom, with lower abundances found in all groups. In addition, to determine the overall trophic diversity of infaunal communities, we collected infaunal organisms from two of the quarterly sampled sites for isotope analyses. Values of δ13C and δ15N from infaunal tissue were compared to those of potential food sources at each site. Substantial interspecific variation in isotope values of infaunal organisms within a site suggests the presence of diverse nutritional modes that include suspension and deposit feeding and predation. Together, these data suggest that infaunal communities contribute to benthic pelagic coupling and nutrient cycling within the estuarine communities, but the overall function of these communities may be tightly linked to their species composition.

Strategies for Successful Mangrove Living Shoreline Stabilizations in Shallow Water Subtropical Estuaries

By combatting erosion and increasing habitat, mangrove living shorelines are an effective alternative to hard-armoring in tropical and subtropical areas. An experimental red mangrove living shoreline was deployed within Mosquito Lagoon, Florida, using a factorial design to test the impact of mangrove age, breakwater presence, and mangrove placement on mangrove survival within the first year of deployment. Mixed mangrove age treatments were included to identify if seedling (11-month-old) survival could be enhanced by the presence of transitional (23-month-old) and adult (35 to 47-month-old) mangroves. Environmental factors were monitored to detect possible causes of mangrove mortalities. Approximately half (50.6%) of mangroves died, and of those, 90.7% occurred within the annual high-water season, and 88.9% showed signs of flooding stress. Planting seedlings haphazardly among older mangroves did not attenuate enough wave energy to significantly increase seedling survival. Breakwaters alleviated stress through a reduction in water velocity and wave height, increasing the odds of survival by 197% and 437% when mangroves were planted in the landward and seaward rows, respectively. Compared to seedlings, deployment of adult mangroves increased survival odds by 1087%. Collectively, our results indicate that sites with a high-water season should utilize a breakwater structure and mangroves with a woody stem.

Male and female Anolis carolinensis maintain their dimorphism despite the presence of novel interspecific competition.

Natural selection favors sexual dimorphism that reduces resource competition between the sexes of the same species. However, niche partitioning among interspecific competitors should counter such divergence, as partitioning the niche results in smaller total niche widths for each individual species, leaving less room for the sexes to diverge. A straightforward (and long-standing) hypothesis emerges: species in competitor-rich ecological communities should show less sexual dimorphism than species in competitor-poor ecological communities. Here, we test this prediction using a well-documented natural experiment generated by the recent arrival of Anolis sagrei to a set of small islands in Mosquito Lagoon, Florida, containing Anolis carolinensis. Despite known interspecific habitat partitioning and rapid evolution in habitat-use traits by A. carolinensis in this system, sexual dimorphism between male and female A. carolinensis was not reduced as predicted on two-species islands relative to islands with only A. carolinensis. This is consistent with a small but growing body of empirical tests of the dimorphism-richness hypothesis that have been ambiguous in their support at best. A rethinking of the validity of this intuitive hypothesis is needed.

Dynamics of microcystins and saxitoxin in the Indian River Lagoon, Florida

Harmful algal blooms that can produce toxins are common in the Indian River Lagoon (IRL), which covers ~250 km of Florida's east coast. The current study assessed the dynamics of microcystins and saxitoxin in six segments of the IRL: Banana River Lagoon (BRL), Mosquito Lagoon (ML), Northern IRL (NIRL), Central IRL (CIRL), Southern IRL (SIRL), and the St. Lucie Estuary (SLE). Surface water samples (n=40) collected during the 2018 wet and 2019 dry season were analyzed to determine associations between toxins and temperature, salinity, pH, oxygen saturation, concentrations of dissolved nutrients and chlorophyll-a, presence of biosynthetic genes for toxins, relative abundance of planktonic species, and composition of the microbial community. The potential toxicity of samples was assessed using multiple mammalian cell lines. Enzyme-Linked Immunosorbent Assays were used to determine concentrations of microcystins and saxitoxin. Overall, the microcystins concentration ranged between 0.01-85.70 µg/L, and saxitoxin concentrations ranged between 0.01-2.43 µg/L across the IRL. Microcystins concentrations were 65% below the limit of quantification (0.05 µg/L), and saxitoxin concentrations were 85% below the limit of detection (0.02 µg/L). Microcystins concentrations were higher in the SLE, while saxitoxin was elevated in the NIRL and BRL. Cytotoxicity related to the presence of microcystins was seen in the SLE during the wet season. No significant patterns between cytotoxicity and saxitoxin were identified. Dissolved nutrients were identified as the most highly related parameters, explaining 53% of microcystin and 47% of saxitoxin variability. Multivariate models suggested cyanobacteria, flagellates, ciliates, and diatoms as the subset of microorganisms whose abundances were maximally correlated with saxitoxin and microcystins concentrations. Lastly, biosynthetic genes for microcystins were detected in the SLE and for saxitoxin in the BRL and NIRL. These results highlight the synergistic roles environmental and biological parameters play in influencing the dynamics of toxin production by harmful algae in the IRL.

Flushing rates and hydrodynamical characteristics of Mosquito Lagoon (Florida, USA).

A hydrodynamic model is applied to a domain encompassing Mosquito Lagoon and a segment of north Indian River Lagoon on the east coast of Florida with the goals of (1) describing the hydrodynamic regime of the area according to existing conditions and (2) to determine the flushing rates of the system after introducing a hypothetical pollutant (numerical dye tracer). Results from the 1-year simulation agree with observations and show that the Mosquito Lagoon (ML) and North Indian River Lagoon (NIRL) are dominated by the nontidal (low frequency) water level oscillations except at the northernmost part of the ML where the influence of tidal renewal dominates. The global tracer application results reveal that only the two northernmost segments of Mosquito Lagoon (ML-ac and ML-df) reach 50% of tracer concentrations (R50) within the year of simulation (day 19 and day 176 respectively). The five (discrete) segments tracer study resulted in lower R50 values and the hypothetical pollutant is removed (flushed) from each of the segments within the year and with an averaged renewal time value for the Mosquito Lagoon basin of 98days. Observed throughout the simulation period is the interaction across the different segments and a predominantly two-layered water mass exchange through the Haulover Canal. Most significant is that the resulting renewal times (R50) indicate the existence of three dynamically distinct sections within Mosquito Lagoon. These findings aid in the identification of poorly flushed zones and serve as a baseline for the duration and possible propagation of detrimental conditions such as a harmful algal bloom (HAB) event or a contaminant spill.

Replacement of oyster reefs by mangroves: Unexpected climate-driven ecosystem shifts.

Increases in minimum air temperatures have facilitated transitions of salt marshes to mangroves along coastlines in the southeastern United States. Numerous studies have documented mangrove expansion into salt marshes; however, a present-day conversion of oyster reefs to mangrove islands has not been documented. Using aerial photographs and high-resolution satellite imagery, we determined percent cover and number of mangrove patches on oyster reefs in Mosquito Lagoon, FL, USA over 74years (1943-2017) by digitizing oyster reef and "mangrove on oyster reef" areas. Live oyster reefs present in 1943 were tracked through time and the mangrove area on every reef calculated for seven time periods. There was a 103% increase in mangrove cover on live oyster reefs from 1943 (6.6%) to 2017 (13.4%). Between 1943 and 1984, the cover remained consistent (~7%), while between 1984 and 2017, mangrove cover increased rapidly with a 6% year-1 increase in mangrove area on oyster reefs (198% increase). In 1943, 8.7% of individual reefs had at least one mangrove patch on them; by 2017, 21.8% of reefs did. Site visits found at least one mature Avicennia germinans on each tracked mangrove reef, with large numbers of smaller Rhizophora mangle, suggesting the post-1984 mangrove increases were the result of increased R. mangle recruitment and survival. Escalation in the coverage and number of mangrove stands on oyster reefs coincided with a period that lacked extreme freeze events. The time since a temperature of ≤-6.6°C (A. germinans mortality threshold) and ≤-4°C (R. mangle mortality threshold) were significantly correlated with the increased ratio of mangrove area:oyster area, total mangrove area, and number of mangrove patches, with greater variation explained by time since ≤ -4°C. The lack of freezes could lead globally to an ecosystem shift of intertidal oyster reefs to mangrove islands near poleward mangrove range limits.

Juvenile Oyster (Crassostrea virginica) Biodeposits Contribute to a Rapid Rise in Sediment Nutrients on Restored Intertidal Oyster Reefs (Mosquito Lagoon, FL, USA)

By filtering large volumes of water and releasing nutrient-rich biodeposits (feces and pseudofeces), oysters can locally enhance sediment biogeochemical cycling. An active Crassostrea virginica restoration program in Mosquito Lagoon, FL (USA), was leveraged to assess the immediate (first-year) effects of restoration on sediment nutrients. Measurements included extractable and total carbon, nitrogen, and phosphorus on dead, natural, and restored reefs using a before-after-control-impact design. To investigate an observed “age-nutrient paradox” in sediment nutrient concentrations, a laboratory experiment compared feeding rates and biodeposit nutrient content between juvenile and older oysters. The field study documented a 136% increase in ammonium, 78% increase in total nitrogen, 46% increase in total phosphorus, and 75% increase in organic matter concentrations 12 months post-restoration, with extractable nutrients responding more rapidly to restoration than total nutrients. Sediment nutrient increases were positively correlated with oyster density, shell length, and reef height. Moreover, the laboratory study indicated juvenile oysters had higher rates of chlorophyll-a removal and ammonium efflux and produced biodeposits with higher concentrations of dissolved organic carbon, nitrate, and ammonium than older oysters. Overall, this study documented increases in sediment nutrients on intertidal reefs within the first year of restoration, which may be explained by a greater filtration rate and more nutrient-enriched biodeposits contributed by young oysters as compared to older oysters. Sediment total nitrogen and ammonium content may be the most robust monitoring metrics for documenting the ecosystem service of enhanced biogeochemical cycling on restored oyster reefs.

Does size matter? Quantifying the cumulative impact of small‐scale living shoreline and oyster reef restoration projects on shoreline erosion

Shoreline erosion is a common problem for coastal systems, especially in areas of high human use. Small‐scale living shoreline (LSL) and oyster reef restoration projects can potentially slow or reverse shoreline erosion in low‐energy coastal environments. These projects are often easier and cheaper to implement when compared to hard armoring. However, their small size can also lead to limited funds for long‐term monitoring and an underestimation of their impact on altering local erosion dynamics. Universal metrics are popular for monitoring the biological success of small‐scale restoration projects, but may lack an affordable, easy method to quantify shoreline change over large spatial and temporal scales, including understanding losses prior to project initiation. Digital Shoreline Analysis System (DSAS) is a viable method to quantify cumulative shoreline change for multiple small‐scale restoration projects in one ecosystem. For example, over the past 12 years, 89 oyster reef and 14 small‐scale LSL restoration projects have occurred in Mosquito Lagoon, FL, U.S.A. While each project has been individually monitored, there has yet to be a combined quantification of the cumulative impact to shoreline erosion. Using imagery from USGS's Earthexplorer and the DSAS tool in ArcGIS, we calculated cumulative shoreline change impacts of small‐scale restorations in one ecosystem. Both small‐scale LSL and oyster reef restoration reversed shoreline erosion to accretion. Cumulative net shoreline gain for the LSL and oyster restoration projects were 347.62 m2/year and 288.91 m2/year, respectively. Quantifying cumulative shoreline change of multiple small‐scale restoration projects is a beneficial addition to universal monitoring.

An Ecological Characterization of Fish Assemblages in Mosquito Lagoon, Florida

Coastal marine ecosystems are increasingly threatened by urbanization, land-based sources of pollution, and climate change. Changes in the environment due to these pressures could lead to shifts in community composition and dynamics. To address this issue, we sampled the fish assemblage of a coastal lagoon to assess species richness, rates of occurrence, and relative abundance. We caught 176,136 individuals representing 87 taxa. We compared our results to the last published survey of the study area conducted during the mid-1990s. Compared to historic data, there have been large shifts in percent occurrence in some economically important taxa, such as Lagodon rhomboides (Pinfish) increasing from 4% to 53% and Anchoa spp. (anchovies) increasing from 23% to 66%. These findings possibly indicate changes in the fish assemblage, essential fish habitat, or environment over the past 2 decades. As environmental and anthropogenic stressors continue to impact this complex coastal ecosystem, continued monitoring will be critical to detecting and understanding changes in the fish community in Mosquito Lagoon.

Cryptic speciation in the ectocommensal Bdelloura candida (Platyhelminthes, Tricladida, Maricola) follows habitat specialization of the American horseshoe crab, Limulus polyphemus

AbstractIn strict symbiotic associations, the genetic structure of the symbiont often mirrors that of its host, with interesting implications for population dynamics and phylogeography. An unresolved case of symbiotic specificity and phylogeographic consequence is the relationship between the marine triclad Bdelloura candida and its host, the American horseshoe crab, Limulus polyphemus. A recent study by Riesgo et al. (2017, Marine Biology, 164, 111) identified a strong genetic break between populations of B. candida in the Gulf of Mexico and the Atlantic Ocean but had minimal sampling around the Florida peninsula such that the exact location of the boundary zone was not specified. To solve this, a comprehensive analysis of 16S rRNA and ITS2 genetic markers was conducted from new collections around the Florida peninsula. A clear and significant genetic break was identified between populations of supposed B. candida between Cumberland Island, Georgia, and Mosquito Lagoon, Florida. This genetic break establishes two cryptic lineages, an Atlantic population as far south as Georgia and a Floridian population inclusive of the entire peninsula and Gulf of Mexico, potentially due to niche partitioning of the unique intertidal habitats of its horseshoe crab hosts in Florida. This result directly refutes the previous hypothesis that a population break exists between the coasts of the Atlantic Ocean and Gulf of Mexico, and instead matches the genetic break of its host. Furthermore, a third cryptic lineage was identified in Key West. Overall, this work demonstrates the challenges in maintaining genetic connections between populations of both B. candida and L. polyphemus across their distributions, and poses meaningful implications for both species in the larger context of marine conservation and biodiversity.

Carbon and nutrient fluxes from seagrass and mangrove wrack are mediated by soil interactions

Shoreline accumulation of vegetative wrack may contribute nutrient subsidies for primary or secondary production, detritivore food-web support, habitat provision, and sediment stabilization. This study addresses a knowledge gap in the literature by going beyond quantification of carbon (C) and nutrient flux potentials to investigate the biogeochemical interaction between wrack and shoreline soil. Results from a year-long shoreline survey of wrack type and abundance in Mosquito Lagoon, FL, were combined with a two-month intact core experiment observing the interaction of mangrove and seagrass leaves with organic and mineral shoreline soils. Experimental treatments were subjected to tidal cycles; at low tide, measurements were made of soil respiration and drainage water nutrient content. A measure called Soil Interaction with Litter Effect (SoILE) is introduced to quantify the suppression or enhancement of C and nutrient fluxes from a combination of wrack with shoreline soils compared to the potential fluxes of wrack and soil separately.Monthly mean (±1 S.E.) accumulation of wrack dry mass in Mosquito Lagoon was 37.65 ± 2.99 g m−2. Unusually high values (72.16 ± 13.74 g m−2) occurred in September 2017 following Hurricane Irma. In a comparison of seagrass and mangrove leaves and organic and mineral soils, seagrass leaves were the greatest source of dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) by factors of 24 and 13, respectively. Seagrass also had the highest fluxes of dissolved organic carbon (DOC) and CO2 by factors of 2 and 2.7, respectively. The most common effect of combining wrack and soil was to suppress the magnitude of DOC and CO2 fluxes. There were few differences between combined and additive fluxes of DIN and SRP; the DIN flux was suppressed from the combination of seagrass with organic soil, and the SRP flux was enhanced from the combination of mangrove leaves with mineral soil. Suppression and enhancement of SoILE values were likely both attributable to a “smothering” effect caused by the physical interaction of vegetation with the soil surface that altered redox conditions. Wrack accumulation on restored living shorelines is likely to have a two-fold positive effect of subsidizing nutrients for primary production by shoreline plants and contributing to an increase in soil carbon by interacting with soils to result in a net suppression of DOC and CO2 effluxes.

Quantity and types of microplastics in the organic tissues of the eastern oyster Crassostrea virginica and Atlantic mud crab Panopeus herbstii from a Florida estuary

This study determined the quantity and diversity of microplastics in water and soft tissues of eastern oysters (Crassostrea virginica) and Atlantic mud crabs (Panopeus herbstii) in Mosquito Lagoon, a shallow, microtidal estuary along the east coast of central Florida. One-liter water samples had an average of 23.1 microplastic pieces (n = 15). Crabs (n = 90) had an average of 4.2 pieces in tissues/individual plus an average of 20.3 pieces/individual temporarily entangled in exposed surfaces and released within 5 days in tanks. Adult oysters (n = 90) had an average of 16.5 microplastic pieces/individual. Fibers, mostly royal/dark blue in color, dominated our collections. When compared per gram of tissue, crabs had two orders of magnitude more microplastic pieces than oysters. Our numbers were higher than previous studies on invertebrate microplastics; this is potentially the result of extensive urbanization, limited flushing, and intensive recreational usage of Mosquito Lagoon.