The green porcelain crab, Petrolisthes armatus, has recently invaded oyster reefs of the South Atlantic Bight at mean densities of up to several thousand individuals m-². Despite the crab’s tremendous densities and wide-spread occurrence, its population dynamics, the reasons for its success, and its ecological impacts have remained unknown. We used field monitoring in two estuaries of coastal Georgia to assess spatial and temporal patterns of distribution, demographics, reproduction, and effects on native crabs. We used field and mesocosm experiments with constructed oyster reef communities of varying native species richness and adult porcelain crab additions to assess why the invader is successful and how it impacts native species and communities. We found P. armatus distributed throughout the estuaries, primarily in the lower regions and low intertidal. Sex ratios were 1:1 throughout the year. During warmer months mean densities ranged from 1,000-11,000 crabs m-², 20-90% of mature females were gravid, and numerous recruits were present. Despite decreases in density of 64->99% in the winter, populations rebounded in the spring. Maximum mean densities were 37 times the highest densities ever recorded and population fecundity exceeded that of the native range by an order of magnitude, but correlations did not show significant negative effects of P. armatus on native crabs. Field experiments suggested that invasion was successful due to tremendous recruitment overwhelming biotic resistance by native species richness or predation. The crab only needed structure to invade, but the presence of adult conspecifics significantly enhanced recruitment (i.e., intraspecific “invasional meltdown”). We documented several impacts on native biota, including the (1) suppression of oyster growth, benthic algal biomass, native crab recruitment, and native goby densities and the (2) enhancement of bivalve recruitment, macroalgal cover, and survivorship of oyster drills. We did not, though, see an effect on native taxonomic richness. The large direct and indirect effects of P. armatus on growth, survivorship, and recruitment of virtually all of the most common native species on oyster reefs in the short-term (4-12 weeks) and at relatively low experimental densities (750-1500 crabs m-²) imply considerable long-term consequences for a major hard-substrate habitat of the South Atlantic Bight.

The present study explored the spatial and temporal demographic trends in oyster population dynamics and their relationships to freshwater inflows and the pathogen Dermo (Perkinsus marinus) on three reefs (Shell, Mad Island, and Sammy?s) in West Matagorda Bay, Texas. The objectives were to design and link three population models that simulate oyster population dynamics and integrate the environmental factors that influence growth, reproduction and settlement of larvae among these three reefs. The following variables were evaluated: relative abundance of oyster spat, submarket- and market-size oysters, average weighted incidence of Dermo and percent Dermo infection (prevalence) in submarket- and market-size oysters and their relationships to environmental variables of salinity, temperature, flow and distance from freshwater sources. Using a 30-month continuous dataset, environmental variables accounted for 36% of the variation in Dermo-related variables among the three reefs, and were also positively correlated with distance from freshwater sources. The relative abundance of spat and dead oysters was related to peaks in freshwater inflows occurring 30 days prior to larval settlement. Using these spatial and temporal relationships among biological and environmental variables, and data from five years of monitoring three reefs in Matagorda Bay, an integrated Stella model was developed that simulated oyster population responses to stochastic environmental changes over a 50-year period. Although the geological and structural complexity of each reef appeared to be similar, the model showed the relationship of growth, spawning and spat set were related to hydrologic variation between different reefs and time periods. The model revealed that up-estuary reefs relied on the distribution of larvae from down-estuary reefs following mortality related to freshwater inflow. The model also indicated that loss of freshwater inflows to down-estuary reefs resulted in higher sustained Dermo infections, thus loss of spawning potential and subsequent distribution of larvae to up-estuary reefs. The three oyster populations in West Matagorda Bay provide spawning connectivity and function as an integrated resource for sustaining all oyster reef populations in this bay system. The model presented in this research provides a basis for understanding the population dynamics of WMB as well as a better understanding of the interaction among the reefs that sustain these populations. The model developed in this investigation provides a basis for developing oyster population models for other bay systems and for future research regarding hydrologic influences on oyster population dynamics.

The present study explored the spatial and temporal demographic trends in oyster population dynamics and their relationships to freshwater inflows and the pathogen Dermo (Perkinsus marinus) on three reefs (Shell, Mad Island, and Sammy?s) in West Matagorda Bay, Texas. The objectives were to design and link three population models that simulate oyster population dynamics and integrate the environmental factors that influence growth, reproduction and settlement of larvae among these three reefs. The following variables were evaluated: relative abundance of oyster spat, submarket- and market-size oysters, average weighted incidence of Dermo and percent Dermo infection (prevalence) in submarket- and market-size oysters and their relationships to environmental variables of salinity, temperature, flow and distance from freshwater sources. Using a 30-month continuous dataset, environmental variables accounted for 36% of the variation in Dermo-related variables among the three reefs, and were also positively correlated with distance from freshwater sources. The relative abundance of spat and dead oysters was related to peaks in freshwater inflows occurring 30 days prior to larval settlement. Using these spatial and temporal relationships among biological and environmental variables, and data from five years of monitoring three reefs in Matagorda Bay, an integrated Stella model was developed that simulated oyster population responses to stochastic environmental changes over a 50-year period. Although the geological and structural complexity of each reef appeared to be similar, the model showed the relationship of growth, spawning and spat set were related to hydrologic variation between different reefs and time periods. The model revealed that up-estuary reefs relied on the distribution of larvae from down-estuary reefs following mortality related to freshwater inflow. The model also indicated that loss of freshwater inflows to down-estuary reefs resulted in higher sustained Dermo infections, thus loss of spawning potential and subsequent distribution of larvae to up-estuary reefs. The three oyster populations in West Matagorda Bay provide spawning connectivity and function as an integrated resource for sustaining all oyster reef populations in this bay system. The model presented in this research provides a basis for understanding the population dynamics of WMB as well as a better understanding of the interaction among the reefs that sustain these populations. The model developed in this investigation provides a basis for developing oyster population models for other bay systems and for future research regarding hydrologic influences on oyster population dynamics.

The objective of this study is to estimate the willingness to pay of U.S. Gulf Coast residents to support oyster reef restoration. The Gulf Coast is the leading commercial oyster- producing region in the United States, accounting for approximately 46% of the total commercial oyster harvest in 2021. My benefit estimates were based on data obtained from a contingent valuation survey of 6,475 Gulf Coast respondents. I estimated the willingness to pay (WTP) for oyster reef restoration using interval regression and Turnbull lower-bound methods. The estimated mean WTP value is in the range of $142 and $436 per household. The results show respondents who eat oysters and those that hold saltwater fishing licenses have significantly higher WTP.

Gray snapper (Lutjanus griseus) is a common reef fish inhabiting the western Atlantic Ocean. In estuaries of the Southeastern United States, such as Mosquito Lagoon, Florida, oyster reefs, seagrass, and mangrove shorelines are vital nurseries, also known as essential fish habitat (EFH), for juvenile fish. However, EFH in Mosquito Lagoon has declined from historic levels due to human activity. To mitigate these losses, oyster reef and living shoreline restoration projects have occurred to putatively increase the availability of EFH. For gray snapper in Mosquito Lagoon, past studies have assessed local habitat preferences and trophic structure, but the biotic and abiotic factors influencing age and growth rates have not been quantified. To address this knowledge gap, this study aims to quantify the mean age and growth rate of gray snapper in Mosquito Lagoon, and investigate if prey and/or other environmental factors (abiotic/biotic conditions, time, and location/site status) impact size at both lagoon and habitat-specific scales. Results indicate the most common life stage for gray snapper in Mosquito Lagoon are mid-stage juveniles, with living shoreline habitats having a greater proportion of younger juveniles and oyster reef habitats having a greater proportion of older juveniles. Estimated growth rate was 0.43 mm/day. Size was correlated with location/site status and lagged salinity levels, with said environmental factors outperforming stable isotope and gut content variables in model comparisons. Gray snapper mass was also correlated with size in all of the most parsimonious models, suggesting future research should consider including weight-length relationships when investigating the environmental or trophic influences on gray snapper growth. Collectively, this study increases our fundamental understanding of gray snapper population dynamics and provides insight that can be used subsequently to benefit the management of recreational and commercial fisheries in the Southeastern US.

Mangrove stands and oyster reefs are two common coastal habitats in the Indian River Lagoon. Each habitat provides diverse ecosystem services, including carbon sequestration and carbon storage. A decrease in freeze events and an increase in sea levels are leading to mangrove habitat expansion, including encroachment onto live oyster reefs in the IRL’s northernmost portion, Mosquito Lagoon. This study investigates how the encroachment of black mangroves (Avicennia germinans) and red mangroves (Rhizophora mangle) on eastern oyster reefs (Crassostrea virginica) impacts the abundance and stability of soil carbon relative to each habitat alone. Soil and sediment samples (0-10cm) were collected from three locations in Mosquito Lagoon, each containing a mangrove-only, oyster-only, and mangrove-encroached oyster reef habitat. Total and active carbon were quantified, and stable carbon was determined through physical and density fractionation that isolates persistent mineral-associated organic matter (MAOM). Results showed total, active, and MAOM-carbon averaged 2-3 times greater in mangroves than oyster reefs, while mangrove-encroached oyster reefs were intermediate in concentration. However, mangrove-oyster soils have the highest proportion of the total carbon pool protected as MAOM (54.9%), compared to each habitat alone (mangrove-only, 35.3%, oyster-only, 30.3%). This research is the first to provide data on blue carbon storage in areas where mangroves encroach on oyster reefs, including differentiating total carbon based on its stability in the soil.