Oyster reef habitat created by the eastern oyster, Crassostrea virginica, has been declining at an alarmingly rapid rate along the United States Atlantic and Gulf Coasts. Oyster reefs support an important commercial fishery as well as provide estuarine ecological services such as filtration, creation of refugia, and provision of feeding habitat for mobile and sessile species across a spectrum of life stages. They also greatly contribute to biomass production of both reef-associated fishes and invertebrates which have long term benefits for estuarine environments and the anglers that utilize reef habitats to target economically important fishes, making the species dynamics on these reefs an important area of study. Predator foraging Finfish species such as Sheepshead (Archosargus probatocephalus) are commonly found on Alabama oyster reefs along with predatory invertebrates such as the stone crab (Menippe mercenaria). Stone crabs are one of many reef-associated invertebrate predators of eastern oysters, with eastern oyster spat (< 30mm) being the most vulnerable life stage. Sheepshead are a generalist species, but previous studies have indicated a diet preference towards crustaceans and gastropods. A manipulative mesocosm experiment was used to assess the interaction and potential non-consumptive effects between Sheepshead, stone crabs, and eastern oysters. Preliminary research showed that when presented with the option of consuming a stone crab or eastern oysters, crabs are preferentially selected by Sheepshead every time. By consuming the predatory invertebrates found on oyster reefs, Sheepshead could protect the vulnerable eastern oyster from stone crab predation. This potential predator-prey interaction, if found to exist, could be used to inform management to protect these valuable and sensitive environments.

The Oysters in the Mississippi Sound are depleting because of a range of environmental and anthropogenic stressors. While some of the organic matter in water can be helpful for oyster survival and growth, the detritus in the suspended particulate matter (SPM) can foul these suspension feeding animals. Oysters are also subjected to additional stress because of bioavailability of the contaminants associated with SPM. Runoff from adjacent watersheds and resuspension of bottom sediments increase SPM in the water column. Remote sensing is useful in mapping the spatio-temporal distribution of SPM. The overarching objective of this research is to develop remote sensing algorithms for mapping SPM using Unmanned Aerial Systems (UAS). UAS imagery was collected by 71 flights during seven week-long trips in the months of March, May, June, July, and December 2018, and June and July, 2019 over the Henderson Point and Pass Christian Oyster Reefs, Mississippi, the largest oyster reef in the Mississippi Sound. Water samples and ancillary data were also collected from 71 locations during each flight. An empirical algorithm was developed using field data and data collected using a handheld radiometer. A series of image processing techniques were applied to the UAS imagery and the output were validated using a second method of image processing to ensure the accuracy of the UAS imagery output. The SPM algorithm was then applied to all the UAS imagery to generate SPM images. Subsequently, a time series analysis was performed with discharge to the Wwestern Mississippi Sound. The outcome of this study will not only help monitoring the water quality over the oyster reef in Mississippi but also the procedures developed to process the UAS imagery and algorithm development could act as a blueprint for future research in exploring the potential of using UAS for remote sensing of water quality.

Estuaries are naturally dynamic systems facing increasing variability of water quality conditions due to increased rainfall and snow melt caused by climate change, coastal land loss, and river management. Across the northern Gulf of Mexico, one ecologically and economically important species residing in estuaries is Crassostrea virginica, the eastern oyster. Although highly tolerant to a wide range of salinities and salinity variation, more frequent exposure of oysters to extreme low salinity (< 5) may impact overall population sustainability within some estuaries. This study assesses previously unexamined populations of C. virginica from low salinity areas of the Louisiana coast for population-specific tolerance to low salinities (< 5). Spat (< 25 mm) from four C. virginica populations were grown in an off-bottom long-line system in both a high salinity (10-15) (Grand Isle, LA) and a low salinity (< 6) (Cocodrie, LA) environment. Oysters were set out in December 2019 and growth and mortality are being tracked for a 12-month period. Upon completion of sampling, population specific growth, mortality, condition and dermo infection intensity will be analyzed examining population and site and their interaction. These analyses will determine if there is population-specific adaptation to low salinity based on the conditions in which the parent stock of populations came from. Identifying populations of C. virginica that are tolerant of low salinity would facilitate the strategic placement of oyster seed in areas to be impacted by lower salinity to promote restoration, aquaculture, and industry along coastal Louisiana.

Project Oyster Pensacola is a partnership between the Bream Fishermen Association (BFA), a volunteer monitoring and citizen engagement organization, and the Pensacola Bay Oyster Company. Project goals were to engage citizens to learn about water quality and how oysters improve water quality, as well as encourage citizens to consider ways they can improve water quality. Interested citizens, schools, and organizations participated in the project to deploy cages with 75 triploid oysters at various locations throughout Pensacola and Perdido Bay systems. Cages were deployed at 25 locations. BFA members and citizen volunteers monitored water quality, oyster survival and growth approximately every 4 months. After 14 months of deployment, oyster survival and growth were again measured, along with recruitment of fish and invertebrates. Salinity over the study period ranged from 1 to 29 with the lowest salinities in Perdido and Blackwater Bays and the highest salinity in Big Lagoon. Dissolved oxygen concentrations in surface waters averaged 91% saturation and were generally higher in winter than summer of fall. Salinity and dissolved oxygen were positively correlated. Oyster mortality was highest at sites with low salinity, particularly those less than 5. Oyster growth rates were positively correlated with salinity and dissolved oxygen. Recruitment of wild oysters at sites was highest above 20 PSU. Diverse fish and invertebrate communities were associated with cages. Blennies were the most common fish taxa. Crustaceans were dominated by amphipods and barnacles, while mussels were the most abundant mollusk. Oyster drills were only found at high salinity locations along with other marine species such as soft corals, tunicates, sponges and anemones. At sites with the average salinity greater than 20 PSU, the community composition was significantly different than sites between 10 and 20 PSU. These results may be helpful in guiding future oyster restoration efforts in the region.

Many mollusks alter their shell morphology in response to predator exudates or injured conspecifics to lower their predation risk. However, studies have yet to examine whether this predator-avoidance response can be applied under aquaculture scenarios to improve fisheries. We tested whether exposure to predator cues under hatchery conditions can increase the survival of oysters, Crassostrea virginica, planted in the wild. Juvenile oysters grown in a flow-through system were exposed to either caged blue crabs, Callinectes sapidus, or controls of empty cages for four and eight weeks then placed in the field for 30 days. We compared the shell crushing force, shell morphological characteristics, and individual survival of oysters across predator exposure time and treatments. Oysters grown in the hatchery for eight weeks were, on average, 46% larger and almost 2x stronger than oysters grown for four weeks. However, predator exposure also caused a 50% increase in shell strength for both time periods. These differences yielded significantly greater gains in survivorship over time as predator induced oysters nursed for four weeks exhibiting 53% higher survival in the field than unexposed oysters while this survivorship gain jumped to 300% for eight weeks of cue exposure. Our findings demonstrate that predator cues can be an effective means for the industry to increase the operational efficiency of aquaculture and restoration efforts, and may potentially be applied to other bivalve fisheries (e.g. clams, mussels).