This project will assess the ecosystem services of shellfish farming by measuring impacts of newly established farms in the North Carolina Research Reserve. Because there is an opportunity to assess conditions before farm installation, North Carolina estuaries provide an ideal place to measure these effects. Two years of intensive sampling in and adjacent to oyster farms, concentrating on wild shellfish resources and the physical and chemical environment, will aim to link small-scale changes with larger-scale ecosystem-level alterations. Coastal managers, state agencies, and shellfish farmers will provide input throughout the course of the project to ensure that the study parameters align with decision-making needs. The project will culminate with the production of visualization tools and models to allow resource managers, culturists, and reserve staff members to make better decisions when determining the locations and scales of shellfish farming operations.

Particulate matter removal by shellfish was quantified in several geographic locations, across several years. Data include filter and shellfish tissue weights.

Coastal researchers, fishermen, fishery managers and educators teamed up to understand changes in shrimp populations in response to shifting environmental conditions in estuaries. The Project Shrimping has deep cultural and economic ties to the South Carolina and Georgia coasts, and the southeast US Atlantic coast region as a whole. However, over the past two decades, commercial shrimp landings have been highly variable. Fishery management agencies, extension offices, and several southeastern Reserves have identified the need to better understand how shrimp populations are responding to changing environmental conditions, including warmer winters and altered salinity regimes. To do this work, a diverse team with members from universities, fishery management agencies, fisheries extension offices, and Reserves came together to form the Lowcountry Shrimp Collaborative. The Lowcountry Shrimp Collaborative used a comprehensive approach to examine how environmental conditions in estuaries are affecting abundance and timing of shrimp populations throughout the region through examination of each stage of the shrimp life cycle. Together, the Collaborative: Analyzed and synthesized numerous ongoing, long-term (30+ years) datasets on multiple shrimp life history stages (postlarval, juvenile, sub-adult, adult, commercially harvested) and environmental conditions (water quality, including System-Wide Monitoring Program data); Conducted field sampling targeting shrimp and their prey in salt marsh creeks during spring and summer seasons, over two years, at three southeast Reserves; Ran controlled seawater laboratory experiments to understand the impacts of competition for limited resources between shrimp species during their overlapping periods of estuarine residency; and, Interviewed commercial shrimpers based in Georgia and South Carolina, to better understand historical changes in, and perceptions of environmental impacts on, the shrimp industry in the southeast US. The project found that estuarine water temperature is rising across the region, mainly driven by increases during winter months. Warming temperatures can alter the life histories of shrimp, including shifting body size, altering the timing of migratory cues, and modifying habitat use. These warmer temperatures are also resulting in longer shrimping seasons with shrimpers often able to continue harvesting well into January. These results were confirmed by observations shared by shrimpers, who joined for a project wrap-up event where the team presented results and engaged in lively discussions about research needs and opportunities for collaboration between researchers, managers, and the industry.

The project team established an experiment that mimicked commercial aquaculture practices and allowed for a robust comparison of nitrogen removal rates from three commonly used gear types: floating bags of oysters, oyster condos suspended in midwater, and bottom cages of oysters. All gear was deployed in the same environmental setting (Waquoit Bay, Falmouth, MA) and maintained by the Town of Falmouth in a manner that a typical grower would follow. The growing systems were maintained for two full growing seasons (2018 and 2019) and compared to a nearby control site. Every two weeks during the growing season, the team conducted a series of measurements to provide a robust estimate of nitrogen fluxes and microbial activity below each of the aquaculture operations. Measurements included: (1) nutrient analyses of sediment, porewater and bottom water samples, (2) genetic sequencing of RNA and DNA extracted from sediment samples to determine the presence and activity level of certain bacteria; and 3) measurements of N2 fluxes from sediment cores placed in flux chambers to measure N2 production rates. All three oyster growing methods enhanced nitrogen removal relative to the control site. However, gene expression data indicate that nitrogen retention may be induced under some gear, particularly after the end of July under bottom cages, and to a lesser extent other gear types.

The effects of hydraulic shellfish harvesting on the ecology of biological communities and chemistry of benthic sediments were investigated through a series of experiments conducted over a 5-year period from 2009 to 2013. Studies on a variety of different clam beds were undertaken in collaboration with local shellfish harvesters. Sediment samples were collected over the summer and early fall (June to October) and sorted to identify and count benthic organisms and to measure chemical parameters (e.g., pH, oxygen, aragonite saturation state), at the sediment/water interface. Comparisons of dredged to not dredged seafloor found that the effects of season (date of sampling) and location (sediment grain size) exceeded those of shellfish harvesting. Numbers of newly settled bivalves were often higher on recently harvested bottom. Shallow inshore marine communities appear to be highly resilient to disturbance, whether natural or manmade. Shellfish harvesting had only minor impacts on the ecology of seafloor communities and on chemistry of marine sediments.