Science Serving Maryland's Coasts

R/P-AQ-65

Effects of Bivalve Biodeposits and Bottom Shear Stress On Sediment Erodibility with Implications for Biodeposit Export for Aquaculture Areas and Sediment Biogeochemistry

Principal Investigator: 

Elka Porter

Start/End Year: 

2020 to 2022

Institution: 

University of Baltimore

Co-Principal investigator: 

Jeffrey Cornwell, University of Maryland Center for Environmental Science, Horn Point Laboratory; Lawrence Sanford, University of Maryland Center for Environmental Science, Horn Point Laboratory

Strategic focus area: 

Healthy coastal ecosystems

Description: 

The net environmental impacts of oyster aquaculture are strongly related to the transport and fate of biodeposits, though little is known of their physical and biological properties. Biodeposits exported from aquaculture sites may result in net denitrification elsewhere while mitigating the impacts of organic matter over-enrichment at the aquaculture site. Consequently, the susceptibility of biodeposits to erosion and long range transport is key to determining the ecological effects of oyster aquaculture. Current oyster biodeposit models do not use realistic values of critical shear stress, (Tc), or values of the cumulative suspended mass (CSM) available for export at aquaculture sites. We propose one 6-week long experiment in six shear-turbulence-resuspension-mesocosm (STURM) tanks mimicking off-bottom aquaculture sites with daily biodeposit additions. Three of six tanks will be subject to biodeposit export, the rest will retain biodeposits. Additionally, we will determine the effect of exporting material on sediment biogeochemical fluxes off- and in- the aquaculture footprint. In addition, we will use duplicate Gust microcosms to determine Tc and CSM using cores obtained at aquaculture and nearby sites in the field to estimate biodeposit export and measure biogeochemical fluxes. The data generated will be used in ecosystem models by Jeremy Testa, Chesapeake Biological Laboratory/UMCES and NOAA. The Maryland Sea Grant supported STURM facility designed by Porter and Sanford and located at the Patuxent Environmental and Aquatic Research Laboratory (PEARL) will be used for the summer 2020 experiment. The STURM facility is a unique system that simulates high bottom shear stress due to tides and storms, realistic water column turbulence levels, and realistic benthic-planktonic interactions over extended periods (Porter et al. 2018a). Our data will be used by the oyster Best Management Practice (BMP) committee, the Chesapeake Bay Foundation, Maryland DNR, NOAA, the Oyster Recovery Partnership and The Nature Conservancy. We will offer undergraduate research internships.