R/CT-5

Strategic focus area:

Description:

Oyster aquaculture is a rapidly growing industry in Maryland’s Chesapeake waters which stimulates economic activity and may provide a host of ecosystem benefits. A potential concern associated with the intensification of the oyster aquaculture is the local production and accumulation of oyster biodeposits, which can lead to a porewater sulfide accumulation and declining bioturbation, symptoms of declining ecosystem function. Sulfide is naturally removed from the seafloor by the interactions between bioturbating infauna and sulfide oxidizing bacteria. Here, we propose exploring the feasibility of using benthic microbial fuel cells (BMFCs) to accelerate sulfide oxidation in areas of high biodeposit accumulation, below oyster aquaculture cages. BMFCs take advantage of the natural assemblage of bacteria in sediments which catalyze the transfer of electrons from reduced compounds (including sulfide) to an anode buried a few centimeters in the sediments. When coupled electrically with a cathode suspended 10s of cm above in oxygenated water, the fuel cell generates low voltage electricity. When further configured with capacitors and an energy management system, this power may be used to drive useful instrumentation (e.g., LED lights, conductivity sensors). In the first year, we propose fuel cell development and lab experimentation utilizing locally sourced oyster biodeposits, and field measurements to characterize variation in sediment redox potential in proximity to oyster aquaculture cages. In the second year, we propose extending to pilot-scale field experiments coordinated at Horn Point Lab and with local growers. Key goals are to demonstrate proof-of-concept that BMFCs may mitigate sulfide accumulation from oyster biodeposits and that the sulfide removal confers positive ecosystem benefits in terms of benthic infauna biomass and denitrification potential. We will work cooperatively with Maryland Sea Grant Extension to examine the range and oscillations of sediment redox conditions encountered, and to assess the utility of this technology for oyster aquaculture operators.