Aquaculture Nitrogen Removal Via Microbial Denitrification: Experimental Measurements With Realistic Resuspension of Bivalve Biodeposits

Principal Investigator:

Elka Porter

Start/End Year:

2022 - 2024


St. Mary's College of Maryland

Co-Principal Investigator:

Jeffrey Cornwell, Horn Point Laboratory, UMCES; Lawrence Sanford, Horn Point Laboratory, UMCES


Strategic focus area:

Healthy coastal ecosystems


The potential for net nitrogen removal due to oyster aquaculture is strongly related to the transport and fate of oyster biodeposits. Biodeposits exported from aquaculture sites may enhance denitrification rates elsewhere while mitigating the impacts of organic matter over-enrichment at the aquaculture site, and/or suspended biodeposit organic matter may be denitrified in the water column. Both processes are currently not well understood. We propose a 6-wk ecosystem experiment in six shear-turbulence-resuspension-mesocosm (STURM, Porter et al. 2018a) tanks with tidal resuspension to address these questions. Three tanks will receive daily oyster biodeposit additions to mimic an aquaculture site and three tanks will not in order to represent background natural conditions. Whole ecosystem denitrification rates under in situ resuspension and non-resuspension will be measured using a novel approach in which entire STURM tanks are sealed off as experimental denitrification chambers. The effects of particle size and biodeposit/organic controls on whole system nitrification and denitrification will be studied. Currently there is no information on resuspension-mediated whole ecosystem denitrification in the US coastal zone nor from aquaculture areas. This research is critical for modeling and nutrient crediting for aquaculture, currently under consideration by the Oyster Best Management Practice (BMP) committee. This research is supported by our research and management partners - the Chesapeake Bay Foundation, NOAA Milford Laboratory, the Oyster Recovery Partnership, NOAA Cooperative Oxford Laboratory, and The Nature Conservancy and our modeling partners from the University of Colorado and UMCES. Undergraduate research internships will be integral to this project. Further consideration of aquaculture as a nitrogen-reducing BMP cannot proceed without high quality, whole ecosystem biogeochemical data, requiring new measurement approaches such as our proposed novel STURM application.

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