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The role of oyster restoration and aquaculture in nutrient cycling within a Rhode Island estuary
Citation:
Humphries, A., S. Ayvazian, J. Carey, AND R. Fulweiler. The role of oyster restoration and aquaculture in nutrient cycling within a Rhode Island estuary. International Oyster Sympsium, Falmouth, MA, October 21 - 23, 2015.
Impact/Purpose:
The results from this research will be used by resource managers to better understand the role of oyster restoration and aquaculture to improve water quality
Description:
Coastal ecosystems are increasingly impacted by over-enrichment of nutrients, which has cascading effects for other organisms. Oyster aquaculture and restoration are hypothesized to mitigate excessive nitrogen (N) loads via benthic denitrification. However, this has not been examined in New England, where oyster aquaculture and restoration are increasing and nutrient runoff is high. Using 50L chambers, we conducted benthic experiments to examine the influence of oyster aquaculture and oyster reef restoration on benthic metabolism and net N2 fluxes across the sediment-water interface. In a shallow (~1m) estuary in southern Rhode Island, we collected samples seasonally in 2014 using the N2/Ar technique. Preliminary results indicate oyster restoration and aquaculture had greater denitrification rates than bare sediment, but the degree to which they were different was highly seasonal. We relate our net N2 fluxes to differences in site-specific environmental factors, such as sediment oxygen demand, sediment chlorophyll a, dissolved inorganic nutrient availability, and associated benthic organism abundance and diversity. Our results demonstrate that oyster reef restoration and aquaculture can increase denitrification rates, but nutrient processing varies dramatically over small spatial scales.