Denitrification and nutrient assimilation on a restored oyster reef

Abstract

Resale or republication not permitted without written consent of the publisherOyster reefs reduce eutrophication by enhancing denitrification rates and assimilating nutrients into macrofauna.

Changes in Sediment Characteristics upon Oyster Reef Restoration, NE Florida, USA

“…Benthic microalgae may also stimulate denitrification by contributing labile organic carbon and increasing oxygenation of surface sediments [33]. Sediments from restored oyster reefs have been shown to be active sites of denitrification [18][19][20], with the highest sedimentary denitrification rate ever reported [17]. However, OM enrichment may also cause persistent anoxia within sediments, which may cause reduced N2 production if the supply of NO3 becomes limiting [33].…”

“…Several recent studies suggest that sediments associated with natural and restored oyster reefs have high rates of denitrification and may thus represent important sites for long term nitrogen removal [17][18][19][20]. Whole-creek studies and some mesocosm studies do not parse the contributions of the oysters themselves versus the associated sediments but rather consider the reef-sediment system as a whole [3,5,17]. Indeed, it is difficult to separate these effects because the presence of the reef will likely alter the depositional environment and ultimately the biogeochemistry of the surrounding sediment.…”

“…However, mesocosm experiments show that physical factors such as bottom shear can influence sediment resuspension and benthic micro-algal biomass, making the system more complex and the likelihood of OM burial versus remineralization more difficult to predict [7]. Several recent studies suggest that sediments associated with natural and restored oyster reefs have high rates of denitrification and may thus represent important sites for long term nitrogen removal [17][18][19][20]. Whole-creek studies and some mesocosm studies do not parse the contributions of the oysters themselves versus the associated sediments but rather consider the reef-sediment system as a whole [3,5,17].…”

“…Reefs act to attenuate wave energy, possibly facilitating deposition of fine sediment [8]; this process may work in concert with oyster filtration to increase light penetration that may then shift ecosystems towards more benthic primary producers [6]. Finer particles and much higher organic matter (OM) content in oyster-associated sediments suggests a substantial role for carbon and nutrient removal by burial [8,17] and benthic algal uptake where light penetration is sufficient [6]. However, mesocosm experiments show that physical factors such as bottom shear can influence sediment resuspension and benthic micro-algal biomass, making the system more complex and the likelihood of OM burial versus remineralization more difficult to predict [7].…”

Ecosystem services are lost when facilitation between two ecosystem engineers is compromised by oil

“…Oysters remove sediments, phytoplankton, and detrital particles, potentially reducing turbidity and improving water quality (Dame & Patten 1981). The enhanced benthic− pelagic coupling that results from the suspension feeding of dense assemblages of bivalves can create hotspots of biogeochemical cycling (Piehler & Smyth 190 Kellogg et al 2013) within the estuarine landscape. The complex habitat formed by the gregarious settlement of oysters (reefs or hummocks) also provides critical refuge for benthic invertebrates as well as fishes and mobile crustaceans (Meyer & Townsend 2000, Peterson et al 2003, Coen et al 2007, Grabowski & Peterson 2007.…”