Bivalve Shellfish Aquaculture and Eutrophication

Effects of a commercial, suspended eastern oyster nursery upon nutrient and sediment chemistry in a temperate, coastal embayment

“…Our finding of negligible or only localized effects of the East Creek FLUPSY is consistent with that for 93% of 62 other ecosystems studied (Burkholder & Shumway 2011). Overall, the chemical ecology of East Creek was little affected by the oyster nursery, and the few effects detected were not unexpected, based upon previous literature.…”

“…Measurements considered both water-column and sediment chemistry, with a focus on macronutrients and chemical compounds associated with hypoxia to address concerns about possible, adverse environmental impacts of bivalve shellfish aquaculture (Davenport et al 2000, Prins & Escaravage 2005, Burkholder & Shumway 2011. Characterization of the temporal variability of the embayment revealed conditions typical of many small, coastal embayments suitable for oyster aquaculture; therefore, these results should be widely applicable.…”

“…Furthermore, in estuarine environments with high hydrogen sulfide concentrations (anoxic sediments), the hydrogen sulfide can inhibit nitrification/denitrificaiton of nitrogen to nitrogen gas (Newell et al 2002, Newell 2004, Batley & Simpson 2009. When this happens, nitrogen becomes regenerated solely as total ammonia and is often returned to the water column to stimulate further phytoplankton production (Newell et al 2002, Newell 2004, Burkholder & Shumway 2011. For all sites at East Creek, there was a high flux of hydrogen sulfide and total ammonia from sediments to the water column, suggesting that microbial nitrification/denitrification of organic matter was being inhibited (Fig.…”

Open water integrated multi-trophic aquaculture: constraints on the effectiveness of mussels as an organic extractive component

“…The organic enrichment effects of organic biodeposition by commercial mussel culture operations have been reviewed on several occasions and tend to be either negligible or localized (e.g. Burkholder & Shumway 2011, McKindsey et al 2011. Larger-scale adverse impacts have been observed under site-specific conditions of relatively poor water flushing, high culture density, shallow water, and/or the presence of additional sources of organic enrichment (Hargrave et al 2008a, Cranford et al 2009).…”

Effect of oyster aquaculture on seagrass Zostera marina at the estuarine landscape scale in Willapa Bay, Washington (USA)

“…Experimental evaluations of the effects of shading due to oyster culture in suspended bags and hanging culture of floating oyster bags showed reduced eelgrass structure, morphometrics and photosynthesis observed at 26% reduction in subsurface irradiance, but design of the structures was clearly important, as the floating bags only reduced eelgrass directly below the structures (Bulmer et al 2012, Skinner et al 2014. Bivalves have also been shown to enhance seagrass growth by supplying nutrients via biodeposits and by improving water clarity via filtration, especially where nutrients in sediment limit seagrass growth and in eutrophic waters where phytoplankton blooms cause shading effects (Peterson & Heck 2001, Booth & Heck 2009, Burkholder & Shumway 2011. Though nutrients in sediment porewater were enhanced by the presence of oysters in Willapa Bay and oysters measurably cleared the water (Wheat & Ruesink 2013), only eelgrass shoot size was affected by oysters at the local scale , suggesting that seagrass response differs depending on estuarine conditions.…”