MEPS 646:13-27 (2020)  -  DOI: https://doi.org/10.3354/meps13377

ABSTRACT: Oyster aquaculture is expanding globally, and there has been a recent research surge examining how oyster farms alter coastal ecosystems. Yet, until now, the role of time in these studies has largely been missing. Here we used an in situ chronosequence approach to determine how the presence of oyster aquaculture (Crassostrea virginica) altered sediment nitrogen (N), oxygen (O₂), and phosphorus (P) cycling. Overall we found that the sum of nitrogen fluxes increased significantly following addition of aquaculture, and switched from net N consumption (i.e. net nitrogen fixation: -14.41 µmol N m^-2 h^-1) to production (i.e. net denitrification: 553.57 µmol N m^-2 h^-1). Ammonium (NH₄⁺) fluxes did not differ between bare sediment and oyster aquaculture. Additionally, both the magnitude of N₂ and NH₄⁺ fluxes oscillated on an annual scale of aquaculture age, but not predictably so. We observed significantly more variance (σ²) in dinitrogen and NH₄⁺ fluxes in sediments beneath aquaculture, indicating increased non-linearity. O₂ fluxes increased from Years 4 to 6, before returning to baseline conditions. There were no differences in sediment P cycling. This study demonstrates that sediment biogeochemical processes can become non-linear under the pressure of oyster aquaculture, and this non-linearity likely has important implications for ecosystem function.

KEY WORDS: Denitrification · Dissolved inorganic nitrogen · Dissolved inorganic phosphorus · N:P · Nitrous oxide · Oysters · Aquaculture

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Cite this article as: Ray NE, Al-Haj AN, Fulweiler RW (2020) Sediment biogeochemistry along an oyster aquaculture chronosequence. Mar Ecol Prog Ser 646:13-27. https://doi.org/10.3354/meps13377 Export citation Share:    Facebook - - linkedIn