Nutrient fluxes from reduced Baltic Sea sediment: effects of oxygenation and macrobenthos
Number of Authors: 3
2016 (English)In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 544, 77-92 p.Article in journal (Refereed) Published
Effects of bottom water oxygenation and macrofaunal colonisation on benthic fluxes of nitrogen (N), phosphorus (P) and silicon (Si) from long-term anoxic Baltic Sea bottom sediment were investigated. Sediment boxcosms from an anoxic site at 150 m depth in the open Baltic proper were incubated in the laboratory to follow the development of benthic nutrient fluxes during 74 d exposure to flow-through of oxygen-rich water. In contrast to traditional end-point experimental designs, our repeated measurement approach allowed for separation of transient and long-term effects of oxygenation and bioturbation on benthic nutrient recycling. The composition, but not the rate, of the benthic total dissolved N efflux changed by oxygenation from being dominated by NH4 in situ to being mostly composed of NO2 + NO3 and dissolved organic N (DON) under oxic conditions. Oxygenation in the boxcosms decreased the benthic efflux of dissolved silicate (DSi) and essentially shut off the in situ flux of dissolved inorganic phosphorus (DIP). After 20 d of oxygenation, 2 bottom macrofauna taxa, the polychaete Marenzelleria spp. and the amphipod Monoporiea affinis, were introduced to a subset of the boxcosms. Bioturbation by either taxa increased the efflux of dissolved inorganic N (DIN), DON and DSi to the overlying water. The P-rich benthic flux under in situ anoxic conditions roughly approached Redfield N: P stoichiometry after oxygenation in the sediment boxcosms. Upon addition of macrofauna, bioturbation gene rated even higher N:P flux ratios.
Place, publisher, year, edition, pages
2016. Vol. 544, 77-92 p.
Bioturbation, Oxygenation, Benthic nutrient fluxes, Baltic Sea, Bottom sediment
Biological Sciences Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-128546DOI: 10.3354/meps11592ISI: 000371142500006OAI: oai:DiVA.org:su-128546DiVA: diva2:939913