Benthic Metabolism and the Quality of Sediment Organic Carbon

Abstract

AbstractWe have used changes in oxygen uptake of sediment cores incubated in the laboratory and receiving no particulate input to examine the utilization of labile organic carbon by the benthos. A model is described that predicts a decline in sediment oxygen consumption after primary labile organic carbon (G01) is depleted. Oxygen consumption by cores taken from an intertidal sandflat in Nova Scotia and incubated in darkness (11–13°C) declined after about two months. G01 organic carbon was estimated as ∼8% of total sediment carbon (GT) in the upper 1 cm of sediment. Anaerobic metabolism (based on CO2 production), a significant portion of community metabolism, increased rather than declined during the incubations. Similar calculations were performed using published data on cores from Narragansett Bay. At this location, organic matter in the G01 fraction was 5% of GT. A less labile organic carbon fraction (G02) was estimated to be 44% of GT based on declining oxygen consumption after 27 days. Refractory car...