Benthic community respiration in relation to sedimentation of phytoplankton in the Øresund

Publisher Website
Google Scholar
Abstract
Oxygen uptake was measured in the laboratory on sediment cores taken on 23 occasions with the Haps sampler (135 cm2) from a depth of 27 m in the middle of the Helsingør-Hälsingborg-Hven basin in the Øresund. The cores were incubated at temperature and salinity conditions of the sampling locality. Sedimentation of phytoplankton during the spring bloom (April) had no immediate effect on total benthic community respiration. Most of the input was stored and mineralized during summer and autumn. High temperature (10°C) was a prerequisite for a high mineralization rate. Oxygen consumption of macrofauna was calculated from biomass, which remained almost constant during the year. In spring macrofauna accounted for 40 % and in autumn for 30 % of total benthic community respiration, which was approximately 100 l O2/m2/year. This was equivalent to 44 g of organic carbon, of which 40 and 60 % respectively were consumed during first and second half of the year. Feeding and growth of macrofauna were high during spring and bioturbation instantaneously dispersed spring-bloom plant material homogeneously in the sediment. The result was that activity of macroinvertebrates lasted a short time and was low during summer and autumn when sediment consumed oxygen at a high rate primarily by bacterial respiration. Macrofaunal activity seemed not to be limited by low temperatures (3–4°C) in spring.