Experimental studies of sediment reworking and growth of Scoloplos spp. (Orbiniidae: Polychaeta)

Surface biodeposition of organic carbon and total sediment from the conveyor-belt feeding activity of Scoloplos spp. were monitored concomitantly with worm growth in experimental microcosms. At constant temperature and under conditions where available particle size did not limit ingestion, particle reworking rate was proportional to worm biomass. If competition between individuals for particles of preferred size is intense, Scoloplos may adjust its size selectivity to meet physiological maintenance requirements. Scoloplos assimilated organic carbon from its native sediments from Lowes Cove, Maine, with an efficiency of about 24 %. Gross growth efficiencies based on total and metabolizable particulate organic carbon were 2.4 and 8.3 % respectively. Based on total and metabolizable particulate organic nitrogen gross growth efficiencies were 4 and 63 % respectively. Incorporating the results of other nutritional studies, we estimate that approximately 4 % of the total nitrogen in an experimental sediment from Flax Pond, New York, was nutritionally available to these worms. Microbes may account for most of the organic nitrogen required by Scoloplos, although most of the organic carbon (i.e. caloric) requirement must be met by utilizing organic detritus.