The utilization of organic matter in shallow marine sediments by an epibenthic deposit-feeding holothurian

The utilization of organic matter and constituent food items in shallow marine sediments by Parastichopus parvimensis (Clark), an epibenthic deposit-feeding holothurian, has been investigated.Organic matter ingested from sediments of varying organic content was used by P. parvimensis with 22 % efficiency. In experiments with ¹⁴C labelled food all microorganisms associated with both plant detritus and decomposed matter of animal origin were used with over 40 % efficiency. Species of fresh brown, red, green, and blue-green algae were not assimilated. Detritus derived from the brown alga Dictyopteris zonarioides (Farlow) was used with a low efficiency while detritus from red and green algae was not assimilated. These results indicate that P. parvimensis does not utilize the large energy reserve available as plant detritus in near shore bottom habitats off Santa Catalina Island before to its decomposition by bacteria and fungi.