BIOMASS OF DEEP-SEA BENTHIC COMMUNITIES - POLYCHAETES AND OTHER INVERTEBRATES

Biomass measurements were made for benthic samples from the U.S. Atlantic continental slope and rise as part of a program on benthic processes in the deep sea. Box-core samples were collected from off Georges Bank near Massachusetts south to off Georgia, primarily along the 2,000-m depth contour. Ash-free dry weight (AFDW) measurements were made on replicates from six stations. Samples were sieved through nested 0.3-mm and 2.0-mm screens. AFDW biomass ranged between 0.1665 and 2.1439 g.m-2. Polychaetes dominated biomass in the 0.3-mm fractions and in the 2.0-mm fraction except whenever large organisms, such as echinoderms, were present. Wet weight biomass was measured on samples taken from off Cape Hatteras in depths varying between 583 and 3,500 m. A sharp decrease (five-to ten-fold) in biomass was observed between 2,000 and 3,000 m depth.