Enhanced particle flux through the biodeposition by the Antarctic suspension-feeding bivalve Laternula elliptica in Marian Cove, King George Island

Abstract

The infaunal lamellibranch Laternula elliptica (Laternulidae), one of the most common Antarctic bivalves, is widely distributed in shallow waters around the Antarctic Continent. In order to evaluate the contribution of this species to organic carbon flux in an Antarctic coastal ecosystem, biodeposition rates by L. elliptica were measured and compared with sedimentation without this bivalve species in laboratory experiments during one austral summer. The amount of deposited material increased in the presence of L. elliptica. Weight-specific biodeposition rates varied from 0.26 to 2.17 mg dry wt·g wet wt −1 · d −1 and the rate decreased with increase in body weight. Due to massive inflows of terrigenous sediment through coastal meltwater stream into the coastal water, fecal and pseudofecal material contained a considerable amount of mineral particles and only a small percentage of organic carbon (1.6–5.2%). Estimated particulate organic carbon flux through the biodeposition of L. elliptica is ≈95 mg C·m −2·d −1, an amount comparable to that of a typical suspension-feeding bivalve, Mytilus edulis. L. elliptica is apparently an important agent for sedimentation of both lithogenic particles and organic particles. Thus, this study suggests that L. elliptica play an important role in enhancing particle flux from water column to sea bed through biodeposition and possibly nourishing other benthic fauna, particularly in phytoplankton-impoverished nearshore waters.