Influence of increasing suspended particulate matter concentration on benthic and planktonic Antarctic filter-feeding organisms: a relation with glacier melting

VERÓNICA FUENTES; RICARDO SAHADE; LUCIANA TORRE; BETTINA MEYER

Incheon, Korea

Simposio; The 15th International Symposium on Polar Sciences "Polar Ecosystems : Biodiversity and Adaptation"; 2008

There is strong evidence that the majority of polar glaciers of the Antarctic Peninsula are rapidly retreating. Melt water flow into seas causes, among others, a strong near-shore sedimentation. The increasing of suspended particulate matter in Antarctic coastal affects its physical, chemical and biological characteristics. In order to estimate the effect of sediment concentration on an Antarctic coastal ecosystem, the metabolic rates of 3 ascidians species and the Antarctic krill (Euphausia superba ) were measured under different conditions in Potter Cove (King George Island). The most abundant ascidians species in Potter Cove: Ascidia challengeri, Cnemidocarpa verrucosa and Molgula peduncula had similar patterns of respiratory response to increasing sediment concentration,  showing a gradual increment of their metabolic rate at medium levels up to a limit concentration. However, this limit concentration was markedly different among the species, 200, 100 and 15 mg·l-1 for A. challengeri, C. verrucosa and M. pedunculata respectively. Indicating different tolerances to sediment load. The daily ingestion rate of the Antarctic krill, decreases while the sediment concentration increase, independently of the phytoplankton concentration. With sediments concentrations similar to that found in Potter Cove, actually in summer (maximal melting period), the feeding capacity of the species was notably affected.