Food web and ecology of deep sea sponge grounds at the Karasik Seamount, Arctic.
During the Polarstern expedition PS101 a giant assemblage of bacteriosponges, mostly dominated by Demospongiae Geodia spp. and Stelletta spp., was discovered at about 600 m depth at the Karasik Seamounts. My role is to investigate the mechanisms that facilitate the presence and stability of such dense sponge assemblage in such oligotrophic condition.
Sponges are active filter feeders; they depend on hydrodynamics and water column processes for their feeding. In order to understand what sponges feed and how they can survive in such low productivity area, environmental samples as organic matter, fecal pellet, zooplankton and water samples for bacteria counts and nutrient analysis are examined to quantify potential sources of food available for sponges. Simultaneously, C and N isotope analysis on sponge tissue, water and sediment samples and lipid content in sponge tissue allow to reconstruct the diet, examine the food web dynamic and trophic ecology of these benthic inhabitants.