Geodia barretti - Energy budget data sheet for Limnology and Oceanography

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  • Geodia barretti is a massive nearly spherical sponge that forms dense assemblages on the continental shelf of the North Altantic and the Norwegian Sea. We studied the metabolism of individual sponges collected using a remotely operated vehicle and maintained in large tanks with high volumes of unfiltered water brought from 160m depth. We used direct methods (In-Ex) to measure excurrent flow rates, oxygen removed, and carbon and nutrient flux through the sponges. G. barretti had very low specific filtration (0.26 mL min-1 mL-1sponge tissue) and low respiration (5.34± 0.98 nmol O2 min-1 mL-1 sponge tissue; 8.44 ± 1.51 µmol O2 hr-1 g C-1) rates in comparison to other sponges. A net release of nitrogen was detected as NO3-. Bacteria were removed from the water filtered with up to 99% efficiency, yet comprised only 5% of the sponges’ total carbon budget; the remainder consisted of dissolved organic carbon and detritus. High bacterial removal was aided by the presence of a tight gasket of cells that surrounds the collar of each choanocyte filter. A test for potential bypass canals showed removal of fluorescent microspheres until they were excreted 5-12 hours after feeding. Electron micrographs showed active uptake of E. coli ‘fed’ to the sponge as well as phagocytosis of symbiont microbes by sponge cells in the mesohyl. These data provide the first comprehensive study of metabolism in a deep-water high microbial abundance sponge.

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    Attribution-NonCommercial-NoDerivatives 4.0 International