Meeting Abstract
Benthic communities beneath the ocean’s photic zone cannot rely on locally produced food as light cannot penetrate to fuel photosynthesis. Deep benthic communities thus rely mainly on imported nutrients, either as material sinking from the photic zone or arriving via lateral currents. The food that arrives is often limiting, yet in some locations, dense communities manage to persist and even flourish. Sur Ridge off the coast of Big Sur, California is such a community. This deep submarine ridge (800-1700 m) has diverse and dense communities supported in part by habitat-forming, deep-sea corals and sponges. The impact of corals and sponges as foundation species is clear, but what affects their distributions is not fully resolved. To investigate this, we focused on sponges to understand 1) their own energetic needs via metabolic rate, and 2) the effects of pumping activity on the surrounding water. We measured in situ respiration and activity levels, as pumping rates, using optical oxygen sensors and a novel deep particle imaging velocimetry system (DeepPIV) deployed by remotely operated vehicle. Respiration was variable between species, with some having very constant oxygen removal rates and other species with removal rates that varied even over a 5 minute span. DeepPIV revealed that the glass sponges of Sur Ridge pump many times their own body volume of water each day, with pumping rates dependent on osculum size. Given the efficient particle capture of other glass sponge species, this may indicate that dense patches of sponges at Sur Ridge can affect the overlying water column and create different microenvironments for other benthic fauna.
