Meeting Abstract
Suspension feeders transfer carbon and nutrients from the water column into benthic communities. Sponges in particular link the biomass of the pelagic microbial loop to animal food webs by filter feeding on bacteria. On ship cruises between 2004 and 2017, glass sponge reefs in British Columbia, Canada were surveyed to measure live sponge cover, species composition, sponge density, volumetric pumping rate, and bacterial carbon consumption. Combined, these numbers were used to estimate the benthic grazing rate of a square meter patch of reef, then scale up to the entire expanse of reefs. Glass sponge reefs in the Strait of Georgia, composed predominantly of Aphrocallistes vastus, are estimated to process 130-290 m3 m-2 d-1 of water and to import up to 1.5 kg of bacterial biomass per square meter of reef annually. Sponge reefs in Hecate Strait are dominated by different species, either Farrea occa or Heterochone calyx. We set out to determine whether the strength and nature of benthic-pelagic coupling by reef sponges is affected by species diversity. We found that at least two reef subtypes exist in Hecate Strait: those dominated by F. occa and those dominated by H. calyx, and that both have different levels of water processing capacity and bacterial uptake in comparison with the Aphrocallistes-dominated reefs in the Strait of Georgia. The degree of benthic-pelagic coupling, and likely other ecosystem services, therefore varies depending on reef community structure. Understanding this variability is an important consideration for future conservation planning to protect sponge reef habitats.
