Benthic grazing and carbon sequestration by deep-water glass sponge reefs

Abstract

Glass sponges are conspicuous members of the deep-sea fauna, but in the northeastern Pacific they form unusual reefs covering kilometers of seafloor. Individual sponges in fjords can process up to 10 m 3 water d 21 osculum 21 ; sponge reefs must therefore process considerable volumes and could significantly affect local water properties. We measured, in situ, the flux of carbon and nitrogen through Aphrocallistes vastus, the dominant reef-building species on Fraser Ridge reef, and calculated the energetics of feeding for all reefs in the Strait of Georgia, British Columbia. Sponges removed up to 90% of bacteria from the water and released ammonium. Because of the high density of sponges, high volumetric flow rates (up to 210 6 35 m 3 m 22 d 21 , mean 6 standard error, 95% confidence interval (CI) 132-288 m 3 m 22 d 21 ), and the efficient extraction of bacteria, we calculate a grazing rate of 165 6 29 m 3 m 22 d 21 (95% CI 102-228 m 3 m 22 d 21 ) for sponge reefs, the highest benthic grazing rate of any suspension-feeding community measured to date. Reefs of A. vastus extract seven times more carbon (3.4 6 1.4 g C m 22 d 21 ) than can be supported by vertical flux of total carbon alone and therefore require productive waters and steady currents to sustain their strong grazing. We calculate that modern sponge reefs in the northeastern Pacific remove 2.27 3 10 5 6 0.91 3 10 5 kg of bacterial carbon daily, nearly an order of magnitude less than the 1.38 3 10 6 6 0.55 3 10 6 kg removed by past sponge reefs estimated to have covered the continental shelf.

Phagocytosis of microbial symbionts balances the carbon and nitrogen budget for the deep‐water boreal sponge Geodia barretti

“…The lower specific respiration and filtration rates are likely dictated by water temperature and habitat because similarly low rates are found in the glass sponge A. vastus . However, A. vastus has a complete absence of microbial symbionts in its tissues and whereas G. barretti removes 15.1 μM oxygen L −1 filtered (similar to T. swinhoei 3–15 μM oxygen L −1 ) A. vastus removes a mere 0.5 μM oxygen L −1 (Leys et al ; Kahn et al ).…”

“…Other deep sponges, including one glass sponge Rosella nodastrella collected from 600 m in the NE Atlantic, are suggested to fix carbon (Van Duyl et al ), however glass sponges appear specially adapted to capture the small amounts of POC available (Leys et al ). Work on deep sponges is challenged by access, so in situ methods for direct In‐Ex measurements or maintenance of sponges in high quality seawater systems (e.g., Yahel et al ; Yahel et al ; Kahn et al ) is needed.…”

Abiotic conditions drive significant variability in nutrient processing by a common Caribbean sponge, Ircinia felix

“…Many sponges host abundant and diverse microbial communities that include members capable of complex chemical transformations (Fiore et al ; Thacker and Freeman ). This, in addition to sponges' ability to pump large amounts of water (Reiswig a ), results in sponges having a large impact on nutrient dynamics (Southwell et al ; Maldonado et al ; Kahn et al ). Despite recording large variances, previous studies have concentrated on mean sponge nutrient fluxes when discussing sponges' impact on nutrient cycling on reefs (Corredor et al ; Diaz and Ward ; Southwell et al but see Fiore et al ).…”

Spicule and flagellated chamber formation in a growth zone of Aphrocallistes vastus (Porifera, Hexactinellida)

“…; Kahn et al. ). Some of the greatest densities of glass sponges are found in the northeastern Pacific (Kahn et al.…”

“…Some of the greatest densities of glass sponges are found in the northeastern Pacific (Kahn et al. ), where three species— Farrea occa Bowerbank 1862, Heterochone calyx ( Schulze 1886), and Aphrocallistes vastus Schulze 1886—form reefs by new recruits settling and growing on the skeletons of previous generations (Fig. A) (Conway et al.…”