There is growing evidence of the key role that sponges play in nutrient cycling in shallow and deep-water communities ( Maldonado et al., 2016 Pawlik and McMurray, 2019 Zhang et al., 2019 Folkers and Rombouts, 2020). Their role in organic matter cycling has been equated to that of the microbial loop because some sponges can remove dissolved organic matter from the water column and make it available in the form of detritus to higher trophic levels ( de Goeij et al., 2013 Rix et al., 2016a, b, 2017, 2020).
Such dense sponge aggregations can filter hundreds of cubic meters of water per m 2 daily, with significant consequences to the benthic-pelagic coupling and local biogeochemical cycles ( Kutti et al., 2013 Kahn et al., 2015).
In some areas they can constitute ~90% of the benthic biomass, excluding benthic fishes ( Klitgaard and Tendal, 2004 Murillo et al., 2012). Sponges are widespread across different ocean regions from intertidal to abyssal depths ( Van Soest et al., 2020). The pumping rate of a sponge population can be estimated by measuring the osculum density and cross-sectional area distribution once the relationships between the OSA and OFR are established for each species. The number of oscula and their OSA were the best predictors of the PR in sponges, explaining 75–94% of the in situ variation in PR throughout the natural range of sponge size. Osculum jet speed declined with the increase in the OSA for most species. As a result, and in contrast to former reports, the PR of most of the sponges increased allometrically ( PR= a∑ OSA b) with scaling exponent b≈0.75, whereas PR of tropical HMAs increased isometrically. Osculum flow rate (OFR) also increased allometrically with OSA and oscula of the same size pumped at the same rate irrespective of sponge volume. The total oscula area (∑OSA) increased allometrically with sponge volume (V) exhibiting similar exponents (∑ OSA= aV b, b ranging 0.6–0.7) for all species, except for tropical HMAs ( b = 0.99). To examine how these relationships apply to field populations we measured, in situ, the pumping rate (PR) of 20 species representative of different morphologies and host types (high- and low-microbial-abundance, HMA and LMA) from temperate and tropical regions. Theoretical scaling relationships between sponge volume, osculum cross-sectional area, and pumping rates were recently proposed and confirmed for small sponge specimens in the lab. Sponges play a key role in the transfer of energy and nutrients into many benthic ecosystems, and the volume of water they process is an important regulator of these fluxes. 6Department of Biology, Linfield University, McMinnville, OR, United States.5Faculty of Marine Sciences, Ruppin Academic Center, Michmoret, Israel.Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel 3Centre d'Estudis Avançats de Blanes, Consejo Superior de Investigaciones Cientifícas (CEAB-CSIC), Girona, Spain.2Institut de Ciències del Mar, Consejo Superior de Investigaciones Cientifícas (ICM-CSIC), Barcelona, Spain.1Max Planck Institute for Marine Microbiology, Bremen, Germany.Teresa Maria Morganti 1,2,3 *, Marta Ribes 2, Raz Moskovich 4,5, Jeremy Brian Weisz 6, Gitai Yahel 5 and Rafel Coma 3 *
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