Dissolved organic carbon (DOC) is essential to balance the metabolicdemands of four dominant North-Atlantic deep-sea sponges

ABSTRACT Sponges are ubiquitous components of various deep-sea habitats, including cold water coral reefs and deep-sea sponge grounds. Despite being surrounded by oligotrophic waters, these ecosystems are known to be hotspots of biodiversity and carbon cycling. To assess the role of sponges in the c...

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Bibliographic Details
Published in:Limnology and Oceanography
Main Authors: Bart, Martijn C, Mueller, Benjamin, Rombouts, Titus, van de Ven, Clea, Tompkins, Gabrielle J, Osinga, Ronald, Brussaard, Corina PD, MacDonald, Barry, Engel, Anja, Rapp, Hans Tore, de Goeij, Jasper M
Format: Article in Journal/Newspaper
Language:unknown
Published: Zenodo 2020
Subjects:
DOC
Online Access:https://doi.org/10.1002/lno.11652
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Summary:ABSTRACT Sponges are ubiquitous components of various deep-sea habitats, including cold water coral reefs and deep-sea sponge grounds. Despite being surrounded by oligotrophic waters, these ecosystems are known to be hotspots of biodiversity and carbon cycling. To assess the role of sponges in the carbon cycling of deep-sea ecosystems, we studied the energy budgets of six dominant deep-sea sponges (the hexactinellid species Vazella pourtalesi , and demosponge species Geodia barretti , Geodia atlantica , Craniella zetlandica , Hymedesmia paupertas and Acantheurypon spinispinosum )in an ex situ aquarium setup. Additionally, we determined morphological metrics for all species (volume, dry weight (DW), wet weight (WW), carbon (C) content, and ash-free dry weight (AFDW)) and provide species-specific conversion factors. Oxygen (O 2 ) removal rates averaged 3.3 ± 2.8µmol O 2 DW sponge h −1 (all values mean ± SD), live particulate (bacterial and phytoplankton) organic carbon (LPOC) removal rates averaged 0.30 ± 0.39µmol C DW sponge h −1 and dissolved organic carbon (DOC) removal rates averaged 18.70 ± 25.02µmol C DW sponge h −1 . Carbon mass balances were calculated for four species ( V. pourtalesi , G. barretti , G. atlantica and H. paupertas ) and revealed that the sponges acquired 1.3–6.6 times the amount of carbon needed to sustain their minimal respiratory demands. These results indicate that irrespective of taxonomic class, growth form, and abundance of microbial symbionts, DOC is responsible for over 90 % of the total net organic carbon removal of deep-sea sponges and allows them to sustain in otherwise food-limited environments on the ocean floor. ACKNOWLEDGEMENTS We want to dedicate this publication to our EU Horizon 2020 SponGES project coordinator and co‐author Prof. Hans Tore Rapp, who sadly, and too soon, passed on March 7, 2020. We want to thank all our collaborators within the EU Horizon 2020 SponGES project. Dr. Ellen Kenchington at the Bedford Institute of Oceanography (BIO), Nova Scotia, Canada, and ...