Differential processing of dissolved and particulate organic matter by deep-sea sponges and their microbial symbionts

• Published in: Scientific Reports
• Main Authors: Bart, Martijn C, de Kluijver, Anna, Hoetjes, Sean, Absalah, Samira, Mueller, Benjamin, Kenchington, Ellen, Rapp, Hans Tore, de Goeij, Jasper M
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2020
• Subjects: deep-se sponges; particulate organic matter; POM; microbiome; European Union (EU); Horizon 2020; Grant Agreement No 679849; Deep-sea Sponge Grounds Ecosystems of the North Atlantic: an integrated approach towards their preservation and sustainable exploitation; SponGES; Canada; Norway; Bergen; Bedford; Beazley; North Atlantic
• Online Access: https://zenodo.org/record/4279098; https://doi.org/10.1038/s41598-020-74670-0

ABSTRACT Deep-sea sponges create hotspots of biodiversity and biological activity in the otherwise barren deep-sea. However, it remains elusive how sponge hosts and their microbial symbionts acquire and process food in these food-limited environments. Therefore, we traced the processing (i.e. assimilation and respiration) of 13C- and 15N-enriched dissolved organic matter (DOM) and bacteria by three dominant North Atlantic deep-sea sponges: the high microbial abundance (HMA) demosponge Geodia barretti, the low microbial abundance (LMA) demosponge Hymedesmia paupertas, and the LMA hexactinellid Vazella pourtalesii. We also assessed the assimilation of both food sources into sponge- and bacteria-specific phospholipid-derived fatty acid (PLFA) biomarkers. All sponges were capable of assimilating DOM as well as bacteria. However, processing of the two food sources differed considerably between the tested species: the DOM assimilation-to-respiration efficiency was highest for the HMA sponge, yet uptake rates were 4–5 times lower compared to LMA sponges. In contrast, bacteria were assimilated most efficiently and at the highest rate by the hexactinellid compared to the demosponges. Our results indicate that phylogeny and functional traits (e.g., abundance of microbial symbionts, morphology) influence food preferences and diet composition of sponges, which further helps to understand their role as key ecosystem engineers of deep-sea habitats. ACKNOWLEDGMENTS. 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 thank all our collaborators at the EU Horizon 2020 SponGES project, Barry MacDonald, Sarah Thompson, Lindsay Beazley, and Gabrielle Tompkins at the Bedford Institute of Oceanography (BIO), Nova Scotia, Canada, for their help with collecting and maintaining the V. pourtalesii specimens, and all colleagues at the Department of Biological Sciences at the University of Bergen, Norway, for the ...