Nudibranch predation boosts sponge silicon cycling

Type Article
Date 2023-01
Language English
Author(s) López-Acosta María1, 2, Potel Clémence3, Gallinari Morgane2, Pérez Fiz F.1, Leynaert Aude4
Affiliation(s) 1 : Instituto de Investigaciones Marinas (IIM), CSIC, C/Eduardo Cabello 6, 36208, Vigo, Spain
2 : Laboratoire des Sciences de l’Environnement Marin, UMR 6539, Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, 29280, Plouzané, France
3 : Learning Planet Institute, Université de Paris, 8 bis rue Charles V, 75004, Paris, France
4 : Laboratoire des Sciences de l’Environnement Marin, UMR 6539, Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, 29280, Plouzané, France
Source Scientific Reports (2045-2322) (Springer Science and Business Media LLC), 2023-01 , Vol. 13 , N. 1 , P. 1178 (11p.)
DOI 10.1038/s41598-023-27411-y
WOS© Times Cited 2
Abstract

Diatoms play a key role in the marine silica cycle, but recent studies have shown that sponges can also have an important effect on this dynamic. They accumulate large stocks of biogenic silica within their bodies over long periods, which are thought to vary little on an intra-annual scale. The observation of an abrupt decline in sponge biomass in parallel with large increases in abundance of a spongivorous nudibranch (Doris verrucosa) led us to conduct a year-long study on the effect of nudibranch predation on the silicon budget of a sponge (Hymeniacidon perlevis) population. After 5 months of predation, the abundance of sponge individuals did not change but their biomass decreased by 95%, of which 48% was explained by nudibranch predation. About 97% of sponge spicules ingested by nudibranchs while feeding was excreted, most of them unbroken, implying a high rate of sponge silica deposition in the surrounding sediments. After predation, sponges partially recovered their biomass stocks within 7 months. This involved a rapid growth rate and large assimilation of dissolved silicon. Surprisingly, the highest rates of silicon absorption occurred when dissolved silicon concentration in seawater was minimal (< 1.5 µM). These findings suggest that the annual sponge predation-recovery cycle triggers unprecedented intra-annual changes in sponge silicon stocks and boosts the cycling of this nutrient. They also highlight the need for intra-annual data collection to understand the dynamics and resilience of sponge ecosystem functioning.

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