Deep-Sea Coral and Sponge Taxa Increase Demersal Fish Diversity and the Probability of Fish Presence

Abstract

Fishes are known to use deep-sea coral and sponge (DSCS) species as habitat, but it is uncertain whether this relationship is facultative (circumstantial and not restricted to a particular function) or obligate (necessary to sustain fish populations). To explore whether DSCS provide essential habitats for demersal fishes, we analyzed 10 years of submersible survey video transect data, documenting the locations and abundance of DSCS and demersal fishes in the Southern California Bight (SCB). We first classified the different habitats in which fishes and DSCS taxa occurred using cluster analysis, which revealed four distinct DSCS assemblages based on depth and substratum. We then used logistic regression and gradient forest analysis to identify the ecological correlates most associated with the presence of rockfish taxa (Sebastes spp.) and biodiversity. After accounting for spatial autocorrelation, the factors most related to the presence of rockfishes were depth, coral height, and the abundance of a few key DSCS taxa. Of particular interest, we found that young-of-the-year rockfishes were more likely to be present in locations with taller coral and increased densities of Plumarella longispina, Lophelia pertusa, and two sponge taxa. This suggests these DSCS taxa may serve as important rearing habitat for rockfishes. Similarly, the gradient forest analysis found the most important ecological correlates for fish biodiversity were depth, coral cover, coral height, and a subset of DSCS taxa. Of the 10 top-ranked DSCS taxa in the gradient forest (out of 39 potential DSCS taxa), 6 also were associated with increased probability of fish presence in the logistic regression. The weight of evidence from these multiple analytical methods suggests that this subset of DSCS taxa are important fish habitats. In this paper we describe methods to characterize demersal communities and highlight which DSCS taxa provide habitat to demersal fishes, which is valuable information to fisheries agencies tasked to manage these fishes and their essential habitats.

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Nudibranch predation boosts sponge silicon cycling

“…Sponges contribute to the recycling of nutrients to higher trophic levels through benthic-pelagic coupling and to increasing marine biodiversity of micro- and macro-organisms 4 , 5 . Thus, silicon is a critical resource for silicifiers, which can be important in sustaining marine biodiversity and food webs with ultimate influences on human populations 6 , 7 .…”

Evaluation of collaboratively developed management measures to reduce coral and sponge bycatch in a fully monitored multispecies trawl fishery

“…Cold-water corals and sponges (CWCS) provide important benthic habitat for a diverse group of fish and invertebrates (Chu and Leys 2010;Henderson et al 2020), and have roles in carbon and silica cycling (Chu et al 2011;Cathalot et al 2015). Worldwide, human activities such as fishing, resource extraction (oil, gas, and minerals), underwater infrastructure (e.g., cables), pollution, and climate change threaten CWCS (Rossi 2013;Ragnarsson et al 2016).…”