Diet shapes cold‐water corals bacterial communities

Abstract

For the cold-water corals (CWC), living in the deep and dark ocean, heterotrophs are the key microbiome partners of the host. The role of the CWC microbiome and the type of association to the host remain however poorly known. In this paper we tested whether diet shapes the composition of the bacterial community associated to the two most common cold water coral species: L. pertusa and M. oculata. We demonstrate that a large portion of the corals" bacterial community represents a food influenced microbiome. The differences between diets were seen in terms of beta diversity, richness, individual OTU dynamics and coral metabolisms (energy reserves). The microbiomes remained, however, species-specific independently of the diet, which suggest that the niche offered to the microbes by the host also shapes community composition. This study, which is the first to test the effect of diet on coral microbiomes, casts a new light on coral microbial ecology by showing that the coral specific bacterial communities should also be considered as a food influenced microbiome. This result is important and will certainly inspire further research on CWC but also on tropical coral microbiomes.

Microbiomes of Caribbean Octocorals Vary Over Time but Are Resistant to Environmental Change

“…Seasonal changes in the relative abundances of Tenericutes and Proteobacteria that we found in P. crucis and E. tourneforti collected from the back reef are similar to seasonal changes reported in the microbiomes of temperate gorgonian corals (van de Water et al, 2018b). This seasonality may reflect changes in gorgonian diets (Cocito et al, 2013), similar to changes in diet influencing the microbial communities of deep sea scleractinian corals (Galand et al, 2020). While the relative abundances of Tenericutes and Proteobacteria changed seasonally, the dominant bacteria generally remained stable.…”

Local Variability in Microbiome Composition and Growth Suggests Habitat Preferences for Two Reef-Building Cold-Water Coral Species

“…The different habitat preferences may be associated to the different physiological characteristics of the two species coupled to the different hydrological features defining the two sites in the canyon. Lophelia pertusa and M. oculata exhibit distinct physiological functions, including skeletal growth rates (Lartaud et al, 2014), feeding behavior and preferences (Tsounis et al, 2010;Galand et al, 2020), reproduction cycles (Waller and Tyler, 2005), but also distinct associated microbial communities (Meistertzheim et al, 2016). Different patterns of distribution between L. pertusa and M. oculata have been reported in the Atlantic and Mediterranean regions where M. oculata is the dominant species in the mid slope while L. pertusa is more abundant in the down slope (Foubert et al, 2011;Fabri et al, 2017;Boolukos et al, 2019).…”

“…Both Lophelia pertusa and Madrepora oculata feed mostly on zooplankton, but it has been demonstrated that they do not share the same metabolism (Gori et al, 2014). Analyses of lipid compositions, and their nitrogen isotopic signatures, suggest that the two species adopt different feeding strategies (Kiriakoulakis et al, 2005;Galand et al, 2020). Lophelia pertusa is a more opportunistic suspended feeder, so its capacity to catch enough prey to sustain growth may be higher compared to M. oculata (Mueller et al, 2014).…”

“…Scleractinian cold-water corals (CWC) such as Lophelia pertusa and Madrepora oculata, iconic engineer species of submarine canyons, are important frame-builders that provide shelter for a large diversity of associated fauna (Buhl-Mortensen et al, 2010). During the last decades, significant efforts have been dedicated to characterize CWC's feeding, reproduction, growth, and their associated coral microbiome (Waller and Tyler, 2005;Tsounis et al, 2010;Lartaud et al, 2014;Meistertzheim et al, 2016;Galand et al, 2020). However, due to the difficulty of sampling in the deep sea, a detailed knowledge of their ecology is still lacking when compared to their shallow water counterparts.…”

“…The relative abundance and/or spatial distribution of L. pertusa and M. oculata change following geographical locations, which suggests different living strategies (Freiwald et al, 2004;Schröder-Ritzrau et al, 2005;Lartaud et al, 2019). The two species exhibit different responses to environmental changes (Naumann et al, 2014), different skeletal growth rates (Lartaud et al, 2014), reproductive cycles (Waller and Tyler, 2005), feeding strategies (Tsounis et al, 2010;Gori et al, 2014;Galand et al, 2020), and bacterial community associations (Hansson et al, 2009;Meistertzheim et al, 2016;Galand et al, 2018Galand et al, , 2020, with a more stable microbiome for M. oculata.…”