Abstract
Cold-water coral reefs are known to locally enhance the diversity of deep-sea fauna as well as of microbes. Sponges are among the most diverse faunal groups in these ecosystems, and many of them host large abundances of microbes in their tissues. In this study, twelve sponge species from three cold-water coral reefs off Norway were investigated for the relationship between sponge phylogenetic classification (species and family level), as well as sponge type (high versus low microbial abundance), and the diversity of sponge-associated bacterial communities, taking also geographic location and water depth into account. Community analysis by Automated Ribosomal Intergenic Spacer Analysis (ARISA) showed that as many as 345 (79%) of the 437 different bacterial operational taxonomic units (OTUs) detected in the dataset were shared between sponges and sediments, while only 70 (16%) appeared purely sponge-associated. Furthermore, changes in bacterial community structure were significantly related to sponge species (63% of explained community variation), sponge family (52%) or sponge type (30%), whereas mesoscale geographic distances and water depth showed comparatively small effects (<5% each). In addition, a highly significant, positive relationship between bacterial community dissimilarity and sponge phylogenetic distance was observed within the ancient family of the Geodiidae. Overall, the high diversity of sponges in cold-water coral reefs, combined with the observed sponge-related variation in bacterial community structure, support the idea that sponges represent heterogeneous, yet structured microbial habitats that contribute significantly to enhancing bacterial diversity in deep-sea ecosystems.
Highlights
Cold-water coral reefs are considered as ‘‘biodiversity hotspots’’ due to their potential to locally enhance faunal biodiversity on continental margins and in the deep ocean [1,2,3,4]
By studying samples from three cold-water coral reef ecosystems on the Norwegian continental margin, the following research questions and hypotheses were addressed: (1) Can we identify differences in the number and distribution of bacterial operational taxonomic units (OTUs) depending on sponge phylogeny as well as sponge type (HMA versus Low-microbial abundance (LMA))? (2) How much do the potential host-microbe associations depend on other environmental factors such as geographic location and water depth?
The different sponge species were grouped into the LMA or High-microbial abundance (HMA) sponge type based on microscopic investigation of tissue sections stained with DAPI as described previously [15]
Summary
Cold-water coral reefs are considered as ‘‘biodiversity hotspots’’ due to their potential to locally enhance faunal biodiversity on continental margins and in the deep ocean [1,2,3,4]. For this reason, the microbial diversity associated with cold-water reef ecosystems has attracted increasing scientific interest lately [5,6,7,8,9,10]. As cold-water corals release considerable amounts of both particulate and dissolved organic matter [22], diverse sponge-microbe associations may play an important role for the rapid nutrient recirculation in cold-water coral reef systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
