In four shallow and mesophotic tropical reef sponges from Guam the microbial community largely depends on host identity

Abstract

Sponges (phylum Porifera) are important members of almost all aquatic ecosystems, and are renowned for hosting often dense and diverse microbial communities. While the specificity of the sponge microbiota seems to be closely related to host phylogeny, the environmental factors that could shape differences within local sponge-specific communities remain less understood. On tropical coral reefs, sponge habitats can span from shallow areas to deeper, mesophotic sites. These habitats differ in terms of environmental factors such as light, temperature, and food availability, as well as anthropogenic impact. In order to study the host specificity and potential influence of varying habitats on the sponge microbiota within a local area, four tropical reef sponges, Rhabdastrella globostellata, Callyspongia sp., Rhaphoxya sp., and Acanthella cavernosa, were collected from exposed shallow reef slopes and a deep reef drop-off. Based on 16S rRNA gene pyrosequencing profiles, beta diversity analyses revealed that each sponge species possessed a specific microbiota that was significantly different to those of the other species and exhibited attributes that are characteristic of high- and/or low-microbial-abundance sponges. These findings emphasize the influence of host identity on the associated microbiota. Dominant sponge- and seawater-associated bacterial phyla were Chloroflexi, Cyanobacteria, and Proteobacteria. Comparison of individual sponge taxa and seawater samples between shallow and deep reef sites revealed no significant variation in alpha diversity estimates, while differences in microbial beta diversity (variation in community composition) were significant for Callyspongia sp. sponges and seawater samples. Overall, the sponge-associated microbiota is significantly shaped by host identity across all samples, while the effect of habitat differentiation seems to be less predominant in tropical reef sponges.

Deciphering the genomic toolkit underlying animal-bacteria interactions – insights through the demosponge Amphimedon queenslandica

“…3.2A). Steinert et al (2016) similarly noted that OTUs from these lineages were highly abundant components of the bacterial community in R. globostellata sampled in Guam. In contrast, the bacterial communities of both the healthy and unhealthy A. queenslandica adults were low in diversity and overwhelmingly dominated by Gammaproteobacteria and Betaproteobacteria (Fig.…”

“…Furthermore, a recent global-scale study documenting the bacterial diversity associated with marine sponges demonstrates that these bacterial communities have little in common across species or with free-living bacterial communities in the surrounding sea water (Hentschel, et al 2002;Simister, et al 2012;Steinert, et al 2016;). The differences in the bacterial communities across sponge species appear to influence sponge morphology, physiology and metabolism (Weisz, et al 2008;Giles, et al 2013).…”

“…Next generation sequencing technologies have catalysed a recent explosion of publications cataloguing the microbial community associated with sponges (Schmitt, et al 2012;Webster and Taylor 2012;Dupont, et al 2013;Kennedy, et al 2014;Reveillaud, et al 2014;Steinert, et al 2016;Webster and Thomas 2016). While these studies have provided insight into the true complexity of the sponge-bacteria association, they also leave many important questions unaddressed, as few studies have applied an experimental approach to dissect the host's role in controlling the composition of its bacterial community (but see Steindler, et al 2007;Ryu, et al 2016).…”

“…The R. globostellata resident bacterial community is species-rich, specific to this sponge species, and distinct from the free-living bacterial community in the surrounding water (Steinert, et al 2016). A. queenslandica hosts a vertically-inherited bacterial community that is low in diversity and stably persists throughout its lifecycle (Bayes 2013;Fieth et al, in review).…”

“…R. globostellata houses a highly species rich bacterial community that consists of a particularly high abundance of Chloroflexi, and that is also distinct to the free-living bacterial community in the environment (Steinert, et al 2016). The native bacterial community of A. queenslandica, on the other hand, is relatively species poor and dominated by Gammaproteobacteria bacteria that are a stable presence throughout its lifecycle (Bayes 2013;Fieth et al, in review).…”