Sponge

Abstract: Why write a book on sponge taxonomy; who would read such a book; what is the relevance of sponges; and what are sponges anyway?

Abstract: Despite the wide range of functional roles performed by marine sponges they are still poorly represented in many research, monitoring and conservation programmes. The aim of this review is to examine recent developments in our understanding of sponge functional roles in tropical, temperate and polar ecosystems. Functions have been categorised into three areas: (a) impacts on substrate (including bioerosion, reef creation, and substrate stabilisation, consolidation and regeneration); (b) bentho-pelagic coupling (including carbon cycling, silicon cycling, oxygen depletion and nitrogen cycling); and (c) associations with other organisms (facilitating primary production, secondary production, provision of microhabitat, enhanced predation protection, survival success, range expansions and camouflage though association with sponges, sponges as a settlement substrate, disrupting near-boundary and reef level flow regimes, sponges as agents of biological disturbance, sponges as releasers of chemicals and sponges as tools for other organisms). The importance of sponges on substrate, sponge bentho-pelagic coupling, and sponge interactions and associations is described. Although the scientific evidence strongly supports the significance and widespread nature of these functional roles sponges still remain underappreciated in marine systems.

Abstract: Marine sponges (phylum Porifera) often contain dense and diverse microbial communities, which can constitute up to 35% of the sponge biomass. The genome of one sponge, Amphimedon queenslandica, was recently sequenced, and this has provided new insights into the origins of animal evolution. Complementary efforts to sequence the genomes of uncultivated sponge symbionts have yielded the first glimpse of how these intimate partnerships are formed. The remarkable microbial and chemical diversity of the sponge-microorganism association, coupled with its postulated antiquity, makes sponges important model systems for the study of metazoan host-microorganism interactions, and their evolution, as well as for enabling access to biotechnologically important symbiont-derived natural products. In this Review, we discuss our current understanding of the interactions between marine sponges and their microbial symbiotic consortia, and highlight recent insights into these relationships from genomic studies.

Abstract: Marine sponges are well known for their associations with highly diverse, yet very specific and often highly similar microbiota. The aim of this study was to identify potential bacterial sub-populations in relation to sponge phylogeny and sampling sites and to define the core bacterial community. 16S ribosomal RNA gene amplicon pyrosequencing was applied to 32 sponge species from eight locations around the world's oceans, thereby generating 2567 operational taxonomic units (OTUs at the 97% sequence similarity level) in total and up to 364 different OTUs per sponge species. The taxonomic richness detected in this study comprised 25 bacterial phyla with Proteobacteria, Chloroflexi and Poribacteria being most diverse in sponges. Among these phyla were nine candidate phyla, six of them found for the first time in sponges. Similarity comparison of bacterial communities revealed no correlation with host phylogeny but a tropical sub-population in that tropical sponges have more similar bacterial communities to each other than to subtropical sponges. A minimal core bacterial community consisting of very few OTUs (97%, 95% and 90%) was found. These microbes have a global distribution and are probably acquired via environmental transmission. In contrast, a large species-specific bacterial community was detected, which is represented by OTUs present in only a single sponge species. The species-specific bacterial community is probably mainly vertically transmitted. It is proposed that different sponges contain different bacterial species, however, these bacteria are still closely related to each other explaining the observed similarity of bacterial communities in sponges in this and previous studies. This global analysis represents the most comprehensive study of bacterial symbionts in sponges to date and provides novel insights into the complex structure of these unique associations.