The Microbial Ecology of New Zealand Marine Sponges

Abstract

Sponges (Porifera) are among the earliest Metazoa. Their association with diverse microbes is raising many new questions in ecology, evolution, and biotechnology. However, despite much interest in these associations, large gaps still remain in our understanding of the individual phylogenies of these sponge-associated bacteria, as well as their community-level ecology. The establishment of a sponge-microbe experimental system is imperative to facilitate future analyses of these associations. Many sponges can be explanted with relative ease, but it remains unknown how the microbial community changes from parent to clone. Here I used denaturing gradient gel electrophoresis (DGGE) to investigate how the microbial community of the New Zealand demosponge Ancorina alata changes using two methods of aquaculture (open ocean and flow-through aquarium) under various time treatments. As no experimental system has been set up to study the microbial ecology of NZ sponges, this should greatly facilitate investigation of NZ sponge-associated microbial communities. Secondly, although the field of sponge microbial ecology is expanding, there remains a paucity of studies addressing broad ecological questions of these bacteria on the community level. I test whether the diversity-stability relationships documented in other ecosystems (e.g. grasslands, gut microbiota, and synthetic microcosms) can be observed in sponge-associated bacterial communities. Finally, previous tag pyrosequencing data had indicated that the bacterial community of the NZ sponge Stelletta maori is dominated by up to 12 operational taxonomic units (OTUs) within the phylum Fusobacteria. This phylum is poorly understood in the marine environment and has never been reported in such high abundance in a marine sponge, making it a potential exception to the general pattern of sponge-associated bacterial communities worldwide. I investigate the occurrence of this phylum in S. maori using a suite of molecular techniques I developed including PCR for phylogenetic analysis, DGGE for community structure analysis, and fluorescence in situ hybridization for localization and quantification of bacterial cells.