Abstract
PurposeMarine lakes are unique habitats that house diverse assemblages of benthic and planktonic organisms including endemic species. In this study, we aimed to assess to what extent geographical location (Berau versus Papua) and the degree of marine lake connectivity (relatively open versus closed) to the surrounding marine environment structures the prokaryotic community composition of the sponge species Suberites diversicolor.MethodsSponge specimens were sampled in five marine lakes in Borneo and Papua and one open sea habitat in Taiwan.ResultProkaryotic communities of S. diversicolor were dominated by members assigned to the Proteobacteria (particularly Alphaproteobacteria and Gammaproteobacteria) and Cyanobacteria, which together made up from 78 to 87% of sequences in all samples. The dominant operational taxonomic units (OTUs) in most samples, OTUs 1 and 3, were both assigned to the alphaproteobacterial order Rhodospirillales with OTU-1 dominant in the marine lakes of Berau and Papua and OTU-3 in Taiwan. OTU-3 was also largely absent from Papuan samples but present in all Berau samples. Compositionally, S. diversicolor samples clustered according to geographical location with the main axis of variation separating marine lake samples collected in Berau from those collected in Papua and the second axis of variation separating open sea samples collected in Taiwan from all marine lake samples. In addition, our results suggest that the degree of lake connectivity to the open sea also influences prokaryotic composition.ConclusionAlthough previous studies have shown that sponge-associated microbial communities tend to be stable across different geographical and environmental gradients, in the present study, both geography and local environmental conditions were significant predictors of variation in prokaryotic community composition of S. diversicolor.
Highlights
Marine lakes, known as anchialine systems, are small seawater bodies, isolated in the interior of islands and connected to the surrounding marine environment through subterranean fissures, tunnels or small dissolution channels in the surrounding rock (Holthuis 1973; Hamner and Hamner 1998; Becking et al 2011, 2013a)
S. diversicolor samples clustered according to geographical location with the main axis of variation separating marine lake samples collected in Berau from those collected in Papua and the second axis of variation separating open sea samples collected in Taiwan from all marine lake samples
Conclusion: previous studies have shown that sponge-associated microbial communities tend to be stable across different geographical and environmental gradients, in the present study, both geography and local environmental conditions were significant predictors of variation in prokaryotic community composition of S. diversicolor
Summary
Known as anchialine systems, are small seawater bodies, isolated in the interior of islands and connected to the surrounding marine environment through subterranean fissures, tunnels or small dissolution channels in the surrounding rock (Holthuis 1973; Hamner and Hamner 1998; Becking et al 2011, 2013a). Based on the connection to the sea, marine lakes can be limnologically classified as holomictic or meromictic. Holomictic lakes are well connected to the outer marine environment, and at least once each year, there is a physical mixing of superficial and deeper waters. Meromictic lakes have limited connection to the surrounding marine environment. Waters tend to stratify in meromictic lakes with denser water (saline) in the deeper parts and less dense fresher water closer to the surface (Gotoh et al 2011; Saitoh et al 2011). The connection between the marine lakes and the outer marine environment strongly influences the communities inhabiting these lakes (Saitoh et al 2011). Lakes with a limited connection tend to house a smaller
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