Diversity of Microbial Communities and Quantitative Chemodiversity in Layers of Marine Sediment Cores from a Causeway (Kaichu-Doro) in Okinawa Island, Japan

Abstract

Microbial community diversity and chemodiversity were investigated in marine sediments adjacent to the Okinawan “Kaichu-Doro” Causeway, which was constructed 46 years ago to connect a group of four islands (Henza-jima, Miyagi-jima, Ikei-jima, Hamahiga-jima) to the Okinawan main island. This causeway was not built on pilings, but by land reclamation; hence, it now acts as a long, thin peninsula. The construction of this causeway was previously shown to have influenced the surrounding marine ecosystem, causing ecosystem fragmentation and loss of water circulation. In this study, we collected sediment cores (n = 10) from five paired sites in 1 m water depths. Each pair of sites consisted of one site each on the immediate north and south sides of the causeway. Originally the members of each pair were much closer to each other (<150 m) than to other pairs, but now the members of each pair are isolated by the causeway. Each core was 60–80 cm long and was divided into 15-cm layers. We examined the vertical diversity of microbial communities and chemical compounds to determine the correlation between chemodiversity and microbial communities among marine sediment cores and layers. Principal coordinate analyses (PCoA) of detected compounds and of bacterial and archaeal operational taxonomic units (OTUs) revealed that the north and south sides of the causeway are relatively isolated, with each side having unique microbial OTUs. Additionally, some bacterial families (e.g., Acidaminobacteraceae, Rhizobiaceae, and Xanthomonadaceae) were found only on the south side of Kaichu-Doro. Interestingly, we found that the relative abundance of OTUs for some microbial families increased from top to bottom, but this was reversed in some other families. We conclude that the causeway has altered microbial community composition and metabolite profiles in marine sediments.

Marine bacterial communities in the upper gulf of Thailand assessed by Illumina next-generation sequencing platform

“…The considerably more OTUs were observed in marine sediments. Totals of 6039 OTUs, 6059 OTUs, and 5700 to 7600 OTUs were obtained from marine sediments around the Kaichu-Doro Causeway in Okinawa, Japan [31], marine sediments in Yam O Wan Bay, Hong Kong [32], and marine sediments from Jeju Island, South Korea [20], respectively. Moreover, this study found that the proportions of the Proteobacteria were highest in all sampling sites, followed by the Bacteroidetes and Actinobacteria.…”

Microbial Community Diversity of Coral Reef Sediments on Liuqiu Island, Southwestern Taiwan

“…The microbial community structures of sediment samples from different environments exhibit various characteristics. Microbial community examination of sediments from different regions-including the Sea of Japan, the South China Sea, the Sea of Okhotsk, the Marginal Sea of Peru, the Red Sea, the Bohai Sea, and Okinawa-has shown that the structure and diversity of their microbial communities are divergent [17,[22][23][24][25][26][27]. For example, in some polluted areas, the petroleum-eating bacteria-which belong to the phyla Pseudomonadota, Bacillota, Actinomycetota, and Bacteroidota-are abundant in coastal sediments [28][29][30][31][32].…”

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“…Until recently, spatial surveys of marine biodiversity have primarily focused on megafauna and macrofauna (Gaston, 2000; Tittensor et al, 2010) or microfauna (Sunagawa et al, 2015; Soliman et al, 2017), rather than meiofauna (the polyphyletic group of organisms that fall somewhere in between) (Lambshead & Boucher, 2003; Giere, 2008; Fonseca et al, 2010; Curini-Galletti et al, 2012; Fonseca et al, 2014; Guardiola et al, 2015; Leray & Knowlton, 2015; Guardiola et al, 2016). These organisms arguably represent the most abundant component amongst benthic metazoans in all marine systems from the intertidal zone to the deep-sea floor (Danovaro & Fraschetti, 2002; Giere, 2008).…”