Differences seen in the major quinone species indicate that bacteria of different taxonomic groups inhabit the sediments. To quantitatively identify the differences in the microbial community structure based on respiratory quinone, D-values were calculated and subjected to MDS and cluster analyses. The stress value and R 2 value were estimated to be 0.14 and 0.95, respectively, indicating an acceptable level for the fit and validity of the MDS analysis. These analyses categorized the six sites into four groups: site1, sites Protein Tyrosine Kinase inhibitor 2-1, 2-2, 2-3 and 2-4, and site 3 (Fig. 5a, b). This indicates that the microbial community https://www.selleckchem.com/products/mln-4924.html structures were similar at sites 2-1, 2-2, 2-3 and 2-4, and significantly different

from that of site1. The microbial community structure at site 3 is also distinct from that of site 1. The Shannon–Wiener diversity values at sites 2-1, 2-2, 2-3 and 2-4, and site 3 were relatively low compared to those at site 1 (Fig. 6). This is because specific bacteria, such as Q-8-containing proteobacterial species,

were significantly predominant at sites 2-1, 2-2, 2-3 and 2-4, and site 3 although the abundance of the number of quinone PD0332991 species was similar at the other sites. These results indicate that coastal sediments near populated areas tend to have pockets of sediments with high contents of organic matter and nutrients. Generally, bioindicators are used for the evaluation of long-term environmental impacts. Thus, this study indicates that water pollution is a chronic problem on the lagoon side of the island near the populated area, also taking into account the high density of population. Fig. 5 Statistical analyses using respiratory

quinone fraction data at each site. a Multidimensional Methocarbamol scaling. b Cluster analysis. A D-value greater than 0.20 indicates that the microbial community structures are significantly different Fig. 6 Shannon–Wiener diversity based on respiratory quinone fraction at each site Water pollution mechanism Water pollution sources Considering the land use/coverage on Fongafale Islet (Yamano et al. 2007), it is unlikely that non-point source pollution and/or industrial wastewater were the primary sources of pollution. Fongafale Islet has 639 households (Secretariat of the Pacific Community 2005). Although there is no centralized treatment system such as a wastewater treatment plant, 424 households have buried septic tanks that receive domestic wastewaters including human waste. Specifications require the septic tank to have two compartments: one for settling and one for anaerobic treatment. In addition, 163 households have pit toilets with a pour flush (Secretariat of the Pacific Community 2005; Lal et al. 2006). Thus, 92 % of households have access to improved sanitary facilities. However, studies have shown that septic tank systems (Borchardt et al.