The spatial distribution of macrobenthic infauna on the soft-bottoms of Dok-do in the East Sea, Korea

Abstract

For the investigation on the distribution of macrobenthic infauna at the subtidal area around an island, Dok-do, in the East Sea, faunal samples were collected at 15 sites during September, 2016. Using a Smith-McIntyre Grab (0.1m2), duplicate grab samples were collected at each site. Bottom sediments consisted of more than 90% of sand and gravel at all sampling sites, and the gravel content was particularly high at the sites located in the eastern shelf area of the island. The total number of species and mean density of macrobenthic fauna were 178 and 1,658 ind.m-2, respectively. The whole benthic community was mainly composed of crustaceans (52 spp./0.3m2), mollusks (50 spp./0.3m2), and polychaetes (47 spp./0.3m2). Crustaceans was found to be the most contributor to the total faunal density with 721 ind./m2, and followed by polychaetes (437 ind./m2) and mollusks (209 ind./m2). The major dominant species were Melita denticulata (7.8%) and Melita shimizui (2.6%) in Crustacea, an unidentified species in Nematoda (2.8%), Brania clavata in Polychaeta, and Glycymeris aspera in Mollusca. The species number at each site was ranged from 26 to 70, and their density was from 790 to 3,520 ind. m-2. From the cluster analysis, the sampling sites with more similar faunal composition and abundance were classified into 4 site groups including two single site group such as site 51 (Group A) and site 80 (Group B). The dominant specieste grab samples were collected at each site. Bottom sediments consisted of more than 90% of sand and gravel at all sampling sites, and the gravel content was particularly high at the sites located in the eastern shelf area of the island. The total number of species and mean density of macrobenthic fauna were 178 and 1,658 ind.m-2, respectively. The whole benthic community was mainly composed of crustaceans (52 spp./0.3m2), mollusks (50 spp./0.3m2), and polychaetes (47 spp./0.3m2). Crustaceans was found to be the most contributor to the total faunal density with 721 ind./m2, and followed by polychaetes (437 ind./m2) and mollusks (209 ind./m2). The major dominant species were Melita denticulata (7.8%) and Melita shimizui (2.6%) in Crustacea, an unidentified species in Nematoda (2.8%), Brania clavata in Polychaeta, and Glycymeris aspera in Mollusca. The species number at each site was ranged from 26 to 70, and their density was from 790 to 3,520 ind. m-2. From the cluster analysis, the sampling sites with more similar faunal composition and abundance were classified into 4 site groups including two single site group such as site 51 (Group A) and site 80 (Group B). The dominant species