Thyasira tokunagai as an ecological indicator for the quality of sediment and benthic communities in the East Sea-Byeong, Korea

Abstract

The biomass and abundance of molluscan species were identified to evaluate the ecological quality of the surface sediment at the East Sea-Byeong ocean dumping site, Korea. To identify the dominant molluscan species, sediment samples were collected at nine selected stations during five expeditions in 2009, 2012, 2013, 2014, and 2015. In total, 16 molluscan species, including Aplacophora, Gastropoda, Bivalvia, and Scaphopoda, were observed. The bivalve Thyasira tokunagai was the dominant species, accounting for 82.6% of the total abundance of all identified species. This species was also the dominant benthic molluscan in sediments rich in organic matter and with a low manganese content. In addition, environmental variables, including sediment grain size, water depth, total organic carbon, and heavy metals, were found to be critical drivers affecting the spatial distribution of molluscan species.