The influence of pelagic organisms and environmental properties on the distribution of marine benthos in the adjacent East China Sea and Korea Strait

Abstract

Although the pelagic ecosystem affects the macrobenthic community, few studies have examined pelagic-benthic coupling in the adjacent East China Sea and Korea Strait. This study analyzed the species composition and abundance of the macrobenthic community, and the potential food sources of benthic fauna, such as particulate organic matter (POM) in seawater and sediment organic matter (SOM) in sediment, phytoplankton, and zooplankton using stable isotope analysis (δ13C and δ15N). The density and biomass of benthic fauna increased going from offshore shelf sites (the adjacent Each China Sea) to coastal sites approaching the Korea Strait. Non-metric Multidimensional Scaling analysis indicated that the macrobenthic community was divided into three distinct groups: group A in the Korea Strait; group B in the adjacent East China Sea; and group C near Ieodo. The dominant species in group A were the amphipods Photis japonica and Ampelisca miharaensis, and the polychaete Scolotoma longifolia. The dominant species in group B were the polychaetes Notomastus latericeus, Magelona sp. Ophelina acuminata, Apoprionospio sp. In this study, community structure was affected by environmental variables, such as the temperature of seawater, sediment, oxygen, and chlorophyll a, suggesting that the pelagic system controls the macrobenthic community. In the C and N stable isotope analysis, the δ13C values of phytoplankton and zooplankton ranged from &#8211;20.63 to &#8211;22.85‰, and &#8211;19.92 to &#8211;21.86‰, respectively, and there was a relatively narrow range (<1‰) between the two systems. SOM (-18.78 to -21.89‰) was less than 1‰ of the pelagic values. The δ13C values of macrobenthos increased from sites near the adjacent China Sea to sites approaching the Korea Strait, and correlated with the δ13C values of the pelagic organisms, suggesting that the organic source of the macrobenthos is the pelagic system, which is an important factor controlling the macrobenthic community