Spatial Distributions of Macrozoobenthic Communities in the Seomjin River Estuary

Abstract

: This study was carried out to investigate the spatial distributions of the macrobenthic communities in the Seomjin River estuary from May, 2015 to May, 2016. The number of species was 163, the mean density was 1,865 ind.m -2 , biomass was 204 g·wet m -2 during this study period. The highest number of species and density appeared among polychaetes whereas the most biomass was contributed by mollusks due to the presence of Corbicula japonica in every season. The study area was divided into 3 regions with similar benthic fauna responding to the gradient of the salinity. Praxillella praetermissa was the dominant species in regions of over 30 psu during all seasons. C. japonica and Hediste diadroma were dominant in the upper regions of the Seomjin River where the salinity was less than 10 psu. Heteromastus filiformis showed the broadest distributional range and dominated in all seasons except for the most upper stream at st. 7. From the result of the Bio-Env analysis, salinity was the most important environmental factor affecting the formation of macrobenthic communities in the study area, and salinity and TOC were the highest contributors to the macrobenthic communities. From the correlation analysis between major dominant species and environmental factors, C. japonica, Prionospio japonica and H. diadroma showed a negative correlation with salinity, while P. praetermissa and Scolectoma longifolia showed a positive correlation. H. filiformis was little affected by salinity but showed a positive correlation with TOC or silt content of sediment.

Identifying patterns in the multitrophic community and food-web structure of a low-turbidity temperate estuarine bay

“…Previous studies also proposed seasonal succession in the phytoplankton community (i.e., relative abundances of centric and pennate diatoms and flagellates) in response to temperature fluctuation, inorganic nutrient loading status and N:P stoichiometry 47 as well as zooplankton assemblages linked to temperature, salinity and Noctiluca vs. diatom densities 43,48 . Our SOM training intuitively differentiated the macrobenthic community into clusters 1 and 2 (estuarine channel) and cluster 3 (deep bay), reflecting a salinity gradient 49 . The dominance of the brackish-water indicator species C. japonica and Prionospio japonicus in the estuarine-channel clusters supports the longitudinal transition of the macrobenthic community.…”

“…Our SOM training intuitively differentiated the macrobenthic community into clusters 1 and 2 (estuarine channel) and cluster 3 (deep bay), reflecting a salinity gradient 49 . The dominance of the brackish-water indicator species C. japonica and Prionospio japonicus in the estuarine-channel clusters supports the longitudinal transition of the macrobenthic community.…”