Seasonal and spatial variations in nematode assemblages affected by thermal influence of nuclear power plant in Korea (East Sea, Pacific Ocean)

The effects of the thermal discharge from a coastal nuclear power plant on the spatial and seasonal variability of nematode assemblages were investigated in the Gori coastal waters of the southern East Sea. Taxonomic and functional approaches were taken to describe the assemblage structure and relate it to the abiotic environment based on a sampling scheme involving three stations and four seasons. The analysis of the nematode communities suggested that heated effluent influenced the assemblage structure or the spatial distribution of the taxa studied. The abundance of the nematodes differed significantly among seasons and stations and the numbers of species also differed significantly between stations. The seasonal variation was greater in winter and summer than in spring and autumn. The numbers of species and their abundances were highest at station 3 (impact station), attributable to the increased bottom temperature. However, the functional diversity of the assemblages did not change notably between stations or seasons. Species such as Sabatieria sp. (34%), Linhystera sp. (18%) and Parodontophora sp. (11%) were usually dominant in all seasons and at all stations. Parodontophora sp. displayed a significantly negative correlation with the bottom temperature (P<0.05). These results indicate that the nematode species composition was significantly affected by the bottom temperature.