북서여수해만의 해양환경과 식물플랑크톤 생물량의 시ㆍ공간적 변화와 기초생산자의 성장제한 영양염의 변화

Seasonal Variations of Marine Environment and Phytoplankton Biomass with Reference Limiting Nutrients for Phytoplankton Growth in Northwestern Area of Yeosuhae Bay, South Sea of Korea

To investigate spatio-temporal variations in marine environments such as water types and nutrients (nitrogen, phosphorus and silicon) and phytoplankton biomass in the northwestern area of Yeosuhae bay, as well as variations of limiting factor for phytoplankton growth, this researcher conducted a field survey for four seasons of 2012. According to the results of the survey, the marine environment of Yeosuhae bay showed that the water in winter and spring water had low temperature and high salinity, the water in summer had high temperature and high salinity and the water in fall had high temperature and low salinity. The water quality in the bay changed drastically depending on the season; however, nitrogen and silicon were provided by waters from inland and phosphorate levels were strongly affected by a nearby industrial complex. Variations in phytoplankton biomass as chlorophyll a concentration in the present study area, compared to those in Korean southwester sea, was found to be high in winter and summer and low in spring and fall. In particular, the fall survey which was conducted right after the occurrence of a large typhoon, indicated many differences from the general marine environments. The standing crop in spring was higher than that in winter, but biomass in spring was lower. As a result, no systematic relations between standing crop and biomass were found. In addition, during the time when a coastal industrial complex in Gwangyang bay near Yeosuhae bay was first built and while it was operating (i,e., between the late 1970s and the 200s), the growth-limiting nutrient for phytoplankton was nitrogen, but now it was found to be phosphorus. In other words, the phosphate that was abnormally high in density during the time when the complex was operating was found to be improved through the management of the quality of waters flowing into Gwangyang bay and the change to the industrial structure of the complex. It is believed that these results will be able to be used as good examples in managing the water quality in eutrophied bays.