남해전선역 동물플랑크톤의 생체 탄소와 질소 함량

Abstract

Carbon and nitrogen content of zooplankton was used to determine the quality of zooplankton as food source in the fontal zone of south sea in Korea. South sea frontal zone is created by the forcing mechanisms between two water bodies. Korea southern coastal water transits with Tsushima Warm current creating stratified water column impacting the distribution of temperature and salinity, which influences the distribution of nutrients, phytoplankton and zooplankton. Determining the carbon and nitrogen content of zooplankton can assess the water column nutrient status and determine the quality of zooplankton as a food source in the trophic level. In this study, zooplankton was investigated at a transect of 5 stations perpendicular to the frontal zone of southern sea (stations B0, B2, B4, B6, B8) in April 2016 on R/V Eardo (KIOST). Samples were collected by zooplankton net of 60 cm diameter with 200 ㎛ mesh size, and vertically trawled at the depth of surface mixing layer. 2% of the total volume of the sample was filtered through 25 ㎜ GF/F and dried at 60℃ for 24 hours and placed in desiccator until analysis. The amount of C, N in relation to dry weight of zooplankton were measured in using Flash EA 1112, Thermo. South sea frontal zone was formed in between st. B4 and st. B6 where the water temperature stratified rapidly. The total zooplankton biomass was highest in st. B4 (5.22 mg/m3) and lowest in st. B0 (4.00 mg/m3). This suggest that water temperature of frontal zone region and zooplankton biomass are positively correlated. The carbon and nitrogen content of zooplankton was highest in st. B0 (C: 13.26 mg/m3. N: 7.03 mg/m3) and lowest in st. B6 (C: 4.75 mg/m3, N: 2.5 mg/m3). While C:N ratio of zooplankton was highest in st. B6 (1.9) and lowest in st. B2 (1.77). Element content was lowest but C:N ratio was highest in st. B6 suggest that environmental factors of frontal zone allows high growth and production of phytoplankton and nutritional level for zooplankton’s C:N ratio to be high but the element content was low due to the abundance in predator such as fish of the higher trophic level. Consequently, based on the findings of this research, we can predict the level of contribution of zooplankton in the marine food web and nutrient cycle by the analysis of C, N content.