2022년 춘계에서 하계 제주 연안의 해양 물리화학적 특성 및 식물플랑크톤 출현 변동

Abstract

Phytoplankton, as key primary producers, play a critical role in the dynamics of marine ecosystems. This study explores the variation in phytoplankton species appearance along the Jeju coast from spring to summer 2022, emphasizing the stratification and changes in nutrient dynamics. Through extensive field surveys at twelve points around Jeju Island, we measured a range of physical and chemical oceanographic parameters. Monthly average stratification indices displayed an abrupt increase from 22 in May to 3,196 in August, highlighting intense stratification, significantly influenced by the influx of Changjiang River Diluted Water during the summer months. Concurrently, nutrient concentrations exhibited a downward trend, with nitrate and nitrite levels decreasing from 6.7 μM in March to 1.3 μM in July, and phosphate levels declining from 0.31 μM to 0.02 μM during the same period, while silicate concentrations, ranging from 6.8 to 9.8 μM, remained consistently high throughout the study. Similarly, a reduction in monthly average phytoplankton biomass was observed, with concentrations peaking in the spring (April and May) at 406,053 to 409,139 cells L-1 and declining to 45,546 to 118,214 cells L-1 by summer (June to August). Diatoms (Chaetoceros spp. and Skeletonema spp.) dominated the phytoplankton community throughout the period; however, an increased proportion of dinoflagellates (Gyrodinium spp. and Heterocapsa spp.) was observed during the summer months, when stratification was most pronounced. This study confirms that variations in currents and water masses impacting the Jeju coast can significantly influence phytoplankton community dynamics, emphasizing the need for ongoing monitoring in this region.