Continuous Observation of Chlorophyll-a Concentration and Changes in Phytoplankton Communities in Tongyeong Coastal Water of South Korea

Abstract

To understand the changes in chlorophyll-a concentrations and phytoplankton communities during the summer in Tongyeong coastal waters, Korea, we continuously monitored chlorophyll-a concentrations using a fluorescence sensor from July 29 to September 28, 2017(62 days). Furthermore, phytoplankton analyses were conducted periodically to monitor changes in dominant species affected by variations in chlorophyll-a concentrations. In the presented study, chlorophyll-a concentrations increased rapidly three times(event 1-3). During the first event(August 6 to 14), rapid and repeated increases in chlorophyll-a concentration during every 14:00 to 16:00 pm were the result of the diel vertical migration of Alexandrium affine(the dominant species during the event). The second and third events occurred from August 24 to 30 and September 12 to 17, respectively. During these events, increases in chlorophyll-a concentrations were caused by diatoms(common species: Chaetoceros curvisetus, Skeletonema marinoi-dohrnii complex etc.). Unlike event 1, we did not observe any characteristic changes such as vertical migration of A. affine during these events. Therefore, the continuous monitoring of chlorophyll-a concentrations using a real-time detection device, such as a fluorescence sensor, is necessary and important because of the variations that occur in chlorophyll-a and phytoplankton communities in the short-term. September 28, 2017(62 days). Furthermore, phytoplankton analyses were conducted periodically to monitor changes in dominant species affected by variations in chlorophyll-a concentrations. In the presented study, chlorophyll-a concentrations increased rapidly three times(event 1-3). During the first event(August 6 to 14), rapid and repeated increases in chlorophyll-a concentration during every 14:00 to 16:00 pm were the result of the diel vertical migration of Alexandrium affine(the dominant species during the event). The second and third events occurred from August 24 to 30 and September 12 to 17, respectively. During these events, increases in chlorophyll-a concentrations were caused by diatoms(common species: Chaetoceros curvisetus, Skeletonema marinoi-dohrnii complex etc.). Unlike event 1, we did not observe any characteristic changes such as vertical migration of A. affine during these events. Therefore, the continuous monitoring of chlorophyll-a concentrations using a real-time detection device, such as a fluorescence sensor, is necessary and important because of the variations that occur in chlorophyll-a and phytoplankton communities in the short-term.