Phytoplankton responses to eutrophic inshore waters and oligotrophic offshore waters during spring of 2017

Abstract

After episodic wind-driven events during the spring of 2017, we investigated the horizontal distribution of phytoplankton assemblages and their relationships with environmental factors at 29 stations that ranged from eutrophic inshore waters to oligotrophic offshore waters, and we also investigated the vertical distribution of physical―chemical―biological factors between Ulleungdo and Dokdo in East Sea, Korea. In addition, we confirmed the phytoplankton community response to nutrient additions using bioassay experiments. The large survey area was divided into three zones based on the geo―oceanographic region: the southwest coastal area of the Korean Peninsula (Zone D, the offshore area (Zone II), and the water around the Ulleungdo and Dokdo (Zone II). In terms of abiotic factors, the water temperature ranged from 16.4°C tol 8.6°C and was not significantly different among Zones I, II, and III (p>0.05). Surface salinity ranged from 33.2 to 34.5 and was slightly lower in Zone I than those in Zones II and III(p<0.001).The nitrate+nitrite and silicate concentrations in Zone I were significantly higher than those in Zones II and III (p<0.001) however, ammonia and phosphate were not significantly different among the zones(p>0.05). With respect to biotic factors, the chlorophyll a, in vivo Chl. a, ,and Fv/Fm in Zone I were significantly higher than those in Zones II and III (p < 0.001 ) these results implied that res to oligotrophic offshore waters, and we also investigated the vertical distribution of physical―chemical―biological factors between Ulleungdo and Dokdo in East Sea, Korea. In addition, we confirmed the phytoplankton community response to nutrient additions using bioassay experiments. The large survey area was divided into three zones based on the geo―oceanographic region: the southwest coastal area of the Korean Peninsula (Zone D, the offshore area (Zone II), and the water around the Ulleungdo and Dokdo (Zone II). In terms of abiotic factors, the water temperature ranged from 16.4°C tol 8.6°C and was not significantly different among Zones I, II, and III (p>0.05). Surface salinity ranged from 33.2 to 34.5 and was slightly lower in Zone I than those in Zones II and III(p<0.001).The nitrate+nitrite and silicate concentrations in Zone I were significantly higher than those in Zones II and III (p<0.001) however, ammonia and phosphate were not significantly different among the zones(p>0.05). With respect to biotic factors, the chlorophyll a, in vivo Chl. a, ,and Fv/Fm in Zone I were significantly higher than those in Zones II and III (p < 0.001 ) these results implied that re