The floral composition and seasonal succession of phytoplankton in the Naktong and Sonaktong River, which have a estuarine dam at each river mouth, were studied during 1991 and 1992. We evaluate some factors contributing to the seasonal variation of p...
The floral composition and seasonal succession of phytoplankton in the Naktong and Sonaktong River, which have a estuarine dam at each river mouth, were studied during 1991 and 1992. We evaluate some factors contributing to the seasonal variation of phytoplankton. The phytoplakton consisted of main algal group : diatoms, blue-green algae, green algae and cryptomonads. Freshwater zone, which is upper part of the estuarine dam, was characterized by eutrophic diatoms and blue-green algal association. Stephanodiscus hantzschia was persistent from October through mid-May and bloomed throughout the Naktong Estuary. In the Sonaktong River, diatom Extubocellulus spinifer and cryptomonad Chroomonas sp. succeeded Stephanodiscus. Microcystis aeruginosa coincided with the disappearance of diatoms such as Stephanodiscus and Extubocellulus and cryptomonads, and Microcystis outbreaks were primarily mono-specific blooms. There was a pronounced rise in chlorophyll a standing crop through the spring - summer and it ranged from 200 ug/l to 331 ug/l. Viewed from chlorophyll concentration and persistent bloom of eutrophic phytoplankton, the degree of eutrophication was higher than that reported previously. Eutrophication in the Naktong Estuary would be partly regulated by rainfall deficits as well as physico-chemical factors such as nutrient and temperature.