| Title |
Primary Productivity of Phytoplankton in a Eutrophic River (Kum River System) |
| Authors |
신명선 ( Myoung Sun Shin ) ; 이윤경 ( Yun Kyung Lee ) ; 박주현 ( Ju Hyun Park ) ; 김범철 ( Bom Chul Kim ) |
| Keywords |
Assimilation number; C-14 methods; Kum River; Phytoplankton; Primary production |
| Abstract |
The middle and lower reaches of the Kum River system become stagnant in dry seasons with florishing of phytoplankton. In this study primary productivity of phytoplankton were measured by the C-14 uptake method and the P-I model method at seven main stream sites of the Kum River from the Daechung Dam outet to the river mouth. Nutrients (TN, TP, DIP, TIN) concentrations were measured in the mainstream and tributaries and compared with the variation of assimilation number. The range of primary productivity was 40~4,558 mgC·m+2·day-1 and it was higher than those of lentic ecosystems in Korea. Average TN and TP were 4.1 mgN·L-1, 70.6 mgP·m-3, respectively. Tributaries showed higher nutrient concentrations than the main stream. After two major tributaries merged with the discharging water of the Daechung Dam phyotplankton biomass and productivity increased drastically and remained at the similar eutrophic level through the downstream reach to the river mouth. Both dissolved phosphorus and nitrogen concentrations showed positive correlation with assimilation number of phytoplankton. In conclusion phytoplankton productivity is at the level of eutrophic water and it was higher than usual lentic habitats. Nutrient concentrations are critical factors in controlling productivity in the lower reach of the Kum River. |