Algae. 2001; 16(2): 157-163.

Structure and Dynamics of Phytoplankton Communities in the Natural Wetland, Yunchon-gun, Kyunggi-do

Jin Hwan Lee, Jung Eun Choi

Division of Natural Sciences, College of Natural Sciences, Sangmyung University

The present studies were investigated the water quality and the structure and dynamics of phytoplankton communities at 2 stations during the period from Aug. 1999 to July 2000 in the natural wetland, Yunchon-gun, Kyunggido. In order to evaluate the water quality, water temperature, pH, dissolved oxygen, chlorophyll-a, NO sub(2)-N, NO sub(3)-N, NH sub(4)-N and PO sub(4)-P were measured. Water temperatures changed from 7.9℃ to 29.1℃, and was entirely under the influence of the air temperatures. pH is slightly acid, varied from 5.39 to 6.51 and concentrations of dissolved oxygen showed 1.69-10.55 mg·l super(-1). chlorophyll-a concentrations varied from 5.82 mg·m super(-3) (St. 1, Nov.) to 238.06 mg·m super(-3) (St. 2, July) and it could be pointed out hypereutrophication from the viewpoint of the standard value of eutrophication. Concentrations of nitrogen and phosphorus were extensively changed by month and stations. Total 170 taxa of phytoplankton belong to 71 green algae, 37 euglenoids, 19 blue green alge, 32 diatoms, 5 xanthophytes, 3 chrysophytes, 2 dinoflagellates and 1 chryptophyte were tentatively identified. Number of phytoplankton species varied from minimum 11 taxa (St. 2, May) to maximum 39 taxa (St. 2, July). Phytoplankton standing crops showed always blooming level more than 1.0×10 super(6) cells·l super(-1) every month and station except St. 2 in May showing minimum 544,730 cells·l super(-1). Phytoplankton dominant species were very various by month and stations. Planktosphaeria gelatinosa occupied 79.42% at St. 1 in Aug. and 44.08% at St. 1 in July. The other species at the same station were Dictyosphaerium ehrenbergianum in sept., Synura petersenii in Nov., Westella botryoides in Apr., Euglena gracillis in May, and Pediastrum tetras in June. The dominant species at St. 2 were also very different every month: Trachelomonas komarovii var. punctata in Aug., Merismopedia elegans in Sept., Euglena acutissima in Nov., Mougeotia viridis in Apr., Ankistrodesmus falcatus in May, Meriosmopedia punctata in June and Volvox sp. in July. Phytoplankton blooms seemed to be caused by high water temperature, and the concentrated nutrients for phytoplankton supplied with wastewaters from the agricultural area. Agricultural wastewaters are released into this wetland, and many emergent and submerged anchored hydrophytes decay after growth become the organic pollution. It could be thought that eutrophication caused by the above mentioned reasons.

Keywords : phytoplankton communities, water quality, wetland, Yunchon-gun