In this study, four surveys were conducted From September, 2012 to April,2013. Examined items included basic properties of water (Temperature, pH, DO, salinity and conductivity), micro-organism content (total viable bacterial count (TVBC), coli-form group, mold and yeast count, Enterococcus and sulfur-oxidizing bacteria), micro-algae community (benthic algae and planktonic algae), benthic animal community and fish community. All the investigation methods were in accordance with the standard method announced by EPA. NanKan river with 11 sampling stations, after four surveys, 65 taxa of micro algae, 13 taxa of benthic animals and 17 species of fishes were found in this year. The entire NanKan river basin with high of human activities, TVBC was high at all the sampling stations. The composition of algae communities, benthic communities and fish communities indicated that, the pollution status of NanKan river was too serious polluted and poor for aquatic organisms. Upstream area from GuiShan bridge, the pollution was lighter than the downstream area. From GuiShan bridge up to flow into point of FengShuKeng stream, the biodiversity was highest on this site. The improvement of river condition on this site show the effects on fish assemblage with Opsariichthys pachycephalus and Cadidia barbata reappearance. LaoJye river with 9 sampling stations, after four surveys, 72 taxa of micro algae, 17 taxa of benthic animals and 21 species of fishes were found in this year. LaoJye river basin also with high human activities, untreated sewage discharge into the river, TVBC was high at all the sampling stations. The composition of algae communities, benthic communities and fish communities indicated that, the serious pollution status of LaoJye river was bad for aquatic animals living. The newly constructed ShinShi on-site treatment plant function began March, 2013, the real improvement effects could not be evaluated in this study. JiShui river with 10 sampling stations, after four surveys, 122 taxa of micro algae, 37 taxa of benthic animals and 47 species of fishes were found in this year. The activities of poultry and livestock farming were very significant in the JiShui river basin. ShinYing and LiuYing district were the largest aggregation of dairy farming site in Taiwan. TVBC was high at all the sampling stations except GanZhai No.2 bridge. The composition of algae communities, benthic communities and fish communities indicated that, the serious polluted water of JiShui river flow down from GanZhai No.2 bridge and branch flow from XingXiang bridge. The organic pollution of water was key factor of eutrophication. The downstream area with tidal movement, even dilution by sea water could not mitigate the extent of pollution. YanShui river with 10 sampling stations, after four surveys, 135 taxa of micro algae, 33 taxa of benthic animals and 44 species of fishes were found in this year. TVBC increased significantly after QianNiao bridge. The composition of algae communities, benthic communities and fish communities indicated that, only TongXin bridge with mild water pollution, after QianNiao bridge pollution state increased as intermediate level, serious pollution of downstream area began from the bridge of South No. 175 road. After FengHau bridge, YanShui river flow into the downtown of Tainan city with open water and affected by tidal movement. The retention time of water would prolong between flood tide and ebb tide. In dry season, without plenty of freshwater in stream, a small dead zone water would move back and forward between BeiAn bridge and AnPing ancient fortress. In this area, the benthic substrates was in serious reduction condition without oxygen, the diversity of benthic animal community and fish community were low.

Biodiversity, Benthic communities, Fish communities