淡水河口因長期受流域附近城鎮廢水流入及工程作業所致，此區海域之底棲生態結構必應長期環境的影響而有了改變。 在河口域12個測站底棲生物的採集及底質樣品，經分析與鑑定的結果，底棲生物種類組成具有明顯的季節差異，仍以軟體及節肢動物佔的比例較大，冬季主要的種類網紋螺（Nassarius sp.）及竹節夕虫（Malaanidae）見於C3及C7二測站，底棲生物群落結構參數Simpsons index對之季節變動來看，以沿岸各測站變化較大，而近海各測站較穩定。
The benthic ecological structure of Tan-Shui estuary is changing due to long term effects of dumping or urban waste water and engineering actions. Twelve stations were established on the Tan-Shui estuary for benthos and sediment sampling. The composition of the dominant species of benthos were seasonal variated, with the mollusca and crustacea species having higher frequency of occurrence probability and higher number. The dominant species during winter were Nassarius sp. and Malanidae at stations C3 and C7. analysis using Simpson's index and Shannon's index showed the benithic community vary more in coastal areas than in offshore areas. Physidochemical analysis showed that most of Tan-Shui estuary consisted of sandy sediment. The variations in concentratins of orangic carbon the TON at each station were Small. The Eh values raged from+187 to +210mv. Although the concentrations of chlorphyll a and carotenoid at all stations were generally low, the C3 and C7 stations hand highest concentration, we conclude that the concentrations of pigments in the sediment were related to the abundance of benthos. The community structure of benthos reflected the characteristics of the sediments and benthic species had their own selection and adaptation to the sedimentary environment.
