附著性矽藻對水中生態環境極為敏感，群落結構易受物理、化學因子變化而改變，故被用作水質監測指標。本研究以鏡檢計數和次世代定序方法 (Next-generation Sequencing, NGS) 調查滙入三類放流水後，河川附著性矽藻群落結構之變化、群落結構與環境變因之關聯和藻類指數的應用。在台中市筏子溪之東海橋民生放流口、台中工業區與台中精密創新科技園區放流口之上下游分別設置樣點，六個樣點距離在五公里內，分別採集附著性矽藻樣本三個，混合後，以顯微鏡檢計數，分析群落結構，計算矽藻群聚指數 (DAIpo)、矽藻營養化指數 (TDI)、汙染耐受物種百分數 (PTV) 與綜合藻屬指數 (GI)。所獲樣本同時抽取DNA，以18S rDNA 矽藻專一性引子增幅後經 454 Pyrosequencing定序，以NGS方法調查矽藻多樣性。兩類數據均以重複分析法 (Redundancy Analysis) 分析群落結構與物化因子的相關性。鏡檢計數紀錄筏子溪矽藻17屬42種，分子定序分析紀錄33屬164種。分析發現三種放流水對各矽藻藻屬影響不同，根據樣點間矽藻群落相似度距離分析，證明放流水影響矽藻群落結構。從矽藻群落及物化因子之相關性分析得知矽藻對重金屬及環境荷爾蒙耐受，部分藻屬族群量對二者濃度有偏好，但影響並不顯著。Navicula cryptocephala、Stauroneis phoenicenteron、Gomphonema parvulum、Nitzschia palea 和 N. subacicularis 等藻種的族群量變化與重金屬與環境荷爾蒙濃度相關。藻類指數反映出筏子溪之生態，DAIpo與PTV顯示筏子溪三個河段為中度及重度汙染，GI顯示為重度汙染，TDI則反映該河段為優中度優養化。 Benthic diatoms are sensitive to physical and chemical factors in the freshwater ecosystem and are commonly used as biological indicators for monitoring river water quality changes. This study investigated the changes of the benthic diatom communities after three types of effluents and in order to elucidate the relationship between changes of the community and environmental factors, using microscopic observations and next generation sequencing of 18S rDNA. The application of diatom index was studied. Six mixed samples were collected from upstream and downstream sites of three selected discharge points at Donghai Bridge domestic point, Taichung Industrial Park and Taichung City Precision Machinery Innovation Technology Park within a span of five kilometers in Fazi River, Taichung. Diversity and community of diatoms were investigated by morphological diatom and used to calculated DAIpo, TDI, PTV and GI. DNA was extracted from the same samples and 18S rDNA of diatom was amplified and analyzed by 454 Pyrosequencing. Diversity data from microscopy and NGS were both used to analyze the relationship with environments by Redundancy Analysis. Using classic method, 17 genus and 42 species were recorded; whereas 33 genus and 164 species were obtained using molecular survey. Relationship between community similarity and geographic distance show that effluents influenced diatom community. Redundancy analysis show that some diatom were tolerant of endocrine disrupting chemicals and heavy metals and have environmental preference, however, the correlation was not significant. The variations in population of Navicula cryptocephala,Stauroneis phoenicenteron,Gomphonema parvulum, Nitzschia palea and N. subacicularis were correlated with concentration of endocrine disrupting chemicals and heavy metals. Diatom community index (DAIpo) and pollution tolerant valves (PTV) indicates the study sites of Fazi River were moderate pollution. Generic index (GI) showed serious pollution. Trophic diatom index (TDI) indicates the meso-eutrophic. These four indices demonstrate the ecological status of Fazi River.
