| Summary: | 碩士 === 東海大學 === 環境科學系 === 86 === Fish community and environmental ecology studies were conducted from 1997 to 1998 in Li-Chi Stream. Eight species were collected in the study stream areas, located in the middle of the stream, as well as downstream. They wereAcrossocheilus formosanus, Zacco platypus, Hemimyzon formosanum, Crossostomalacustre, Leiocassis taiwanensis, Varicorhinus barbatulus, Pseudorasbora himantegus and Rhinogobius brunneus. The number of species increased from 1 to6 from upstream to downstream, with the typical phenomenon of longitudinaladdition. It was proven that sand-retention obstructured the fish in Li-Chi Stream.There was a with more than 7 time difference in fish numbers from the two areasthat were separated by sand-retention. Also, there was an obvious difference in formosanum and Varicorhinus barbatulus in Li-Chi Stream, and to the dominanceof Acrossocheilus formosanus and Zacco platypus in Zuo-Sui Stream.The large Acrossocheilus formosanus prefer deep pools, but the small onesconcentrate in side banks with good coverage. Large Zacco platypus prefersrunning condition. It is better adapted to deep and running conditions than theother species. The distribution of small Zacco platypus was limited by the current.If the current ran slower, it could stay in center stream. Large Hemimyzonformosanum prefers riffles. Both large and small Hemimyzon formosanum have ahigh ability to resist current. Large Rhinogobius brunneus is a generalist, whilesmall Rhinogobius brunneus prefers pools and shallow runs. Large Varicorhinus barbatulus have more resistance to current than Acrossocheilus formosanus andZacco platypus, but small Acrossocheilus formosanus concentrate in side bankhabitats that are 0.2-0.4m in depth.It is suggested that the target species for conservation should includeVaricorhinus barbatulus, Acrossocheilus formosanus and Zacco platypus. The firstpriority for conservation should be the reach near Li-Chi Dam which has the highestabundance of Varicorhinus barbatulus. The second priority is near LC5 stationwhich has the most species and hight diversity. In addition, in the sensitive periodfor fish, from August to January, any interference should be avoided.
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