| Summary: | 碩士 === 臺灣大學 === 生態學與演化生物學研究所 === 98 === This study set up four sampling areas, located in the upstream and downstream of the check dam, in Jingualiao Stream. The researchers conducted field works by employing three types of angling methods and one kind of fish traps to collect fish samples, once per month, to investigate the impact, of the invasive predator, Culter alburnus, posed on native fish communities.
To summarize the result in the sampling area, there were 21 different fish species collected in Jingualiao Stream between April 2008 and May 2009. And 7 species out of them are invasive aliens, Culter alburnus, for example. And the first dominate specie is Candidia barbata, followed by Acrossocheilus paradoxus, and Culter alburnus. Above three species take 80.2% of the collected samples. Culter alburnus appears only in the downstream of the check dam and thus did not decrease the number of the native fish species in sampling areas. However, the population of Candidia barbata, in preference of surface water habitats, has decreased significantly below the check dam, and plays 1/8 of the population above the check dam. The population of Candidia barbata community shows negative correlation with Culter alburnus community. The fry population of Candidia barbata shows dramatic difference above and below the check dam, which is one to thirty-eight. Meanwhile, study indicates fry and sub-adult of Candidia barbata as the main component of the digestive tract of the Culter alburnus. Thus, we suggest that Culter alburnus poses great predatory pressure over Candidia barbata community, specifically on fry population, whose habitat is in the downstream of the check dam. On the other hand, Acrossocheilus paradoxus, which habitats in bottom water shows no difference in population structure above and below the check dam. To make a conclusion, Culter alburnus decreased the Candidia barbata population and changed the fish community below the check dam.
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