| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 107 === As there are more and more human activities along the rivers, flood-protecting structures are built to prevent or reduce the loss of human lives and belongings. In order to increase convenience and prevention of disasters, human beings have carried out a large number of channelized engineering such as revetment and dike. However, although these engineered structures have brought convenience to human beings, they seriously affected aquatic ecosystems. Therefore, we would like to investigate the changes of fish community in the river due to the channelization.
For this purpose, some environmental variables were measured and compared from the protected upstream and unprotected downstream, respectively. Furthermore, fishes of different spices were collected to measure the length and weight to investigate the impact of the channelization on fish communities. In addition to comparing differences in the length and weight of fishes, biodiversity index was used as well to detect fish communities. Functional traits were used to detect the functional diversity of species, compare the situation and efficiency of resource utilization among communities, and finally try to search the functional structure affected by channelization. The results of Principal Component Analysis (PCA) showed that there was a significant difference in the degree of channel morphological change between the upstream and the downstream regions, which showed the impact of the channelization on the environment. Due to the influence of channelization, there were considerable differences in fish morphology between different regions . However, the results of the biodiversity index did not reflect the changes in fish communities well. On the other hand, the results of functional diversity showed high correlation to the impact of channelization, and was suitable for further utilization in the functional traits to explore the functional structure changed. It shows that this kind of trait-based approach had a good response to human disturbance, but complemented the unexplained information of biodiversity well. For these reasons, this approach could be suitable for ecological assessment.
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