Distribution and Behavior of Aquatic Insects in Different Velocity and Bed Materials as A Basis for Ecological Engineering Design

• Main Authors: Hsin-Yi Chou, 周心儀
• Other Authors: 張文亮
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/44836708118153014015

碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 92 === In order to improve the impact of the traditional river stream remediation on ecosystem, the concept of ecological engineering has been developed. This investigation concerns aquatic insect fauna distribution and physical habitat factors in Yuan-Tan-Zi canal, Pu-Tou canal, Zhen-Shan canal and Nei-Cheng canal in northeastern Taiwan. The sampling was conducted in March, June, August and November, 2003. Various statistical analysis were used, including Pearson correlation, multiple regression model and interspecific normal distribution curve interaction analysis. It is hoped that the analysis in this study can be served as a reference for stream ecological engineering in Taiwan. By analyzing the relationship between the Shannon index and the physical habitat factors, it showed that the biodiversity increased with d90 and decreased with the square of water velocity. With the water velocity between 0.62-0.73 m/s and d90 between 5-20 cm, there was high biodiversity. Thus the Shannon index can be an important index of stream ecosystem. As a result of the field experiments, we can classify the condition of aquatic insects adapting to water velocity into three types: (1) swiftwater species, such us caddis-fly, water-penny and so on, are the dominant insects in flow of water velocity up to 0.82 m/s, (2) Stillwater species, such us damselfly and so on, prefer the water velocity between 0.2-0.3 m/s, (3) the species between swiftwater and stillwater, like stone-fly, water-beetle and so on, live in water velocity between 0.55-0.62 m/s. We suggest to implement ecological engineering methods, which aim to form various flows and stream bottom sediment diversity, to enhance the biodiversity and to enrich the habitat environment. Aquatic insects are the species of the bottom-end of food chain in stream ecosystem. Their physiological characteristics are sensitive to the changes of the physical environment. The water velocity is the key physical factor of their thrive or decline. In this study, circular statistics were used to analyze the behavior of damselflies climbing over to the rectangular and cylindrical stones under different water velocities as a reference for ecological engineering design. When damselflies climb over to the cylindrical stones, the insignificant cluster of mean angle under the water velocity of 0.23~0.51m/s indicates that they have better mobility. When the damselflies climb over to the rectangular stones, the significant cluster of mean angle under the water velocity of 0.23~0.67m/s indicates that they have better mobility. The ones on the smaller rectangular or cylindrical stones, mean angle deviations are less. Larger stones provide more diversity of the micro-environment, and enlarge the habitats of the damselflies.