The role of Acrossocheilus paradoxus in stream ecosystems

• Main Authors: Te-jung Sun, 孫德容
• Other Authors: Yi-kuang Wang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/50957024439758902831

碩士 === 南華大學 === 環境管理研究所 === 96 === 　　The purpose of this research is to study the effects of Acrossocheilus paradoxus on algae, organic matters, and macroinvertebrates in order to understand the role of A. paradoxus in stream ecosystems. This study was conducted in a section of Jiao-Lung Stream in the Lian-Hua-Chi Research Center in Nantou County of Taiwan. This experiment had 4 treatments with 0, 2, 4, and 6 fish, respectively. Samples were collected on the 2nd, 3rd, and 4th weeks. In the fourth week, macroinvertebrates were collected. The gut contents A. paradoxus form the stream were analyzed . Chlorophyll a, organic matters, algal species identification, and counting were analyzed in the lab. Samples of macroinvertebrates were sorted and identified in the lab. 　　 　　The gut contents of A. paradoxus showed that diatom, green algae, blue green algae, organic matters, and sands were the preferred food items. Only few macroinvertebrates were found in the contents. Experimental results showed that chlorophyll a and organic matters decreased with increasing fish densities, indicating that A. paradoxus reduced the amount of algae and organic matters by consuming them. The control had higher algal biovolumes than other treatments. Algal composition did not differ among treatments and diatom was the dominant algal group. After removing 4 groups (A1, A6, C1 and D1) with great variations, the densities of macroinvertebrates decreased when A. paradoxus was present.