This study aims to study the species composition and distribution of chaetognaths in the waters surrounding Taiwan January 2005 to July 2006, and to explore the relationship between environmental factors and their dynamic distribution. Waters surrounding Taiwan are affected by monsoons and water masses. In winter, the northwestern Taiwan area is under the impact of low-temperature low-salinity China Coastal Current, but in summer, Taiwan Strait is affected by South China Sea Current going northward with high-temperature and high-salinity. As for eastern waters of Taiwan, Kuroshio current passes throughout the year so it is high-temperature and high-salinity. In July 2006, when three typhoons struck Taiwan, excessive fresh water from land flowed into the ocean and stations along the coast where low in salinity. This study identified a total of 28 species of chaetognath under 14 genera of 4 families, with average abundance at 475 ¡Ó 35 ind./100m3, which shows an obvious change related to seasons, relatively low in winter and spring and high in summer and fall. The seven most dominant species are: Flaccisagitta enflata, Serratosagitta pacifica, Zonosagitta littoralis, Pterosagitta draco, Aidanosagitta regularis, Aidanosagitta bedfordii and Aidanosagitta neglecta, accounting for 85% of the total abundance. The distribution of chaetognath in waters surrounding Taiwan is affected by the different water masses. The northwestern area where China Coastal Current passes through has high abundance but less number and low Shannon diversity index, but the eastern and southern waters dominated by Kuroshio current shows a completely different trend. From the results of multiple regression analysis, it is found that the abundance of chaetognath and F. enflata are in positive correlation with that of the abundance of copepod, indicating that the quantity of food might be a factor affecting the distribution of chaetognath. The second dominant species S. pacifica has no relation with hydrographic or biological factors, and the third dominant species Z. littoralis is in negative correlation with temperature and salinity. Along with the results of indicator species analysis, Z. littoralis can possibly be used as indicators species of China Coastal Current. The three predominant species are dominated by the Stage I and significantly less in other growth stages. The average body lengths (ABL) of F. enflata and S. pacifica are the larger in spring and smaller in fall, with obvious changes with seasons, but that of Z. littoralis is larger in winter and summer and smaller in spring and fall. Different water masses have impacts on distribution of weight mean stage (WMS) and ABL of chaetognath; for example, F. enflata and S. pacifica with the equivalent growth have larger bodies in Kuroshio current than in China Coastal Current, but Z. littoralis which prefers cold water shows an opposite trend. In addition, this study found that abundance, species, Shannon diversity index, WMS and ABL of chaetognath has no differences between day and night, but the succession of water masses in waters surrounding Taiwan may be an important factor affecting the distribution patterns of chaetognaths.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0205110-174620 |
| Date | 05 February 2010 |
| Creators | Mei, Pu-kai |
| Contributors | Kwee-Siong Tew, Meng-Hsien Chen, Wen-Tseng Lo, Chang-Tai Shih |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0205110-174620 |
| Rights | unrestricted, Copyright information available at source archive |
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