碩士 / 國立臺灣大學 / 海洋研究所 / 91 / The outbreak of the sea anemones has been proposed as a factor associated with the degradation of coral reefs at Tiaoshi in Nanwan Bay, southern Taiwan. These sea anemones replace the branching coral colonies and form dense aggregations on the surface of dead coral skeletons. The taxonomy of the sea anemone and the mechanism of this outbreak were studied in this study.
The sea anemone is considered as a new species, Condylactis nanwanensis (Actiniaria, Actiniidae). The morphological description was based on 81 specimens collected in May and October 2002, and based on observations of many living organisms in situ and in aquaria. C. nanwanensis is similar to the Caribbean species, C. gigantea (Weinland, 1860), in number of tentacles and mesenteries as well as features of the column and tentacles, but different in color, size, cnidom and reproductive characteristics.
Reproduction and population structure of C. nanwanensis were studied from December 1999 to December 2002. Monthly population structures based on size-frequency distributions were dominated by small individuals (< 0.5 g, wet weight) in December 1999, January, September-November 2000, and August, December 2001. The anemones reproduced asexually by longitudinal fission throughout the year with the monthly division ratio ranging from 0.87 to 6.46%. Fission occurred in all size classes of the population and fission ratio gradually increased with increasing body size, and the highest fission ratio of 18.18% occurred in size class of 6.5-7.0 g. Spermary was not found by intensive examinations of 969 individuals over three years. Most individuals larger than 0.5 g were mature sexually. Oogenesis started in April 2000, and May 2001. Releasing of eggs or planulae possibly occurred in April 2000, May 2001 and May 2002 based on results of histological studies and observation in aquarium. The larvae were found in a bottle with three sea anemones once in May 2003 and might be reproduced asexually. The results suggest that the population outbreak of C. nanwanensis at Tiaoshi in Nanwan Bay is possibly resulted from asexual reproduction.
| Identifer | oai:union.ndltd.org:TW/091NTU00279035 |
| Date | January 2003 |
| Creators | Tsai, Wan-Hsu, 蔡宛栩 |
| Contributors | Professor Dai, Chang-Feng, Fan, Tung-Yung, 戴昌鳳, 樊同雲 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 1 |
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