| Summary: | 博士 === 國立中山大學 === 海洋生物科技暨資源學系研究所 === 101 === This study was aimed to investigate the ascidian species biodiversity in Taiwanese waters. Three topics were included: 1. Study of ascidian species biodiversity in Taiwan. 2. The invasive ascidians in Kaohsiung harbor, Taiwan and in the harbors in Okinawa, Japan. 3. The geographical distribution of photosynthetic symbiotic ascidians in Taiwan and Singapore. The ascidian species biodiversity were investigated in 8 sites around Taiwan and Taiwan islets. 46 species belonging to 3 orders, 9 families and 19 genera were recorded, in which 42 species were new records. Didemnidae dominates the Taiwanese waters; 20 species were included. The most common genera were Clavelina (5 species), Didemnum (5 species), Diplosoma (6 species), Lissoclinum (4species), Ascidia (6 species) and Polycarpa (4 species) and they cumulated to a total of 30 species. There were 32 colonial ascidian and 14 solitary ascidian species. The ascidian species were 21, 17, 26, 15 and 24 from Northeast Coast, East Coast, Lyudao, Kenting and Orchid Island, respectively. 7 and 8 species were recorded in the western islets of Peng-hu and Hsiao-Lu-Chiao, respectively. This study includes an identification key to order, family, genus and species of ascidians in Taiwanese waters. Two ascidian species were recorded in Kaohsiung harbor. There were 15 ascidians species recorded from 17 harbors in Okinawa, Japan. Among these species, 4 species, Phallusia nigra, Pyura vittata, Styela canopus and Styela plicata were invasive species (non-indigenous species). The results showed that U.S. Naval base, Naha harbor (mainly transporting with mainland Japan) and oil refinery were the pathways for invasive ascidians, and the recording of invasive species Phallusia nigra, Pyura sacciformis and Styela plicata in the harbors near the oil refinery indicated a northward spreading trend. We only recorded 2 species of Ascidia gemmata and Styela canopus in winter (Dec.-Apr) in Kaohsiung harbor, Taiwan. The water temperature was low, and water salinity was stable and associated with low precipitation in this season. A total of ten species of photosymbiotic ascidian species were recorded from Lyudao and Kenting, but no photosymbiotic species were found in Keelung, probably due to the cold surface water in winter (ca. 16°C) in that region. A total of five photosymbiotic species were recorded in Singapore, with Lissoclinum timorense and T. cyclops being new records. However, no photosymbiotic species were found at Changi Beach, probably due to the polluted waters in the region. Coastal development has caused Singapore waters to become turbid, leading to decrease in suitable habitats for photosymbiotic ascidians. Clean waters in Pulau Semakau probably provide a better environment for the growth of photosymbiotic ascidians and this area has a greater variety of these ascidians than the other areas in Singapore.
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