The marine organisms of green island investigate

Project Duration	2005-12-31 ~ 2006-12-30
Research Title	The marine organisms of green island investigate
Contracted Organization	Coral Reef Society of the Republic of China
Principal Investigators	Chen Cheng-Ping, Huang Hsing-Cho, Lee Tse-Min, Tu Ming-Chang
Co-Principal Investigators	Chan Jung-Kuei, Chen Ming-Hui, Lee Kun-Hsuan
Project Personnel	Kuo Jen-Wei
Keywords	Green Island, fishes, invertebrates, algae, reptiles, conservation
Abstract	Subtidal diving and intertidal surveys conducted this year recorded a total of 318 fish species. The cumulative fish fauna of Green Island now reaches 660 species in 76 families, with 657 considered valid species. Among the 18 newly recorded species this year, seven are new records for Taiwan. Species richness and abundance were significantly higher in subtidal zones than in intertidal zones. Ecological reserves (Shilang and Chaikou) showed positive conservation effects on fish populations, whereas artificial reefs supported noticeably fewer fish species than natural reefs, suggesting that artificial reef deployment is not suitable for fisheries enhancement in Green Island waters. For future fish conservation planning, it is recommended that Loumen Rock, currently the most species-rich subtidal site, be included in a new ecological reserve, and Dabaisha be prioritized for intertidal protection. Surveys at 25 stations recorded 168 species of mollusks in 56 families, 75 crustacean species in 28 families, and 48 echinoderm species in 24 families. Intertidal zones exhibited higher species richness and abundance than subtidal zones. Green Island harbors a rich diversity of nudibranchs, which have strong potential for ecotourism development through recreational diving. Numerous large sea anemones occur in the lower intertidal and subtidal zones, serving as hosts for symbiotic organisms and offering high educational and research value if properly protected. Economically and aesthetically important species include giant clams and various marine gastropods among mollusks; mantis shrimps, coconut crabs, spiny lobsters, and other notable species among crustaceans; and sea cucumbers, crown-of-thorns starfish, and blue sea stars among echinoderms. Overharvesting of high-value marine organisms and tourist disturbance remain pressing management issues. A total of 109 species of macroalgae were recorded: 33 green algae, 18 brown algae, and 58 red algae, with red algae being the most diverse. Macroalgal abundance and species richness per unit area exhibited marked seasonal variation. Patterns differed among sites and were closely related to habitat conditions and levels of human disturbance. Chaikou showed the highest macroalgal cover and diversity, indicating favorable growth conditions or low grazing pressure. Shilang had the lowest algal diversity, likely associated with greater anthropogenic disturbance and possible wastewater discharge. Haishenping experienced relatively low human disturbance. Marine reptiles historically included four species of sea snakes during the Japanese colonial period, though subsequent surveys recorded fewer species. This study identified three sea snake species: the yellow-lipped sea krait, black-lipped sea krait, and Ijima’s sea snake. Yellow- and black-lipped sea kraits were more abundant and mainly observed in the northeastern waters of the island, while Ijima’s sea snake was less common but widely distributed. The banded sea krait, dominant on nearby Orchid Island, was not observed in this survey. Only one distant sea turtle sighting was recorded this year, preventing species identification; interviews suggest hawksbill turtles may still occur in recent years, while green turtles have been recorded historically but were not observed this year. Overall, the marine biological condition of Green Island remains relatively good. However, economically valuable species are noticeably depleted due to harvesting pressure. Subtidal areas within the two ecological reserves demonstrate clear conservation benefits, whereas intertidal conservation effects vary by taxonomic group: invertebrates remain relatively stable, but fishes and algae may be negatively affected by human disturbance.