| Project Duration | 2011-12-31 ~ 2012-12-30 |
|---|---|
| Research Title | Survey of Biodiversity and Habitat Composition of the Northern Reef Crest of Dongsha Atoll |
| Contracted Organization | National Sun Yat-sen University |
| Principal Investigator | Sung Ke-Yi |
| Co-Principal Investigators | Chen Cheng-Ping, Chang Jui-Sheng, Liu Li-Lien, Su Yen |
| Project Participants | Jen Hsuan, Yu Hui-Ying, Lin Wen-Ju, Kao Hung-Ming, Kuo Jen-Wei, Huang Chien-Hua |
| Keywords | Dongsha Atoll, corals, fishes, large invertebrates |
| Abstract | Between May 4 and September 27, 2012, a total of 28 survey sites were investigated in the waters of Dongsha Atoll, including 23 sites on the northern reef crest, 2 sites in the inner lagoon, and 3 sites on the outer reef slope. Depending on field conditions, access to the reef crest was achieved using small boats, inflatable boats, and light craft. Surveys were conducted by scuba diving, snorkeling, and on-foot transects to document substrate types, corals, fishes, large benthic invertebrates (echinoderms, crustaceans, and mollusks), as well as macroalgae and seagrasses. The substrate distribution of the northern reef crest was heterogeneous. Four major habitat types were identified: seagrass, macroalgae, scleractinian corals, and coral rubble. Seagrass-dominated habitats were most extensive, particularly along the inner margin of the reef crest. Given its large spatial coverage, the seagrass bed likely represents the area of highest net primary productivity within the Dongsha Atoll ecosystem. Future research should further investigate the pathways of energy flow and material transfer derived from this productivity. In terms of biodiversity, 53 coral genera from 15 families were recorded. Coral diversity on the reef crest was lower than that of the inner lagoon and outer reef slope. A total of 271 fish species from 37 families were documented, including five new records for Dongsha waters, of which two were new records for Taiwan. Large benthic invertebrates comprised 156 species from 64 families, including: - 91 mollusk species (32 families) - 31 echinoderm species (16 families) - 34 crustacean species (16 families) One crustacean species (family Pilumnidae) was recorded as a new record for Taiwan. Macroalgae exhibit seasonal variation in growth and occurrence. In May, 29 species (including filamentous algae) were recorded, whereas in July, the number decreased to 20 species (including filamentous algae). Because the reef crest is shallow and receives sufficient light penetration to the substrate, satellite imagery can be effectively applied for large-scale habitat distribution and area assessment following ground-truth validation. This study preliminarily verified the feasibility of such remote sensing applications. The survey revealed that the reef crest differs substantially from the outer reef slope and inner lagoon environments. As the only zone where large-scale spatial patterns and historical changes can be effectively monitored through remote sensing, the reef crest is suitable as an indicator area for assessing coral reef conditions. Effective monitoring, however, requires integration of satellite imagery, aerial photography, and underwater verification. |
2012, Large invertebrates, Dongsha Atoll, Corals, Fishes