| Project Duration | 2011-12-31 ~ 2012-12-30 |
|---|---|
| Research Title | Biodiversity and Habitat Composition Survey of the Northern Reef Flat of Dongsha Atoll |
| Contracted Organization | National Sun Yat-sen University |
| Principal Investigator | Sung Ko-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 benthic invertebrates |
| Abstract | From May 4 to September 27, 2012, surveys were conducted at 28 sites within the waters of Dongsha Atoll, including 23 sites on the northern reef flat, 2 sites in the inner lagoon, and 3 sites on the outer reef slope. Access to the reef flat was achieved using a one-ton boat, inflatable boats, and small craft, depending on site conditions. Surveys were conducted by scuba diving, snorkeling, and on-foot exploration. Investigations included substrate composition, corals, fishes, large benthic invertebrates (echinoderms, crustaceans, and mollusks), as well as macroalgae and seagrasses. The substrate distribution of the northern reef flat was heterogeneous. Four major habitat types were identified, dominated by seagrass, macroalgae, scleractinian corals, and coral rubble. Most habitats were primarily composed of seagrass, particularly along the inner margin of the reef flat. Given its extensive coverage, the seagrass bed represents a key habitat and is likely the most productive area in terms of net primary production within the Dongsha Atoll ecosystem. The pathways of energy flow and material transfer associated with this productivity warrant further research. In terms of biodiversity, 53 coral genera from 15 families were recorded. Compared to the inner lagoon and outer reef slope, the reef flat supported fewer coral species. A total of 271 fish species from 37 families were documented, including five new records for Dongsha waters, two of which were new records for Taiwan. Large benthic invertebrates totaled 156 species from 64 families, including 91 mollusk species (32 families), 31 echinoderm species (16 families), and 34 crustacean species (16 families). One crustacean species from the Pilumnidae family was newly recorded for Taiwan. Due to seasonal growth patterns of macroalgae, surveys conducted in May recorded 29 species of macroalgae and seagrasses (including filamentous algae), whereas July surveys documented 20 species. The shallow depth of the reef flat allows sufficient light penetration to the substrate, making it suitable for large-scale habitat distribution and area assessments using satellite imagery combined with ground truthing. This study preliminarily confirmed the feasibility of such remote sensing approaches. The survey revealed that the reef flat differs substantially from the other two major environments—the outer reef slope and the inner lagoon. As the only area suitable for large-scale remote sensing analysis of current conditions and historical changes, the reef flat is appropriate as an indicator zone for assessing coral reef status. However, effective monitoring requires integration of satellite imagery, aerial photography, and underwater verification. |
2012, Large benthic invertebrates, Dongsha Atoll, Corals, Fishes