Abstract:
The relationship between larval abundance and water current pattern around reefs of Koh Nok, Koh Phai, Koh Khram, and Koh Tao Mo was investigated. Fertilized eggs were collected after coral spawning every hour from 1-10 hours. Then, current patterns were estimated from a two-dimensional hydrodynamic model. The results showed that larval abundance rapidly decreased (71% from the original releasing) at first hour after coral spawning. In addition, no larvae were found in the plankton net after 7-10 hours. From stimulation of trajectory drogue, it indicated that during the spawning periods, current flowed out of Koh Khram to the southeastern direction covering between areas of Koh Khram to Moo Koh Samaesan. Moreover, the current patterns during other periods of coral spawning (i.e. during seasonal spawning periods) showed that current flowed out of Koh Khram, and went through islands around the southeast of Koh Khram in the Sattahip area. These current patterns suggested that coral larvae may disperse from Koh Khram to Moo Koh Samaesan. However, the opportunity of widespread dispersal may be limited depending on the quantity of coral larvae. In conclusion, coral larvae from Koh Khram may be able to disperse to Sattahip area while coral larvae from other areas have less chance to disperse to Koh Khram. Therefore, coral recruitment around Koh Khram Island may be from self-seeding process.