The authors thank W.S. Moore and one anonymous reviewer for their very useful comments on an earlier version of this paper. The investigators thank the National Science Foundation (Award no. OCE-0350514), the Japan Society for the Promotion of Science (Award no. 13304036), SARCS (the Southeast Asia Regional Committee for START; System for Analysis, Research, and Training) and the Asia-Pacific Network (APN 2004-16-NSY) for the financial assistance that made this research
possible. We also thank the crew of the R/V Chula Vijai for their helpful assistance during the river–-estuary cruises.