ISSN 2094-2818

Editors: Eduardo A. Padlan and
Gisela P. Padilla-Concepcion
VOLUME 7 NUMBER 2 (July to December 2014)
 

Phil. Sci. Lett. 2014 7 (2) 428-437
available online: December 26, 2014

*Corresponding author
Email Address: olive@msi.upd.edu.ph
Submitted: October 29, 2014
Revised: December 6, 2014
Accepted: December 6, 2014
Published: December 26, 2014
Editor-in-charge: Kevin S. Rodolfo

Keywords: Salt-plug estuary, thermohaline circulation, numerical model, Malampaya Sound

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  ARTICLE
Salt-plug estuarine circulation in Malampaya Sound, Palawan, Philippines

Olivia C. Cabrera*1, Cesar L. Villanoy1, Gil S. Jacinto1, Lawrence Patrick C. Bernardo1,2, Charissa M. Ferrera1,3, Imelda B. Velasquez1,4, and Rhodora V. Azanza1

1Marine Science Institute, University of the Philippines, Diliman, Quezon City, Philippines, 1101
2Department of Civil Engineering, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan, 152-8552
3Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan, 152-8552
4Hill Laboratories 101c Waterloo Road, Hornby, Christchurch New Zealand

Malampaya Sound is an enclosed bay in Palawan, Philippines. A salinity maximum or salt plug was discovered in the middle of the Sound by a field survey in May 2005 and successfully simulated using a Delft3D numerical model of the sound, forced with tide and freshwater discharge at the lateral boundaries, and evaporation at the surface. Different conditions to simulate the major monsoonal regimes of 2005 (dry inter-monsoon, southwest-wet, and northeast-dry) indicate that the salt plug persists, although its relative position changes with the magnitude of freshwater discharge. The salt plug effectively limits the exchange of water between the Inner and the Outer Sound, which may account for differences in nutrient levels and the phytoplankton assemblage during the same survey. Such a thermohaline circulation has important consequences for sediment transport, phytoplankton bloom formation, and accumulation of pollutants in the Sound.