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Journal of Marine Biology
Volume 2011, Article ID 981273, 17 pages
Research Article

Effects of Land-Use Change on Characteristics and Dynamics of Watershed Discharges in Babeldaob, Palau, Micronesia

1Palau International Coral Reef Center, P.O. Box 7086, Koror, 96940, Palau
2School of Environmental Science and Management, Southern Cross University, P.O. Box 157, Lismore, NSW 2840, Australia
3Australian Center for Tropical Freshwater Research, James Cook University, Townsville, QLD 4811, Australia
4Australian Institute of Marine Science, PMB no.3, Townsville MC, QLD 4810, Australia
5Kewalo Marine Laboratory, University of Hawaii at Manoa, 41 Ahui Street, Honolulu, HI 96813, USA
6The Nature Conservancy, Palau Field Office, P.O. Box 1738, Koror 96940, Palau

Received 24 June 2010; Accepted 15 September 2010

Academic Editor: Kim Selkoe

Copyright © 2011 Yimnang Golbuu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study assessed the impacts of differing levels of land development in four watersheds in Palau on river sediment yield and on sedimentation and turbidity. Area corrected sediment yield was strongly related to land development ( , ), varying from 9.7 to 216 tons km−2 yr−1 between the least and most developed watershed. Mean sedimentation rates on reefs ranged from 0.7 to 46 mg cm−2 d−1, and mean turbidity ranged from 9 to 139 mg l−1. The higher values exceeded those known to harm corals. Because Palau's watersheds and estuaries are small, river floods were short-lived (typically lasting less than a day) and the estuaries adjusted just as quickly to a number of different estuarine circulation patterns that, in turn, generated a large variability in the export of riverine fine sediment to the reefs. The ultimate fate of the fine sediment deposited on the reefs depended on wind resuspension, local currents, and geomorphology (whether the bay was open or semi-enclosed). Palau's small estuaries were generally not as effective as bigger estuaries in trapping sediments and thus at sheltering the reefs. Therefore, greater efforts are needed to control and mitigate land activities that contribute to the increase in sediment yield.