SGER: Examining the Impact of Land-Use on Offshore Sediment Transport and Reef Degradation during a Category Five Hurricane on a Mountainous Caribbean Island: Roatan, Honduras

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Young OCE 9903922Although there has been a general understanding that development may have a variety of negative impacts on nearshore reef ecosystems, researchers have had difficulty tying specific land use practices directly to changes in the physical environment, and ultimately to reef degradation. This project will use previously collected physical and biological data, combined with new data collected after Hurricane Mitch (the largest storm in the region this century) to examine how various land use practices impact coastal storm processes along a developing, mountainous Caribbean shoreline. The island of Roatan is the largest of the Bay Islands, a chain of islands roughly 60 km off the north coast of Honduras. The Bay Islands are a part of the Belize Reef System, the second longest coral reef tract on the globe. In response to the certainty of increased development, a long-term monitoring program was initiated in the summer of 1998. This program involves the monitoring of sediment accumulation, sediment spatial distribution, terrigenous sediment input, percent live coral, water quality, and fecal coliform bacteria. Roatan is a mountainous island that can be divided into distinct watersheds with distinct nearshore ecosystems that have little apparent exchange along shore of sediment or other physical characteristics. This provides a natural setting to study the impacts of particular land-use practices on offshore physical parameters, and ultimately on the reef. Monitoring stations were placed to monitor conditions immediately offshore of watersheds with varying types of land use, varying drainage, and varying human impact. For example, there is a site offshore of a steep watershed that has little development, but it has been cleared for grazing cattle. There is a site offshore of a similar watershed that is being subdivided and developed and a control site offshore of a similar drainage where there has been no human impact at all. We hope to be able to directly tie particular land-use practices to storm-induced changes in offshore physical parameters, and then assess any impact to coral mortality. Because baseline data were collected so soon before the hurricane, and there were no other events between site placement and the storm's passage, there should be an excellent record of storm-caused damage. This study will provide the first good approximation of the relative impact of varying land use on coral mortality in response to the passage of a large tropical system. The data gathered will be of important scientific and management interest.