Historic impact of watershed change and sedimentation to reefs along west-central Guam

摘要: Using coral growth parameters (extension, density, calcification rates, and luminescence) geochemical measurements (barium to calcium rations; Ba/Ca) from cores collected in west-central Guam, we provide a historic perspective on sediment input reefs adjacent the Piti-Asan watershed. The months of August through December are dominated by increased Ba/Ca values, corresponding rainy season. With river water enriched barium related nearshore seawater, ratios presented as proxy for fine-grained terrigenous environment. century-long record indicates that Asan fore reef is within zone impact discharged sediments transported watershed has experienced terrestrial sedimentation since 1940s. This abrupt shift occurred at same time both sudden denudation landscape military ordinance immediate subsequent development area end war, 1944 1945. In response rapid sediment, determined rates were reduced almost two decades, while recovered much more quickly. Furthermore, luminescence decoupled record, which consistent with degradation soil organic matter disturbance forest fires, suggesting potential index fire history matter. These patterns not seen nearby associated watersheds have undergone degree denudation. Taken together, these records valuable tool understanding compounding effects land-use change health.