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The concentration of colored dissolved organic matter (CDOM) in lakes is strongly influenced by climate, land cover, and topographic settings, but it is not known how drought may affect the relative importance of these controls. Here, we evaluate the controls of CDOM during two summers with strongly contrasting values of the Palmer drought index (PDI), indicating wet vs. dry conditions. We hypothesized that lake CDOM during a wet summer season is regulated mainly by the surrounding land cover to which the lakes are hydrologically connected, while, during drought, the lakes are disconnected from the catchment and CDOM is regulated by climatic and morphometric factors that govern the internal turnover of CDOM in the lakes. A suite of climate, land cover, and morphometric variables was assembled and used to explain remotely sensed CDOM values for 255 boreal lakes distributed across broad environmental and geographic gradients in Sweden and Norway. We found that PDI explained the variability in CDOM among lakes in a dry year, but not in a wet year, and that severe drought strongly decreased CDOM during the dry year. Large lakes, especially, with a presumed high degree of catchment uncoupling, showed low CDOM during the dry year. However, in disagreement with our hypothesis, climate, land cover, and morphometry all showed a stronger impact on lake CDOM in wet vs. dry years. Thus, drought systematically weakened the predictability of CDOM variations at the same time as CDOM was offset toward lower values. Our results show that drought not only has a direct effect on CDOM, but also acts indirectly by changing the spatial regulation of CDOM in boreal lakes. [ABSTRACT FROM AUTHOR]

It has been well established that numerous coastal areas are threatened by sea-level rise and coastal flooding. Some of these vulnerable lands contain significant archeological sites and cultural resources. The accurate calculation of shoreline rates of change and identification of coastal hazard zones for areas containing cultural resources is crucial for the development of effective coastal zone management strategies that address resource conservation and preservation. This investigation employed geospatial and analytical statistical techniques to conduct a shoreline change study on Rainsford Island occurring from 1944 to 2008. The 4.45-ha island, located in Boston Harbor, Massachusetts, consists of two heavily eroded drumlins connected by a low-lying bar. Past archeological surveys have concluded that Rainsford Island has numerous historical sites and is an area of high prehistoric sensitivity. A recent geophysical survey mapped a Revolutionary War era cemetery on the island. Multiple data sources were integrated, including historical maps, aerial photographs, and airborne laser topographic data for shoreline delineation over various temporal and spatial scales. The Digital Shoreline Analysis System was used to determine rate-of-change statistics and distances, and to identify hotspot areas of erosion and accretion. The results show that the island eroded during the study period at a rate of 0.05 m/y on average, with erosion rates as high as -0.59 m/y. The bar has migrated SE resulting in erosion along the island's northern shoreline. Predictive modeling indicates that 26% of the island would become inundated with 1 m of sea-level rise including the area containing the cemetery. [ABSTRACT FROM AUTHOR]