The Changing Landscape of the Copper River Delta, Alaska: Implications for Understanding Climate Change

The Copper River Delta is the most intact coastal wetlands in western North America and provide habitat for a variety of fish and wildlife as well as supporting a valuable economic and subsistence fishery.  It may, however, be particularly susceptible to the potential impacts of climate change while at the same time having the inherent capacity to be buffered against and to respond to these impacts.  It is located on the most northern National Forest in the National Forest system.  Climate change impacts are expected to be more pronounced in northern latitudes.  Because of its proximity to the Gulf of Alaska and the Chugach Mountains, the Delta is also likely to be affected by changes that impact marine and terrestrial systems.  Projections suggest that the Delta will experience warmer seasonal temperatures, have more rain and less snow, and higher, more variable stream flows in the winter.  Warmer winter temperatures may be particularly important ecologically.  They can accelerate the development of cold blooded organisms such as fish and aquatic invertebrates, which in turn could alter the availability of invertebrates for nesting and fledging birds, and result in the earlier emergence of smaller fish from the gravel.   Warmer summer temperatures may increase the melting of glaciers, which will affect water flows and chemistry.  The adjacent nearshore marine environment is expected to more productive because of an influx of iron from melting glaciers.  Concurrently, the offshore area is expected to be warmer and more acidic, resulting in smaller sized salmon returning to the Delta.  Smaller fish do not place their eggs as deep in the gravel as larger fish so developing eggs may be more susceptible to scouring by higher winter flows. The effects of sea-level rise will likely be exacerbated because the Delta is in a period of subsidence following the uplift experienced from the 1964 earthquake.  This could alter the structure and composition of the invertebrate community, which are a primary food source for many birds, and reduce the amount of habitat available for nesting and rearing by birds, including some ESA candidate species.  The intact nature of the Delta along with the tremendous variability in ecological conditions, however, may be the key to adapting to and mitigating the potential challenges of climate change.