Time Series of Temperature and Salinity Profiles in the Coastal Ocean of the Northeastern Bering Sea

A time series of temperature-salinity profiles will be produced for the nearshore ocean adjacent the Yukon River Delta. No systematic studies of this type have been conducted before. This is a crucial data gap in the coastal oceanography of the eastern Bering Sea. The nearshore is too shallow for oceanographic vessels, and the region is also less accessible to satellite oceanography due to frequent cloud cover. Furthermore, the coastal ocean is complex and variable in its physical, chemical, and biological characteristics, complicates interpretation of satellite observations. For all of these reasons the nearshore ocean is an important and unstudied component of the global ocean circulation. The Yukon River has the largest discharge of any river in Alaska, and it has a profound effect on coastal oceanography and regional circulation patterns that reach across the northern shelf of the Bering Sea and Bering Strait into the Chukchi Sea and Arctic Ocean. It is also the region where climate change is having some of the most drastic effects. Habitats, prey assemblages, and ecosystems are being displaced northward in the Bering Sea due to warming temperatures. These changes may be responsible for declines in salmon populations. It has been hypothesized from anecdotal observations that the nearshore ocean is becoming warmer and more saline. This in turn is suspected of altering the prey assemblages available to juvenile Chinook salmon at a critical stage in their life history. Reductions in salmon stocks have threatened fisheries based commercial and subsistence economies from the Bering Sea coast to the Yukon Territory of Canada. In this project a portable conductivity-temperature-depth recorder with onboard GPS will be used to profile temperature and salinity in the nearshore adjacent the Yukon River Delta. This will be done on a regular schedule during the summer months from June through August at approximately 10 day intervals. Eleven stations will be spaced at 2 km intervals out to 20 km offshore. This time series will allow us to test the null hypothesis that the shallow nearshore has a stable halocline and thermocline during summer months. It will also enable us to model the physical oceanography of the nearshore over time.