The Saint Lawrence Island Polynya: A 25 Year Evaluation of an Analogue for Climate Change in Polar Regions
The northern Bering Sea in the Pacific Arctic is seasonally ice covered, and includes winter polynyas (open areas in ice covered seas) Overall, this marine system climatically in the winter is little different from the ice covered Arctic Ocean proper. The macrofauna living in the sediments in this region provide prey for sentinel benthivores in the Arctic, including walrus, gray whales, bearded seals, and diving sea ducks. We have been evaluating the area south of St. Lawrence Island (SLI) for the last 25 years (1990 2015) and this chapter provides a synthesis and overview of ecosystem dynamics in this region seasonally. We initiated our studies during the spring summer sea ice transition to open water period (May August) for a decade from 1988 to 1998, but had the opportunity from 1999 to 2007 to use icebreakers for research cruises in the late winter to early spring transition period (March June) as well as for late winter observations (March April) from 2008 to 2010. In 2010 we facilitated the development of the Distributed Biological Observatory (DBO) a national and international network of coordinated cruises at five latitudinally arrayed transect lines from south of SLI (DBO1) north to Barrow, Alaska (DBO5) DBO1 includes five time series stations that have been sampled over two decades. The opportunity to sample in different seasons has allowed us to evaluate the phenology of physical, chemical, and biological patterns using an ecosystem approach to understand the transitions. The overall picture that emerges from these seasonal observations is of a biologically active system with strong atmospheric and hydrographic controls that predetermine nutrient distributions and water column mixing through brine rejection. These processes ultimately influence the intensity of seasonal productivity and associated activities of biological components from ice algae to zooplankton to the benthos, and to apex predators that are emblematic features of this subpolar ecosystem that is a sentinel for Arctic subarctic interactions.