Protecting Life in the Arctic

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The Chukchi Food Web

A science brief

The second in our series of science briefs and analyses, this report was prepared for The Pew Charitable Trusts' work in the U.S. Arctic by Andy Whitehouse and released in November of 2012. 

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INTRODUCTION

The Chukchi is a seasonally ice-covered, peripheral sea of the western Arctic Ocean. It lies off the northwestern coast of Alaska and extends from the Bering Strait in the south to the edge of the continental shelf (200-meter isobath) in the north, and from east to west from Point Barrow, Alaska, to Wrangel Island off the coast of Russia. The Chukchi is a broad and shallow continental shelf sea, with most depths less than 60 meters and a total area of about 565,000 square kilometers. Ice covers the Chukchi Sea for about six to eight months a year, with ice cover advancing southward beginning in October and retreating northward starting in June. The Chukchi Sea is an inflow shelf to the Arctic. At its southern margin, a net northward flow brings cold, nutrient-enriched water of Pacific Ocean origin. The combination of seasonal ice coverage, shallow depths, and the advection of cold Pacific waters helps to shape the structure and function of the Chukchi Sea food web.

SUMMARY

The Chukchi Sea is a shallow, seasonally ice-covered Arctic continental shelf system. The dynamics of primary production are influenced by the seasonal advance and retreat of sea ice and the advection of nutrient-rich water from the Bering Sea to the south. The high levels of primary production and shallow depths combine to facilitate the deposition of phytoplankton to the seafloor, where it becomes available to support the abundant and characteristic community of benthic invertebrates. This abundant seafloor food web forms an important prey base for benthic foraging marine mammals and seabirds, which in turn support human communities practicing a subsistence way of life.
Food web modeling has highlighted the dominant role of the benthos in food web structure and function, and its effect on total system production.

Compared with the eastern Bering Sea, the eastern Chukchi Sea has low productivity in relation to total biomass. This suggests that the eastern Chukchi Sea is vulnerable to extractive activities (fishing) and may be slow to recover from other disturbances, such as an oil spill reaching the benthos. These results have raised new questions about the resilience of the eastern Chukchi Sea food web and its vulnerability to human activities. Future modeling studies can help address these questions by assessing the sensitivity of the food web to individual stressors, such as fishing, vessel traffic, oil and gas exploration and development, and other anthropogenic activities, including climate change, by looking at the cumulative impacts of stressors over time and by examining the interactive effects of multiple stressors occurring simultaneously.

RELATED IMAGES

Chukchi Sea Map

Chukchi Sea Food Web Diagram

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