Polar bears, walrus using land areas more frequently
By Summit Voice
SUMMIT COUNTY — Much has been said and written about rapid global warming-driven changes in the Arctic, but for all the rhetoric, scientists are just in the early stages of understanding the implications for ecosystems in the region.
A new multidisciplinary study by the U.S. Geological Survey may help understand how dynamic ecosystems and their wildlife communities will respond to rapid change in the Arctic.
Changes to the physical environment include warming temperatures, diminishing sea ice, increasing coastal erosion, deteriorating permafrost, and changing water regimes. The shifts to Arctic ecosystems will be felt broadly because the Arctic is a production zone for hundreds of species that migrate south for the winter.
The changes will influence biological communities and the ways in which human communities interact with them.
The goals of the Changing Arctic Ecosystems initiative are to:
- Understand the potential suite of wildlife population responses to these physical changes to inform key resource management decisions such as those related to the Endangered Species Act;
- Understand how and why changes in the ice-dominated ecosystems of the Arctic are affecting wildlife, and the manner in which wildlife species respond and adapt to rapid environmental change.
The three areas of study include the Arctic marine ecosystem, the coastal plain and the boreal-Arctic transition zone.
In the Arctic marine ecoystem, sea ice extent and structure is rapidly changing. Sea ice is a critical platform for wildlife species to access food and to complete critical components of their life cycle, and it exerts a strong influence on pelagic and benthic food webs.
The USGS research will focus on two species dependent on the sea ice environment: the polar bear and the Pacific walrus. These focal species differ in trophic pathways (pelagic for the polar bear and benthic for the walrus) and differ in how much terrestrial habitat is incorporated into their life cycles.
Understanding the responses of these two species to sea ice change will allow for a more holistic understanding of how projected changes in physical processes linked to sea ice will be expressed through ecosystem processes to top consumers.
In Alaska’s coastal plain, erosion is accelerating as sea ice retreats, storm patterns are changing, permafrost is thawing, and the nature of water storage on this landscape is in flux.
Observed and projected changes in precipitation and temperature are hypothesized to affect aquatic and terrestrial food webs critical to nationally and internationally important resident and migratory wildlife.
The researchers hope to determine some of the key ecological drivers of population change and project future abundance and distribution of focal species, including mammals, birds, fish, and aquatic invertebrates that use the landscapes of the Arctic in different ways and likely will express differently the consequences of changes to the associated ecosystems.
The boreal-Arctic transition zone is expected to be one of the most dynamically changing zones in the far north. The boreal forest of Alaska grows near the physiological limits of trees, and the forest is underlain primarily by discontinuous permafrost.
The forest also is an environment particularly sensitive to changes in temperature, precipitation, and permafrost loss. Fire is a primary driver of vegetation change in this region, and is expected to continue as an important ecological process in the future.
The initial emphasis in this zone is on landbirds and shorebirds — useful indicators because they are widely distributed, samples are collected by similar methods, and they occupy a wide variety of habitats including wetlands, forests, and shrublands.
Projects in the Boreal-Arctic transition zone are (1) assessing existing population changes, (2) evaluating ecological drivers of population change, and (3) developing scenarios of future abundance and distribution within the boreal and Arctic coastal plain systems.
Click here for the USGS fact sheet: Geiselman, Joy, DeGange, Tony, Oakley, Karen, Derksen, Dirk, and Whalen, Mary, 2012, Changing Arctic ecosystems—Research to understand and project changes in marine and terrestrial ecosystems of the Arctic: U.S. Geological Survey Fact Sheet 2011-3136, 4 p.