Marine Ecosystems Summary
Section Coordinators: Sue Moore1, Mike Gill2
1NOAA/Fisheries Office of Science and Technology, USA
2Canadian Wildlife Service, Environment Canada, Whitehorse, YT, Canada & CAFF/CBMP
December 3, 2012
|Extensive phytoplankton blooms at the sea ice edge in the Chukchi Sea seen from space in July 2011. Large version available from NOAA Climate.gov.|
The Marine Ecosystem section of the 2012 Arctic Report Card highlights the highly variable nature of Arctic ecosystems and provides some insight into how the marine ecosystem and the biodiversity it supports are responding to changing environmental conditions. Recent changes in the marine ecosystem, from primary and secondary productivity to responses by seabirds and some marine mammals species, are summarized in six essays. They provide a glimpse of what can only be described as profound, continuing changes in the Arctic marine ecosystem. For example, there is increased evidence of linkages between sea ice conditions and primary productivity, affecting the abundance and composition of phytoplankton communities. New satellite remote sensing observations show the near ubiquity of ice-edge blooms throughout the Arctic and the importance of seasonal sea ice variability in regulating primary production. These results suggest that previous estimates of annual primary production in waters where under-ice blooms develop may be about ten times too low. Shifts in primary and secondary production have direct impacts on benthic communities. Recent findings on temporal trends in the benthic system include: species range changes in sub-Arctic seas and on inflow shelves; changes in feeding guild composition in the deep Fram Strait; reduction of benthic biomass in the Barents and northern Bering seas; and no apparent change in infaunal biomass in the Kara Sea. Recent sea ice declines have allowed gray whales to stay longer and feed on both benthic amphipods and zooplankton in the Barrow Canyon region of northwest Alaska. Seabirds, long considered a valuable indicator of changing marine conditions, are showing changes in phenology, diet, foraging behavior and survival rates across the Arctic. Seabirds, it is believed, are responding, at least in part, to warming sea surface temperatures and concurrent changes in prey availability.
|Melt ponds on the sea ice surface act as skylights (top), illuminating the underside of the ice and promoting phytoplankton blooms (bottom).|
New programs are underway to more effectively measure, monitor and document changes in the marine ecosystem. The Distributed Biological Observatory (DBO) is an international change detection array for the identification and consistent monitoring of biophysical responses in the Pacific Arctic. One essay highlights provisional results from a production 'hotspot' in Barrow Canyon, which was investigated during the DBO pilot program. Another essay describes an international collaboration, the Arctic Biodiversity Assessment (ABA) of the Arctic Council Conservation of Arctic Flora and Fauna (CAFF) Working Group, which summarizes what is known about population sizes, trends and distributions for species that inhabit sub-Arctic and Arctic waters. During International Polar Year (2007-2009), the first coordinated, year-round sampling of underwater acoustic marine mammal habitats at two sites in the High Arctic documented the seasonal occurrence of both Arctic and sub-Arctic species in Fram Strait (Atlantic Arctic), but only Arctic species on the Chukchi Plateau (Pacific Arctic). The Fram Strait recorders also discovered that Spitzbergen's bowhead whales were singing almost continuously through the winter, suggesting that this critically endangered population may be larger than previously thought and that Fram Strait may be an important over-wintering area for it.