Biology Reference
In-Depth Information
1. THE POLAR ENVIRONMENTS
Although many cold-ocean species have been studied, we still have
limited knowledge about adaptation to low temperatures in sea water. In
the light of the ongoing climate change, there is growing interest in polar
marine organisms and how they have evolved at constantly cold tempera-
tures. The rate of the impact of current climate change in relation to the
capacity of species to acclimate or adapt is a crucial study area for managing
polar ecosystems in the future.
While the early biological works focussed on specific aspects of molec-
ular adaptation of single genes and proteins to cold, progress in genomics and
postgenomics, as well as the availability of genomic sequences of several
model species, allowed highlighting the adaptation mechanisms permitting
species evolution in polar regions (
Peck, 2011; Somero, 2010
).
The planet is currently losing sea ice, most notably in the Arctic region,
because of warming trends over the last century (
Moritz, Bitz, & Steig,
2002
). The dramatic sea-ice decrease is progressing from the Barents and
Bering Seas to the central Arctic Ocean.
Isolation of the two polar oceans has occurred to a different extent. The
land masses surrounding the Arctic Ocean have partially limited water
exchanges with other oceans for the last 60 million years or so. The Southern
Ocean was isolated much more thoroughly by the Antarctic Circumpolar
Current, the strongest current system in the world, since 20-40 million years
ago (
Eastman, 2005
).
Geography, oceanography and biology of species inhabiting Arctic and
Antarctic polar regions have often been intercompared (see
Dayton,
Mordida, & Bacon, 1994
) to detect and outline differences between the
two ecosystems. The northern polar region is characterised by extensive,
shallow shelf sea areas of the land masses that surround a partially land-locked
ocean; in contrast, the Antarctic region comprises a dynamic open ocean
that surrounds the continent, and a continental shelf (
Smetacek & Nicol,
2005
) that is very deep because of the enormous weight exerted on the con-
tinent by the covering ice sheet, which has a thickness of 2-4000 m.
Although the climate drivers acting on the biota are relatively similar, the
two polar environments are quite different from each other. One of the main
differences is the freshwater supply. Arctic surface waters are modified by the
