The traditional vision portrayed Antarctica as a continent with low biodiversity and limited by a hostile environment. However, biodiversity studies over the last few years have shown that life in Antarctica and the Southern Ocean is quite rich.
Recently felt climatic changes and the changes predicted to the future have brought interest to the planet-wide consequences of the loss of ice in polar regions. Antarctic biodiversity faces the same risk of environmental changes as any other region on the planet. Understanding how this biodiversity spreads across Antarctica and the mechanisms driving the spatial variability observed is key to protecting this ecosystem in the future.
The Antarctic region is neither as isolated nor as depauperate in biodiversity as once thought
Oceanic fronts can be permeable, with mesoscale eddies transporting pockets of water and associated organisms across them (inset figure lower left). Dispersal of marine species around Antarctica has been facilitated by the Antarctic Circumpolar Current (ACC) and Antarctic Coastal Current (ACoC), as well as by trans-Antarctic seaways during some interglacials. Glacial cycles have driven diversification, with some species surviving within the Antarctic region during glacial periods – for example, in terrestrial refugia such as geothermal areas or marine shelf refugia – and undergoing allopatric divergence. Species flock radiations have been inferred for some groups, such as Antarctic notothenioid fish which have diversified during periods of climate change. The mean positions of the major oceanic fronts are shown: Southern Antarctic Circumpolar Current Front (SACCF), Antarctic Polar Front (APF), Subantarctic Front (SAF) and the Subtropical Front (STF). Locations of possible terrestrial geothermal refugia (volcanoes and heated rocks) are indicated by yellow dots. Antarctic bedrock (>0 m) is roughly indicated in pale brown, and the Antarctic continental shelf in blue (not shown for other continents). The diversity and position of the 15 distinct Antarctic Conservation Biogeographic regions are indicated in the central panel on the right.
Source: Chown SL, Clarke A, Fraser CI, Cary SC, Moon KL, McGeoch MA (2015) The changing form of Antarctic biodiversity. Nature 522:431-438. doi: 10.1038/nature14505
Author: Mafalda Baptista