Effects of Climate change in Polar Shallow benthic Ecosystems


Antarctic marine communities are rich and diverse; this high diversity can be comparable and in some groups higher than in temperate or even tropical areas. This determines that the macroevolutionary trend of a latitudinal cline in biodiversity, is not clear for the marine realm in the Southern Hemisphere as is in the Northern one. Antarctic benthic communities are not only diverse but also present unique features; they are dominated by suspension feeders groups and posses complex 3rd dimensional structures. Characteristic that is not found in the vast majority of marine ecosystems and is nowadays restricted, in temperate, tropical or even Arctic waters, to hard bottoms and reefs. It has been hypothesized that this particular structure of Antarctic communities resembles a paleozoic “looking” and it can be caused by the absence of hard squeleton predators and the limited action of sedimentation processes during glaciation-deglaciation periods and the absence of riverine and aeolic input of sediments that can severely affect suspension feeders groups. However, this image of diverse and unique communities can be threaten by the current process of Global Warming particularly in the Antarctic Peninsula.
The Western Antarctic Peninsula (WAP) is a hot spot of global warming with a surface air temperature increase of 2,5 °C over the last 50 years, the highest in the southern hemisphere, and among the highest in the world, that registered a mean warming trend of 0,6 º C. The glacial systems on the WAP and the nearby islands showed direct responses to the air temperature increment, including increasingly rapid retreat of glacier frontal positions, break-up and disintegration of ice shelves and speed-up of inland ice masses. These processes produce an increased inorganic matter input, of terrigenous origin, into coastal ecosystems that together with fresh water run-off and ice calving are factors that strongly affect benthic and pelagic systems. Consistently, detected shifts in some Antarctic marine ecosystems were related to fresh water and sediments run-off from retreating glaciers. Our working group reported at Potter Cove, King George Island, a marked shift in benthic communities structure related to increased sediment rates caused by glacier retreat. Communities are shifting from the mentioned complex structure dominated by epibenthic suspension feeders to a more “modern” structure for soft bottoms, dominated by other groups as infaunal filter feeders, predators, scavengers or necrophagous. This trend detected at small scale, clearly indicates the importance that the warming in the WAP can have on coastal ecosystems. Therefore on this project we will study benthic ecosystems with different glacier fronts influence which will be of crucial importance to assess the potential of the Warming Process on Antarctic Coastal Ecosystems