Likely responses of the Antarctic benthos to climate-related changes in physical disturbance during the 21st century, based primarily on evidence from the West Antarctic Peninsula region
Disturbance has always shaped the evolution and ecology of organisms and nowhere is this more apparent that on the iceberg gouged continental shelves of the Antarctic Peninsula (AP). The vast majority of currently described polar biodiversity occurs on the Southern Ocean shelf but current and projected climate change is rapidly altering disturbance intensities in some regions. The AP is now amongst the fastest warming and changing regions on earth. Seasonal sea ice has decreased in time and extent, most glaciers in the region have retreated, a number of ice shelves have collapsed, and the surface waters of the seas west of the AP have warmed. Here, we review the influences of disturbance from ice, sedimentation, freshening events, wave action and humans on shallow water benthic assemblages, and suggest how disturbance pressures will change during the 21st century in the West Antarctic Peninsula (WAP) and Scotia Arc region. We suggest that the intensity of ice scouring will increase in the region over the next few decades as a result of decreased winter sea ice periods and increased ice loading into coastal waters. Thus, the most frequently disturbed environment on earth will become more so, which will lead to considerable changes in community structure and species distributions. However, as ice fronts retreat past their respective grounding lines, sedimentation and freshening events will become relatively more important. Human presence in the region is increasing, through research, tourism, and resource exploitation, which represents a considerable threat to polar biodiversity over the next century. Adapting to or tolerating multiple, changing environmental stressors will be difficult for a fauna with typically slow generation turnovers that has evolved largely in isolation. We suggest that intensifying acute and chronic disturbances are likely to cause significant changes in ecosystem structure, and probably a considerable loss of polar marine biodiversity, over relatively short timescales.