OS12A-01
Variability and Change in Southern Ocean Ecosystems: Whither the Ice and What of Krill?

Monday, 14 December 2015: 10:20
3009 (Moscone West)
Eugene John Murphy, British Antarctic Survey, Cambridge, United Kingdom
Abstract:
Changes occurring in the Southern Ocean involve multiple physical, biogeochemical and ecological processes that have global connections. Developing a quantitative understanding of how biogeochemical cycles and ecosystems are affected by changes in these multiple processes is crucial for generating projections of the impacts of future change in the Southern Ocean. The changes occurring are not homogeneous, but instead show marked spatial and temporal variability, demonstrated most clearly by the regional nature of trends in sea-ice concentration over the last few decades. The impacts of these changes have also been observed at multiple trophic levels in Southern Ocean ecosystems, from primary producers to top predators, affecting the structure of the food webs in which they occur. Here, I consider briefly the changes occurring in the Southern Ocean and current views of expected future change, highlighting some of the complexity of the system interactions involved. I illustrate some of the major issues through a focus on sea-ice variability and change, noting the impacts on various ecosystem components, and particularly the effects on Antarctic krill. This perspective highlights that current knowledge of the detailed causes and consequences of change in Southern Ocean ecosystems, and hence future trajectories, are generally uncertain. It also shows the importance of understanding the intrinsic variability of the system and how interactions and feedbacks can influence the structure and functioning of ecosystems and associated biogeochemical cycles. Developing useful projections of the impacts of change requires integrated understanding of how physical, biogeochemical and ecological process interactions affect responses to change and provides a valuable focus for future research effort.