The Antarctic Peninsula is one the regions of the world that has experienced the highest impacts of climate change. In the last 40 years the mean annual air temperature has increased 2.8 degrees C causing massive ice shelves to disintegrate, declines in sea ice extent and a strong impact on all trophic levels of the ecosystem. Dr. Volker Siegel and collaborators highlight the importance of understanding the role of Antarctic krill in mediating the carbon flux to higher trophic levels, as well as, understanding the spatial and temporal variability in their abundance and distribution. This observational study, one the largest field studies carried out since the late 1980s, shows that regions within the Bellingshausen Sea and the Weddell Sea are important sources of krill larvae for the Antarctic Peninsula. They observe an across shelf gradient in the size distribution of krill with small krill concentrating onshore and large krill present offshore. Inferred regions of krill spawning are identified along the shelf break off Marguerite Bay, north of the South Shetland Islands and in the coastal region of Antarctic Sound. These distributions suggest an interaction of krill behavior and the topographically controlled ocean circulation, and support the results obtained by recent modeling studies of the connectivity of Antarctic krill populations and transport pathways of Antarctic krill larvae along the West Antarctic Peninsula. Rapid changes in the environmental conditions of the Antarctic Peninsula are contributing to the decline of krill abundance and recruitment, with great impact in their populations. A remarkable point of this study, suggests that further research integrating modeling and field campaigns are needed to test the role of areas less well sampled such as the Weddell Sea, that could influence population dynamics in the Antarctic Peninsula as the climate changes.
Volker Siegel, Christian S. Reiss, Kimberly S. Dietrich, Matilda Haraldsson and Gerhard Rohardt (2013) Distribution and abundance of Antarctic krill (Euphausia superba) along the Antarctic Peninsula, Deep-Sea Research I.