Do pelagic grazers benefit from sea ice? Insights from the Antarctic sea ice proxy IPSO25

• Published in: Biogeosciences
• Main Authors: Schmidt, K, Brown, TA, Belt, ST, Ireland, LC, Taylor, KWR, Thorpe, SE, Ward, P, Atkinson, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus 2018
• Subjects: Ecology and Environment; Oceanography; Antarctic; The Antarctic; Antarc*; Antarctic Krill; Euphausia superba; ice algae; Sea ice
• Online Access: http://plymsea.ac.uk/id/eprint/7863/; http://plymsea.ac.uk/id/eprint/7863/1/Schmidt%20et%20al.%20Biogeosciences_%202018.pdf; https://www.biogeosciences.net/15/1987/2018/; https://doi.org/10.5194/bg-15-1987-2018

Sea ice affects primary production in polar regions in multiple ways. It can dampen water column productivity by reducing light or nutrient supply, provide a habitat for ice algae and condition the marginal ice zone (MIZ) for phytoplankton blooms on its seasonal retreat. The relative importance of three different carbon sources (sea ice derived, sea ice conditioned, non-sea-ice associated) for the polar food web is not well understood, partly due to the lack of methods that enable their unambiguous distinction. Here we analysed two highly branched isoprenoid (HBI) biomarkers to trace sea-ice-derived and sea-ice-conditioned carbon in Antarctic krill (Euphausia superba) and relate their concentrations to the grazers’ body reserves, growth and recruitment. During our sampling in January–February 2003, the proxy for sea ice diatoms (a di-unsaturated HBI termed IPSO25, �13CD