Fig. 2

Differences in sea ice DMSP δ³⁴S, physiochemical conditions and microalgal taxonomy between two distinct seasonal periods in the McMurdo Sound. a Depth profiles of DMSP δ³⁴S values in sea ice from two stations in the McMurdo Sound sampled during the winter–spring transition (19 September–18 October 2012). δ³⁴S values in four distinct sea ice horizons (surface ice, interior ice, bottom ice, and ice–ocean interface) are compared to the temperature and brine salinity range observed in these horizons during the transition, and the microalgal taxonomy observed in these horizons halfway through the transition (5 October 2012). b Similar comparison for two stations in the McMurdo Sound sampled during the spring–summer transition (1 November–30 November 2012). Sea ice depths were normalized. The vertical dashed lines represent the range of DMSP δ³⁴S values observed in surface oceanic waters