Adaptations of microalgae

Figure 8. Algal colouration of sea ice (Napp 2007)

The estimated percentage contribution of pack ice microalgae to primary production in the Southern Ocean varies from up to 25% to a minimum of 1% and although dependent upon season.  Different studies have made different assessments of the importance of pack ice algae in maintaining life in polar ecosystems (Lizotte 2001, Meiners et al. 2009). Whichever estimate is more accurate, the volume of algae in the ice can be shown by the colour (Figure 8). Studies have shown that much of the ice edge bloom algae are inoculated from the algae within the ice and that the slow release of this algae helps sustain these blooms over several weeks (Ligowski 1991).

The algae within the ice are surviving under extreme conditions, as shown by the gradient graphs in Figure 9.  Large fluctuations in conditions over short time periods make adaptation to this environment even more challenging. Numerous adaptations by these species deal with differing light and salinity levels and prevent ice crystal formation in tissues. Many of these adaptations are linked to more than one parameter; for example high salinity and low temperature.

Figure 9. Gradients within the ice (adapted from: Eicken 1992)

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