Melt pools (Figure 4) have a very high surface area of ice for microorgamisms to grow on; however they have high light intensities as they are only covered by at most a thin crust of ice. This characteristic, combined with oligotrophic waters make melt pools a harsh environment that requires adaptations (discussed later) in order for organisms to survive. The salinity of these pools is often very low due to ice and snow melt. In the Arctic the pools are often freshwater and so are home to terrestrial algae species and can cover 50% of the surface area of the ice floes (Brinkmeyer et al. 2004). The pools in the Antarctic are often linked through rotten ice or channels to the seawater below and hence marine algae are dominant here. Most of the algal growth occurs on the ice surface at the bottom of the pools. However, these microhabitats are dominated by bacteria able to withstand the fluctuating conditions, and further research is required into the productivity of algal species found here (Brinkmeyer et al. 2004, Thomas et al. 2008).