Melt pools

Due to the different nature of how ice is formed at each pole, melt pools (fig 3) are far more significant in the arctic and cover almost 50% of the ice in the summer months (Brinkmeyer et al. 2004). Once a melt pool forms on the surface, it has a lower albedo of the surrounding ice, so it absorbs more energy, which in turn melts more ice. The salinity of theses areas is extremely low due to the fact the water is from melted snow and ice. They have often been known as lakes floating on the surface of the ice (Thomas 2004) Melt pools have a high surface area for microorganisms, such as bacteria, microalgae and protozoa, to grow. Due to the oligothropic nature of the water and the extreme levels of light due to the fact that the surface will only have a thin layer ice which normally melts during the day the melt pools are quite harsh (Brinkmeyer et al. 2004). It’s common to find terrestrial species, which have found their way to melt pools, which survive due to the low salinities. In comparison melt pools that form in the Antarctic are far less harsh, as they are commonly linked at the bottom by rotten ice, which allow marine species to become dominant (Thomas 2004).

Figure 3) A melt pool in Copenhagen

Due to the arctic having periods of 24 hour sunlight in the summer, many of the organisms that live there are under extreme levels of ultraviolet radiation (UVB, Wickham and Carstens 1998). Melt pools exposure to UVB radiation is multiplied by the fact that that there are low levels of dissolved organic carbon to absorb the radiation. And also many UVB rays are reflected back from the icy bottom so organisms are hit multiple times by the same wave of radiation (Gibson et al. 2001). Studies have shown that certain bacteria are the least vulnerable to the radiation, suggesting there have evolved some kind of resistance (Wickham and Carstens 1998).

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