Newly ice-free areas exposed by glacial retreat in Potter Cove, Antarctica, are being colonized by seaweed. With glaciers melting, the original white, mostly lifeless Antarctica is now becoming darker and lively with seaweed. These macroalgae not only produce oxygen for marine species through photosynthesis but also serve as the base of the marine food chain. Scientists predict this seaweed colonization could lead to a higher rate of carbon sequestration and higher productivity in marine system, but the local biodiversity might be reduced.

Palmaria decipiens, found on sub-Antarctic islands. Image credit: University of California, Berkeley

Glacial retreat has a major influence on coastal ecosystems – it creates ice-free areas which can then be taken over by marine species. However, the process is not always that simple. A recent study published in Polar Biology by D. Deregibus et al. discovered that although newly exposed ice-free areas favor colonization, sediments carried by glacial runoff makes seawater less clear and affects coastal marine species adversely by reducing the survival or reproductive rate. Nonetheless, seaweed in Potter Cove has adapted to shade and can tolerate darkness for a long period as it is accustomed to ice cover blocking sunlight. Increased turbidity, or cloudiness, caused by sediments affects the distribution rather than survival of Antarctic seaweed, Deregibus and his colleagues found.