3.2.2 Changes in the Antarctic

Unlike in the Arctic, it is expected that in the Antarctic the amount of biomass available to the benthos will increase. This is because the sea ice has been declining for several years, especially in the western Antarctic, and as a result there is more open water available for primary production. In the last 50 years, sea-ice loss and the decline in glaciers have meant that there are an additional 24,000 square kilometres of open water in the western Antarctic alone. The calving of a huge iceberg and the disintegration of entire shelf regions, such as at the Larsen-B Ice Shelf in 2002, have added to this. We are gradually beginning to understand the biology at the seafloor. The dense ice masses mean that in many regions there is permanent darkness there. If the ice shelf disappeared, light could penetrate. This would lead to a tremendous growth in algae and kelp. With the loss of sea ice, not only would algal blooms increase, but the composition of the zooplankton and other benthic species communities would also change (Massom et al., 2010).

As a rule, the benthic communities in shallow coastal areas that are permanently covered by ice largely consist of invertebrates that are adapted to the darkness. If the amount of light increases, major changes will ensue. Above all, the invertebrate communities will be replaced by kelp-dominated species communities. Using computer models, experts have concluded that, with continuing high carbon dioxide emissions through the end of the century, up to 79% of endemic benthic organisms could be affected by these changes, in that they could withdraw from several ocean regions. Taking the average for nearly 1,000 fauna species, their stocks would decrease by at least 12 percent. However, even greater losses are expected for the especially hard-hit regions of the Antarctic Peninsula and adjacent Scotia Sea (IPCC, 2019).

Generally speaking, the waters of the Antarctic are not only expected to produce more algal biomass; their benthic communities, thanks to the higher biomass input, will also likely bind more carbon (IPCC, 2019).

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