Antarctica and Southern Ocean Conservation: Part 1
Current challenges for ecosystem biodiversity
Kitty Cheng
The Southern Ocean, home to the Antarctic Peninsula, has recorded a regional temperature increase of 3°C - way beyond the 1.5°C increase target as set in the Paris Agreement. Due to the geographic location and unique characteristics of Antarctic marine ecosystems, species are vulnerable to large oscillations in temperature. As Kitty Cheng explains in a 3-part series, the effects of climate change are challenging, not only for biodiversity conservation, but also current management policies. Here, she talks about the main threats facing the Antarctic ecosystem today.
Whaling
The Antarctic ecosystem is believed to be isolated from anthropogenic impacts due to the physiological barrier created by high southern latitudes and the Antarctic Circumpolar Current. While the biggest driver of global biodiversity loss is due to changes in land/sea uses, in Antarctica this is not the case. Instead, overexploitation of keystone marine species had been a major concern in the past decades. Since the beginning of industrial whaling in 1904, sequential whaling had wiped out a majority of species, to a point where only 3% of the original population of the blue whale was left. The near disappearance of a species did not stop the demand on whale meat and oil; human turned to the next biggest species, Fin and Sei whales. By the end of 1910, 55% of the whale populations were killed, with specific species experiencing a 90% population decrease. The loss of biomass in the Southern Ocean marine ecosystem changes the structure of the food web. In 1986, the International Whaling Commission banned commercial whaling and now Japan is the only country that still hunts Minke Whale. Yet, it is questionable whether the whale stock will ever recover.
Whales in Antarctica. Photo: Pixabay.
Sealing
Exploitation of fur seals began even earlier - between 1700s to 1800s, with populations almost being wiped out in 1820. The scarcity of seal fur and seal oil made it a luxurious product that is high in demand. In 1972, the Convention for the Conservation of Antarctic Seals (CCAS) was established in protecting the Antarctic Seals, where only certain species were allowed for commercial sealing, with a catch limit that changes annually. The recovery of fur seal received an outstanding result by raising the population from 5 thousand to 6.2 million in less than 50 years. Currently, 95% of fur seal population are concentrated in South Georgia Region and is protected under the Convention on International Trade of Endangered Species (CITES). While this had proved the possibility in bringing back a species that suffers from overexploitation, it also expresses the complexity of the ocean as an interconnected system, where exploitation of a single species will create knock-on effects to the whole system.
Antarctic fur seal & Antarctic leopard seal. Photos: Pixabay
Traffic
An increase in shipping traffic in the Southern Ocean also disturbs biodiversity conservation. The main source of shipping traffic are research vessels and tourist boats. Expedition cruises carrying thousands of passengers would travel across the Southern Ocean to Antarctic Peninsula. Although the Antarctic Treaty created guidelines for cruises to have a maximum of 100 people per landing, tourists making repeated landings will interact with wildlife, spread waste and introduce invasive species. Most tourist impact assessments focuses on penguin populations in the Antarctic Peninsula rather than the broader marine ecosystem. Permanent Antarctic research stations are also being resupplied through ice-strengthened ships and large research vessels are used for conducting scientific activities. These icebreakers affect both local land and sea-use changes.
Icebreaker. Photo: Pixabay.
Invasive species
The Antarctic circumpolar current plays a huge role in global thermohaline circulation, sea ice extent and surface temperatures, which drives the distribution of marine species. This current had been acting as a barrier to invasion, and maintains the health of Antarctic marine biodiversity. In recent years, an increase of genetic exchange between benthic fauna has been recorded in the Antarctic Peninsula, which suggests that an invasion of pelagic organisms is caused by warming of Subantarctic waters. Invasions can also occur due to the release of ship ballast water from ships (carrying thousands of foreign aquatic organisms into the water) which will further accelerate the rate of biodiversity loss / ecosystem resilience.
Ocean warming
Marine organisms are sensitive to ocean warming and acidification. The thermal tolerance of species are mostly limited to their natural habitat, so the physiological constraint of marine species in Antarctic waters causes them to be more vulnerable to global warming. Ocean acidification will also lead to significant biodiversity loss, as this causes corrosion of calcium carbonate skeletons for certain species.
A warming Antarctica. Photo: Pixabay.
The situation is bleak. If we do not act upon the global crisis immediately, by 2070 we would have created irreversible biodiversity loss, and the acceleration of GHG concentration will cause severe impact on atmospheric temperature, ocean acidification, ecosystem structure, sea ice extent and sea level rise. Conserving biodiversity is not only crucial in bringing back endangered megafauna, but for creating a resilient ecosystem that can survive the upcoming challenges of climate change.
Stay tuned for Part 2 - COMING SOON
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