Scientists based in the United Kingdom and the United States have combined to warn the world that Antarctic and the Southern Ocean are currently being stressed by multiple human-related activities.
“Although Antarctica is still the most pristine environment on Earth, its marine ecosystems are being degraded through the introduction of alien species, pollution, overfishing, and a mix of other human activities,” said team member Dr Sven Thatje of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the UK’s National Oceanography Centre.
“By damaging the ecological fabric of Antarctica, we are effectively dumbing it down – decreasing its information content – and endangering its uniqueness and resilience,” added lead author Professor Richard Aronson, a paleoecologist at the Florida Institute of Technology, USA.
The scientific conclusions are based on an extensive review of a wide variety of human activities in the region and their impacts.
Some human activity in Antarctica is already monitored as a result of the Antarctic Treaty System – regulations focused on international relations in respect to Antarctica, entered into force in 1961 and eventually signed by 47 countries, which in short, set aside Antarctica as a scientific preserve – but there are some threats which are simply not currently addressed by the regulations.
Pollution is one such threat, but one that can be localised and dealt with by individual communities and enterprises. Global climate change, however, is not something that can be easily fixed, and has the potential to affect the entire Antarctic and Southern Ocean region for many decades to come. Rising ocean temperatures are already having an effect on the sea life which is having to adapt to warmer waters.
Additionally, ocean acidification, another side effect of the increase in atmospheric carbon dioxide, is also set to takes its toll, according to co-author Dr. James McClintock of the University of Alabama at Birmingham, USA.
“The Southern Ocean is the canary in the coal mine with respect to ocean acidification. This vulnerability is caused by a combination of ocean mixing patterns and low temperature enhancing the solubility of carbon dioxide,” noted McClintock.
“Simultaneous action at local, regional and global scales is needed if we are to halt the damage being done to the marine ecosystems of the Southern Ocean,” Dr Aronson added.
The researchers identified a range of regional historical and ongoing human activities that have damaged or restructured food webs in the Southern Ocean over the past few decades;
- The hunting of top predators such as whales and seals.
- Overexploitation of some fish species, leading to stock collapses.
- Air and water pollution from shipping traffic, wrecks, and the transport of invasive alien species on hulls and in ballast tanks.
- Tourism, including potential disturbance to breeding bird and seal colonies, as well as being responsible for chemical and noise pollution, and littering.
- Chemical and sewage pollution from research stations and ships, the legacy of historical waste dumping, and pollution from
The researchers also listed global threats which cannot be addressed by the current Antarctic Treaty. Among these threats, the researchers highlighted the following;
- Depletion of atmospheric ozone (O3). The ‘ozone hole’ was discovered by BAS scientists in 1985 and is caused by the accumulation of atmospheric chlorofluorocarbons (CFCs) used as refrigerants and spray propellants.
- Introduced species. The researchers are concerned that the warming conditions in Antarctica could facilitate colonisation of species previously unreported from the region, with consequences for the structure of its marine food webs. Alien species accidentally introduced by humans are also a major concern.
- The vulnerability of cold-adapted species to observed rising sea temperatures caused by global warming. The researchers argue that the extinction of some species is likely, and that changes in the geographical distribution of others are to be expected. They warn that the further spread and establishment of predatory king crabs on the continental slope of the western Antarctic Peninsula could wreak havoc among its unique seafloor animal communities. The possible invasion by bottom-feeding fishes, rays and sharks with crushing jaws could be equally damaging. They also expect increasing dominance of salps over Antarctic krill, with consequences for animals such as whales, penguins and seals that depend either directly or indirectly on krill.
- Ocean acidification. The researchers note that organisms living in polar regions are uniquely vulnerable to the effects of ocean acidification because of low concentrations of dissolved calcium carbonate in the water column. They cite evidence that declining seawater pH will particularly affect organisms with calcified shells and skeletal elements, such as molluscs, seastars, sea urchins, coralline algae and cold-water corals, They also highlight evidence suggesting that ocean acidification could profoundly alter the structure and functioning of the planktonic food web, with unknown consequences for animals further up the food chain, including commercially exploited fish. They therefore advocate continued and expanded baseline monitoring of ocean chemistry as well as further field and laboratory studies of the impacts of acidification on physiology, growth, and calcification.
Another potential threat in Antarctica’s future is the likelihood that big-business and countries will look to Antarctica to solve its lack of resources. The Antarctic Treaty currently prohibits the extraction of oil and other minerals, in large supply, but there are large swathes of the Southern Ocean which simply are not covered by the Treaty and could be exploited with damaging consequences.
“It is clear that multiple causal factors are damaging the health of marine systems in Antarctica; we need to understand the relative importance of these factors and how they interact.” concluded Dr Thatje.