Human activities putting Antarctica's marine ecosystems under threat

The native fauna and unique ecology of the Southern Ocean, the vast body of water around the Antarctic continent, is under threat from human activity, according to a team of scientists in the United Kingdom and the United States.

"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 Sven Thatje of the University of Southampton's School of Ocean and Earth Science (SOES) based at the UK's National Oceanography Centre.

Biodiversity can be conceptualised in terms of its information content: the greater the diversity of species and interactions between them, the more 'information' the ecosystem has.

"By damaging the ecological fabric of Antarctica, we are effectively dumbing it down - decreasing its information content - and endangering its uniqueness and resilience," said lead author Prof Richard Aronson, a paleoecologist at the Florida Institute of Technology, USA.

The team's conclusions are based on an extensive review of the impacts of a wide range of human activities on the ecosystems of Antarctica.

The Antarctic Treaty system, which includes environmental and fisheries management, provides an effective framework for the management and protection of the continent, but some of the threats are not currently being fully addressed.
Some of these impacts, such as pollution, can be relatively localised. However, global climate change caused by human emissions of carbon dioxide and other greenhouse gases has the potential to affect the entire Antarctic region for decades to come.

The researchers point out that rising sea temperatures are already affecting marine creatures adapted to living within a particular temperature range.

A second major consequence of carbon dioxide emission from human activities - ocean acidification - is also likely to take its toll.

"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 co-author James McClintock of the University of Alabama at Birmingham, USA.

"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," he said.
The researchers have identified a range of historical and ongoing human activities that have damaged or restructured food webs in the Southern Ocean over recent decades.

 At the local to regional scale, these include -

1. The hunting of top predators such as whales and seals.
2. Overexploitation of some fish species, leading to stock collapses.
3. Air and water pollution from shipping traffic, wrecks, and the transport of invasive alien species on hulls and in ballast tanks.
4. Tourism, including potential disturbance to breeding bird and seal colonies, as well as being responsible for chemical and noise pollution, and littering.
5. Chemical and sewage pollution from research stations and ships, the legacy of historical waste dumping, and pollution from scientific experiments, including lost or unrecovered equipment.

The study has been published in the journal Annals of the New York Academy of Sciences.