LONDON — A team of scientists in the United Kingdom and the United States has
warned that the native fauna and unique ecology of the Southern Ocean, the vast
body of water that surrounds the Antarctic continent, is under threat from human
activity.
Their study is published this week in the peer-reviewed journal Annals of the
New York Academy of Sciences.
"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.
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
Professor 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 Dr.
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,"
urged Dr Aronson.
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 -
•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 scientific experiments, including
lost or unrecovered equipment.
Antarctica has great, untapped natural resources. The Antarctic Treaty currently
prohibits the extraction of oil and other mineral resources from Antarctica. The
researchers note, however, that many major areas of the Southern Ocean fall
outside the Antarctic Treaty region and could be claimed by nations as valuable
'real estate' for the future.
Although the Antarctic Treaty and other conventions have measures aimed at
reducing the local- and regional-scale impacts of human activity on Antarctica
and the Southern Ocean, they cannot address global-scale threats. Among these
threats, the researchers highlight 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.
"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.
The researchers are Richard Aronson (Florida Institute of Technology), Sven
Thatje (SOES), James McClintock (University of Alabama at Birmingham) and Kevin
Hughes (British Antarctic Survey).
The research was supported by the US National Science Foundation, the Total
Foundation (Abyss2100) and the Royal Society.
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