The short and simple marine food chain in the Antarctic, diatoms to krill to whales, is well known. The simplicity of the system makes it more vulnerable to outside disturbances than the more complex and stable ecosytems encountered in tropical and subtropical waters. Its vulnerability is now being tested under the strain of two man-made factors: the commercial exploitation of the mammalian populations, and the influence of toxic chemicals introduced from the industrial regions to the north.
There can be no doubt that the Antarctic marine ecosystem has been significantly influenced by man's exploitation of baleen whales. The disastrous decline in these stocks is well documented and has had profound effects on other parts of the ecosystem. (Please note that this section of the report was written before several international whaling conventions extended protection to many species of whale, several of which have, as a consequence, recovered in numbers.) The detection of DDT and other chlorinated hydrocarbon pesticides in Antarctic organisms furnished the first evidence of the global dispersal of this class of persistent pollutants.
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Pollutants recognize no national boundaries or territorial seas, and are transported from their place of origin to the marine environment via the atmosphere, water movements and migrating organisms. Pesticides have not been found in Emperor Penguins, which may suggest that birds and seals that are more or less confined to higher latitudes are likely to be less contaminated than those spending part of their life away from the continent.
The existence of large amounts of krill in the Antarctic has been known for many years, but interest in commercial exploitation arose only in the mid 1960s, at a time when the baleen whale stocks had greatly declined due to over-harvesting. Pressure to exploit krill is increasing, since in recent years the stocks of fish taken in traditional waters have declined or become less accessible to many nations. This has sharpened peoples' focus on the virtually untouched krill stocks.
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Because of the reduction of Antarctic whale populations, the consumption of krill has fallen from an estimated 190 million tonnes per year to only 40 million tonnes per year. However, this decline in whales has been matched to some extent by increases in other krill consumers, for example, seals and penguins. If a substantial fishery for krill develops, as seems likely, humans will be another major consumer in the system, and the effects on the other components of the system are unknown, and could be undesired.
So there is a need for careful control of krill exploitation, which will involve not only the collection of statistics about krill catches but also observations on the biology of krill and its consumers. A start has already been made: SCAR, in association with other international scientific bodies, has launched a major international long-term scientific study of the marine ecosystem, entitled Biological Investigations of Marine Antarctic Systems and Stocks (BIOMASS); the Antarctic Treaty governments have also recently concluded the Convention for the Conservation of Antarctic Marine Living Resources.
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WANT TO LEARN MORE?
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Websites
• Australian Antarctic Data Centre fact files Introductory information about Antarctic and subantarctic animals, plants and features. • Human Impacts Research How to protect the Antarctic environment for future generations. • Science in the Polar Regions Links to articles and information about Antarctica. • Prehistory More background information on the prehistory of Antarctica. • Antarctic Adventure 1997 Information on the geography and climate of Antarctica. |
