Issue date: 09 Sep 2002
Environmental change in Antarctic lakes and seas: the chances for survival or extinction?
Press Release No.9/2002 SCIENCE and The American Association for the Advancement of Science special seminar. 09.30 University of Leicester, Ken Edwards Building, Lecture Theatre 2 The effects of the warming of the Earth?s climate on Antarctic lakes and seas is a matter of life or death for many plants and animals at the frozen continent. Professor Lloyd Peck, biologist with British Antarctic Survey (BAS) discusses the prospects for survival or extinction of Antarctic marine and lake life today (9 Sept) at a special seminar – Frontiers in Polar Science session organised by the international journal SCIENCE and the American Association for the Advancement of Science (AAAS). If predictions from global climate models are correct the prospects for cold-blooded marine animals like giant sea spiders are bleak. But, by contrast, recent warming in some Antarctic lakes has allowed microalgae to thrive.
Issued by BAS Press Office: Contacts: British Antarctic Survey. Linda Capper tel: 01223 221448, mobile 07714 233744 Email: [email protected] Athena Dinar tel: 01223 221414, mobile: 07740 822229 email: [email protected] Professor Lloyd Peck, tel: 01223 221603
British Antarctic Survey The British Antarctic Survey (BAS) undertakes a world-class programme of science in the Antarctic and related regions, addressing key global and regional issues through research, survey and monitoring. BAS also helps to discharge the UK’s international responsibilities under the Antarctic Treaty System. British Antarctic Survey is part of the Natural Environment Research Council. For more information on British Antarctic Survey please visit the website at: www.antarctica.ac.uk
Notes for editors: Text from Professor Peck?s talk. ? In a recent paper in the journal Science, researchers from the British Antarctic Survey showed that the environmental and ecological characteristics of Lakes on Signy Island in the Antarctic were changing as fast, if not faster than any site on earth. Average temperatures have risen by around 1?C in 15 years, and in response to this open water periods extended by around 4 weeks, and microalgae and nutrients in the water increased by 2 to 10 times. These changes are an amplification of an underlying wider-scale, but smaller environmental change in air temperature of around 1?C in 40 years. They are also associated with a large reduction in ice cover on the island, of around 40% in some areas. Life in Antarctic lakes, as on land, is generally of low diversity and abundance. However, species living there have great biological flexibility, with some being able to survive temperature down to -25?C as eggs in winter and up to 25?C as adults in summer. These characteristics are necessary because the environments they inhabit are young in evolutionary timescales, and many are ephemeral. The real problem for many such species in a changing environment is not coping with the change, but surviving competition from invasions by alien species from lower latitudes. In contrast, the Antarctic marine environment has possibly the most constant temperature regime on earth, with some sites seeing temperature variations of only 0.1?C throughout the year. Signy Island is one of the most variable in the Southern Ocean, but even here annual temperatures vary by only 1.5?C annually. These marine conditions have existed around Antarctica for 10-15 million years. The cold-blooded animals living on the Antarctic seabed are characterised by limited ability to cope with temperature change. Experiments, show that most have upper lethal temperatures between 4?C and 10?C. Their ability to survive long-term temperature rise for periods of weeks to months is even lower, typically 3?C to 6?C. Of even more concern is that the limits for essential activities, such as swimming in scallops are at temperatures around 2?C to 3?C. Although survival is possible, biological capabilities above these temperatures are severely compromised. Current environmental change models predict that global sea temperature will rise by around 2?C in the next 100 years (Hadley Centre model III). There will be strong differences from area to area and responses will be patchy, but the polar seas are likely to warm by at least the global average. Summer maximum temperatures in the seas around Antarctica are often between 0?C and 1?C. A rise of 2?C will elevate temperatures to those that compromise animal capability, at a time when restricted summer food supplies are available and many species need to feed. Marine species, therefore, appear to be highly vulnerable in the face of predicted environmental temperature change. And indeed they and may be amongst the most vulnerable on Earth, because of their limited physiological capacity to cope with rising temperature. The isolation of Antarctica means that scope for migration in the face of a changing environment is restricted. Life cycles are long, reducing the ability to adapt biologically to change. The prospects are not encouraging. Many cold-blooded species in Antarctica grow to giant size, because of the high levels of oxygen present in cold-water environments. This includes sea spiders over 30 cm across and isopods, the relatives of woodlice, over 13 cm long. It would thus appear that some of the worlds most exotic and impressive marine species are amongst the most fragile in the face of predicted rising temperatures.