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Antarctic: Climate Change Affects Key Marine Life, Study Finds |
| November 9, 2004 |
Compiled by: Erin McPhee, AquaNews Correspondent
 | Scientists are blaming large-scale melting ice for a significant decline in Antarctic krill, which forms the base of the Southern Ocean's food web.
Photo: NOAA |
The decline of a tiny Antarctic crustacean has researchers worried about its effects on larger wildlife such as whales, seals and penguins.
A dramatic decline in the number of Antarctic krill (Euphausia superba), which researchers from the British Antarctic Survey (BAS) attribute to a decrease in sea ice, is raising questions about the effects of climate change on the environment and food webs.
Antarctic krill are one of the most important animals in the Southern Ocean, say BAS researchers, but their newly-released research shows that krill numbers have dropped by about 80 percent since the 1970s. The study, entitled "Long-term decline in Antarctic krill stock and increase in salps within the Southern Ocean," was published last week in the journal Nature.
Krill are shrimp-like crustaceans that can grow up to six centimeters in length and live for up to six years. Krill feed on phytoplankton (tiny plant-like algae) and in turn, are a food source for a wide range of animals like fish, penguins, seals and whales. They are also a potential source of protein for humans, since they can be easily fished for with large nets.
"This is the first time that we have understood the full scale of this decline," said Dr. Angus Atkinson, lead author of the study from the BAS, in a written statement. "Krill feed on the algae found under the surface of the sea ice, which acts as a kind of 'nursery.'
"The Antarctic Peninsula, a key breeding ground for the krill, has warmed by 2.5 degrees Celsius in the last 50 years, with a striking decrease in sea ice," he said. “We don't fully understand how the loss of sea ice here is connected to the warming, but we believe that it could be behind the decline in krill.”
Previous speculation that krill numbers may have been declining was based on localized surveys spanning a shorter period of time than the current study. Building on almost 60 years of scientific research on and around the Antarctic continent, the BAS four years ago began an "international collaborative project" to widen the time and space scales of sample coverage. Data from nine of the 30 countries working in Antarctica were pooled, spanning 40 Antarctic summers for the period 1926 to 2003. This allowed for a large-scale view of change across the Southern Ocean.
A principal finding is that in the last 50 years, air temperatures in the Antarctic Peninsula region have risen about five times faster than the global mean rate, researchers say. They suggest that less sea ice during the winter is likely to be the cause and may explain declines seen in several species of penguins. Antarctic whales, seals and penguins could also be threatened by food shortages.
The researchers also warn of commercial implications that could impact humans, noting that the Southern Ocean is a "valuable resource" for fisheries. As well, thousands of tourists are attracted to Antarctica to enjoy the wildlife - most of which feed on krill.
By better understanding how the environment affects the Antarctic's unique food web, researchers hope to predict how it will respond to future change.
Global Pollution, Local Solutions
As the effects of climate change in the Antarctic become increasingly evident, the Canadian government is taking steps to counteract this global problem at home.
The One-Tonne Challenge is a federal initiative encouraging individual Canadians to take action on climate change and clean air by reducing their annual greenhouse gas emissions (GHGs) by one tonne. On average, individual Canadians produce five tonnes of GHGs each year; one tonne is a reduction of about 20 percent.
While one tonne sounds like a huge reduction, developers of the challenge say that it is easier than they may think. About half of the total GHGs of automobile operators comes from driving. Driving less will ‘significantly’ reduce fuel consumption and emissions as well as saving the individual money, the government says.
Source: Vancouver Aquarium Marine Science Centre
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