By Luisanna Carillo-Rubio
Figure 1: Arctic Fur Seal, Cape Shireff-
Source U.S Antarctic Ecosystem Research Division
(NOAA’s National Marine Fisheries Services)
With the rapid ice loss in the Arctic and Antarctic regions, many subspecies of seals are currently racing against the ticking clock of climate change. The worldwide status of seal population is alarming. According to the Union of Concerned Scientists, “almost no seal pups, dependent on sea ice, survived in Canada’s Gulf of St. Lawrence during the ice-free years of 1967, 1981, 2000, 2001, and 2002.” The southern hemisphere seal population has been likewise affected by ice loss. Environmental scientists, Dr. Clive McMahon and Dr. Harry Burton of the Australian Antarctic Division, have concluded that warming climate is changing the ocean’s ecology to such a degree that the survival of seals and their young has increasingly become a concern for marine biologists.
Scientists have continued to monitor the decline in seal numbers considering also what is known about climate in the Southern Ocean and conclude that the decline is due to a drop in the amount of squid and fish available for the seals to eat . Dr. Burton also explained that ice loss around Antarctica has affected the area’s ocean ecology by causing a decrease in the amount of algae, plankton and krill. All of these organisms constitute the very foundation of the ocean’s food chain. Marine biologists continue to express their concern over the reduction of nutrients essential to seals’ diets in the Southern Ocean, because mothers are then unable to nurse their young pups properly.
It is, however, in the Arctic region where the seals’ predicament is most pressing. In Canada, 2007 had one of the worst ice conditions on record, causing serious problems for harp seals. The International Fund for Animal Welfare (IFAW) monitored the gulf of Saint Lawrence last year, and reported that it was practically devoid of ice, and, naturally, devoid of harp seals. Sheryl Fink, a senior researcher with IFAW stated: “the conditions this year are disastrous. I’ve surveyed this region for six years and I haven’t seen anything like this. [. . .] There is wide open water and almost no seals.”
The Gulf of Saint Lawrence sustained below average ice conditions in 9 out of the past 11 years. In 2002, 75 percent of harp seal pups died due to a lack of ice. Dr. David Lavigne, Science Advisor for IFAW, concluded during the 2007 survey that “it’s likely that this year we could have, due to the poor ice conditions caused by rising temperatures,” close to 100 percent pup mortality in the Gulf of St. Lawrence.
Another serious consequence of climate fluctuations is the reduction of food for bottom dwelling creatures in the oceans. In recent years, scientists have directed their attention to the impacts of climate change in the Bering Sea’s ecosystem, which is considered by scientists "a canary in a coal mine because it appears to be showing climate change effects before the rest of the ocean" ). Although it is “a good start” that people begin to realize the gravity of melting ice and rising sea level, we must be aware that humans are now responsible for comprehensive changes in the way Earth’s ecosystem works” said marine ecologist Dave Hutchins.
Figure 2: Seals (www.mongobay.com)
A recent study published in Marine Ecology Progress Series shows that global warming will greatly affect the Bering Sea’s phytoplankton, the cornerstone of the ocean’s ecosystem and food-chain. Any changes affecting this ecosystem are of crucial importance, as the Bering Sea produces one half of the fish caught in the United States (and almost a third worldwide) every year. It is precisely because of a large presence of phytoplankton that the Bering Sea is so productive. Phytoplankton organisms are eaten by larger organisms, known as zooplankton, which are in turn eaten by large fishes. Recent studies show that as the Bering Sea increases in temperature, the presence of zooplankton or phytoplankton tends to decrease. Because of climate change, "the food chain seems to be changing in a way that is not supporting […] top predators, of which, of course, we [human beings] are the biggest," and this phenomenon is occurring at an unprecedented rate.
The changes observed in the Bering Sea’s ecosystem will inevitably affect all marine mammals which are part of its food-chain. The number of seals is already dwindling. The IPCC concluded that without serious curbing of greenhouse gas emissions, the Arctic ice will “almost entirely disappear” by the end of this century. Whether we are talking about the Peary caribou in the Canadian Arctic islands—with a population drop from 26,000 in 1961 down to 1,000 in 1997—or the near absence of ringed seal pups in the Bering Sea area in 2007, it is certain that if the current trend of emissions continues, all ice-dependant animals will continue to face a grim future.
Climate Change Impacts on the United States The Potential Consequences of Climate Variability and Change by the National Assessment Synthesis Team, US Global Change Research Program. Published in 2000
Global warming will diminish fish catch in the Bering sea (Jeremy Hance) January 16, 2008 (http://news.mongabay.com/2008/0115-hance_bering.html)
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