Snippets

Snippets

All set to brave thin ice, polar bears

Scientists and explorers will brave polar bears, thin ice and frostbite as they embark on an Arctic expedition to examine the impact of an acidifying ocean on the region’s animals and plants. The Catlin Arctic Survey will set up an “ice base” in northern Canada for scientists while a separate team of adventurers will undertake a 500km trek across sea ice off Greenland. Both will investigate the impact of ocean acidification on marine life, while the explorers will also measure variations in sea ice thickness. Last year’s Catlin Arctic Survey showed the Arctic ice was thinner than expected.

The expedition will also be the first to take water samples from sea ice in winter, as all previous Arctic measurements have been taken from ships in open water in summer. As well as taking water samples, scientists will collect plankton, sea butterflies, a type of swimming sea snail, and other local marine life and examine their reaction to increasing levels of acidity and also test how much carbon dioxide passes through sea ice from the air into the sea.

Globally, oceans have seen a 30 per cent increase in acidity on pre-industrial levels, the fastest rate of change in 55 million years. The Catlin scientists aim to establish the acidity of the Arctic ocean, which appears to be acidifying faster than the rest of the world’s oceans because cold water absorbs more CO2.

Marine life that depends on calcification such as coral, crustacea and molluscs are particularly sensitive to changes in acidity because the calcium carbonate that form their shells or skeletons dissolves in more acidic water. A type of snail known commonly as sea butterflies (pteropods), which are an important part of the marine food chain, are among the organisms potentially at risk.

Pen Hadow, the director of the survey who also led last year’s expedition, said the Arctic ocean’s vulnerability motivated the trip.  The ice base on the western shore of Ellef Rignes Island in Canada will be home to a team of six scientists who will work on the ice protected by two guides armed with guns and bangers to ward off curious polar bears attracted by the smell of humans. They will also face hazards such as breaking ice and the risk of frostbite as they undertake the fiddly work of drilling for water samples. An analysis of the data collected will be published in late 2010 or 2011.

Adam Vaughan
The Guardian


Will this zone save  fish species?

A marine conservation zone that is closed to commercial fishing helps save the targeted fish species, or so one would hope. But what about birds or other top predators that dine on those species? If the fish are oceangoing, and not limited to the protected area, it is unclear if protecting them is any help to predators that inhabit the same area. The fish might be here today, gone tomorrow. But a paper in Biology Letters suggests that even a relatively small protected area can have a positive impact on a top predator — in this case, the African penguin, an endangered species. Lorien Pichegru of the University of Cape Town and colleagues looked at the effects of closing sardine and anchovy fisheries within 12 miles of a penguin colony on the South African coast. They attached tracking devices to birds from the colony and from another colony outside the protected area.
They found that within three months after the closure, penguins within the protected zone were travelling shorter distances to find these fish species for their young, saving energy by reducing the average time of foraging trips by about 25 per cent. The birds from the colony outside the zone, on the other hand, spent about 15 per cent more time, on average, foraging.

Henry Fountain
NYT News Service

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