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maandag 3 juli 2017

Antarctic wildlife may change

Antarctic wildlife may change as climate warms

As the ice retreats, there’s more room for Antarctic wildlife to grow. But that may not be good news for the life already there.
By Tim Radford

LONDON, 3 July, 2017
 – Antarctic wildlife could be about to gain ground. As global temperatures rise and the ice melts, the continent's biodiversity could gain an extra 17,000 square kilometres of living space.
It doesn’t sound much, for a continent that measures 14 million square kilometres, that is the coldest and driest place on earth, almost completely masked by 30 million cubic kilometres of ice. 
Yet for the continent’s permanent residents – seals, sea birds, arthropods, nematodes, microbes and mosses – it represents a gain of living space the size of Swaziland, or Kuwait.
Although the ice over Antarctica is on average more than 2 kilometres deep, there have always been patches of rock and parched soil free from ice, where water can sometimes collect.

Green trailblazers

These patches add up to less than 1% of the entire region, and they range in size from an area little bigger than a football pitch to terrain the size of a small Pacific island. Rock, water and seasonal sunlight are enough for some green things: these then create a potential home for other settlers. 
“Ice-free areas make for small patches of suitable habitat for plants and animals – like islands in a sea of ice,” said Jasmine Lee, a biologist at the University of Queensland. 
“These areas are home to the majority of Antarctic species – from seals and seabirds to mosses, lichens and small invertebrates, such as tardigrades and springtails. Many of these species occur nowhere else in the world.”
Climate change, driven by prodigal human combustion of fossil fuels, creates new threats for the wild things almost everywhere. Biologists have warned that the loss of sea ice creates problems for the Emperor penguin and have warned of a potential population decline for Adélie penguins

Fast-warming 

Warming, too, creates problems for fur seals that depend on a secure supply of krill. But until now very little attention has focussed on the opportunities for growth and change for the smaller citizens of the polar shores
The Antarctic Peninsula is one of the fastest-warming places in the Southern Hemisphere and is likely to become even warmer as the century progresses. But there have always been exposed patches of rock and soil – the tops of mountains, cliffs, scree slopes, valleys kept dry by a freak of the winds, coastal oases and islands. 
These are the only home for the continent’s lichen, fungi, mosses and algae, the breeding grounds for seals and seabirds and the tiny animals that make a living on the margins: because of conditions for most of the year on most of the landmass, many of these small creatures are unique to Antarctica, and found only in one place or zone.
The Australian researchers report in Nature that they asked themselves one big question: what happens as the ice begins to retreat?

“This expansion of ice-free habitat could lead to new opportunities for Antarctic biodiversity, although the warmer conditions will also encourage invasive species to establish”

They calculated that over the next 80 years, the areas free of ice could increase by 25%, creating another 17,000 sq km of living space, most of it on the Antarctic Peninsula. 
They think that if the world’s nations cannot keep the promise made in Paris in 2015 to contain global warming to less than 2°C on average, then as these small patches of living space enlarge, and begin to join each other, the less competitive species will be at risk from aggressive invaders: Antarctica would end up with more life, but less diversity. 
“This expansion of ice-free habitat could lead to new opportunities for Antarctic biodiversity, although the warmer conditions will also encourage invasive species to establish,” Lee said.
“Many native species have evolved isolated from each other for extended time periods; they are mainly constrained by the availability of resources, such as water and nutrients. How they will cope with increasing connectivity and competition from invasive species is largely unknown.” – Climate News Network
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