| dethalternate | Date: Monday, 18-June-2012, 2:42 AM | Message # 1 |
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| Secret gardens may hide beneath floating slabs of ice in the Arctic. A pea soup of plantlike plankton has been uncovered that extends more than 100 kilometers under ice off Alaska’s coast.
The explosion of microscopic life, spotted last July, could cause problems for other critters in the Chukchi Sea, researchers report online June 7 in Science. Seasonal blooms this big traditionally happen later in the summer, and only in open waters exposed to the sun after ice melts.
“I’ve been in this field for almost 30 years now, and I would have said this was impossible,” says Kevin Arrigo, a biological oceanographer at Stanford University. “The assumption has always been that where you’ve got ice, nothing will grow in the water beneath it.”
Light doesn’t penetrate ice well, especially the thick ice historically found in the Arctic. Snow covering the ice can add an opaque blanket, making the water beneath a dim, dismal place for phytoplankton, which need light for photosynthesis.
But climate change has altered the character of much of the ice. Gone in many places are the meters-thick grand old slabs that persisted year after year. New ice born every winter that tends to fade away during the summer is thinner and allows more light through.
Warmer air also melts snow and small grains of ice on top of young ice. This melt darkens the surface, like water poured on a sidewalk, allowing the ice to absorb more light.
More than half of the light striking a young slab of ice can reach the water below, the researchers found.
Full article/source - http://www.sciencenews.org/view....sea_ice
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