Thinning Arctic Sea Ice Prompts Algae Blooms, Which Then Drop, Rot, Drain Oxygen From Ocean
Professor Antje Boetius was surprised by the answer she found during a scientific cruise last summer aboard the German research vessel Polarstern, owned by the Alfred-Wegener Institute for Polar and Marine Science (AWI). Boetius, who heads AWI's Deepsea Ecology and Technology team, spent two months in the central Arctic. That summer the sea ice declined to a record extent.
The researchers discovered that the melting ice on the surface was affecting conditions down to a depth of 4,000 meters. "We took a look at the sea floor and found that most of the ice algae which form thick carpets under the ice had dropped right down into the depths when the ice melted," Boetius said in an interview with DW.
"We travelled through a very wide area of the Arctic and found that this process was happening everywhere. We also found out that only a few lifeforms in the Arctic Ocean can actually make use of these algae as food. For the most part, they lie around on the ocean floor and are attacked by bacteria." The problem, the scientist explains, is that this uses up large amounts of oxygen. The team found areas of the seabed where the oxygen supply had been depleted.
The scientists concluded that the ice algae has started growing faster than usual because the thinner ice is letting much more light through. At the same time, the thinner and warmer ice melts faster, releasing the algae, causing it to sink to the bottom.
EDIT
http://www.dw.de/oxygen-rich-ice-algae-lost-as-arctic-warms/a-16622736