Antarctic melt shakes up food chain
By Tim Barlass
7 April 2013 (Sydney Morning Herald) – Major changes to the food chain, weather, and landscape of Antarctica have provided stark evidence of the impact of global warming, a report on a polar expedition has revealed. The preliminary report on the research by scientists from the Australian Antarctic Division and the Woods Hole Oceanographic Institute near Boston suggest significant changes at the lowest level of the food chain, a vital source of sustenance for seabirds, seals, and whales. The Climate Commission recently said there was evidence natural events were being influenced by climate change as greenhouse gases accumulated and trapped measurable amounts of extra energy in the atmosphere and oceans. Eight of the 21 hottest days on record have occurred so far this year. The expedition senior scientist of the Australian Antarctic Division, Steve Nicol, said in 25 years of surveying Antarctica, this was the first time he had experienced rain. […] ”Warming is evident in the moistness of the air in this area of the world’s driest continent. Rain is now not uncommon and whilst this may encourage plant life, it is probably detrimental to the health of many of the breeding birds,” it found. ”This moistness also results in more snow falling and this too can affect the breeding habits of nesting birds when it falls during their incubation period, burying their eggs in the cold snow. ”The glaciers draining the ice caps of the islands and the mountains of the peninsula are shrinking, too. This has resulted in the formation of more icebergs and a greater run-off of freshwater.” Expedition leader Michael Aw said the team witnessed an increase in herbivores called salps, possibly at the expense of phytoplankton, which are consumed by fish and krill. ”The balance in the herbivore elements of the food chain determine the types of larger animals that can be supported,” he said. ”There are suggestions it is changing from one that supports krill and its predators [seabirds, seals, whales] to one that may result in more fish and possibly squid … The whales also feed on the krill so there is a chain reaction.” [more]
