14 DAY TRIAL // Can ice be considered life deserted? If you think so, check out an iceberg. Icebergs can take lives in sea incidents (of course, Titanic remains the most severe accident involving an iceberg), but they can also boost marine life.
People had noticed that algae, krill (shrimplike crustaceans) and seabirds gather on and around the chunks of ice. And icebergs are just proliferating in the Antarctic due to global warming and rising temperatures that chop the continent's ice shelves. A 2002 research discovered that a Connecticut-sized iceberg in Antarctica's Ross Sea in fact decreased marine life abundance in the area by 70 %.
"That was catastrophically bad for the ecosystem," said lead researcher of that study, Kevin Arrigo, a biological oceanographer at Stanford University in California.
But the new research on much smaller icebergs in the Weddell Sea, on the other side of the continent, found the opposite: those melting icebergs released nutrients into the ocean, boosting the phytoplankton (microscopic algae) bloom. Krill gather in the area to feast on the plants, followed by their consumers: seabirds, seals and whales. The life explosion extends out 2.3 mi (3.7 kilometers) around the icebergs.
"These species are the same that are in the surrounding waters, it's just a concentration of them around the iceberg because it's an enriched area," said lead author Kenneth Smith, a senior scientist at the Monterey Bay Aquarium Research Institute in Moss Landing, California.
"It's the first time anybody's actually documented increased biological activity around the icebergs," said Arrigo.
Smith's team selected two icebergs based on satellite images and got to them aboard a research vessel. They were up to 12 miles (19 km) long and over 120 ft (37 m) high. One extended about 1,000 ft (305 m) under the water.
During the investigation, the oblong icebergs spiraled while slowly moving. Waterfalls on the icebergs pointed rapid melting. The team believes the meltwater releases large levels of iron, which stimulates the phytoplankton to grow. The researchers will investigate if this abundance persists while the icebergs move northward. 89 similar icebergs were counted in the area, increasing local biological productivity by nearly 40 %.
"This rise in activity may play a role in soaking up the carbon dioxide that is causing Earth's temperature to rise. It could possibly be a very important source of [carbon dioxide] drawdown from the atmosphere," said Smith. This carbon would be stored in the biological compounds.
"The iceberg biological activity may have some effect on the global carbon budget, but it amounts to only "a blip." That's because the area investigated is one of the few areas in the whole Antarctic where there is a lot of calving icebergs and melting icebergs," said Arrigo.
"Icebergs in the Ross Sea aren't melting much and thus not concentrating marine life around them like those in the Weddell Sea. Total biological production in the seas around Antarctica is less than 10 % of the total production worldwide. The amount that would be associated with these icebergs would be a small fraction of that, so we're talking about a pretty small number."