Baleen whales play a key role in the Southern Ocean food web and ecosystem. (Photo: Dave and Fiona Harvey, Australian Antarctic Division)
Whale feces key to marine ecosystem
Thursday, May 06, 2010, 17:00 (GMT + 9)
The feces of baleen whales in the Southern Ocean are rich in iron and consequently promote phytoplankton growth. This makes the feces of these endangered whales a vital component of the Antarctic ecosystem, researchers have found.
Whale feces contain approximately 10 million times as much iron as Antarctic seawater, according to findings by Stephen Nicol of the Australian Antarctic Division and colleagues. Their new study was published in the journal Fish and Fisheries.
|Marine Biologist Nick Gales scoops whale poo from water. (Photo: Sarah Robinson, Australian Antarctic Division)
The scientists sampled the genetic material in 27 fecal samples from four separate whale species and in this way established that the bulk of this iron originated from krill. The researchers thus realised that whale feces play a vital role in the Southern Ocean food web and ecosystem.
It appears that the whales’ feces stimulate the growth of phytoplankton, which is then consumed by krill. The krill concentrate the iron in their tissue, and the krill is in turn eaten by whales, reports SeaWeb.
Prior to commercial whaling, Nicol and colleagues estimated, baleen whales ate some 190 million tonnes of krill per year and produced 7,600 tonnes of iron-rich feces, accounting for approximately 12 per cent of the iron found at the surface of the Southern Ocean.
The researchers pointed out that, apart from supporting the ocean food web, phytoplankton are also responsible for absorbing carbon dioxide. Therefore, if whale populations were allowed to recover and phytoplankton growth rose accordingly, the overall effect could help alleviate the adverse impact of climate change by lowering carbon dioxide concentrations in the atmosphere.
Nicol and colleagues concluded that their findings offer additional arguments for protecting whale populations –- which are already depleted -- from further exploitation and backing efforts to rouse their recovery.
By Natalia Real