Tuesday, August 25, 2009

Warmer seas mean more food for fish

The sheer diversity of ocean food webs has made experts fear it would be impossible to predict how climate change will affect marine ecology. But Mary O'Connor and colleagues at the University of North Carolina, Chapel Hill, may have solved the problem. They have found that plankton, the basis of marine food webs, might react predictably to ocean warming.

The team warmed 4-litre "microcosms" of seawater. They found that phytoplankton grew slightly faster with every degree of temperature rise. But zooplankton grew – and ate the phytoplankton – faster still. Zooplankton only retain about 10 per cent of the biomass of phytoplankton they eat, so there was a fall in biomass overall.

This might not be entirely bad news for people, says O'Connor. More zooplankton means more food for fish, though such top-heavy food webs could crash, she warns. "The effect could be translated up the food chain," she says. But if nutrients in the water are limited, "that top-heavy food web structure could be less stable, and crash all together."

Journal reference: PLoS Biology, vol 7 p e1000178
Courtesy: Newscientist


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