Different species will respond in varying ways to a particular change and that, in turn, could alter how they interact with each other.
Fishing, pollution and the erosion of soil and nutrients into the water will combine with the climate impacts. For example, fish harvests rising in tandem with world population reduces the age, size and geographical diversity of fish populations, making them more sensitive to climate stress.
Marine species are tending to migrate toward the poles, but they're doing so at varying speeds, again, making it difficult to predict how they'll interact.
In enclosed seas, species that require cooler conditions might have nowhere to go when the waters warm. Researchers predict that by 2060, as the Mediterranean warms, one-third of its 75 fish species will be threatened and six will be extinct.
On the other hand, in the almost equally enclosed Black Sea, where "new Mediterranean species are arriving and establishing new niches," warming air and seawater are expected to result in increased diversity, with adverse effects limited to declines or loss of a small number of native species, according to Temel Oguz of the Institute of Marine Sciences at Turkey's Middle East Technical University.
Other researchers including Manuel Barange, director of science at the UK's Plymouth Marine Laboratory, point out that linear change isn't likely. Marine life might alter abruptly as new conditions push a species beyond a tipping point. "Gradual changes in future climate may provoke sudden and perhaps unpredictable biological responses as ecosystems shift from one state to another," he says.
Typical of the uncertainty is a study by scientists from the Institute for Marine Resources & Ecosystem Studies, in the Netherlands, which found that warmin
|Contact: Terry Collins|
Flanders Marine Institute (VLIZ)