Climate change: red alert for oceans

International experts discuss climate impacts for the oceans

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More than 350 international experts have come together in Kiel to share the latest findings on the impact of global environmental change on marine ecosystems. The signals from the ocean are clear, because changes as a result of climate change have already occurred, the researchers concluded.

Too little pack ice in the Arctic

The predictions and observations of some international marine research experts gathered in Kiel for the 42nd European Marine Biology Symposium (EMBS) already point to much faster and more complex changes than previously thought. Louis Fortier of the University of Laval reports that this summer the Arctic pack ice would have reached its lowest level in living memory since August. Normally, the ice minimum will not be reached until September. If it is indeed a long-term trend and not an exceptional summer, then the Arctic would be according to previous forecasts not only 2100 during the summer months completely ice-free, but in just a few decades.

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"Of all ecosystems in the ocean, Arctic ice bound communities are most in line with global warming, " explains Ulrich Sommer, professor of marine ecology at the Leibniz Institute of Marine Sciences (IFM-GEOMAR) in Kiel and one of the Coordinators of the meeting. "Polar bears and some seal species will unfortunately disappear completely or survive only in small, limited areas of the Arctic."

Heat-loving anchovies in Denmark

But Europeans do not need to look far to see the consequences of global warming. The impact can be measured on your own doorstep, reports Brian MacKenzie, who works at the Danish Institute for Fisheries Research. "We have analyzed the data from four time series in the North and Baltic Seas since 1861 and they show a clear and rapid warming of seawater, " he tells his colleagues. In the summer months, the surface temperature between 1985 and 2002 increased by an average of 1.4 degrees Celsius. Not only swordfish and anchovies have been caught in Danish waters, but also other species such as the red mullet or the seabream. "These fish are usually known from the Mediterranean or the Bay of Biscay, " says the fishery biologist. display

Chemical interactions as indicators

Important findings on the interaction of complex ecosystems can be reported by researchers, for example in the field of chemical messengers. Close collaborations between biologists and chemists provide new insights into processes at the cellular level. "Organisms use messengers to defend themselves against predators, against pathogens or against other creatures they want to overgrow.

"As scientists increasingly find that chemistry is often the language of the sea, " says Martin Wahl, professor of benthic ecology at IFM-GEOMAR in Kiel and co-coordinator of the symposium. His research group is studying the creatures on the seabed, especially in the coastal areas of the Baltic Sea. Many animals have sensors with which they can perceive chemical hazards. In response, they may in turn send out messengers or put them on their surface like a protective cover. "We now get insights into highly exciting processes that are based on versatile interactions, " Martin Wahl describes the developments in his field of work.

Ecosystem re-sort themselves

Research projects worldwide show that the ecosystems of the ocean are re-sorting. But it is not just the scale, but above all the speed of change that is affecting the plants and animals in the sea. "Development is rapid, " reports Joanie Kleypas, a US coral expert, "we see that these sensitive organisms are likely to avoid warming in some areas of the ocean by moving to colder areas. But what threatens them to a much greater extent is acidification. "The ingestion of human-emitted CO2 by the ocean leads to acidification of seawater. This change affects such large areas of the oceans that organisms that make up their limestone skeletons will not survive in many places. "According to the Arctic ecosystems, cold-water corals are the habitats most threatened by climate change, " adds Ulrich Sommer.

"The changes in marine ecosystems that have been initiated will continue for the next 50 years, " Martin Wahl concludes from the symposium. "It is imperative that we reduce emissions quickly and heavily so that the environmental changes do not occur so rapidly that the communities can no longer adapt. "The EMBS took place at the University of Kiel and was funded by the German Research Foundation (DFG), the Kiel Cluster of Excellence" Ocean of the Future "and the Inter-Research Science Center in Oldenburg / Luhe.

(Leibniz Institute of Marine Sciences, 04.09.2007 - NPO)