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Rising sea temperatures attributed to global climate change could drive many marine creatures away from the equator, but their move toward the poles promises to put them in peril in habitats that are smaller and less hospitable, scientists say.
Two studies published on Thursday in the journal Science illustrate dangers researchers forecast for sea animals as diverse as corals, fish and crustaceans.
University of Washington oceanographer Curtis Deutsch said warmer ocean temperatures increase both the metabolic rates of ocean creatures and their demand for oxygen, but warm water contains less oxygen than cold, necessitating a move toward the poles to find cooler seas.
As species migrate, they may end up in new environments with different ocean conditions, predators and prey, Deutsch added.
By the year 2100, cool-water marine species could be displaced from 20 percent or more of their current ranges as they shift toward higher latitudes, the researchers found.
Another study focused on the world's largest group of reef corals, called staghorn corals, that dominate most reefs of the Indo-Pacific region and also reside in the Caribbean but are highly susceptible to a phenomenon called coral bleaching. In high ocean temperatures, corals expel algae living in their tissues, making the creatures turn white. This can kill them or make them more susceptible to other hazards.
The corals may have a hard time in cooler-water environments farther from the equator, the study found. Because corals are dependent on sunlight — which does not penetrate the surface as well in higher latitudes, especially during winter — they would be restricted to habitats in shallower waters if they migrate toward cooler waters.
In addition to Deutsch, the authors of "Climate Change Tightens a Metabolic Constraint on Marine Habitats" include Aaron Ferrel, Brad Seibel, Hans-Otto Pörtner and Raymond Huey. The authors of the second study, "Limited Scope for Latitudinal Extension of Reef Corals," include Paul Muir of the Museum of Tropical Queensland as well as Carden Wallace, Terence Done and J. David Aguirre.