Aliens pushing ocean natives out

UC DAVIS (US) — When oceans warm, invasive animals move in, threatening and crowding out native species, according to a new study.

Marine biologists have monitored plant and animal life in the eastern Pacific fishing harbor of Bodega Bay, California for 50 years.

In that time, water temperatures have climbed more than 2.5 degrees Fahrenheit, and there are now twice as many nonnative species as there are natives, says Susan Williams, professor of evolution and ecology at the University of California at Davis.

Researchers recently studied “fouling organisms”—the squishy or prickly creatures that live on rocks, docks, boat hulls, seawater pipelines, and shellfish farms to better understand what continued warming might mean for saltwater communities.

Bryozoans (also called moss animals) and tunicates (sea squirts) were taken from Bodega Bay to the lab, where their tolerance to higher water temperatures predicted by climate scientists was tested.

“We determined that introduced species tolerated significantly higher temperatures than natives,” Williams says.

“Our results strongly suggest that, as ocean temperatures continue to increase, native species in this system will decrease in abundance, whereas introduced species are likely to increase.”

The research was published in the August issue of Ecology and online in Oikos. The American Association of University Women, the California Ocean Protection Council, and the National Science Foundation provided funding.

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