Metro

Invasive seaweed in Gulf of Maine may threaten fish who need protection from predators, report says

Cunner, a common species of fish in the Gulf of Maine, prefer to take refuge in native kelp to invasive species of lower-turf seaweed that have recently been taking over in the habitat, researchers at UNH say.
Kristen Mello/University of New Hampshire
Cunner, a common species of fish in the Gulf of Maine, prefer to take refuge in native kelp to invasive species of lower-turf seaweed that have recently been taking over in the habitat, researchers at UNH say.

As invasive species of seaweed take over some areas of the ocean off Maine, certain fish could be at risk of losing protection from predators, according to researchers at the University of New Hampshire.

In a study recently published in the Journal of Experimental Marine Biology and Ecology, researchers found that a common fish in the Gulf of Maine, called cunner, prefers to take cover in kelp native to the region rather than short, tufty seaweed that has grown rapidly in number in recent years.

“Some species migrate in and out of an ecosystem — but cunner, once they’ve settled into an area, they tend to stay there for most of their life,” PhD student Brandon O’Brien said. “Anything that affects cunner is going to be affecting this ecosystem.”

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In a series of three experiments in which researchers observed the fishes’ behavior in the native kelp and invasive seaweed, they found the fish preferred kelp as a refuge about three times as much as short-tufty seaweed, according to the study.

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“What that certainly implies for the cunner is that they may be more exposed to predators and they could be consumed more or eaten more and will be easier to find in a habitat that has a number of [invasive] seaweed,” said Jennifer Dijkstra, research assistant professor in the Center for Coastal and Ocean Mapping at UNH.

Dijkstra said she believes more studies need to be done before researchers understand the full implications of the seaweed for the ecosystem as a whole.

“I think certainly looking at whether the hypothesis that we stated in the paper, whether the fish species is actually preyed upon more in habitats dominated by these short invasive [seaweeds], would be a really good follow-up study,” she said.

The change in seaweed species is just one ongoing change to rocky ocean habitats like the Gulf of Maine affecting ecosystems, Dijkstra said, in addition to a number of other invasive species and the warming of oceans.

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“These changes don’t appear to be stopping at all,” she said. “I think it’s just important to understand how these changes will affect species that live in the environment.”

Laney Ruckstuhl can be reached at laney.ruckstuhl@globe.com. Follow her on Twitter @laneyruckstuhl.