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article imageGulf of Maine's wild blue mussels disappearing as ocean warms

By Karen Graham     Aug 28, 2016 in Environment
The Gulf of Maine has historically been home to one of the richest shellfish populations in the U.S. But a recent study by marine ecologists has found that their numbers have declined by over 60 percent in the past 40 years.
Cascade Sorte, an assistant professor of ecology & evolutionary biology at the University of California Irvine, and colleagues from around the U.S. compared recent data on shellfish numbers along the gulf coast with 40 years worth of historical benchmarks.
The researchers found that there has been an overall decline in blue mussels (Mytilus edulis) along the coastline of the survey area that stretches from Cape Cod north to the Canadian border. At one time, the mussels covered as much as two-thirds of the intertidal zone, and now they cover less than 15 percent.
Blue mussels are known as a foundation species, and the biodiversity of the intertidal community is dependent on them. And while blue mussels as a consumer product are worth millions to the New England economy, they are even more important because as filter-feeders, they remove bacteria and toxins from the water.
In the study published in Global Change Biology this month, two reasons for the decline in mussel numbers are suspected. One is the warming oceans and the other is an increase in human harvesting. Warming air and ocean surface temperatures have pushed the mussels out of their comfort zone, creating physiological stress and increasing mortality rates.
"It's so disheartening to see it (the loss) in our marine habitats. We're losing the habitats they create," says Sorte. Not only is it disheartening, but the declining numbers can produce a smelly mess.
Last week, thousands of dead mussels washed up along the shores of Long Island, New York. A Stony Brook University professor said the die-off could be attributed to warmer waters, reports
“The Earth is in the midst of a biodiversity crisis,” Sorte said, “and the Gulf of Maine is one of the fastest-warming areas of the global ocean, so the impacts of ocean warming are likely to happen much sooner there.”
Scott Morello is a researcher who has studied mussels with The Downeast Institute for Applied Marine Research & Education in Maine. He says that Sorte's work goes hand-in-hand with observations made in recent years by people who work the waters in the gulf.
"It's not just scientists," he said. "I can tell you that most residents I've talked to, most fishermen I've talked to will point out the same dramatic decrease in mussels."
Basically, the study brings to light the evidence being seen in other "hot spots" around the world. Key species, foundation species, are disappearing and this will lead to a catastrophic change in the ecosystem. We are already witnessing this in the Gulf of Maine where all that can be seen are barnacles and algae
This study, "Long-term declines in an intertidal foundation species parallel shifts in community composition," was published in the August issue of the journal Global Change Biology.
More about blue mussels, New england, decline in population, biodiversity crisis, warming ocean
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