Blue mussels in the northwest Atlantic Ocean have seen their range contract 30 percent to 50 percent as ocean temperatures rise. Andreas Trepte/Wikimedia Commons
In recent decades, ocean species from whales to corals have begun to shift poleward in search of cooler waters. But new research finds that many sedentary marine species — including snails, worms, and mussels — are actually being transported in the wrong direction.
The study, published in the journal Nature Climate Change, found that as water temperatures climb, benthic species in the northwest Atlantic Ocean are spawning earlier in the year, when currents travel southward. As a result, their larvae are being carried into warmer waters rather than cooler ones, threatening their survival and shrinking their ranges. The larvae then grow into adults in these warmer areas and get trapped in a feedback loop, unable to reach more habitable regions. Species such as the common sand dollar and the economically important blue mussel have seen their ranges contract by 30 percent to 50 percent.
“It’s pretty worrying that so many benthic species that used to be really abundant have disappeared from the outer shelf,” Heidi Fuchs, a marine biologist at Rutgers University and lead author of the new study, told Science.
Fuchs and her colleagues likened the “wrong-way migration” of benthic species to “elevator-to-extinction” events most commonly seen in mountainous regions, where species such as birds and butterflies move upslope to escape rising temperatures until there is nowhere else for them to go.
“The big take-home message is, you can’t just assume critters will spread to wherever the climate is congenial for them,” James Pringle, a physical oceanographer at the University of New Hampshire who was not involved with the new work, told Science.
