Scallops Under Threat

Scallop (Illustration credit: Raleigh McElvery ’16)

Illustration credit: Raleigh McElvery ’16

Reported by Raleigh McElvery ’16

What’s the big deal about scallops? According to Dr. Meredith White of Maine’s Bigelow Laboratory for Ocean Sciences, who presented her research at Bowdoin on Oct. 10, these shelled invertebrates are more than just a gourmet delicacy.

Scallops also improve water quality, play a crucial part in the food chain, and provide fisherman with a source of income. But these bivalves are under threat as rising CO2 emissions contribute to ocean acidification.

It’s a simple equation: carbon dioxide plus water equals carbonic acid, which lowers the ocean’s concentration of carbonate ions — leaving too few of these particles available for building shells. Here’s where White’s research comes in. She performed a series of experiments subjecting scallops of different ages to varying amounts of CO2, to identify the developmental stage in which CO2 exposure had the greatest impact on bay scallop larvae.

The bad news? Heightened CO2 levels before shell-building resulted in mysterious indentations in the bivalves’ shells, and CO2 exposure during initial shell-building stunted shell growth. “The good news is that exposure to high CO2 after the first day does not negatively impact the larval size,” White said. One implication is that hatcheries could save resources by reducing monitoring after that period.

White’s presentation was part of a weekly series sponsored by the Bowdoin College Biology Department.

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