With oversight by the U.S. Food and Drug Administration (FDA), the Maine Department of Marine Resources (DMR) is responsible for ensuring the safety of Maine’s shellfish for consumers.

Phytoplankton are tiny, plant-like organisms that form the base of the Earth’s food web. Because they respire like plants, they also produce at least 60% of the oxygen we breathe. While most are harmless and vital to marine ecosystems, some types—such as Alexandrium spp.—can produce toxins that make animals—including people—sick or cause death.

From May to August, trained volunteers collect weekly water samples in Christmas Cove, South Bristol. Within 25 hours, they examine these samples under a microscope to count the number of potentially toxic cells.

The data gathered by volunteers is immediately shared with DMR staff, who use it to decide where to focus their monitoring efforts for shellfish safety along the coast.