In late September, seagrass ecologist Alyssa Novak pulled on her neoprene wetsuit, pressed her snorkel mask against her face, and jumped off an oyster farming boat into the shallow waters of Pleasant Bay, an estuary in the Cape Cod National Seashore in Massachusetts. Through her mask she gazed toward the sandy seabed, about 3 feet below the surface at low tide, where she was about to plant an experimental underwater garden of eelgrass.
Naturally occurring meadows of eelgrass—the most common type of seagrass found along the East Coast of the United States—are vanishing. Like seagrasses around the world, they have been plagued for decades by dredging, disease, and nutrient pollution from wastewater and agricultural runoff. The nutrient overloads have fueled algal blooms and clouded coastal waters with sediments, blocking out sunlight the marine plants need to make food through photosynthesis and suffocating them.
The United Nations Environment Program reports more than 20 of the world’s 72 seagrass species are on the decline. As a result, an estimated 7 percent of these habitats are lost each year.
