How does water clarity affect eelgrass growth? Click on the image above to see what researchers found.
Sheltering meadows of eelgrass trim southern New England’s coast like lace. The area’s shallow bays, estuaries and lagoons offer an ideal environment for Zostera marina, and its lush beds provide shelter and food for important species—such as flounder, bay scallop and hard clams—and reduce the power of storm waves.
In 1931, these once-abundant “prairies of the sea” began to disappear. They since have dwindled by as much as 90 percent. Scientists have identified factors ranging from pollution to disease, brown tides, waterway impacts and lack of genetic diversification. Whatever the cause, the effect was clear—and worrisome.
“Eelgrass meadows provide essential habitat, improve water quality and can help reduce shoreline erosion,” says Chantal Collier, director of the Conservancy’s Long Island Sound Program. “Eelgrass is critical to sustaining the ecosystem services that people rely on for food, jobs and recreation.”
Regional efforts at restoration— including distributing eelgrass seeds and transplanting shoots—were costly and only occasionally successful.
Aiming to reverse this decades-long decline, the Conservancy recently sponsored a new study, funded by the National Oceanic and Atmospheric Administration and led by renowned eelgrass expert Dr. Fred Short of the University of New Hampshire. Dr. Short and his team collected and analyzed plants from 10 locations—from Cape Cod to Long Island Sound.
What they found surprised them. Eelgrass, it turns out, is remarkably genetically diverse. If not a genetic bottleneck, then, what was responsible for the decline? Dr. Short’s team determined the biggest threats were high nitrogen content—from sewage treatment plants, septic systems and polluted runoff—coupled with warming ocean temperatures.
Their recommended solution is three-fold:
- Reduce nitrogen pollution.
- Protect the region’s most resilient sea-grass populations.
- Use grasses from resilient areas as donors for future restoration to ensure the best chance of success.
“These findings will inform the steps we need to take to protect remaining eelgrass meadows from further decline and ensure a healthy future for the Sound,” says Collier.
With strong science, practical solutions and your continued support, eelgrass may once again boast a plentiful, sheltering presence in New England’s coastal waters.