Warmer water temperatures and nitrogen pollution stemming from septic systems and fertilizers are “killer threats” to seagrass in the coastal waters of southern New England and New York, according to a new federally funded study.
Released Monday by The Nature Conservancy and prepared by The Woods Hole Group Inc., the study examined several coastal areas, including Nasketucket Bay, the Wareham River Estuary and Little Buttermilk Bay in Massachusetts. The majority of nitrogen delivered to Little Buttermilk Bay, which is east of the Wareham River, is from septic wastewater and by 2001 “all eelgrass that existed in the bay, and in the adjacent downstream Buttermilk Bay, has vanished,” the study said.
Researchers reported that eelgrass in the Wareham River Estuary, which is near the head of Buzzards Bay just south of the southern entrance to the Cape Cod Canal, has “declined precipitously” since the 1980s.
“As evolving science continues to confirm, excess nitrogen in our coastal waters is having a profound negative impact on our salt marshes, shellfish populations and seagrass meadows,” Jon Kachmar, coastal director for The Nature Conservancy in Massachusetts, said in a statement. “This study provides the foundation for developing regional solutions to restoring water quality conditions to produce thriving and robust seagrass meadows as well as other coastal habitats, which provide ecological, social and economic benefits not only to Massachusetts but to the Southern New England region.”
Seagrass provides a critical habitat for fish and shellfish and helps improve water quality and stabilize sediments. Researchers say the region’s seagrass has “suffered massive losses” since 1930 due to disease, brown tides, and nitrogen stemming from human sources. Nitrogen loading is controllable, according to the report, which describes the direct effects of climate change as “undoubtedly uncontrollable in the near-term.”