Often out of sight and out of mind for both the public and resource managers, underwater grass beds face a “global crisis” as their coastal habitats are dramatically altered by human activities, a new study says.
An international team of scientists, led by researchers from the Chesapeake Bay, said the reported cases of seagrass losses—sometimes over huge areas—have increased tenfold worldwide over the last 40 years in an article, “A Global Crisis for Seagrass Ecosystems,” which appeared in the December issue of the journal Bioscience.
“This report is a call to the world’s coastal managers that we need to do more to protect seagrass habitat,” said co-author Tim Carruthers, of the University of Maryland Center for Environmental Science. “Seagrasses are just one of the many keys to maintaining healthy coastal ecosystems.”
A major problem facing seagrass systems is that they have historically received far less attention from scientists and the public than other marine habitats. That has begun to turn around among scientists: In the last 35 years, there has been a hundredfold increase in the number of papers published in scientific journals about seagrass research.
But public awareness has not grown, the scientists said. Salt marshes, mangroves and coral reefs get threefold to hundredfold more media attention than seagrass ecosystems, although the latter is a more productive marine habitat, the scientists said.
“Based on media reports of scientific papers, we’re pretty low on the totem pole,” said Bob Orth, a researcher with the Virginia Institute of Marine Science and lead author of the paper. “Without strong public support, seagrass conservation efforts will continue to lag behind those of other key coastal systems.”
Improving water quality to support underwater grasses is one of the main goals of the Bay cleanup effort—improving water clarity specifically to restore grass beds is part of the legally binding water quality standards adopted by states bordering the Bay. But that is not the case for most areas, the scientists said.
To most people, the scientists said, seagrasses are invisible resources that live underwater in shallow areas generally avoided by the public. Further, while grass beds are important nursery grounds, and support the growth of organisms that help to drive the aquatic food web, they lack “large and dazzling organisms that attract the general public to coral reefs,” the scientists wrote.
“Without strong public support for seagrasses and the uncharismatic but highly productive animals they shelter, conservation efforts will continue to lag behind those of other key coastal ecosystems,” the scientists warned.
Seagrasses have survived for more than 100 million years, a period that encompassed dramatic changes in temperature and sea levels. But those changes were gradual. Today’s grass beds face increased algae blooms from nutrient runoff, sediment-clouded water, changing climates, invasions by exotic species and other threats.
The scientists called for stepped-up global efforts to gather more information about grasses and predict where declines might occur. With better information, they said, the global decline can be stemmed with more comprehensive efforts to control nutrient runoff, the establishment of sanctuaries or protected areas and greater education for the public and resource managers.
Besides their ecosystem value, the scientists also said that seagrass beds are worth paying attention to because they provide an early warning system about changing conditions in coastal habitats. The beds are highly sensitive to changes in nutrient and sediment inputs, as well as other pollutants.
“Seagrasses are the coal mine canaries of coastal ecosystems,” said Bill Dennison, of the University of Maryland Center for Environmental Science. “The fate of seagrasses can provide resource managers with advance signs of deteriorating ecological conditions caused by poor water quality and pollution.”