Food. Endangered animals as varied as dugongs, sea horses, and sea turtles all graze on seagrass. Many more animals feed on small organisms such as larvae and eggs left on seagrass leaves or, like dolphins and herons, stalk seagrass beds for prey. Without seagrass, these animals disappear.
Shelter. Many species of fish, crustaceans, and other animals shelter in seagrass beds for at least some part of their life cycle.
Storm and erosion mitigation. The extensive root systems of seagrasses stabilize the soft ocean bottom. This inhibits erosion and slows down waves, reducing damage to coastlines from big storms.
Better water quality. Seagrasses trap fine particles, which increases water clarity. They also filter nutrients in runoff from land, protecting coral reefs from contaminants.
Economic support. Because many economically important fish species (including salmon, snapper, and grouper) spend at least part of their life cycle in seagrass communities, seagrasses are vital to fishing industries. One estimate is that seagrass meadows support the production of a fifth of the world’s biggest fisheries. Their loss threatens food security for millions of people.
Carbon sequestration. An acre of seagrass can store about three times as much carbon as an acre of rainforest can. Keeping all of that carbon dioxide, a key greenhouse gas, out of the atmosphere is a huge win in the climate emergency fight.
When Seagrass Vanishes
Seagrass is being lost around the world at a rapid clip. One study estimated that a football field of seagrass disappears every half-hour—torn out by dredging, choked by polluted runoff, or killed by disease. That adds up to a loss of about seven percent of the world’s seagrass every year. It’s estimated that 92% of the seagrass has disappeared from the United Kingdom’s coast in the last century.
When seagrass is destroyed, there are rapid, damaging effects throughout the marine ecosystem. For example, in Puget Sound in the United States, herring spawn in seagrass. If the seagrass disappears, the herring disappear, too. Then do the salmon that ate the herring have nothing to eat. Next, the orcas that preyed on the salmon are left without their primary food source.
The loss of seagrass also has dire consequences for the climate emergency. Clearing an acre of seagrass can release three times as much carbon dioxide into the atmosphere as clearing three acres of rainforest does.
As scientists have sounded the alarm about disappearing seagrass, conservation groups have taken up the challenge. As with any environmental challenge, there is more than one good way to approach the problem.