"Keep Off the Grass"
While this is a sign you might recognize from lush green lawns or newly-seeded playing fields, it’s just as appropriate for many of the areas of Mississippi Sound (between the Mississippi Gulf Coast and the Gulf Islands National Seashore).
The ‘grass’ in this case is sea grass, an aquatic plant that averages around eight inches long and can be considered a Mississippi ‘native.’
The roles that sea grasses play in our near-shore waters are critical. They are nurseries and feeding grounds for crabs, shrimp, fish and waterfowl; are food for animals such as sea turtles; their roots hold sediment in place which helps keep water clear; they minimize beach erosion by protecting shorelines from wave energy; and they help remove nutrients from the water, which prevents algal blooms and the associated fish kills. Examples of these superstar grasses include widgeon grass (Ruppia maritima), turtle grass (Thalassia testudinum ) and shoal grass (Halodule wrightii).
So how do boat propellers make any difference?
Recreational and commercial boats traveling through the areas can cut the sea grass leaves and chop up their root systems. Sea grass beds aren’t always visible, and even though you don’t see any leaves above the sand there may be living roots below the surface.
Once a cut is made into a sea grass bed, natural wave action starts to work on the exposed edges of the cut and increase the size of the ‘scar.’ Not only is the sea grass no longer able to provide amazing services, the seafloor can become unstable and start to erode.
Replacing sea grass after it is gone is costly and not always effective (and can take a long time), so keeping the sea grass in place is the best option. By identifying water ‘lanes’ where boats can easily pass (usually where the channel is a bit deeper and there is no sea grass to be affected) and educating boaters about the need to protect the sea grass beds, these incredible areas will help protect our shorelines, clean our water, and provide homes and feeding areas for fish for decades to come.
The Conservancy has received funding from the Coastal Impact Assistance Program, the National Fish and Wildlife Foundation, and other sources to work with a number of partners to map current sea grass beds, mark their locations, and share the message about their importance.