This winter I had an opportunity to visit the Blackwater National Wildlife Refuge on Maryland’s Eastern Shore. The Blackwater watershed contains one-third of Maryland’s tidal wetlands, however, sea level rise, erosion, subsidence, salt water intrusion, polluted runoff, and invasive species have resulted in the loss of over 8,000 acres of marsh (at a rate of 150 acres per year). The marshes are a great place for viewing wildlife, especially bald eagles, and are used by over 50,000 migratory birds as a stopover during fall migration.
I have to admit that when I visited and looked out at the open water I thought I was looking out on to the Chesapeake Bay. Only after coming home and looking at a map did I realize how far removed the wetlands are from the bay.
The #1 most wanted invasive specie in the refuge is the Nutria. They are large rodents that look like beavers and can weigh up to 20 lbs. They were first introduced to the area in 1943 by the federal government in an attempt to create a market for nutria fur. Unfortunately, the fur turned out to be worthless and the nutria were released. Now they roam the eastern shore with no natural predators – eating and reproducing. They are particularly detrimental to wetlands because, unlike other rodents that only eat the tops of grasses, the nutria dig down and eat the roots, killing the plant. They have decimated hundreds of acres of Blackwater marsh.
Not to worry, the refuge has an aggressive nutria extermination program that involves capturing, neutering, and releasing the nutria so they can be tracked to other popular nutria hangouts.
Thanks to tough Maryland runoff laws, the effects of polluted agricultural runoff are also being curtailed by requiring farmers to plant cover crops. A cover crop sequesters excess fertilizer not used by crops during the growing season. I’ve heard, first-hand, farmers complain about having to plant cover crops claiming that they can’t afford to use any more fertilizer than the minimum necessary for their crops to grow and therefore there shouldn’t be any left over in the ground. However, during my tour I learned that it’s not quite that simple, because the success of a growing season is not entirely up to the farmer. If rains come too late, too soon, or not at all, crops may not grow as robust and therefore use less fertilizer (or none at all). So, the problem is not always that crazy farmers are out there spreading as much fertilizer as possible. Farmers can do everything right and still end up leaving unused fertilizer in the ground. If a hard rain falls and no cover crop has been planted, this fertilizer gets washed into streams and wetlands where it promotes algae blooms and depletes the oxygen content of the water.
All in all, I was heartened by the work being done at Blackwater and hope to visit again during a warmer season. They have several wetland restoration projects and are often looking for volunteers to crawl into the swamps and plant some grass.