An aerial view of Prime Hook National Wildlife Refuge in Milton, Delaware. Wetlands, like those shown here, has many benefits for a bay's ecosystem, including filtering runoff, mitigating floods, and as a home to baby fish and invertebrates. (Photo courtesy U.S. Fish and Wildlife Service)
How can we defend Delaware Bay’s ecosystem?
Fifteen years ago, fishing in the Delaware Bay was drastically different. The diminishing fish population reflects a downturn in water clarity and quality. Bait turns brown within minutes of being placed in the water, and fish fight clouds of mud sweeping down the bay. Just a decade and a half ago, “you would load 200-quart coolers up with croaker, and now you are lucky to catch three,” said Keith Beebe, a Charter Captain from Delaware’s coastal town of Lewes. Each year, the fishing in this area has gotten poorer and poorer.
Some of the ways humans degrade water quality in coastal areas is through nutrient pollution, land-use change, and industrial contamination. The Delaware Bay and its tributaries are not only affected by activities in the immediate area, but from those that might occur at the far reaches of the watershed. These upstream inputs of pollution eventually work their way downstream to the bay where they are accumulated and compounded.
“One of the largest sources of pollution is from fertilizers that lead to nutrient pollution and eutrophication within our waterways,” said Taylor Deemer, a Master of Science student in Marine Biosciences at the University of Delaware, Lewes campus.
Deemer explains that farmers anticipate losing a portion of the fertilizer that they put down on their fields to runoff from rain events. As a result, to ensure that their crops receive the proper amount of nutrients, they often put down extra. These nutrients are not just useful for promoting the growth of terrestrial plants, but also promote the growth of aquatic ones as well, such as phytoplankton. Eutrophication is when these excess nutrients reach the bay, leading to what is known as algal blooms, which are proliferations of various phytoplankton species.
Phytoplankton is generally a good thing in aquatic systems, as it provides much of the oxygen that aquatic organisms need to survive. These bloom events, however, lead to bacterial growth that draws down the oxygen levels and lead to fish kills for those organisms that can’t escape the area.
Options to combat nutrient pollution would be to simply use less pesticides, herbicides, and fertilizers. An additional option is to find methods of application that incorporate the fertilizers into the soil, rather than just spreading them across the surface where they run off more easily.
Another issue that promotes these blooms is land-use change. Changing the usage of land is especially problematic when coastal salt marsh environments are removed and used for other purposes, like home developments, shopping centers, and industrial properties. Salt marshes, when present, act as buffers between the mainland and the estuaries. They absorb runoff pollution from the mainland, trapping it in the sediments. These systems also mitigate coastal flooding events by acting as a drainage area during times of increased water level, such as major storms or extreme tidal events.
Deemer added: “They also provide a nursery habitat for many species of fish and invertebrates, acting as a safe space for the young to grow and mature.”
I, personally, have spent countless hours educating the public on the importance of these wetlands as the creative director of a team of UD students. As a team, we constructed a display on vernal pools for the 2018 Philadelphia Flower Show. With this display, we illustrated how crucial ephemeral pools and wetlands are to the reproduction and development of aquatic species.
When speaking with Deemer, I asked whether building berms to combat nutrient pollution would be effective. But he said, “It would be really difficult to intercept all of the water by building berms. It would be much easier and more environmentally friendly to promote wetland habitat protection and restoration.”
Wetland restoration was the focus of the University of Delaware’s piece at the flower show. The exhibit urged attendees to contact their local department of natural resources to find out if there are certification programs in their areas. Some states even have programs where citizens document vernal pools so they are protected. And you can do the same from your home, and your state. Just look up your local department of natural resources, or check for a local extension office.