Professor of Oceanography Jonathan Sharp suggests ways
to make estuaries cleaner. Photo by Tammy Beeson
In the 400 years since Henry Hudson anchored the Half Moon in the mid-Atlantic, humans have abused the Delaware River and Bay system by loading it with municipal and industrial wastes.
The result? A river so unhealthy that by the 1940s it completely lacked oxygen and was largely void of aquatic life in the summer.
But as attendees learned at the University of Delaware’s April 3 Wilmington Lunch and Lecture event, cleanup efforts have brightened the estuary’s outlook.
In his lecture “Delaware River and Bay Health: History and Implications,” UD Professor of Oceanography Jonathan Sharp detailed how as early as the 1680s, humans were placing stress on the estuary. They put raw sewage into the river even though it was a primary source of drinking water. That led to human disease outbreaks such as typhoid fever.
The sewage, which combined with other contaminants such as industrial outflows and urban runoff, also caused a large demand for oxygen in the estuary. If all the oxygen is used, Sharp explained, aquatic life can’t survive. Also, sulfate is reduced, producing hydrogen sulfide and a rotten egg odor.
As the years passed, that’s exactly what happened. By the 1940s in the waters near Philadelphia, the river completely lacked oxygen in the summers. It produced hydrogen sulfide that turned white ships grey. The river’s smell even threatened its use as a port, according to a July 1944 Philadelphia Record article that Sharp shared.
“Nothing is safe from [the] destructive fumes,” the article reads. “Silverware and trophies aboard ships in port become so deeply tarnished they cannot be cleaned; furniture painted white turns rainbow-hued.”
Thankfully, about 20 years ago the river’s health got a tremendous boost.
“Between 1970 and 1990 there was a very dramatic improvement in water quality due to upgrade in sewage treatment plants,” Sharp said, adding that today the Delaware River and Bay system is relatively healthy and no longer experiences lack of oxygen in the summer.
However, there are other symptoms of human stress on estuaries, and the Delaware still has need for further improvements. Experts are aiming to lower concentrations of contaminants like PCBs and DDT residues. In addition, the cumulative effect of habitat alteration and overexploitation of fisheries resources require continuing remedial efforts.
Sharp also explained that there are lessons to be learned from the Delaware’s challenges. With remediation efforts in other estuaries including the Chesapeake, it’s important to consider ecosystems’ complexities, he said.
First, each river and bay system has its own characteristics that make it react differently to stresses placed upon it. Second, there can be a variety of contaminants affecting the system, including inputs such as fertilizer, waste from farm animals, and even pharmaceuticals. Alteration of habitat or other changes to the ecosystem also can add to the mix.
“All of these together interact,” he said. “It’s arrogant to think ‘well we can do one simple silver bullet magic fix and everything will be fine.’”
Continuing regulation of municipal and industrial inputs, control of inputs from activities such as domestic lawn fertilization, and support of habitat restoration and protection were a few of the action items Sharp suggested.
The Wilmington Lunch and Lecture events are held at the Hotel du Pont and are sponsored by UD’s College of Marine and Earth Studies (CMES) and the Delaware Sea Grant College Program. Sharp’s lecture also was supported by DuPont Clear into the Future.
To watch a video of Sharp’s lecture and to download his presentation slides, visit http://www.ocean.udel.edu/seagrant/wilm_lect_3apr08.html.
To learn more about the Delaware Sea Grant College Program, visit www.deseagrant.org. For more about CMES, visit www.ocean.udel.edu.