July 1 Lecture to Examine the Impacts of Low Oxygen in the Delaware River

July 1 Lecture to Examine the Impacts of Low Oxygen in the Delaware River

June 29, 2021 Written by Adam Thomas

Low oxygen levels have been a problem in the Delaware River for quite some time, and while levels have improved in recent years, there is still work that needs to be done to increase the oxygen in the river that marine creatures depend on for survival.  

The ripple effects that stem from low oxygen in the Delaware River will be the topic of discussion on Thursday, July 1 at 7 p.m. when David Kirchman and Gerald Kauffman give a virtual lecture titled Dead Zone in the Delaware River: Impact of Low Oxygen on Fish, the Economy, and Society. The lecture is part of the Ocean Currents lecture series.

Sponsored by UD’s College of Earth, Ocean and Environment and the Delaware Sea Grant College Program, the Ocean Currents Lectures are virtual events that are free and open to the public, featuring one-hour in-depth presentations on the interesting and impactful work of faculty and staff. The series is presented in partnership and with additional speakers from UD’s College of Agriculture and Natural Resources, Joseph R. Biden, Jr. School of Public Policy and Administration, and Delaware Environmental Institute, known as DENIN.

Kirchman, the Maxwell P. & Mildred H. Harrington Professor Emeritus of Marine Studies at UD, recently authored a book titled Dead Zones: The Loss of Oxygen from Rivers, Lakes, Seas, and the Oceanand said the talk will highlight how much more environmental improvement is needed in the Delaware River.

The Delaware River may not be a dead zone anymore, but it’s not as if we have life 100 percent back in the river,” said Kirchman. 

When bodies of water experience low levels of oxygen, it leads to what is known as hypoxia, which is when water has less than two milligrams of oxygen per liter. Water can’t hold much oxygen to begin with so any decrease of oxygen is a problem, especially when it leads to hypoxia. 

The reason for low levels of oxygen in bodies of water can vary from untreated sewage spilling into waterways, which is what caused hypoxia in the Delaware River in the 20th century and is still an issue in developing countries, as well as nutrients from agricultural sources that enter the water and cause algal blooms and excessive algal growth. 

“When that organic matter from the algae sinks to the bottom, it’s degraded by the bacteria, which uses up all the oxygen in the bottom waters of places such as the Gulf of Mexico, the Chesapeake Bay and the Baltic Sea in Europe,” said Kirchman, who covers these and other areas in his book. “The most famous, or infamous, dead zone is the Gulf of Mexico. Every summer, it has large areas, typically said to be the size of New Jersey, that don’t have enough oxygen. That’s been going on since probably the 1950s.” 

The low levels of oxygen in the Delaware River crop up especially in the summer, and while it might not be quite to dead zone levels today, the low oxygen levels are still a problem and threaten fish species that live in the river, such as the endangered Atlantic Sturgeon. 

Not only are the fish impacted by the low levels of oxygen in the river, but there are also impacts on the local Delaware economy as well. 

Kauffman, director of UD’s Water Resources Center, will address the economic implications of dead zones in the Delaware and elsewhere during the talk, sharing the impact dead zones can have on the economy and other aspects of society.

“It's worth investing in the Delaware as the river supplies drinking water to five percent of the U.S. population, including the first and sixth largest metropolitan economies in America, and supports a $22 billion annual economy and over 500,000 jobs,” said Kauffman. “Our research at UD indicates continued improvement in dissolved oxygen over the last half century from the 1960s dead zone to a year-round fishable standard that provides over $1 billion a year in socioeconomic benefits to the Delaware Valley.” 

To help fight against these dead zones, the biggest focus has been on preventing excess nutrients from entering the waterways. In addition to asking farmers to lessen their use of fertilizers, there are also buffer zones—strips of land that are bordering lakes and rivers—being installed around waterways to help intercept the nutrients before they get into the bodies of water.

Kirchman said that in researching his book, he realized that the best approach to help with the problem would be to lessen the amount of fertilizer farmers are using on their fields. On an individual level, people in the United States can help with the problem by modifying their diets and consuming less food overall, especially less beef. 

He also found that one of the most rewarding parts of writing the book was getting to interview other experts in the field and talk with them about how they got interested in researching dead zones in the water. 

“You always learn more when you talk to someone in person or over the phone. I talked with some of the people working on the dead zone in the Gulf of Mexico and the Baltic—not so much to learn the science, but I wanted to hear their back story about how they got into it and some of the difficulties they had in studying the problem,” said Kirchman. “That was a lot of fun, getting to hear those types of stories. I have the science in the book but also the stories about the people who discovered the science.” 


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