Chesapeake Ecotox Research Program: Lab Tracking Impact of Pollutants

LAB TRACKING IMPACT OF POLLUTANTS

by Tracy Alderman, The Recorder Staff Reporter

A comprehensive program to test the effects of pollution on species is being conducted at the Chesapeake Biological Laboratory. The Chesapeake Ecotoxicology Research Program (CERP) began Jan. 1 and is slated to run through Dec. 31, 2004, pending the renewal of annual funding. The program focuses on energy in animal systems and how contaminants in the Chesapeake Bay can affect processes like reproduction and growth. The $1.5 million research initiative is designed to fill an important gap in our knowledge of how low, yet persistent levels of harmful pollutants affect important Bay species.

Since contaminants that have long term effects are typically found in greatest abundance in the muddy sediments carpeting the bay bottom, researchers will focus on organisms that live on or in the sediment. "Metals and organic compounds that settle to the sediment don't always stay there but can be recycled over and over again through the food web," said CERP Coordinating Investigator and Lab director Ken Tenore. Over time, these toxins can move up the food chain and accumulate in larger predators.

Two particular species, the amphipod [Leptocheirus] and mummichog, will be studied. Many generations of each species will be studied to see how contaminants affect them at the cellular level all the way through to the broader population level. Researchers are looking to see if contaminants influence, for example, the number and quality of eggs each female amphipod or mummichog can produce.

Leptocheirus plumulosus

For the first two years, amphipods, which are small invertebrates that live in the mud, will be studied. As the amphipod sits in the mud, it eats food and then in turn is eaten. Amphipods are important resources to other animals. If the mud has contaminants, the researchers believe that the amphipods should show some reaction to them. Although no larger than a half inch, amphipods have a heart, brain, complex eyes and gills. Female amphipods produce between four to 12 eggs during their 30 day lifespan. Amphipods look similar to shrimp, but without the hard tail portion. They are clear with black markings and have a hard shell over their bodies.

Mummichogs are small fish, which serve as food for many larger fish. The second part of the study will focus on them. Mummichogs can live several months to more than a year. At the adult stage, mummichogs grow to three or four inches long. They eat amphipods.

Mummichog

Because of their short lifespans, researchers will be able to document the average response of each species in a particular generation. At the Lab, tanks are set up side by side with seawater flowing through each of them. Mud at the bottom of the tanks will be collected from three test sites: Baltimore Harbor, the Elizabeth River in Virginia, and the Anacostia River south of Washington, D.C. These sites have been identified by the Environmental Protection Agency as areas of concern. "Given the level of contaminants at these sites, we would be really surprised if there weren't some biological effects going on," said Chris Rowe, an assistant professor at the Lab. These rivers are tributaries to the Chesapeake Bay. Animals move from these sites into the Bay to spawn, Rowe said. The program's findings should be transferable to the Bay and similar coastal ecosystems.

A control tank will be set up with mud from a relatively uncontaminated part of the Bay, Fishing Bay on the Eastern Shore. All of the fish will come from one group of fish in the lowest polluted area. Each year, new fish and mud will be collected and the experiment will be started anew.

The real value of this study is looking at the responses of animals over a long period of time because that's how they're exposed to pollution, Rowe said. If all goes well, researchers hope to discover how, and to what extent, pollutants move up the food chain. Historically scientists examined pollution and its effects by performing experiments that lasted a couple of days. CERP is one of the first programs that is taking a wholistic [sic] perspective and testing contaminants that exist in natural systems. The concentrations of contaminants vary by river.

Researchers will study contaminants including: PCBs, which were originally used to insulate transformers, the industrial chemical dioxin and heavy metals. They will also study chlordane, which is used in pesticides, and polycyclic aromatic hydrocarbons, which come from burning of fossil fuels. Finally they will examine the effects of arsenic, mercury and lead. "Different mixtures of contaminants can behave in ways you can't predict," Rowe said.

The final year of the program is designed to be a time when researchers will meet with regulatory agencies and scientists to review results and develop strategies to make things better or prevent them from getting worse. "In a nutshell," Rowe said, "CERP will provide us with an excellent opportunity to test our general picture of how animals change in response to pollution."

Mesocosms used in the experiments

Taking sample of sediment

Published in The Recorder, Southern Maryland, May 31, 2000