A study from Calvin University found that fish-eating water birds in some contaminated areas of the Great Lakes experience negative health impacts, particularly related to growth and development.
The study assessed herring gulls, Caspian terns, and black-crowned night herons between 2010 and 2019 in Grand Traverse Bay and in polluted areas called Areas of Concern in the Saginaw River, Saginaw Bay and in the River Raisin.
Keith Grasman, professor of biology at Calvin University, is the lead researcher. Grasman said the contaminants that are impacting these water birds primarily come from legacy pesticides and industrial chemicals.
“They're older chemicals, but they're very persistent in the environment,” Grasman said. “And so we still see significant concentrations, even though much of the use of those chemicals or release of those chemicals has been reduced.”
The study found herring gull embryos had a two to three fold relative risk ratio for nonviability in all the areas tested. The contaminated sites also had higher levels of embryo and chick deformities, such as crossed bills and gastroschisis.
Herring gull and Caspian tern chicks had lower immune function at all of the contaminated sites studied compared to non-contaminated sites in the area. Data for the black-crowned night herons were collected in different years but results in Saginaw Bay also saw a decrease in immune function.
The Areas of Concern studied in River Raisin and Saginaw Bay had fewer breeding populations of colonial water birds, a finding that is consistent with earlier studies.
The study was part of the Great Lakes Restoration Initiative and had additional funding from the U.S. Fish and Wildlife Service. Grasman said studies such as this one inform cleanup efforts and can help the Great Lakes community better understand the impact of contamination.
“There's a huge amount of public interest in the lakes as a natural resource [and] places for recreation, but also their ecological value,” Grasman said. “And these studies help us to assess where we're at in terms of cleaning up previous pollution problems and also monitoring for the effects of new chemicals.”
Grasman also said it's important for those in the Great Lakes region to be mindful of the impact of the pesticides and industrial chemicals they use.
“There's an important lesson to be learned here about the chemicals that we use for many different technologies in our society. And many of the chemicals that we're looking at — the polychlorinated biphenyls, dioxins, and dibenzofurans — have been used for many, many decades. And their use and release were restricted many decades ago, but they are still causing problems because they are so persistent in the environment.”
