Biinaagami
Herring gulls soaking up the sunset at a nesting colony in the Fishing Islands, Lake Huron, Ont.
Herring gulls are not typically admired or revered — they are boisterous, noisy and infamous for harassing picnickers and beachgoers. They adapt extremely well to urban environments, building their nesting sites on rooftops, and sometimes dropping unexpected “guano bombs” on those below. Ubiquitous to shorelines of the Great Lakes, the choking call of a herring gull is unmistakable.
Despite their reputation, these unlikely heroes have been instrumental in helping scientists better understand changes to environmental health over long periods of time. Their eggs may hold the secret to understanding the chemicals that permeate the Great Lakes — and what they mean for the region’s environmental future.
Over the past two centuries, rapid settlement and industrialization have dramatically altered ecosystems across the Great Lakes-St. Lawrence watershed. With the outbreak of urban, industrial and agricultural development came chemical contaminants that continue to make their way into the Great Lakes. The same Great Lakes that hold 21 per cent of the world’s fresh surface water.
In the early 1970s, government agencies on both sides of the United States-Canada border launched a series of monitoring programs to ascertain just how pervasive harmful contaminants — derived from pesticides, industrial chemicals and manufacturing — are in the Great Lakes basins, and how they can impact human health.
At that time, waterbirds were observed to have physical abnormalities and a low success rate at hatching eggs throughout the Great Lakes. Numerous species were experiencing widespread reproductive failure, including common terns, double-crested cormorants and herring gulls. The main cause of this was believed to be contaminants astray in the environment, specifically polychlorinated biphenyls (PCBs).
Since 1974, the Canadian Wildlife Service, part of Environment and Climate Change Canada, has been gathering gull eggs each spring at 15 nesting sites across the Great Lakes-St. Lawrence watershed, through the annual Great Lakes Herring Gull Monitoring Program. The program was designed to survey the health of the waterbirds, as well as to track legacy and emerging contaminants in the freshwater environment, while keeping the eggs refrigerated for future examination.
“The big thing about colonial waterbirds, including herring gulls, is that they’re almost all fish eaters,” explains Chip Weseloh, an emeritus wildlife biologist who, before retiring in 2013, was the lead field biologist with the program.
Weseloh navigates his vessel, the Jalak Bali, towards the Brother Islands nesting colonies on Lake Ontario
Weseloh worked for the Canadian Wildlife Service for more than over 35 years — in those decades, the water birds of the Great Lakes and their nesting sites became a big part of his life. “I was the guy who went around to all the colonies, two or three on each of the Great Lakes and made the egg collection in the last part of April and the first part of May,” he says.
Herring gulls weren’t just chosen as study subjects because they’re contaminant magnets. Unlike other waterbird species, Weseloh explains, herring gulls don’t migrate from the Great Lakes — they stay there year round. “You’re pretty sure that the compounds you’re getting in the herring gull, tried and true, come from the Great Lakes and there’s very little chance of input from outside the Great Lakes,” says Weseloh. In the colder months, “herring gulls from Lake Superior, Lake Huron and Lake Michigan migrate south into Lake Ontario, Lake Erie and Southern Lake Michigan — always staying within the Great Lakes ecosystem.”
As opportunistic feeders with multiple entry points to the food chain, the gulls reflect the overall health of the Great Lakes ecosystem. A herring gull’s varied diet of plants, mammals, seabirds, insects, fish and crustaceans means contaminants can come from any direction.
When an organism ingests a compound faster than it can metabolize or excrete it, the contaminant accumulates in that organism over time. This process is called “bioaccumulation.”
But if multiple organisms laden with contaminants, say a fish or crustacean, are then eaten by organisms higher up in the food chain, like a herring gull, the predator ends with an even higher dose of contaminants. This amplification of contaminants through the ecosystem is known as “biomagnification.”
Nesting herring gulls, Fishing Islands, Lake Huron
Because fish are the top predator in the water, they are more exposed to contaminants as they gradually accumulate up the food web, says Weseloh. “The fact that you’ve got another predator feeding on the highest ranking organism in the lake is a really good indicator for transfer of contaminants.”
When herring gulls reproduce, these accumulated contaminants are transferred to their eggs, resulting in intergenerational bioaccumulation.
So: what are the contaminants that are plaguing the Great Lakes?
Marta Venier, an environmental chemist at the Paul O’Neill School of Public and Environmental Affairs at Indiana University in Bloomington, Indiana, studies the fate and fallout of persistent organic pollutants in the indoor and outdoor environment — including both legacy and emerging pollutants. Legacy pollutants are industrial chemicals that, like other persistent organic pollutants (POPs), were introduced into the Great Lakes decades ago — and that are still traceable in the environment today. “They’re known as ‘forever chemicals’ because of their resistance to decomposition.” says Venier during a presentation at the 2024 Let’s Talk Lake Erie webinar.
A group of 12 chemicals are particularly problematic, according to Venier. “One way of grouping these chemicals is in the nickname: the dirty dozen. These are 12 chemicals that were first regulated under the Stockholm Convention on persistent organic pollutants — and they include a wide range of pesticides, such as DDT, that we call legacy pesticides.”
“The dirty dozen also includes industrial chemicals,” she continues. “The most famous ones are polychlorinated biphenyls (PCBs), along with other products that are not produced intentionally — for example, dioxins and furans.”
Starting in 1929, PCBs were broadly used in a range of products including paints, batteries, transformers and capacitors. The import, manufacture and sale of PCBs in Canada were made illegal in Canada in 1977, and release into the environment was made illegal in 1985. They were banned in the United States in 1979 under the Toxic Substances Control Act (TSCA).
“The last but not least group of chemicals that we are interested in are PFAS, a nasty acronym that stands for per- and polyfluoroalkyl substances,” Venier adds. PFAS, are toxic chemicals widely used in household products for their stain-resistant and hydrophobic properties.
Weseloh tallies a nest count on East Brother Island, Lake Ontario
Point sources of contamination are wastewater treatment plants and industrial discharge facilities that directly release into lakes, rivers and streams. However, fertilizers, pesticides and herbicides that are used on agricultural fields and urban areas and that eventually find their way into the watershed, are known as non-point sources, according to Venier.
Legacy contaminants, such as PCBs, Chloroquine, Dox and Sperins have all declined considerably in the waters of the Great Lakes, including Lake Erie, since the early 1970’s. PCBs seem to have levelled off in Lake Erie without further decline in that basin since early 2000s and yet, near the River Raisin Area Of Concern (AOC), they remain the dominant organic contaminant found in gull eggs, says Venier.
This might be due to non-point sources via atmospheric deposition, or dredging up the lake bottom, resulting in the release of contaminants that may have become re-suspended in sediments on the lake floor over time.
PCBs released into the water column are then taken up by phyto- and zoo-plankton and consumed by small fish and so on up the food-chain, explains Weseloh. And thus: they’re present in herring gulls who live generations after these chemicals were banned.
Each year, the herring gull monitoring program collects and stores a few more eggs than needed, and saves them for future testing as new contaminants are detected and scientific advancements improve test efficacy. “There’s a lot of things that are becoming of concern now that weren’t of concern years ago,” says Weseloh.
At just over 50 years old, the Great Lakes Herring Gull Monitoring Program is the longest serving annual monitoring program for contaminants in the Great Lakes basins. “There are other surveys that have been going longer,” says Weseloh, “but they’re either every two years or every five years — something like that. Annual sampling is really the ultimate way to fly.”
A herring gull chick hatches from its egg in early May. Fishing Islands, Lake Huron
Five decades is but a fraction of the time Indigenous Peoples have been monitoring changes in the environment: since time immemorial. Indigenous populations, who maintain close relationships to the land and waters through hunting and fishing, are also among the most vulnerable to the harmful effects of pollutants.
With multiple First Nations living within close proximity to some of the 15 nesting sites used for the collection of gull eggs by the herring gull monitoring program, its findings can also provide insights that may help us further understand disproportionate health concerns in First Nation communities.
Nearly 40 million people who live within the Great Lakes region rely on the same waters as the herring gulls for clean drinking water. It’s not just the gulls and the fish they consume that are exposed to the dirty dozen. Investigating legacy pollutants in herring gull eggs also helps scientists to explore the potential risks to humans living among the Great Lakes.
“Exposure to some types of PFAS has been linked to certain types of cancer, immune disease, developmental delays in children, and reproductive health problems,” Venier explains.
While the herring gull monitoring program examines the health of the Great Lakes through the looking glass of gulls eggs, how do we reduce the level of toxic contaminants in the freshwater ecosystem?
The top priority is to prevent toxic point and non-point sources from entering the environment. However, effectively reducing the current level of contaminants in the Great Lakes demands an extraordinary collective strategy.
Newborn herring gull fledgling bathes in sunlight with her siblings. Fishing Islands colony. Lake Huron
Among the more cutting edge methods of mitigating this mess: scientists are shining light on the issue by exploring the reduction of POPs and contaminants of emerging concern by applying advanced oxidation technologies as well as a process known as photocatalysis. Like photosynthesis, photocatalysis produces a photochemical reaction via sunlight that can degenerate certain toxins and pollutants in the atmosphere as well as in wastewater. Both oxidation and reduction occurs simultaneously — a process that can break down contaminants.
We might also find it encouraging to know that the earth itself can be part of the solution. “There is natural remediation that happens,” says ecotoxicologist Shane De Solla, who is also involved in the monitoring program, and also presented at the 2024 Let’s Talk Lake Erie Webinar. “Microbes can be very effective and break down at least some types of contaminants. Bacteria can actually take apart PCBs and break them down into smaller chunks. So there is sort of a natural remediation that’s happening and there may be ways that we can increase these microbes in soil or sediment to increase it.”
Residents within the Great Lakes region can also make a difference by learning about harmful chemicals used in everyday household products and eliminating their use while properly disposing of household hazardous waste.
Collectively, our shared responsibilities to restore the Great Lakes will continue to involve more than just human effort, too.
As the first light of dawn pierces through the hatching eggshell of a herring gull chick, little does she know how intertwined she is already with the outside world. Within a few hours, she emerges beside two siblings (herring gulls will generally produce a clutch of three eggs). Soon, their mother arrives with a regurgitated meal of savoury rainbow smelt. How quickly the little nestling will have to scramble to her feet to survive on her own.
The fledgling only knows the protective shadow of her parents standing on guard at her side. That regurgitated fishmeal is delicious. Existence among the nesting colonies was to be a raucous celebration for survival.
The partially clouded skies above her appear alluringly, as though they were created to be carved by flight. She knows nothing about the dirty dozens of contaminants, adrift in the freshwater environment, in the fish, nor in the egg she derived from. She is certain, however, she hatched right where she belongs.
