In their cross-country study, researchers Kees Vermeer and David Peakall found that birds from the Great Lakes are contaminated with toxins. These contributed to the thinning of eggshells with Double-crested Cormorants.
They also found that Herring Gull eggs, which are found near Lake Ontario, have high levels of chlorinated hydrocarbon. Aside from that, the fish-eating birds found in Northern Ontario have been contaminated with mercury.
Water pollution has affected the food chain from marine species to birds. These serve as a good indicator of how pollution can affect the population of these birds in Canada. It needs to be noted whether the population decline resulted in water pollution or from other contributors such as the weather, climate change, or season.
These contaminated birds can also serve as indicators of how polluted these ecosystems are. Since there are many niches of fish-eating birds residing near marine habitats, researchers will be able to study more closely the pollution indicators for the aquatic food chain.
Addressing fish-eating birds contaminated with toxic chemicals must be done first by cleaning the water systems they feed in. The source of the contamination should be reduced. This can lead to more strict waste management, especially for chemicals.