Recent testing of failed loon eggs from several lakes and ponds around the state, including one from Pool Pond in Rindge, showed elevated levels of contaminants.
The Loon Preservation Committee said in a press release the committee had found elevated levels of polychlorinated biphenyl ethers, or PCBs, dioxin-like compounds, and chlordane in loon eggs that failed to hatch and were collected from Province Lake, Effingham and Pool Pond.
PCBs are found in industrial insulating agents, dioxin-like compounds are byproducts of industrial processes, and chlordane is a pesticide.
The Loon Preservation Committee is authorized by state and federal permits to collect unhatched, inviable Common Loon eggs from failed nests for research. The Common Loon is a threatened species in New Hampshire. To date, the committee has tested 121 loon eggs collected from 47 lakes throughout the state.
Elevated levels of PCBs and dioxin-like compounds were found in a single loon egg taken from a Pool Pond nest in 2024. The levels exceeded levels found in other bird species. Levels of dioxin-like compounds were more than five times higher than samples from other bird species.
The committee noted that the Pool Pond results represent testing of a single egg, but it shows the need for more testing of loon eggs and fish in the pond.
Ted Diers, the assistant water division director of the New Hampshire Department of Environmental Services, said the Loon Preservation Committee’s research is important to finding how contaminants move through aquatic ecosystems.
“The findings of elevated pesticides and industrial contaminants in loon eggs highlight how these contaminants can accumulate and magnify in apex species as they interact with the ecosystem,” Diers said. “NHDES remains committed to enforcing regulations that prevent the contamination of water bodies and will continue its efforts to monitor contaminants in water bodies and biota across the state, as resources allow.”
Research by the Loon Preservation Committee and others has shown that the majority of nutrients and contaminants in loon eggs come from fish and other prey eaten in the weeks before the birds lay eggs. Contaminant levels in loon eggs can indicate contaminant levels in the fish and other organisms in lakes.
Two inviable Common Loon eggs collected from failed nests on Province Lake in Effingham and Wakefield, one in 2016 and the other in 2023 and recently tested, also showed elevated levels of PCBs, dioxin-like compounds, and chlordane.
Levels in the Province Lake eggs were three to nine times higher than those shown to affect the health or reproductive success of other bird species. PCB results for the 2016 egg were 21,900 parts per billion and 58,500 parts per billion for the 2023 egg, compared with a statewide average of 1,934 parts per billion. The level of PCBs in the 2023 Province Lake egg was last recorded at the height of PCB contamination in the 1970s, and the level of dioxin-like compounds and chlordane in that egg were the highest the committee has ever recorded.
Fish in Pool Pond and Province Lake have not been analyzed for the pollutants that were found in the loon eggs.
The Loon Preservation Committee works to protect loons throughout the state as part of its mission to restore and maintain a healthy population of loons in New Hampshire; to monitor the health and productivity of loon populations as sentinels of environmental quality; and to promote a greater understanding of loons and the natural world. For more information, visit www.loon.org.