Areas of Concern: Effects of Contaminants of Emerging Concern on Avian Biota in the Great Lakes

Science Center Objects

The objectives of this work are to evaluate whether there is compelling evidence that Contaminants of Emerging Concern (CECs) are eliciting adverse effects in Great Lakes fish and wildlife.  A second objective is to develop efficient strategies and develop endpoints to survey for, and monitor threats, that CECs may pose before those threats become large scale impacts on Great Lakes ecosystems or ecosystem services.

Scientist performing egg dissection on collected samples

A scientist performs egg dissection on collected samples. 

(Public domain.)

Using tree swallows, as well-developed avian model species for ecotoxicological studies, exposure and effect endpoints from the molecular and genetic level to population level effects were assessed.  At multiple sites along both the Maumee River and in the Milwaukee Estuary, samples were collected for analytical chemistry, including new agricultural pesticides, pharmaceutical and personal care products, and other newer industrial and urban contaminants.  Additionally, a suite of samples for biomarker analyses targeting ‘effect’ pathways, such as the aryl-hydrocarbon detoxification pathway, the thyroid axis, and genetic damage were assessed in the same individuals for which contaminant exposure was assessed.

Fourteen study sites near Toledo, Ohio (Maumee River) and in the 3 drainages that comprise the Milwaukee Estuary were chosen in collaboration with other Federal Partners (NOAA, EPA [their research centers in Duluth and Cincinnati], USFWS, and USACOE) so that multiple endpoints from different taxa (aquatic insects, mussels, fish and birds) and matrices (sediment and water) could be assessed jointly to better understand possible effects of CECs in different parts of the Great Lakes ecosystem and in different food webs. In addition, information from additional study sites across the Great Lakes, primarily from Areas of Concern (AOCs) and nearby non-AOC sites, are being integrated into the ongoing analyses of CECs.

Despite extremely high exposure to a range of PFASs, predominately perfluorooctane sulfonate, there were few if any physiological responses or reproductive effects documented in tree swallows nesting near the contaminated marsh in Oscoda Township.  The source of the PFASs at that location were a former air force base which conducted extensive fire-fighting training exercises at that site. Few of the 140 pharmaceutical and personal care products (PPCP) that were analyzed along both the Maumee River and Milwaukee area rivers, were detected in tree swallow tissues. The 2 PPCPs that were routinely detected, DEET and Iopamidol, were detected in most biotic tissues, but also in the swallow tissues are remote Wisconsin lakes. Few of the newer agricultural pesticides, which included herbicides, fungicides, and organophosphate and carbamate insecticides, were detected in tree swallow tissues except for 1 metabolite of atrazine, a widely used agricultural herbicide. Data summarization and analysis are ongoing specifically for data from the Maumee and Milwaukee Estuary study locations.

These data are providing a unique assessment of exposure to, and effects of CECs on a model avian species to meet the objectives identified under GLRI, Action Plan II, Focus Area 1, to "Identify emerging contaminants and assess impacts on Great Lakes fish and wildlife".  Additionally, these data are being collected on an unprecedented scale, across all 5 Great lakes at more than 75 individual sites and can be used in conjunction with the restoration and delisting objectives which are also part of Focus Area 1 of the current GLRI Action Plan.


Custer, C.M., Custer, T.W., Delaney, R. et al. Perfluoroalkyl Contaminant Exposure and Effects in Tree Swallows Nesting at Clarks Marsh, Oscoda, Michigan, USA. Arch Environ Contam Toxicol 77, 1–13 (2019).

A Story Map was created and is being updated regularly that uses this web-based tool for easy access exposure and effects data by State and Federal personnel.


  • SGS-AXYS Analytical completed metabolomic analyses on the Maumee River tree swallow samples and on the first of the 2 years of analyses from the Milwaukee Estuary. This included QA/QC analyses and data file creation.
  • Baylor University (Waco, Texas) collaborators have finished sequencing the tree swallow transcriptome and have nearly completed their work on constructing the transcriptome from the Maumee River and Milwaukee Estuary samples. Statistical analyses of those data especially as it relates to contaminant exposure and the other biomarker responses are ongoing.
  • U.S. Army Corps of Engineers (USAOCE)
  • U.S. Fish and Wildlife Service (USEFWS)
  • U.S. Environmental Protection Agency (USEPA)
  • National Oceanic and Atmospheric Administration (NOAA)