You are here:
Reproductive success and contaminant associations in tree swallows (Tachycineta bicolor) used to assess a beneficial use impairment in U.S. and Binational Great Lakes’ Areas of Concern
Citation:
Custer, C., T. Custer, M. Etterson, P. Dummer, D. Goldberg, AND J. Franson. Reproductive success and contaminant associations in tree swallows (Tachycineta bicolor) used to assess a beneficial use impairment in U.S. and Binational Great Lakes’ Areas of Concern. Ecotoxicology. Springer, New York, NY, 27(4):457-476, (2018).
Impact/Purpose:
There has been concern over contamination in the Great Lakes and its effects on biota, especially reproductive effects, for well over a half century. The contaminants of concern in this highly industrialized urban landscape include many legacy organic chemicals such as PCBs, dioxins and furans, pesticides, trace elements, polycyclic aromatic hydrocarbons (PAHs), as well as, some newly emerging contaminants such as polybrominated diphenyl ethers and perfluorinated chemicals. Many of these chemicals have been shown to cause reduced hatching success in multiple species of birds nesting in the Great Lakes and elsewhere, because of embryo toxicity and through behavioral modification mechanisms. The Great Lakes Restoration Initiative was funded to assess current conditions and remediate, as needed, contaminated harbors and rivers across the Great Lakes at specific locations which were designated as Areas of Concern (AOCs) by the Great Lakes Water Quality Agreement (2012), first signed in 1972. The metric to quantify success is when an AOC can be delisted because all of its Beneficial Use Impairments (BUIs) have been removed. The Bird or Animal Deformities or Reproductive Problems is one of 14 BUIs and is listed as impaired at 15 AOCs. This manuscript examines this BUI with respect to Tree Swallow (Tachycineta bicolor) nesting success at AOCs across the Great Lakes. The results will assist the US and Canada to decide whether this BUI impairment has been removed.
Description:
During 2010-2014, tree swallow (Tachycineta bicolor) reproductive success was monitored at 68 sites across all 5 Great Lakes, including 58 sites located within Great Lakes Areas of concern (AOCs) and 10 non-AOCs. Sample eggs were collected from tree swallow clutches and analyzed for contaminants including polychlorinated biphenyls (PCBs), dioxin and furans, polybrominated diphenyl ethers, and 34 other organic compounds. Contaminant data were available for 360 of the 1249 clutches monitored. Markov chain multistate modeling was used to assess the importance of 5 ecological and 11 of the dominant contaminants in explaining the pattern of egg and nestling failure rates. Four of 5 ecological variables (female Age, Date within season, Year, and Site) were important explanatory variables. Of the 11 contaminants, only total dioxin and furan toxic equivalents (TEQs) explained a significant amount of the egg failure probabilities. Neither total PCBs nor PCB TEQs explained the variation in egg failure rates. In a separate analysis, polycyclic aromatic hydrocarbon exposure in nestling diet was significantly correlated with the daily probability of egg failure. The eight sites within AOCs which had poorer reproduction when compared to 9 non-AOC sites, the measure of impaired reproduction as define by the Great Lakes Restoration Initiative, were associated with exposure to dioxins and furans, PAHs, or depredation. Only 2 sites had poorer reproduction than the poorest performing non-AOC. Using a classic (non-modeling) approach to estimating reproductive success, 82% of nests hatched at least 1 egg, and 75% of eggs hatched.
