Reproductive success of passerines exposed to polychlorinated biphenyls through the terrestrial food web of the Kalamazoo River

Nesting success of red-winged blackbirds (Agelaius phoeniceus) in marshes in an anthropogenic landscape

Recent analyses show significant population declines in many abundant avian species, especially marsh-nesting species including the red-winged blackbird (RWBL). Hypothesized causes include reduced nesting success resulting from changing land-use patterns and exposure to contaminants. Our goal was to test the hypothesis that landscape and nest characteristics as well as exposure to polychlorinated biphenyls (PCBs) correlate with nesting success. From 2008 to 2014, we measured clutch size, egg and nestling mass, hatching and fledging success and daily survival of 1293 RWBL nests from 32 marshes in the Hudson River valley of New York. Using generalized linear effect and survival models, we found that: (i) Julian date was negatively related to hatching success and clutch size but positively related to egg mass; (ii) nest height was negatively related to hatching success; (iii) nestling mass decreased with increased nest density and distance to edges; (iv) fledging success was significantly lower in nests closer to the ground that were far from water; and (v) clutch size and daily survival were higher in nests farther from water. Results showed that nesting success was correlated with variables associated with flooding, population density and predation and provided no support for the predicted negative effects of PCB exposure.

Carcinogenic and teratogenic status of human population and polychlorinated biphenyls contaminations of soils and biota (European pied flycatcher) in a Perm (Western Ural, Russia)

Polychlorinated biphenyls (PCBs) are included in the persistent organic pollutants designated by the Stockholm Convention and are hazardous compounds both for the environment and public health. The aim of this study was to determine the level of environmental pollution of PCBs in the Perm, in soil and biota (European pied flycatcher), and to analyze whether its presence was the cause of cancer and congenital malformations in the population. Soils in the study area had PCB concentrations of 101.87 µg/kg in the Industrialniy District and 27.81 µg/kg in the Leninskiy District of the Perm in 2005. The chemical composition of the individual PCBs and PCB groups were the same in the soils of both regions. The blood of nestlings of the European pied flycatcher raised in the Industrialniy District contained 9.61 ng PCB/ml, while those in the Leninskiy District had 5.64 ng PCB/ml in 2005. A linear correlation was established between the PCB contamination of soils and PCB contamination of pied flycatcher nestling's blood, and inverse linear correlation was established between the content of PCB in the blood of nestlings and the success of breeding of the pied flycatcher in Perm. An epidemiological analysis revealed a high incidence of cancer among the human population of the Industrialniy and Leninskiy districts (371.7 and 376.85 cases per 100,000 population, mean for the 2003-2018, respectively), which exceeded the figure for the whole of Perm (350.77 cases per 100,000 population, mean for the 2003-2018). The incidence rate of congenital malformations in Perm for the study period was 48.51 per 1000 human births. However, a decrease in the concentration of PCBs in soil and biota over a 15-year period (2005-2019) to the less than the detection limit did not lead to a decrease in the incidence of these diseases. Probably, PCB contamination was not the main cause of oncological diseases and congenital malformations in the population of the study area.

Deriving Field-Based Ecological Risks for Bird Species

Ecological risks (ERs) of pollutants are typically assessed using species sensitivity distributions (SSDs), based on effect concentrations obtained from bioassays with unknown representativeness for field conditions. Alternatively, monitoring data relating breeding success in bird populations to egg concentrations may be used. In this study, we developed a procedure to derive SSDs for birds based on field data of egg concentrations and reproductive success. As an example, we derived field-based SSDs for p, p'-DDE and polychlorinated biphenyls (PCBs) exposure to birds. These SSDs were used to calculate ERs for these two chemicals in the American Great Lakes and the Arctic. First, we obtained field data of p, p'-DDE and PCBs egg concentrations and reproductive success from the literature. Second, these field data were used to fit exposure-response curves along the upper boundary (right margin) of the response's distribution (95th quantile), also called quantile regression analysis. The upper boundary is used to account for heterogeneity in reproductive success induced by other external factors. Third, the species-specific EC_10/50s obtained from the field-based exposure-response curves were used to derive SSDs per chemical. Finally, the SSDs were combined with specific exposure data for both compounds in the two areas to calculate the ER. We found that the ERs of combined exposure to these two chemicals were a factor of 5-35 higher in the Great Lakes compared to Arctic regions. Uncertainty in the species-specific exposure-response curves and related SSDs was mainly caused by the limited number of field exposure-response data for bird species. With sufficient monitoring data, our method can be used to quantify field-based ecological risks for other chemicals, species groups, and regions of interest.

Seasonal Differences in Contaminant Accumulation in Neotropical Migrant and Resident Songbirds

For many years, it has been hypothesized that Neotropical migrants breeding in the United States and Canada accumulate organochlorine pesticides (OCPs) while on their wintering grounds in Latin America. We investigated the seasonal accumulation of persistent organic pollutant (POPs) in migrant and resident passerines in Texas, Yucatán, and Costa Rica collected during the fall, winter, and spring from 2011 to 2013. A total of 153 birds were collected, and all contained detectable levels of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and OCPs with dichlorodiphenyldichloroethylene (DDE) being the most predominant pesticide. OCPs and PCBs were the predominant contaminants, accounting for ≥80 % of the total POPs burden, whereas PBDEs accounted for ≤16 %. Only spring migrants from Texas had significantly greater DDE concentrations (64.6 ng/g dry weight [dw]) than migrants collected in Costa Rica (23.2 ng/g dw). Resident birds in Texas had significantly greater levels of DDE (121 ng/g dw) and ΣPBDEs (34.8 ng/g dw) compared with residents in Yucatán and Costa Rica. For ΣPCBs, resident birds from Costa Rica had significantly lower concentrations (9.60 ng/g dw) compared with their migrant counterparts (43.7 ng/g dw) and residents from Texas (48.3 ng/g dw) and the Yucatán (32.1 ng/g dw). Migrant and resident passerines had similar congener profiles for PCBs and PBDEs suggesting similar exposure and retention of these contaminants. No significant accumulation of DDE was observed in migrants while on their wintering grounds. Relatively high concentrations of PBDEs in resident birds from Costa Rica warrant future studies of PBDE contamination in Latin America.

A meta-analysis of relationships between polychlorinated biphenyl exposure and performance across studies of free-ranging tree swallows (Tachycineta bicolor)

Habitats worldwide are increasingly being degraded by human activities, with environmental pollution representing a significant threat to species and ecosystems. The presence of persistent organic chemicals, such as polychlorinated biphenyls (PCBs), has generated concern. Captive experiments and field studies have reported some evidence for detrimental effects of PCB exposure, but also significant variation across studies and species. Here, I use a meta-analytical approach to combine findings across 10 studies investigating effects of PCBs on performance (e.g. reproductive success, offspring growth) in free-ranging tree swallows, a common bioindicator species that accumulates high levels of PCBs at some contaminated sites. Contrary to predictions, five complementary analyses revealed no significant negative association between PCB exposure and performance in tree swallows. In fact, in one analysis, increased PCB exposure was associated with improved reproductive success. Possible explanations for these findings include several limitations of field studies, variation in the toxicity of different PCB congener mixtures found across sites included in the analysis, and variation in the degree of tolerance of PCB exposure among species (with high tolerance found in tree swallows). At this point, the available evidence from field studies does not demonstrate negative impacts of PCB exposure on tree swallow performance.

Reproductive success of three passerine species exposed to dioxin-like compounds near Midland, Michigan, USA

Nests of three passerine birds, house wren (HOWR), tree swallow (TRES), and eastern bluebird (EABL) were monitored daily (2005-2007) at study areas (SAs) downstream of Midland, Michigan where soil and sediment concentrations of polychlorinated dibenzofurans (PCDFs) were significantly greater than the regional background concentrations and upstream reference areas (RAs). Similarly, TRES research conducted at sites contaminated with dioxin-like compounds indicated that concentrations of polychlorinated dibenzo-p-dioxins and PCDFs, expressed as ΣPCDD/DFs and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents observed in the diet and eggs of these three species would be predicted to cause significant effects on reproduction. However, site-specific reproductive parameters including hatching success and fledging success at downstream SAs were similar to or greater than those at upstream RAs. Specifically, hatching success was not significantly different among years, species, locations, or between early and late nesting attempts. Of all initiated clutches, 66% (n = 427), 73% (n = 245), and 64% (n = 122) successfully fledged at least one nestling for HOWR, TRES, and EABL, respectively. Overall reproductive performance was similar between SAs and RAs. The reason for these unexpected results is consistent with the fact that there are species-specific and congener-specific differences in sensitivities to the effects of aryl hydrocarbon receptor agonists.

Passerine exposure to primarily PCDFs and PCDDs in the river floodplains near Midland, Michigan, USA

House wren (Troglodytes aedon), tree swallow (Tachycineta bicolor), and eastern bluebird (Sialia sialis) tissues collected in study areas (SAs) downstream of Midland, Michigan (USA) contained concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) greater than in upstream reference areas (RAs) in the region. The sum of concentrations of PCDD/DFs (SigmaPCDD/DFs) in eggs of house wrens and eastern bluebirds from SAs were 4- to 22-fold greater compared to those from RAs, whereas concentrations in tree swallow eggs were similar among areas. Mean concentrations of SigmaPCDD/DFs and sum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (SigmaTEQs(WHO-Avian)), based on 1998 WHO avian toxic equivalency factors, in house wren and eastern bluebird eggs ranged from 860 (430) to 1500 (910) ng/kg wet weight (ww) and 470 (150) to 1100 (510) ng/kg ww, respectively, at the most contaminated study areas along the Tittabawassee River, whereas mean concentrations in tree swallow eggs ranged from 280 (100) to 760 (280) ng/kg ww among all locations. Concentrations of SigmaPCDD/DFs in nestlings of all studied species at SAs were 3- to 50-fold greater compared to RAs. Mean house wren, tree swallow, and eastern bluebird nestling concentrations of SigmaPCDD/DFs and SigmaTEQs(WHO-Avian) ranged from 350 (140) to 610 (300) ng/kg ww, 360 (240) to 1100 (860) ng/kg ww, and 330 (100) to 1200 (690) ng/kg ww, respectively, at SAs along the Tittabawassee River. Concentrations of SigmaTEQs(WHO-Avian) were positively correlated with SigmaPCDD/DF concentrations in both eggs and nestlings of all species studied. Profiles of relative concentrations of individual congeners were dominated by furan congeners (69-84%), primarily 2,3,7,8-tetrachlorodibenzofuran and 2,3,4,7,8-pentachlorodibenzofuran, for all species at SAs on the Tittabawassee and Saginaw rivers but were dominated by dioxin congeners at upstream RAs.

Variation, levels and profiles of organochlorines and brominated flame retardants in great tit (Parus major) eggs from different types of sampling locations in Flanders (Belgium)

Small-scale geographical variation in the occurrence of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was investigated using the eggs of a terrestrial residential songbird species, the great tit (Parus major). In addition, we investigated the influence of the type of sampling location on the presence of these pollutants. To achieve this, 10 different sampling locations in Flanders (Belgium) were classified into 3 groups based on the extent of urbanisation, industrialisation and agriculture. The higher variance among sampling locations for the levels and profiles of PCBs and OCPs, suggests that local contamination sources are more important for the PCBs and OCPs compared to the PBDEs. Levels of PCBs and PBDEs were significantly higher in the industrialised sampling locations compared to the other locations. Sum PCB and sum PBDE levels reached up to 6050 and 79 ng/g lipid weight, respectively. PCBs and PBDEs were highly positively correlated for all groups, suggesting similar exposure pathways and/or mechanisms of accumulation. Significantly higher levels of OCPs (sum OCPs up to 2683 ng/g lipid weight) were detected in the rural sampling locations situated in a residential area. This suggests that local historical usage of OCPs by inhabitants may be an important source of contamination in Flanders. Contamination profiles differed also among the sampling locations. The rural sampling locations had a higher contribution of lower brominated BDE congeners, whereas the industrialised locations had a higher contribution of higher brominated congeners. The differences in contamination profiles among the sampling locations are probably due to differences in exposure. In conclusion, our results showed that the characteristics of a sampling location influence both the levels and profiles of PCBs, OCPs and PBDEs.