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Blood concentrations of p,p'-DDE and PCBs in harriers breeding in Spain and Kazakhstan
Silvia Espín1, Julien Terraube2, Beatriz Arroyo3
1Area of Toxicology, Department of Health Sciences, University of Murcia, Campus de Espinardo, 30100 Murcia, Spain; Section of Ecology, Department of Biology, University of Turku, 20014 Turku, Finland.
Abstract:
Organochlorine compounds (OC) are of interest in current biomonitoring studies because of their well-known persistence, accumulation capacity and the adverse effects they caused in the past. P,p'-DDE has been shown to cause severe reproductive failures and population declines in birds of prey. However, there are knowledge gaps regarding OC exposure for some species (e.g. harriers), the historical record and the broader picture. The main goal was to evaluate exposure to p,p'-DDE and PCBs in two raptor species: Montagu's and pallid harriers (Circus pygargus and Circus macrourus), and to investigate if birds from different breeding areas and wintering grounds differ in pollutant levels. For this purpose, we collected blood of adult and nestling Montagu's and pallid harriers breeding in the natural steppes of Kazakhstan, and adult and nestling Montagu's harriers breeding in agricultural and natural habitats of Spain, in 2007-2008. We determined the blood concentrations of p,p'-DDE and PCBs. Adult harriers generally showed higher concentrations of p,p'-DDE and PCBs than nestlings, probably because they had more time for a progressive accumulation of these compounds due to a higher intake than excretion rate. The p,p'-DDE concentrations in adults were equivalent in all the studied areas. The ratio p,p'-DDE/PCB 153 was higher in adults than in nestlings, suggesting that a portion of the p,p'-DDE in adult harriers may have come from p,p'-DDT applied in the past in the wintering areas. Overall, the concentrations of p,p'-DDE and ∑PCBs reported were generally low and below any demonstrated threshold of harm.
Insights
Organochlorine compounds like p,p-DDE and PCBs were measured in Montagu's and pallid harriers. Concentrations were generally low, with adults showing higher levels than nestlings due to accumulation.
Area of Science:
- Environmental Science
- Ecotoxicology
- Wildlife Biology
Background:
- Organochlorine compounds (OCs) are persistent pollutants with known adverse effects, particularly p,p'-DDE on birds of prey.
- Knowledge gaps exist regarding OC exposure in harrier species, their historical trends, and overall environmental impact.
- Biomonitoring of OCs is crucial for understanding wildlife health and conservation efforts.
Purpose of the Study:
- To assess exposure to p,p'-DDE and Polychlorinated Biphenyls (PCBs) in Montagu's and pallid harriers.
- To compare pollutant levels between different breeding and wintering grounds.
- To investigate age-related differences in OC accumulation within these raptor species.
Main Methods:
- Blood samples were collected from adult and nestling Montagu's and pallid harriers in Kazakhstan and Spain (2007-2008).
- Concentrations of p,p'-DDE and PCBs were determined using analytical chemistry techniques.
- Statistical analysis was employed to compare pollutant levels across species, age groups, and geographic locations.
Main Results:
- Adult harriers exhibited higher concentrations of p,p'-DDE and PCBs than nestlings, indicative of bioaccumulation.
- p,p'-DDE levels in adult harriers were consistent across all studied breeding areas.
- The p,p'-DDE/PCB 153 ratio was higher in adults, suggesting historical DDT contamination in wintering grounds.
Conclusions:
- Overall p,p'-DDE and ∑PCBs concentrations in harriers were low and below harmful thresholds.
- Adults accumulate OCs over time, while nestlings reflect recent environmental exposure.
- Findings contribute to understanding OC dynamics in raptors and inform conservation strategies.