Abstract
Polychlorinated biphenyls (PCBs) are worldwide chemical pollutants that have been linked to disrupted reproduction and altered sexual behaviour in many organisms. However, the effect of developmental PCB-exposure on adult passerine reproductive behaviour remains unknown. A commercial PCB mixture (Aroclor 1242) or an estrogenic congener (PCB 52) were administered in sublethal amounts to nestling zebra finches (Taeniopygia guttata) in the laboratory to identify effects of developmental PCB-exposure on adult zebra finch reproductive parameters. Results indicate that although traditional measures of reproductive success are not altered by this PCB dosage, PCBs do alter sexual behaviours such as male song and nesting behaviour. Males treated with PCB 52 in the nest sang significantly fewer syllables than control males, while females treated with Aroclor 1242 in the nest showed the strongest song preferences. PCB treatment also caused an increase in the number of nesting attempts and abandoned nests in the Aroclor 1242 treatment relative to the PCB 52 treatment, and offspring with control fathers fledged significantly earlier than those with fathers treated with Aroclor 1242. Behavioural differences between males seem to best explain these reproductive effects, most notably aggression. These findings suggest that sublethal PCB-exposure during development can significantly alter key reproductive characteristics of adult zebra finches, likely reducing fitness in the wild.
Highlights
Polychlorinated biphenyls (PCBs) are a class of syththetic chemicals that are ubiquitous in the environment
We focus on two types of PCBs, selected to mimic environmental exposure and estrogenic affects, and administer them at sublethal doses during the nestling stage to determine impacts on reproductive behaviour once individuals reach adulthood
Nestlings exposed to the pure PCB congener, PCB 52, had fewer syllables in their adult songs compared to control birds, while nestlings exposed to the PCB mixture, Aroclor 1242, did not differ significantly in any adult song characteristic we measured
Summary
Polychlorinated biphenyls (PCBs) are a class of syththetic chemicals that are ubiquitous in the environment. They were produced commercially for use in industrial products, such as dielectric, hydraulic and heat transfer fluids [1]. PCBs have a di-benzene backbone, one to ten degrees of chlorination and were manufactured in mixtures of structurally related compounds known as congeners [2]. Congener mixture production was banned in the United States in the late 1970s, the chemical mixtures are still present and identifiable in the environment [3]. There are 209 different PCB congeners with different modes of action and complex individual and interactive effects [4]. Exposure to high levels of most PCB congeners can be lethal
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