Effects of pyrene and benzo[a]pyrene on the reproduction and newborn morphology and behavior of the freshwater planarian Girardia tigrina

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of aquatic ecosystems. Because they are persistent, there is great potential for chronic toxicity to aquatic species, and the evaluation of reproductive effects is fundamental. In this context, planarians are interesting experimental animals, since they can be sensitive to environmental pollutants, and a wide range of reproductive-related endpoints can be assessed. In this work we evaluated fecundity (number of cocoons), fertility (number of newborns), newborn anomalies, adult weight, regenerative abilities and PAH-residues in tissues of the freshwater planarian Girardia tigrina, exposed to either pyrene or benzo[a]pyrene (B[a]P). Pyrene reduced planarian fecundity and fertility at 18.75 μg L−1 and 75.00 μg L−1, while B[a]P reduced planarian fecundity at the 37.50 μg L−1 treatment, which was accompanied by a 33.7% reduction in fertility. Cocoons were kept in clean media and newborns were evaluated for behavioral and morphological anomalies. Many of the newborns resulting from the B[a]P experiment revealed behavioral anomalies, such as spasms and uncoordinated movements. These behavioral anomalies were observed in 12.9% and 38.2% of newborns resulting from the exposure of adult planarians to 9.38 μg L−1 and 37.50 μg L−1 of B[a]P, respectively. This study is the first report on the effects of PAHs in freshwater planarians’ sexual reproduction and a decreased reproductive output was evidenced. Moreover, the exposure of adults to B[a]P lead to defects in newborns, raising concern on the possible long-term consequences of these compounds for natural planarian populations.