Sessions

Nowadays, one of the most prominent ecological and health issues is the presence of pollutants in natural ecosystems. Aquatic habitats are highly exposed to these materials, since chemicals and waste can easily reach water bodies and accumulate in high concentrations. Plastics make up a high percentage of these anthropogenic wastes, and since they are unable to degrade in the short term, their particles are permanently present in the aquatic environment. The effect of plastic particles in the 1 µm to 5 mm size range, or otherwise referred to as microplastics, are a relatively new area of research, with many questions still not being answered. Amphibians are highly exposed to aquatic pollutants, since their reproduction and initial life stages are water dependent. Previous studies showed that in ectothermic vertebrates, several environmental stressors may cause sex reversal, which means the development of gonads that do not match the genetic sex of the individuals. This process can lead to the shift of the sex ratios in a population, negatively affecting reproductive ability and consequently the survival of the population. Several studies suggest that microplastics may affect the hormonal processes that take part in the development of the gonads; however, there is no information on their role in sex reversal yet. To assess this gap in our knowledge, we tested the effect of a common microplastic: polystyrene (10 µm particles) in an ecologically relevant, 180 particles/ ml concentration on agile frogs (Rana dalmatina). The embryos were collected from a natural population and raised in captivity in treated or control water. We applied the treatment until the beginning of the metamorphosis for the tadpoles. Three months after metamorphosis, we examined the gonads, body mass and body fat content of the individuals by dissection. We found no difference in sex ratios between the treatment groups; however, the treated group had significantly higher body mass and body fat content than the control individuals. The latter results are in line with earlier data from laboratory model animals (fishes and mice), which indicate that microplastics influence the metabolism of these species. Using the tissue samples we collected from the dissected animals, we will assess the genetic sex of the individuals to investigate whether sex reversal occurred in our experiment, and we will also investigate the markers of oxidative stress and lipid metabolism to better understand the physiological processes underlying our results.