Abstract
Most criteria of contaminants in aquatic ecosystems are based on their acute or chronic toxicity examined during short periods. However, it is important to evaluate the effects of long-term, low-level chronic exposure of populations to multiple stressors and to identify causative stressors for the conservation of the aquatic ecosystem. In this study, we present a novel approach to identifying multiple stressors to Psedorasbora parva by amplified fragment length polymorphism (AFLP) analysis. Pseudorasbora parva was captured in habitats contaminated mainly with sewage, treated sewage or agricultural effluent. We also analyzed 14 polycyclic aromatic hydrocarbons (PAHs) and 7 heavy metals in the sampling sites. The genetic diversity of the population calculated by AFLP analysis decreased with increasing contamination of their habitats by treated sewage or sewage. Genetic diversity was significantly correlated with concentration of dissolved benzo[k]fluoranthene, dissolved lead, and dissolved manganese. Nickel in sediments was also significantly correlated with the genetic diversity. Some of these contaminants might be acting as strong selective agents that decrease the genetic diversity of the population. Using fluorescence-based AFLP data, we could classify amplified fragment length patterns into several groups and they were found to correspond with the contamination properties of the sampling sites. These genotypes distributions in rivers and lakes may show the direction of selective forces to Psedorasbora parva.
