Pharmaceutically active compounds are only partially removed from wastewaters and hence may be major contaminants of freshwaters. Direct and indirect effects on aquatic organisms are reported at dilute concentrations. This study was focused on the possible effects of environmentally relevant concentrations (~1 µg L⁻¹) of two psychoactive compounds on the behavior of freshwater crayfish. Experimental animals exposed to venlafaxine did not show any behavioral alteration. Crayfish exposed to the benzodiazepine oxazepam exhibited a significant alteration in the distance moved and activity, and the effects were different when individuals were ready for reproduction. Results suggested that even the low concentration of selected psychoactive pharmaceuticals could alter the behavioral patterns of crayfish, as reported for other pharmaceuticals. These results provide new information about the possible adverse effects of pharmaceuticals at dilute concentrations. From previous knowledge and our results, it is obvious that different compounds have different effects and the effects are even specific for different taxa. Detailed studies are therefore needed to assess the possible ecological consequences of particular substances, as well as for their mixtures.

Sulfonamide antibiotics coming from both human and veterinary medicine are among the most common emerging pollutants in freshwater. The present paper shows the successful application of passive sampling using POCIS in combination with an immunochemical ELISA technique and HPLC/MS/MS analysis to study the distribution of sulfonamides in streams around small towns in the Czech Republic, as well as around a major agglomeration of the city of Brno, including its waste water treatment plant (WWTP). Results indicated the presence of sulfonamides at most studied sites with concentrations ranging from <20 up to 736 ng of sulfamethoxazole equivalents per POCIS. Very high levels were detected in both the influent and effluent of the Brno WWTP with maxima > 8000 ng SMX per POCIS. All samplers collected down-stream of the studied towns and WWTPs clearly showed an increase in sulfonamide drug residues. Higher concentrations were determined in rivers at the city of Brno agglomeration. In agreement with other available studies, these findings indicate low efficiency of conventional WWTPs to eliminate polar pharmaceuticals such as sulfonamides. Good performance and correlation with the LC/MS results, as well as ease of use, indicate good potential for the immunochemical ELISA technique to become the screening tool for sulfonamide determination in surface waters including passive samplers.

Freshwater protected areas are designated parts of the inland waters that restrict human activities. They were created as a mechanism to combat the decline of fauna and flora of the world. Some authors have questioned their actual effectiveness in terms of the purpose of protecting endangered fauna and flora. We conducted an experiment in Lipno reservoir in the Czech Republic to evaluate the impact of protection against angling pressure on the fish community. We selected data from two years of gill netting and analyzed the difference between areas of low anthropogenic impact (LAI) and those of high anthropogenic impact (HAI) in terms of abundance, biomass, standard length, and diversity indices. Three groups of fish were found to prefer protected areas with low anthropogenic pressure: 1. YOY (Young-of-the-year) perch (Perca fluviatilis), the dominant of the young-of-the-year fish community. 2. Pike (Esox lucius), wels catfish (Silurus glanis) and rudd (Scardinius erythrophthalmus), which were not found in HAI areas at all. 3. Larger individuals of pikeperch (Stizostedion lucioperca), which survived better in LAI areas. Some factors may affect LAI, such as illegal poaching or setting out food bait to attract the fish outside. Another factor that can be considered is the migration of fish, either to forage or to reproduce, since the LAI areas are open to the reservoir. The areas of LAI act as protective habitats for heavily exploited predatory fish species and increase fish diversity indexes. The example of the protected and low-impact areas of Lipno should be followed in other water bodies with high fishing pressure and anthropogenic impact.