engleski

Recipient fish as model organisms in multilevel assessment studies

Treated wastewater discharged from the wastewater treatment plant (WWTP) was evaluated by assessing its impact on downstream free-living fish (Prussian carp, Carassius gibelio) health status, microbiological contamination and antimicrobial resistance, fish tissue structure, blood biochemistry and erythrocyte nuclear abnormalities. Potential bacterial pathogens from fish and respective waters comprised aeromonads with a zoonotic potential. High resistance profiles were determined towards the tested antimicrobial compounds, mostly sulfamethoxazole and erythromycin. Histopathology primarily revealed gill lamellar fusion and reduction of interlamellar spaces of fish captured from the effluent. A significant increase in plasma values of urea, total proteins, albumins and triglycerides and a significant decrease in the activity of plasma superoxide dismutase were noted in carp from the effluent-receiving canal. A higher frequency of erythrocyte nuclear abnormalities was found in fish sampled from the effluent-receiving canal. Histological and haematological parameters differed significantly in effluent and downstream. Overall, treated wastewater modified the environmental parameters of the receiving surface waters, and played an important role in the antibiotic resistance scheme ; the investigated histological, hematological and plasma biochemical parameters of fish indicated to significant changes related to a complexity of environmental stressors. The histopathological changes observed in gill tissues in particular could be related to xenobiotics in the effluent, microbial load on gills, impaired water quality and increased heavy metal concentrations and may serve as an important end- point in the discrimination between polluted sites. There are potential public health concerns regarding aeromonad exposure amongst recreational fishermen who come into contact with fish inhabiting waters downstream from the WWTP, and WWTP workers who are occupationally exposed to wastewaters and their aerosols. A very high proportion of fish aeromonads demonstrated resistance, and a notable percentage of these exhibited a multiple resistance pattern. In this regard, negative effects of antimicrobial use on the environment, fish and human health should be elucidated, whilst more WWTPs should be involved in these complex studies.

recipient fish ; health

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