Oncorhynchus mykiss Microplastic Exposure: Impacts and Research Gaps

Worldwide, this review brings together scientific studies examining the effects of microplastics, a major pollutant in freshwater ecosystems, on rainbow trout (Oncorhynchus mykiss). Data such as microplastic types, concentrations, exposure times and biological responses of fish (histopathological changes in tissues, immune responses and biochemical parameters) were collected and evaluated from these studies. Microplastics accumulate in the biological systems of farmed trout in particular and cause toxic effects. Additionally, the effects of microplastics on protein, amino acid and fatty acid composition in fish are included in the dataset. The collected data were transferred to SPSS program and analyzed using descriptive statistics. The biological effects of microplastic and some pollutant combinations and experimental periods were evaluated by comparative analyses.As a result of the analysis, it was revealed that the combination of different types of microplastics with pesticides and heavy metals caused histopathological and biochemical changes in fish tissues. It was determined that organs such as gills and liver were more susceptible to microplastic exposure, especially at high concentrations. It has also been determined that some pollutant combinations with microplastic cause negative effects on oxidative stress, amino acid and fatty acid compositions. The shortcomings of existing research on the effects of microplastics on the biological systems of fish and the inability of laboratory experiments to explain the environmental distribution and biological effects of microplastics observed in natural environments are discussed. It was concluded that experiments conducted in laboratory environments do not adequately reflect natural environmental conditions and that more realistic assessments such as environmental risk assessments are needed. It is stated that these findings require comprehensive studies to evaluate microplastic pollution in terms of both environmental and human health.