Michroplastic-Like Debris and Biomarkers in the Fish Pseudochondrostoma duriense: Preliminary Findings

The contamination of the freshwater fish Pseudochondrostoma duriense from the Minho River estuary by anthropogenic debris suspect of being microplastics (MP-S) was investigated. Biomarkers (neurotoxicity, energy-related, biotransformation, oxidative stress, and damage) were also determined. Twelve fish were analyzed for MP-S presence in the gastrointestinal tract (GT), gills, liver, and dorsal muscle. A total of 207 MP-S was recovered from fish with sizes between 79 and 48,900 µm (94% had size <5000 µm, and 6% were larger debris). The predominant shape was fiber-like (89%), followed by fragments (11%). The most common color was black/brown, but other colors were also found. The frequency of MP-S ingestion by fish was 100%. The frequency of specimens with MP-S in gills, liver, and muscle was 8%, 25%, and 25%, respectively. The means (±standard deviation) of the number of MP-S items per fish were 16 ± 9 in the GT, 0.3 ± 1.2 in gills, 0.3 ± 0.5 in the liver, 0.4 ± 0.8 in the muscle, 17 ± 9 in total. The results provide baseline values for P. duriense MP-S contamination and biomarkers in the Minho estuary, and further investigation concerning long-term contamination and climate changes is ongoing.