engleski

Comparison of electrochemically determined metallothionein concentrations in wild freshwater salmon fish and gammarids and their relation to total and cytosolic metal levels

Application of metallothionein (MT) as an early warning sign of metal exposure in aquatic organisms is common in biomonitoring, but there is a huge variability in MT concentrations among different studies. Present research aims to assess MT responses in freshwater fish brown trout (Salmo trutta Linnaeus, 1758) and gammarids(Gammarus balcanicus Schäferna, 1922 and Echinogammarus acarinatus Karaman, 1931) as indicators of metal exposure within the freshwater karst environment (Krka River, Croatia). Sampling was performed upstream (reference site) and downstream (anthropogenically impacted site) of the wastewater discharges in autumn and spring seasons. Brown trout intestine was applied as a bioindicator tissue due to its role in dietborne metal uptake while gammarids were chosen as fish food and potential metal uptake source. Moreover, there is a lack of data on intestinal MT levels, so our results on MT and metal/metalloid concentrations, measured as total and metabolically available cytosolic levels, represent the first data of this kind for the selected indicator species. The results indicated that the ecotoxicological impact of technological and municipal wastewaters on the biota of the karst Krka River was moderate, although higher metal levels at the affected site were evident in both, fish and gammarids. The modified Brdička reaction applied in this study was confirmed as reliable electrochemical technique for MT quantification in both vertebrates and invertebrates, and it indicated higher MT levels in gammarids (1.9–4.1 mg g−1 w.w) than in fish intestine (0.5–2.8 mg g−1 w.w). Due to the lack of the data on MT concentrations in S. trutta and gammarid species G. balcanicus and E. acarinatus, presented results can serve as a preliminary data to establish MT background levels in intestine of wild freshwater fish and gammarids. Obtained MT levels showed species-, tissue- and method- specific differences, so comparison between MT levels should always involve the same species, tissue and measurement method.

Biomarkers ; Metallothioneins ; Fish intestine ; Amphipods ; Karst aquatic environment

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