engleski

Morphometric data of Vardar chub (Squalius vardarensis) in the rivers under the impact of mining activity

Disturbed natural balance as a result of significant pollution pressure by mining activities has been already reported for the major waterways in the Republic of Macedonia. An exceeded metal concentration in the aquatic environment has the potential to induce serious harm in wild organisms, to impair their health, condition, reproduction or their habitats. The implementation of the EU Water Framework Directive establishes that the ecological status of the aquatic ecosystems must be determined by biological quality elements, including fish, and has to be supported by hydro-morphological and physico-chemical parameters. Therefore, the aim of this study was to obtain basic data for the effect of mining activities on fish, using Vardar chub (Squalius vardarensis) as a bioindicator organism, and using biomarkers that are relatively simple and non-specific, but indicative of cumulative organism-level changes. For achieving this goal, 158 chub were captured with electro fishing methods from three rivers in northeastern R. Macedonia, two of them under lead/zinc mine activities (Zletovska River and Kriva Rriver) and one control, reference river, free from mine pollution (Bregalnica River). Fish were captured in two seasons – autumn and spring of 2012. Total length (TL), body mass (BM), liver (LM) and gonad mass (GM) were measured. The condition factor (CF), hepatosomatic index (HSI) and gonadosomatic index (GSI) were calculated. With tendency to minimize the effect of the reproductive cycle on these indices, organosomatic indices corrected for the gonad mass were also calculated by subtracting the mass of the gonads from the body mass in the computation of HSI* and GSI*. All obtained data was statistically analysed by ANOVA/MANOVA followed by post-hoc Newman-Keuls’ test. In general, as was expected for this fish species, females in both seasons were heavier and longer than males. Concerning the localities, females in both seasons and males in autumn revealed significantly lower BM, BM* and TL values in the Zletovska River compared with the reference Bregalnica River. Those observations were also reflected on fish condition, expressed by the condition factor which revealed that both sexes in both seasons had disturbed condition (significantly lower CF) in the Zletovska River when compared to Bregalnica and Kriva rivers. Furthermore, seasonal differences were observed in both sexes, with significantly higher CF values in spring in all three locations (except for males from the Bregalnica River). Strong seasonal influence was also observed for GM, GSI and GSI* with higher values detected in spring compared with autumn and only week effect from localities (only in females in spring with highest values in Kriva River). As for the LM, HSI and HSI*, the lowest values were noticed in the Zletovska River in comparison with the other two rivers, significantly lower for both sexes in autumn. Seasonal differences were observed for LM only in females from Kriva River and for HSI and HSI* in both sexes from Zletovska River. For all parameters spring collected samples revealed higher values than those collected in autumn. Although all investigated parameters are not specific and not very sensitive, they are widely accepted representative indices of overall organism health and they may serve as an initial screening biomarker to indicate the consequences of exposure to contaminants. Observed lower values for almost all investigated parameters in the Zletovska River suggested disturbed general fish condition and organ disturbance in fish that inhabit waterways that are under pressure by mining activities. However, deeper investigations are needed, using several biomarkers at multiple levels of biological organization, to assess the current pollution impacts on the health status of the local ichthyofauna.

chub ; mining ; morphometric parameters

nije evidentirano