Trace element content of marine algae species collected from the Black Sea coasts were determined by atomic absorption spectroscopy after microwave digestion. Trace element content in marine algae species were 1.70-17.1 microg/g for copper, 3.64-64.8 microg/g for zinc, 9.98-285 microg/g for manganese, 99-3,949 microg/g for iron, 0.50-11.6 microg/g for chromium, 0.27-36.2 microg/g for nickel, 11-694 microg/kg for selenium, 0.50-44.6 microg/kg for cadmium, 1.54-3,969 microg/kg for lead, 1.56-81.9 microg/kg for cobalt. While iron was the highest trace element concentration, cadmium was the lowest in samples. Most of the analyzed samples were edible. The samples are consumed for human diet in several countries.

The fish passage performance and flow structure of a brush fish pass were investigated at the İncirli Small Hydropower Plant on the İyidere River, located in the East Black Sea region of Turkey. The spatial distributions of velocity vectors, power velocity, Froude number and turbulent kinetic energy are presented. The flow is quasi-uniform and subcritical, which provides different migration corridors with favourable hydraulic conditions; importantly for the fish, these corridors continue through the complete fish pass. The flow–bristle interaction creates a reduced velocity and low-turbulence resting zones. In addition, the passage efficiency of the brush fish pass was assessed using passive integrated transponder telemetry. The results clearly showed that upstream passage efficiency differs between fish species: Salmo coruhensis performed better than Alburnoides fasciatus on the same fish passage. The passage efficiency for the target fish species S. coruhensis was calculated to be 82.4%. The data revealed that the brush fish passage provides passage for small-bodied fish (total body length <15cm) in a high-gradient channel with a slope of 10%. The monitoring data revealed that bristles as flexible hydraulic elements are beneficial for migrating fish.

Acute toxicity of mercury-II chloride (HgCl2), one of most toxic pollutants for aquatic ecosystems, in chub (Alburnoides bipunctatus) and rainbow trout (Oncorhynchus mykiss) was investigated in the present study. Actual concentration of HgCl2 was ranged from 0.10 to 8.00 mg L(-1). Concentrations of HgCl2 that killed 50% of the chub and rainbow trout within 96 h (96 h LC50) were estimated as 0.205 and 0.814 mg L(-1), respectively. Acute toxicity tests were evaluated by the Finney's Probit Analysis. Chub (Alburnoides bipunctatus) was appeared to be more sensitive than trouts (Oncorhynchus mykiss) to HgCl2.

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