Isoscape Eg-Selenge, Mongolia

Within the Fish and aquatic habitat research study implemented by the Taimen Conservation Fund (TCF) for the Egiin Gol Hydro Power Plant Project Unit together with Dr. Olaf P. Jensen, Rutgers University Institute of Marine and Coastal Sciences, USA, and the TCF’s fish study team the “isoscape” of the Eg-Selenge watershed is being developed. Isoscapes represent the spatial distribution of elements and isotopes, and serve as means to retrospectively study fish migrations by the analysis of fish hard parts like fin rays, scales and otoliths. The focus is on the natural variation of the 87Sr/86Sr isotope ratio, which has been proved as most valuable tool for migration studies of fish, and has the potential to provide important complementary information to radio telemetry studies. However, also a multi-elemental screening of the water samples will be perfomed. Therefore at 30 sites in Eg and Selenge river, samples were collected in 50 mL bottles in triplicates, yielding 90 bottles. The water samples were filtered on site, and transported to Austria for subsequent analysis. In total we used 180 pre-cleaned 50 mL bottles and 90 small syringe-filters, everything packed and sealed individually. In the lab the water samples were treated according to standard protocols and the elemental pattern and 87Sr/86Sr isotope ratio measured by inductively coupled plasma mass spectrometry by a Perkin Elmer NexION 300D and a Nu Plasma HR. 3 otoliths of lenok (2 from River Eg and 1 one from Selenge) will be analysed for their elemental and 87Sr/86Sr isotope ratio by cross sectional line scan. Finally the results will be reported with measurement uncertainties and geographical coordinates.