Use of otolith strontium:calcium ratio as indicator of seasonal displacements of the silverside (Odontesthes bonariensis) in the lower section of Río de la Plata Basin, Argentina

ESTEBAN AVIGLIANO; ALEJANDRA VANINA VOLPEDO

MARINE AND FRESHWATER RESEARCH

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2013 vol. 64 p. 746 - 751

1323-1650

Strontium:calcium ratios were measured in sagittal otoliths of silverside (Odontesthes bonariensis) from a freshwater-marine environment (Paraná River Delta and inner section of Río de la Plata River, South America) in order to understand its seasonal movements. Conductivity was recorded and the water Sr:Ca ratio was determined by ICP-OES. The otolith Sr:Ca ratio was associated with the conductivity of water at the locations where the sample was collected. The water Sr:Ca ratio increased with increasing conductivity along a latitudinal (north-south) gradient in the lower section of the Plata Basin, with a rapid increment in the outer section of the Río de la Plata River. According to this association, the predicted conductivity corresponding to the water Sr:Ca ratio in the outer section of the Río de la Plata River (1.92 mmol mol-1) was 7.45 (mS cm-1). The high values of otolith Sr:Ca ratio found for some fish may indicate that during summer they moved from estuarine waters where salinity increases gradually to the Argentinian Sea.