Use of lapillus otolith microchemistry as indicator of the habitat of Genidens barbus in different estuarine environments from the southwestern Atlantic Ocean.

ESTEBAN AVIGLIANO; GONZALO VELASCO; ALEJANDRA VANINA VOLPEDO

Mallorca

Congreso; 5th International Otolith Symposium 2014 (IOS2014) - ICES; 2014

The marine catfish Genidens barbus is an anadromous species found in South America. The objectives of the present study were to evaluate a new method consisting in the partial polishing and analysis of the microchemistry of the lapilli as indicator of the habitat of G. barbus and identify the potential breeding areas and fish stocks between the populations from the lower section of the Plata Basin (De la Plata River estuary-Argentina) and Lagoa dos Patos coastal lagoon (southern Brazil). Sr:Ca, Ba:Ca and Mg:Ca ratios were measured in the core area (inner 4 rings) and external area (outer 3-4 rings) of the otoliths by ICP-OES. The Sr:Ca ratio tended to be higher in the otolith external area than in the core area, while the Ba:Ca ratio followed the opposite pattern, suggesting the moving towards areas of higher salinity. The results show significant differences (p<0.05) in the Sr:Ca, Ba:Ca, Mg:Ca ratios in the core and external area of otoliths from the Plata Basin and those from Lagoa dos Patos that may indicate the occurrence of at least two different breeding sites and suggests the occurrence of at least two fish stocks in the region.