Abstract
This study aimed to describe the displacements of anchovy ( Anchoa tricolor ) in a subtropical estuary in South America, using the otolith microchemistry. We analyzed 198 specimens of A. tricolor in the Paranagua Estuarine Complex (Brazil) and data of salinity and rainfall. The biological and environmental data were grouped into sectors (internal, intermediate and external) and periods (early and late rainy and dry periods). The concentrations of Ca, Ba and Sr were determined using an ICP-OES. The Sr: Ca ratio indicated the existence of two groups of probably different origins that use the estuary at the same time but occupy different sectors of the estuary. In the other periods and sectors, we observed that part of the A. tricolor population used the estuary for feeding and growth, with an increase in the Sr: Ca ratio. The Ba: Ca ratio did not differ groups of use in the estuary, but rather, revealed low values suggesting that this species does not use freshwater environments. However, this ratio showed a high variation in the rainy period, indicating greater availability of barium in the estuarine regions affected by river discharge. Considering our results, it is possible to classify A. tricolor as an estuarine migrant species that uses estuaries for feeding and growth. Also, Sr: Ca and Ba: Ca ratios can be indicative of spatial and temporal displacement, respectively.
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