Distribution of whitemouth croaker Micropogonias furnieri in relation to environmental factors at the Río de la Plata estuary, South America

Abstract

The age-class distribution of the whitemouth croaker Micropogonias furnieri and its relationship to environmental factors was evaluated from 278 stations sampled between 1993 and 1999 during early winter and spring within the Rio de la Plata estuary (36° S, 56° W). A detrended canonical correspondence analysis (DCCA) was used to define sampling station groups based on age structure of whitemouth croaker, and to estimate their association with depth, type of substrate, tem- perature and salinity of surface and bottom waters. Complementary information for surface temper- ature and location of the turbidity fronts was derived from NOAA-14-AVHRR imagery obtained in 1999. Results indicated that bottom salinity has a major influence on the spatial distribution pattern of M. furnieri, and that distinct preferences for different salinities by the various age-classes of this species result in a differential distribution pattern along the main axis of the estuary. In both seasons, turbidity fronts were located at the inner central area of the estuary and showed a close fit with the distribution of the youngest age-classes.