Historia de vida temprana de la corvina rubia (Micropogonias furnieri, Sciaenidae) en el Estuario del Río de La Plata
This study encompasses the bio-physical interactions of whitemouth croaker (Micropogonias furnieri) early life stages living in La Plata estuary (Argentina-Uruguay, South America) to understand how they take advantage of the estuarine dynamics while traveling from spawning to nursery areas and undergoing ontogenetic and associated ecological changes. The analyses used include studies of spatio-temporal distribution length-dependent patterns; growth patterns looking for settlement marks in otoliths; and development related to metamorphosis and ontogenetic variations of the diet and trophic level. Samples and data come from vertically stratified samplings from 3 cruises (2005, 2006 and 2009). Distributional data also comes from an historic database. Results demonstrate that retention mechanisms maintain croaker early-life stages (3-45 mm SL) alternatively moving horizontally along the bottom salinity front, mixing the length classes. Planktonic larvae (16 mm SL) have a life span of 30-50 days. Metamorphosis and settlement occurs simultaneously from 9 to 18 mm SL. The diet changes significantly from copepod to mysids 20 days after settlement (20-22 mm SL). In the context of saltatory ontogeny, these events represent a threshold in the species early-life history. Regarding spatial processes, retention in the front would allow larvae and early juveniles to benefit from food accumulation in the region; the high turbidity as shelter against predators, and the closeness to the main nursery ground. Thus, the dynamics of this estuarine system and the species reproductive strategy may be the reason of the high population abundance.