Os primeiros estágios de vida da savelha (Brevoortia pectinata) no estuário da Lagoa dos Patos / Early life stages of Argentine menhaden (Brevoortia pectinata) in the Patos Lagoon estuary

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

11/08/2011

RESUMO

Patterns associated to environmental conditions and to the spatial and temporal distributions of the early stages of Argentine menhaden, B. pectinata, and of its development in the Patos Lagoon estuary were investigated using historical records. Two other complementary experiments were performed: one to evaluate the measurement techniques (traditional and image) in larval fishes; and, other, to investigate the effect of main conservatives (alcohol 70 % and formaldehyde 3.6 %) over Argentine menhaden larvae. Significant difference in the measurement of fish larvae between techniques was not observed, and the coefficients of variation were similar, suggesting that these two techniques produce the same average result, despite the gain in precision by image analysis technique. A significant shrinkage was observed for both preservatives, and the correction factors for B. pectinata larvae in formaldehyde was SL live= 1.0799 × SL post-conservation, and in alcohol was SL live= 1.1415 × SL post-conservation. From 1975 to 2009 a total of 10479 eggs and 14066 fish larvae and juveniles were collected at plankton surveys, and sampled water parameters (salinity and temperature), too. Larvae were measured and classified according to their developmental stage. Each development stage was characterized by its size range, which the smallest yolk-sac larvae measured 2.16 mm, and the largest juveniles had 43.25 mm. Analysis of the distributional pattern indicate spawning outside the Patos Lagoon, in high salinities, being important seasonal period for the eggs the winter, spring and early summer, and after occur a transport to the inner estuarine region in the earlier developmental stages, associated to lesser temperature and salinity values. Distribution of juveniles indicated a return to the coastal region, and in this stage the autumn was a very important period. These results are important for knowledge this specie, and will be useful for planning the management of this resource.

ASSUNTO(S)

oceanografia biologica brevoortia pectinata brasil estuários lagoa dos patos biologia ecologia condições ambientais ambiente costeiro clupeidae savelha clupeidae coastal environment environmental conditions ecology biology patos lagoon brazil brevoortia pectinata estuary argentine menhaden

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