Strategie De Reproduction De Macrobrachium Amazonicum En Amazonie Centrale (Decapoda, Caridea, Palaemonidae)

Abstract

The reproduction strategy of the Palaemonid shrimp, Macrobrachium arrtazorticum, has been studied on Careiro Island in a floodplain lake in Central Amazonia. Ovigerous females have been observed all year round. However, three periods of the hydrological cycle were significantly more favourable to gonad ripening: the middle of the rising and of the falling of the water level, as well as the low level. This suggests the direct effect of two factors: the current velocity and the phytoplancton production. At the population level, the maximum reproduction intensity has been observed during low water, and during rising water. This strategy increases the survival of planctonic larvae during the highest phytoplancton production period, and reduces the intraspecific competition, increasing the larval dispersal in the floodplain. In the lake, the percentage of ovigerous females was always higher regardless of size class of the adult prawns and of season, than in the channels or in the river, suggesting that the lacustrine environment is the more favourable to M. amazonicum reproduction. In eastern Amazonia, M. amazonicum shows a typical reproduction pattern of littoral Palaemonids: mass spawning occurs during the falling water, increasing the larval dispersion towards the estuary. The reproduction flexibility of M. amazonicum explains its success in colonizing a variety of environments in a wide geographical range in South America.