Population dynamics of the non-native shrimp Macrobrachium amazonicum (Heller, 1862) in a tropical reservoir

This study evaluated the population dynamics of the non-native shrimp Macrobrachium amazonicum Heller, 1862, in a tropical reservoir in southeastern Minas Gerais, highlighting its adaptive responses to environmental variation. Monthly collections and measurements of water physicochemical variables allowed the analysis of demographic classes, the relationship between carapace length and fecundity, and the estimation of growth patterns using the von Bertalanffy model. The species showed marked sexual dimorphism: females attained larger asymptotic sizes, while males exhibited higher growth rates. Fecundity was positively correlated with female body size, confirming that larger individuals contribute disproportionately to reproductive output. Seasonal fluctuations strongly influenced abundance, with peaks during the dry season and recruitment events at the transition between dry and rainy periods. A generalized linear model indicated that temperature and conductivity negatively affected abundance, whereas pH and dissolved oxygen showed no significant influence. These results suggest the ecological plasticity of M. amazonicum and its ability to persist in altered environments. The findings indicate that the studied reservoir provides favorable conditions for the establishment of this non-native population, reinforcing the need for monitoring environmental conditions and understanding demographic processes to better assess the potential ecological consequences of biological invasions in neotropical aquatic ecosystems.