Spatial synchrony of zooplankton during the impoundment of amazonic reservoir

Abstract

The escalating demand for energy and the strong political and economic pressure to explore the Amazon’s hydroelectric potential has led to the increase of hydroelectric reservoirs in the region. Reservoirs are artificial ecosystems that modify the structure of biological populations. Evaluating the spatial synchrony of populations and environmental variables in the development of reservoirs may reveal determinant factors and processes operating in these ecosystems. This may help understand the impacts, optimize monitoring systems and develop strategies to improve and maintain the ecological integrity (or stability) of these environments. In this study, we evaluated the spatial synchrony in zooplankton populations and limnological environmental variables during the implementation of a hydroelectric reservoir in the Amazon region, on the border of the states of Pará and Amapá. Synchrony was determined by mean cross-correlation between the pairs of points for each variable, followed by Mantel test to investigate its influencing factors. We observed spatial synchronous values for both population and limnological environmental variables. However, we could not identify the mechanisms that are operating, indicating that more than one factor may be influencing the ecosystem dynamics. Population synchrony increased after impoundment. Population synchrony may be associated with some limnological variables, such as the ones related to the amounts of nutrients, whereas environmental synchrony can be related to extrinsic factors, such as climatic variation, not tested this study. In order to increase the understanding of the mechanisms operating over population and environmental dynamics, we suggest that, besides evaluating limnological environmental variables and spatial synchrony, analyses should include meteorological and landscape data.