Restabelecimento da comunidade zooplanctônica em uma lagoa temporária Neotropical : regime hidrológico e formas de dormência.

Abstract

Aquatic environments are increasingly subject to natural and anthropogenic disturbances, which may result in species replacements or losses, as well as changes in ecosystem conditions. These losses can be aggravated in situations of atypical disorders, such as extreme droughts. Thus, we evaluated the zooplankton community response to disturbances in two approaches: the first one we investigated the composition of the zooplankton community before and after two extreme droughts (2001 and 2015) in a shallow lagoon, isolated from the river, in the upper floodplain Paraná River, by comparing the composition of species present in the lagoon and the adjacent river. Our results showed a high reduction in the species richness of the river, while in the lagoon there was greater community resilience. In addition, atypical events of extreme drought cause great effects on the structure of the zooplankton community in temporary environments, the connectivity during the flood pulse is an influent factor in the restoration of these sites, providing the exchange and homogenization of the biota besides the increase of the wealth rates in environments. The second chapter, we evaluated the response of the zooplankton community to extreme drought in a Neotropical temporary lagoon through the emergence of dormant forms present in the sediment of the lagoon. Our results were compared with the samples taken in the active community, before and after the extreme drought period. We evidenced the importance of dormant forms as a source of "Ecological Memory", which allows the restoration of the community after extreme disturbances, as well as the contribution to the dynamics of zooplankton and the increase of local and regional species richness.