Zooplankton resting egg banks as a strategy to maintain diversity in a small tropical reservoir ecosystem

Abstract

Small water bodies host numerous zooplankton species, which are directly influenced by their surroundings. During environmental instability, zooplanktons produce nutrient-rich eggs, via the process of diapause, that sink to the sediment and remain dormant under unfavorable environmental conditions. We aimed to observe how diapause helps maintain the richness of the zooplankton community in the small-sized Amália Reservoir, located in the municipality of Alfenas, Minas Gerais, Brazil. The studied reservoir is a well-defined microbasin with urbanization processes and a predominance of pastures and coffee plantations. The reservoir has low zooplanktonic richness despite having numerous macrophytes on its margin, which contributes to species richness. Zooplankton species were observed in dormant forms that were not recorded in the water column, demonstrating the importance of egg banks for long-term zooplanktonic survival. However, anthropogenic activities may have influenced the low number of species and dormant forms. Thus, knowing the species present in the water column in the sediment of the Amália Reservoir proved the importance of the dormant form bank for the long-term survival and structuring of the community.