Resilience and resistance of zooplankton communities to drought-induced salinity in freshwater and saline lakes of Central Asia

Abstract

Effects of drought-induced salinity changes on aquatic communities are less studied in lentic than in lotic systems. We present changes in zooplankton assemblages from five arid lakes before, during, and after a supra-seasonal drying event in which lake inflow ceased in 2001. We catalogued zooplankton communities in fresh and saline lakes of the Sudochye wetland in Central Asia. During this record low flow period, salinity increased in the lakes. Zooplankton species richness was inversely correlated with salinity. Linear regression using species richness indicated that zooplankton communities in the two least saline lakes were strongly correlated with changes in salinity. Post-drought recovery of species richness suggested resilience to this perturbation. Both saline lakes' zooplankton communities had low correlation with changes in salinity, suggesting greater resistance than the freshwater communities. The fifth lake showed a hybrid response, beginning in the fresh range, but experiencing higher salinities than the other fresh lakes. In the fifth lake species-richness was similarly correlated to changes in salinity as compared to the saline lakes, correlation of % halotolerant species was intermediate between saline and fresh communities, and post-drought species richness was similar to the fresh lakes, which could indicate a “resilient” recovery of species richness.