The stabilizing effect of resting egg banks of the Daphnia longispina species complex for longitudinal taxon heterogeneity in long and narrow reservoirs
Abstract
We compared the spatial distribution of the Daphnia longispina complex (D. longispina, D. galeata, D. cucullata, and their hybrids) in the active water column community and in resting egg banks in five long narrow reservoirs in the Czech Republic. Ephippia abundance in the sediments significantly increased in the downstream direction and similarly to the active zooplankton community, in which D. cucullata and D. longispina tended to occur at opposite ends of the reservoirs, taxa of resting eggs revealed a spatially diversified pattern.
High relative abundances of hybrids (up to 16% of resting eggs, and 74% of Daphnia in the water column) confirm that interspecific hybridization is frequent in reservoirs, and some hybrids are successfully compete with the parents. We assume that the spatial heterogeneity of Daphnia taxonomic composition in reservoirs, being affected by the seasonal selection of taxa, is substantially strengthened by the presence of spatially heterogeneous egg banks.