Impact of habitat heterogeneity on zooplankton assembly in a temperate river-floodplain system

Abstract

Dissimilar life features of Rotifera, Cladocera and Copepoda enable these organisms to respond differently to changes in the hydrological regime which influence alterations in environmental characteristics. We investigated the effect of habitat heterogeneity (e.g. eupotamal, parapotamal, palaeopotamal) on individual zooplankton group assemblages and biodiversity indices (α, β and γ diversity) during hydro regime change in floodplain waterbodies. Dissolved oxygen and organic nitrogen concentrations changed significantly among hydrological states while water depth was affected by both site and hydro regime replacement. Each studied site supported different zooplankton assemblage that highly depended on species-specific responses to hydro regime change. Also, individual zooplankton groups exhibited different correlations with specific environmental parameters regarding site change. Throughout the study, rotifers' local (α) and among-community (β) diversities were susceptible to the site and inundation change while the microcrustacean biodiversity pattern diverged. Copepods highly discriminated different habitat types and hydrological phases at the regional scale (γ diversity), while we found a complete lack of biodiversity dependence on both site and hydrology for Cladocera. Our results show that heterogeneous environments support the development of different zooplankton assemblages that express the within-group dissimilarities. They also point to the importance of identifying processes in hydrologically variable ecosystems that influence biodiversity patterns at an individual zooplankton group level. Our results suggest the use of appropriate zooplankton groups as biological markers in natural habitats and stress the importance of proper management in preserving biodiversity in floodplain areas.

The importance of environmental differences in the structuring of rotifer functional diversity

“…The same pattern is observed in water temperature, pH or the trophic state of the water body (Bērziņš and Pejler, 1987, 1989a, 1989bDuggan et al, 2002;Van der Gucht et al, 2007;Gutkowska et al, 2013). Meanwhile, it is not uncommon for different habitat types within the same floodplain to diverge into their limnological parameters (Weigelhofer et al, 2014;Galir Balkić et al, 2018a). This situation indicates that different habitat types within the same floodplain area may support diverse rotifer communities.…”

“…For a microcrustacean analysis, the entire sample was counted. All zooplankton was identified to species level according to the specialised literature (see in Galir Balkić et al, 2018a).…”