Concordance among zooplankton groups in a near-pristine floodplain system

The search for biological surrogate groups has been an active and contentious area of research. A surrogate group is defined as one that allows researchers to detect a known spatial and temporal environmental gradient and to represent the responses of other biological groups to those gradients. Using spatiotemporal zooplankton data from a near-pristine floodplain (the Araguaia River floodplain in Central Brazil), we first assessed the capacity of four zooplankton assemblages (Cladocera, Copepoda, Rotifera and Protozoa) to depict the effects of flooding. Second, we evaluated whether, during each hydrological period, ordination patterns derived from an assemblage matched those patterns shown by a second assemblage and by the environmental dataset. All four assemblages satisfactorily detected the environmental differences caused by the flood event. Most pairs of assemblages were significantly concordant. Additionally, the ordination patterns generated by these assemblages matched those generated by the environmental data. These results suggest that the patterns of concordance were mediated by similar responses to environmental gradients. However, the strengths of concordance between the assemblages, albeit significant, were low. Our results suggest the potential for use of the surrogacy approach in monitoring hydrological changes. However, due to the low strengths of concordance, the biodiversity pattern revealed by a specific assemblage is unlikely to be a good predictor of another. We also highlighted that conducting a formal meta-analysis on strengths of concordance between assemblages would be a promising avenue for further research.