ABSTRACT This study examined the hydrologic variability of the middle Paraná River and its influence on the dynamics of macroinvertebrate communities. The analysis revealed a wide range of discharge conditions throughout the study period, including five major floods with distinct magnitudes and durations, interspersed with flow pulses and prolonged low‐water phases. One flood was identified as an extraordinary event, while the others were classified as ordinary floods, some followed by successive flow pulses after their recession phases. A hierarchical Bayesian model was developed to describe macroinvertebrate density ( Narapa bonettoi ) as a function of the Modified Index of Discharge Fluctuation (MIDF). The model calibration produced well‐defined posterior distributions, and simulations showed a strong agreement with observed data. Posterior predictive distributions indicated minimal Narapa bonettoi densities for negative MIDF values and exponential growth around MIDF values near zero, corresponding to post‐peak discharge conditions. Based on these results, three flood types were identified: Type A, ordinary floods with moderate discharges and rapid biological recovery; Type B, ordinary floods with higher discharges and delayed recovery due to continuous flow pulses; and Type C, an extraordinary flood causing severe and prolonged reductions in macroinvertebrate densities. The findings demonstrate that macroinvertebrate responses depend not only on mean discharge variations but also on flood magnitude, duration and subsequent flow conditions. Continuous post‐flood pulses hinder the recovery of benthic communities. The proposed Bayesian framework provides a predictive tool for assessing macroinvertebrate responses under varying hydrological regimes and future hydro‐climatic scenarios.
Eberle et al. (Sun,) studied this question.