A Hydroclimatic Approach to Understand Ecological Impacts of Climate Change in a Large River

ABSTRACT An understanding of the hydroclimatic environment in river systems is essential for identifying the main extrinsic factors affecting aquatic communities. This study addresses this topic by using an unprecedented historical dataset (from 1975 to 2017) on the ecological aspects of the key invertebrate species of the large Parana River's sandy bed: Narapa bonettoi (Oligochaeta). This large dataset was examined in the context of a large series of environmental variables measured in the section of the river where invertebrate samples were obtained. The statistical analysis of this information, combined with the findings of previous studies, enabled the selection and/or design of 36 crucial hydroclimatic variables. These variables were used to construct, calibrate and validate a generalized linear models (GLM). This model predicts the densities of N. bonettoi under different hydroclimatic scenarios ( R 2 = 0.52). The general results indicate significant ecological changes during the rising and receding limbs of a flood and the hydrological period following its end. These changes occur due to variations in the intensity of hydraulic forces along the riverbed during flood and drought. Therefore, this model can serve as a valuable tool for understanding the ecological consequences of climate change in large rivers.