Invertebrate functional responses to hydro morphological degradation in Mediterranean Croatian rivers (vol 194, pg 259, 2021)

Hydromorphological alterations are among the most widespread anthropogenic pressures in rivers and streams. They comprise channelization, damming, water abstraction etc. resulting in habitats alteration and subsequent changes in aquatic community composition. Aim of this study was to test to what extent hydromorphological alterations influence aquatic macroinvertebrates as one of the best bioindicators to anthropogenic pressures. Our research took place in the Mediterranean part of Croatia. We sampled 40 sites which include perennial rivers varying in catchment size and altitude with similar environmental conditions along river reaches. Large rivers were omitted from this research because of their different functional group representation to the rivers covered used in this study. We used the functional approach to hydromorphological alteration by testing the following traits: reproduction strategy, functional feeding group and microhabitat (substrate type) preference. From the feeding standpoint shredders were the most affected group by hydrological alteration. Moreover, taxa confined to a specific relatively less common habitat e.g. phytal, pelal and lithal were the most negatively affected by morphological degradation due, mostly, to it leading to a homogenization of the substrate. Finally, the smaller and faster reproductive taxa were more resilient to hydromorphological degradation. We found that the functional approach to bioassessment complements the common biocenotical approach, at the same time it may provide sound ecological knowledge.