Author(s): Jose Maria Santos; Rui Rivaes; Isabel Boavida; Paulo Branco
Linked Author(s): José Maria Santos
Keywords: No Keywords
Abstract: Freshwater fish from the Mediterranean region are amongst the most threatened species worldwide due to increasing river degradation. Because of such threats, the number of river restoration projects has greatly increased. However, they are seldom planned with inputs from the species’life history, often resulting in erroneous practices that failed to achieve their goals. This study assesses the seasonal and size-related microhabitat use of three endemic cyprinids (Iberian barbel, Luciobarbus bocagei; Iberian straight-mouth nase, Pseudochondrostoma polylepis; and calandino, Squalius alburnoides) using a modified point electrofishing procedure in a Mediterranean river. All species showed non-random microhabitat use. The barbel and nase shifted to faster-flowing locations with a coarser substratum during spring and to sheltered locations during autumn. Calandino selected more covered areas in autumn and shifted to shallower locations from this season to summer. Significant size-related differences in microhabitat use were consistent for the three species, with smaller individuals occupying on average shallower microhabitats. Cover was found to be critical for all species, in particular for calandino, which could be classified as a shelter-oriented eurytopic species. Restoration scenarios should therefore consider maintaining cover habitats during unfavourable flow conditions for these species. Lithophilic spawners, which were highly responsive to velocity and substratum, could particularly benefit from the creation of gravel bedforms and artificial riffles to enhance depth and flow variability.
Year: 2018