Response of littoral macroinvertebrates to morphological disturbances in Mediterranean lakes.The case of Lake Piediluco (central Italy)

The assessment of the impacts of human morphological alterations on lake ecological condition based on littoral benthic fauna is still in its infancy, especially in the Mediterranean area of Europe. Lake Piediluco is a riverine lake, sited in Central Italy, whose water level is strictly regulated for hydroelectric reasons and hence can be classified as a Heavily Modified Water Body (HMWB) according to the E.U.Water Framework Directive (WDF). Here, we aim at comparing the invertebrate assemblages among sites with a different degree of morphological alterations by identifying potential indicator species and metrics sensitive to morphological alterations, and by comparing the fauna composition collected using two sampling procedures (composite vs habitat-specific samples) with different processing times. Our results show that the invertebrate assemblages of Lake Piediluco differed according to the three types of shoreline alteration (natural, soft- and hard-altered sites) and this was more evident when we analyzed the habitat-specific samples. Several taxa, diversity and metrics based on the number of Ephemeroptera, Trichoptera, Odonata and Mollusca taxa (ETO and ETOM) are found to be sensitive to shoreline alterations and are candidates for inclusion in assessment metrics for WDF compliant monitoring of the ecological status of this lake. While habitat-specific sampling provided a more detailed picture of the assemblages, composite samples provided consistent results and could be used when processing cost is an issue.