Quantitative Habitat Models for the Conservation of the Endangered European Crayfish Austropotamobius pallipes Complex (
Crayfish are the largest mobile freshwater invertebrates and are keystone species in European aquatic ecosystems particularly in small streams and rivers. The white-clawed crayfish Austropotamobius pallipes (a species complex) is currently classified by t
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Quantitative Habitat Models for the Conservation of the Endangered European Crayfish Austropotamobius pallipes Complex (Astacoidea: Astacidae) Paolo Vezza, Daniela Ghia and Gianluca Fea
Abstract Crayfish are the largest mobile freshwater invertebrates and are keystone species in European aquatic ecosystems particularly in small streams and rivers. The white-clawed crayfish Austropotamobius pallipes (a species complex) is currently classified by the IUCN Red List as an endangered species (EN), because its populations have decreased significantly over the last decades in a number of European countries including Italy, due mainly to habitat modifications and the introduction and spread of alien species. Data on the ecological requirements of A. pallipes are needed to quantify the effects of habitat alteration, to simulate restoration scenarios, and to implement effective conservation measures for this species. We describe here a new methodology for modelling the habitat requirements for this endangered crayfish using the mesohabitat scale approach based on data from crayfish living in small streams draining the Italian foothills of the Alps (Lombardy region) and in streams in the mountainous areas of the Gran Sasso and Monti della Laga National Park (Abruzzo region). Data from seven morphologically different streams were used to train and validate the habitat models. The Random Forests algorithm was used to identify the best and most parsimonious habitat model, and to define the lowest number of variables to be surveyed in the future. The best habitat models were applied to each stream and used to classify each mesohabitat into suitability categories. Habitat flow-rating curves were developed to analyze spatio-temporal variation of habitat availability, and habitat time series analysis were used to define detailed management schemes for environmental river management. Flow releases and water P. Vezza (&) International Centre for Ecohydraulics Research (ICER), University of Southampton, University Rd, Southampton SO17 1BJ, UK e-mail: [email protected] P. Vezza Dpto. de Ingeniería Rural y Agroalimentaria (DIRA), Universitat Politecnica de Valencia, Valencia, Spain D. Ghia G. Fea Dipartimento di Scienze della Terra e dell’Ambiente, Università degli Studi di Pavia, Pavia, Italy © Springer International Publishing AG 2016 T. Kawai and N. Cumberlidge (eds.), A Global Overview of the Conservation of Freshwater Decapod Crustaceans, DOI 10.1007/978-3-319-42527-6_12
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temperature regimes were assessed for individual water diversions in order (1) to represent how physical habitat changes through time, and (2) to identify stress conditions for A. pallipes created by the persistent limitation of habitat availability. Results indicated that the kind of substrate in the stream bed (such as the proportion of fine-grained substrates), the water depth (whether shallow or deep), and the available cover (such as the presence of boulders, woody debris, and undercut banks) were all significant factors governing the occu
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