title: Fine-scale determinants of conservation value of river reaches in a hotspot of native and non-native species diversity.
abstract: Global freshwater biodiversity is declining at unprecedented rates while non-native species are expanding. Examining diversity patterns across variable river conditions can help develop better management strategies. However, many indicators can be used to determine the conservartion value of aquatic communities, and little is known of how well they correlate to each other in making diagnostics, including when testing for the efficacy of protected areas. Using an extensive data set (99,700km2, n=530 sites) across protected and unprotected river reaches in 15 catchments of NE Spain, we examine correlations among 20 indicators of conservation value of fish communities, including the benefits they provide to birds and threatened mammals and mussels. Our results showed that total native fish abundance or richness correlated reasonably well with many native indicators. However, the lack of a strong congruence led modelling techniques to identify different river attributes for each indicator of conservation value. Overall, tributaries were identified as native fish refugees, and nutrient pollution, salinization, low water velocity and poor habitat structure as major threats to the native biota. We also found that protected areas offered limited coverage to major components of biodiversity, including rarity, threat and host-parasite relationships, even though values of non-native indicators were notably reduced. In conclusion, restoring natural hydrological regimes and water chemical status is a priority to stem freshwater biodiversity loss in this region. A complementary action can be the protection of tributaries, but more studies examining multiple components of diversity are necessary to fully test their potential as fluvial reserves in Mediterranean climate areas.
authors.affiliation: Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), E-41092 Sevilla, Spain; Institute of Research in Biodiversity (IRBio), Faculty of Biology, University of Barcelona, E-08028 Barcelona, Spain. Electronic address: albertomaceda@gmail.com.
authors.forename: Alberto
authors.initials: A
authors.lastname: Maceda-Veiga
authors.affiliation: Departamento de Zoología, Facultad de Biología, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Baselga
authors.affiliation: CBMA - Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus Gualtar, P-4710-057 Braga, Portugal; CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, P-4050-123 Porto, Portugal.
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Sousa
authors.affiliation: Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), E-41092 Sevilla, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Vilà
authors.affiliation: Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales-CSIC, E-28006 Madrid, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Doadrio
authors.affiliation: Institute of Research in Biodiversity (IRBio), Faculty of Biology, University of Barcelona, E-08028 Barcelona, Spain; Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, E-08028 Barcelona, Spain.
authors.forename: Adolfo
authors.initials: A
authors.lastname: de Sostoa
keywords: Conservation trade-offs; Diversity patterns; Environmental degradation; Fluvial reserves; Natura 2000; Threatened taxa