title: Long term flow change threatens invertebrate diversity in temporary streams: Evidence from an island.
abstract: Here we provide the first evidence of long term reductions in flow in temporary streams on the Mediterranean island of Mallorca and use a simple metric of the degree of water permanence (the number of days with water) to highlight the implications of flow change for aquatic invertebrate diversity. Analysis of a 33year data set for 13 streams on the island yielded evidence of consistent downward trends in water permanence, particularly in spring and summer. Data from 27 relatively undisturbed mountain streams indicate that the diversity of benthic invertebrates in temporary streams across the island is directly related to water permanence. Streams with lower values of water permanence support few species overall and have less abundant invertebrate assemblages; the abundance and species richness of sensitive mayfly, stonefly and caddisfly taxonomic groups is also reduced in streams with lower water permanence. Although developed using spatial data, these flow-invertebrate relationships suggest that future reductions in water permanence may lead to reduced diversity. We argue that the 'number of days with water' is a simple but ecologically-relevant metric of water permanence that can be used effectively to monitor change in threatened temporary streams worldwide.
authors.affiliation: Department of Geography, University of the Balearic Islands, Palma, Balears, Spain. Electronic address: celso.garcia@uib.es.
authors.forename: Celso
authors.initials: C
authors.lastname: Garcia
authors.affiliation: School of Environmental and Geographical Sciences, University of Nottingham Malaysia Campus, Jalan Broga, Selangor, Malaysia. Electronic address: Christopher.Gibbins@nottingham.edu.my.
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Gibbins
authors.affiliation: Department of Ecology and Animal Biology, University of Vigo, Vigo, Spain. Electronic address: ipardo@uvigo.es.
authors.forename: Isabel
authors.initials: I
authors.lastname: Pardo
authors.affiliation: Fluvial Dynamics Research Group - RIUS, University of Lleida, Lleida, Catalonia, Spain; Catalan Institute for Water Research, Girona, Catalonia, Spain; Faculty of Forest Sciences and Natural Resources, Austral University of Chile, Valdivia, Chile. Electronic address: rbatalla@macs.udl.cat.
authors.forename: Ramon J
authors.initials: RJ
authors.lastname: Batalla
mesh_terms: D000818:Animals; D044822:Biodiversity; D007313:Insecta / Q000145:classification*; D062312:Islands; D045483:Rivers; D012621:Seasons; D013030:Spain; D014872:Water Movements
keywords: Diversity; Global change; Invertebrates; Mediterranean islands; Water permanence