title: The effect of water salinity on wood breakdown in semiarid Mediterranean streams.
abstract: Saline streams occur naturally and they are distributed worldwide, particularly in arid and semiarid regions, but human activities have also increased their number in many parts of the world. Little attention has been paid to assess increasing salt effects on organic matter decomposition. The objectives of this study were to analyse wood breakdown rates and how salinity affects them in 14 streams that exemplify a natural salinity gradient. We also analysed the effect of this gradient on changes in wood chemical composition, fungal biomass and microbial activity. Our results showed low breakdown rates (0.0010-0.0032 d(-1)), but they fell within the same range as those reported in freshwater streams when a similar woody substrate was used. However, salinity had a negative effect on the breakdown rates and fungal biomass along the salinity gradient, and led to noticeable changes in wood composition. Water salinity did not affect microbial activity estimated using hydrolysis of fluorescein diacetate. Variation in breakdown rates and fungal biomass across streams was mediated mainly by salinity, and later by stream discharge. Despite the role of fungi in stick breakdown, the potential wood abrasion by salts must be analysed in detail to accurately understand the effect of increasing salinity on organic matter breakdown. Finally, our results indicate that increased salinity worldwide by human activities or by the global warming would imply organic matter breakdown and mineralisation slowing down, even in natural saline streams. However, because many variables are implicated, the final effect of climatic change on organic matter decomposition in streams is difficult to predict.
authors.affiliation: Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum" - University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Gómez
authors.affiliation: Department of Applied Biology, Miguel Hernandez University, Avda. Universidad, 03202 Elche, Alicante, Spain.
authors.forename: Antonia Dolores
authors.initials: AD
authors.lastname: Asencio
authors.affiliation: Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum" - University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: José María
authors.initials: JM
authors.lastname: Picón
authors.affiliation: Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum" - University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: Rubén
authors.initials: R
authors.lastname: Del Campo
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, 12587 Berlin, Germany.
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Arce
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, 12587 Berlin, Germany.
authors.forename: María
authors.initials: M
authors.lastname: Del Mar Sánchez-Montoya
authors.affiliation: Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum" - University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Suárez
authors.affiliation: Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum" - University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: María Rosario
authors.initials: MR
authors.lastname: Vidal-Abarca
keywords: Chemical composition; Fungal biomass; Mediterranean semiarid streams; Saline streams; Salt crystals; Wood breakdown