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Loss of functionally important and regionally endemic species from streams forced into intermittency by global warming
Journal article   Open access   Peer reviewed

Loss of functionally important and regionally endemic species from streams forced into intermittency by global warming

N. Carey, Edwin T Chester and Belinda J Robson
Global change biology, Vol.29(11), pp.3019-3038
2023
PMID: 36811356
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Global Change Biology - 2023 - Carey - Loss of functionally important and regionally endemic species from streams forced4.41 MBDownloadView
Published (Version of Record)CC BY-NC-ND V4.0 Open Access

Abstract

rivers IRES ephemeral streams flow regime benthic invertebrates climate change Freshwater ecology Climate change impacts and adaptation Assessment and management of freshwater ecosystems
Climate change is altering hydrological cycles globally, and in mediterranean (med-) climate regions it is causing the drying of river flow regimes, including the loss of perennial flows. Water regime exerts a strong influence over stream assemblages, which have developed over geological timeframes with the extant flow regime. Consequently, sudden drying in formerly perennial streams is expected to have large, negative impacts on stream fauna. We compared contemporary (2016/17) macroinvertebrate assemblages of formerly perennial streams that became intermittently flowing (since the early 2000s) to assemblages recorded in the same streams by a study conducted pre-drying (1981/82) in the med-climate region of southwestern Australia (the Wungong Brook catchment, SWA), using a multiple before-after, control-impact design. Assemblage composition in the stream reaches that remained perennial changed very little between the studies. In contrast, recent intermittency had a profound effect on species composition in streams impacted by drying, including the extirpation of nearly all Gondwanan relictual insect species. New species arriving at intermittent streams tended to be widespread, resilient species including desert-adapted taxa. Intermittent streams also had distinct species assemblages, due in part to differences in their hydroperiods, allowing establishment of distinct winter and summer assemblages in streams with longer-lived pools. The remaining perennial stream is the only refuge for ancient Gondwanan relict species and the only place in the Wungong Brook catchment where many of these species still persist. The fauna of SWA upland streams is becoming homogenised with that of the wider Western Australian landscape, as drought tolerant, widespread species replace local endemics. Flow regime drying caused large in situ alterations to stream assemblage composition and demonstrates the threat posed to relictual stream faunas in regions where climates are drying.

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Citation topics
3 Agriculture, Environment & Ecology
3.2 Marine Biology
3.2.62 Freshwater Fish Ecology
Web Of Science research areas
Biodiversity Conservation
Ecology
Environmental Sciences
ESI research areas
Environment/Ecology
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