Riparian arthropod responses to flow regulation and river channelization

Authors

  • Achim Paetzold,

    1. Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Duebendorf, Switzerland;
    2. Catchment Science Centre, University of Sheffield, Sheffield S3 7HQ, UK;
    Search for more papers by this author
    • Correspondence author: A. Paetzold, Catchment Science Centre, University of Sheffield, North Campus, Broad Lane, Sheffield S3 7HQ, UK. E-mail: a.paetzold@sheffield.ac.uk

  • Chihiro Yoshimura,

    1. Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Duebendorf, Switzerland;
    2. University of Yamanashi, Kofu 400-8511, Japan; and
    Search for more papers by this author
  • Klement Tockner

    1. Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Duebendorf, Switzerland;
    2. Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB),12587 Berlin, Germany
    Search for more papers by this author

Summary

  • 1Alterations to river flow and morphology widely impact riverine habitats. Little is known about the consequences of such alterations on riparian arthropods, although they contribute substantially to riverine biodiversity and play a critical role in linking aquatic and terrestrial food webs.
  • 2We investigated the interactive effects of flow regulation (hydropeaking) and river channelization on gravel-bar habitat characteristics and riparian arthropods in seven Alpine rivers. Digital elevation models were developed to simulate inundation dynamics of each gravel bar.
  • 3Channelization significantly increased inundation frequency, and hydropeaking increased substrate embeddedness. The total abundance of riparian arthropods was significantly reduced by hydropeaking, whereas arthropod species richness was reduced by both hydropeaking and channelization. Sites that were affected by both hydrological and morphological modifications together were almost devoid of arthropods.
  • 4The sensitivity of riparian arthropods to alterations in flow and morphology differed among taxa. Spider abundance and richness were significantly reduced by channelization only. Ground beetles showed no significant response. Rove beetle abundance and richness were negatively affected by hydropeaking whereas channelization had a negative effect only in rivers with hydropeaking.
  • 5Abundance and richness of all taxa combined, and of spiders independently, were negatively correlated with inundation frequency and substrate embeddedness. Rove beetle abundance and richness were negatively correlated with embeddedness. Spider and rove beetle richness were also correlated with gravel bar area.
  • 6Synthesis and applications. Our results indicate that the richness and abundance of riparian arthropods were predominantly affected by the availability of exposed gravel above the average high-water level and substrate embeddedness. Restoration of riverbank morphology and mitigation of hydropeaking are likely to benefit riparian arthropods. Riparian arthropods, particularly spiders and rove beetles, appear to be sensitive indicators of the ecological effects of hydromorphological alterations in rivers.

Ancillary