Biodiversity under threat in glacier-fed river systems

Journal name:
Nature Climate Change
Volume:
2,
Pages:
361–364
Year published:
DOI:
doi:10.1038/nclimate1435
Received
Accepted
Published online

Freshwater biodiversity is under threat across the globe1, with climate change being a significant contributor2, 3. One impact of climate change is the rapid shrinking of glaciers4, resulting in a reduction in glacial meltwater contribution to river flow in many glacierized catchments5, 6. These changes potentially affect the biodiversity of specialized glacier-fed river communities7. Perhaps surprisingly then, although freshwater biodiversity is a major conservation priority3, the effects of shrinkage and disappearance of glaciers on river biodiversity have hitherto been poorly quantified. Here we focus on macroinvertebrates (mainly insect larvae) and demonstrate that local (α) and regional (γ) diversity, as well as turnover among reaches (β-diversity), will be consistently reduced by the shrinkage of glaciers. We show that 11–38% of the regional species pools, including endemics, can be expected to be lost following complete disappearance of glaciers in a catchment, and steady shrinkage is likely to reduce taxon turnover in proglacial river systems and local richness at downstream reaches where glacial cover in the catchment is less than 5–30%. Our analysis demonstrates not only the vulnerability of local biodiversity hotspots but also that extinction will probably greatly exceed the few known endemic species in glacier-fed rivers.

At a glance

Figures

  1. Accumulated loss of regional species richness ([gamma] diversity) as a function of glacial cover.
    Figure 1: Accumulated loss of regional species richness (γ diversity) as a function of glacial cover.

    Obligate glacial river macroinvertebrates begin to disappear from assemblages when glacial cover in the catchment drops below approximately 50%. Each data point represents a river site and lines are Lowess fits.

  2. Taxon turnover ([beta] diversity) as a function of glacial cover.
    Figure 2: Taxon turnover (β diversity) as a function of glacial cover.

    The data shown are for species turnover (Alaska) and family turnover (Ecuador and Alps). Assemblages at river sites close to glaciers are more spatially variable than those at sites with less glacial influence. Data are indexed to 1 at non-glacial sites (0% glacial cover). Each data point represents a river site and lines are Lowess fits.

  3. Local richness ([alpha] diversity) as a function of glacial cover.
    Figure 3: Local richness (α diversity) as a function of glacial cover.

    The data shown are for species richness (Alaska) and family richness (Ecuador and Alps). Local taxon richness peaks at 5–30% GCC. Data are indexed to 1, indicated by the horizontal dashed line, at non-glacial sites (0% glacial cover). Each data point represents a river site and lines are Lowess fits.

  4. Confluence of glacier-fed (left) and spring-fed streams in Ecuador.
    Figure 4: Confluence of glacier-fed (left) and spring-fed streams in Ecuador.

    These confluence zones of different river types produce local spikes in taxon richness (photo by D. Jacobsen).

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Author information

  1. These authors contributed equally to this work

    • Dean Jacobsen &
    • Olivier Dangles

Affiliations

  1. Freshwater Biological Section, Department of Biology, University of Copenhagen, Helsingørsgade 51, DK-3400 Hillerød, Denmark

    • Dean Jacobsen
  2. School of Geography, Earth and Environmental Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

    • Alexander M. Milner
  3. Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, USA

    • Alexander M. Milner
  4. School of Geography, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK

    • Lee E. Brown
  5. Institut de Recherche pour le Développement (IRD), UR 072, LEGS, UPR 9034, CNRS 91198 Gif-sur Yvette Cedex, France

    • Olivier Dangles
  6. Université Paris-Sud 11, 91405 Orsay Cedex, France

    • Olivier Dangles
  7. Laboratorio de Entomologı´a, Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, 17-01-2184, Quito, Ecuador

    • Olivier Dangles

Contributions

D.J. and O.D. collected the Ecuadorian data, conceived the study, analysed the data and led the writing of the paper. A.M.M. and L.E.B. collected the Alaska data and contributed to the writing of the manuscript. D.J. and O.D. contributed equally to the study.

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The authors declare no competing financial interests.

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