River restoration success: a question of perception

Authors

  • S. C. Jähnig,

    Corresponding author
    1. Senckenberg Research Institute and Natural History Museum, Department of Limnology and Conservation, Clamecystrasse 12, 63571 Gelnhausen, Germany
    2. Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany
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  • A. W. Lorenz,

    1. University of Duisburg-Essen, Department of Applied Zoology/Hydrobiology, 45117 Essen, Germany
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  • D. Hering,

    1. University of Duisburg-Essen, Department of Applied Zoology/Hydrobiology, 45117 Essen, Germany
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  • C. Antons,

    1. University of Münster, Institute for Evolution and Biodiversity, Huefferstrasse 1, 48149 Münster, Germany
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  • A. Sundermann,

    1. Senckenberg Research Institute and Natural History Museum, Department of Limnology and Conservation, Clamecystrasse 12, 63571 Gelnhausen, Germany
    2. Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany
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  • E. Jedicke,

    1. Goethe University Frankfurt, Department of Physical Geography, Altenhöferallee 1, 60438 Frankfurt, Germany
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  • P. Haase

    1. Senckenberg Research Institute and Natural History Museum, Department of Limnology and Conservation, Clamecystrasse 12, 63571 Gelnhausen, Germany
    2. Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany
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  • Corresponding Editor: C. Nilsson. For reprints of this Invited Feature, see footnote 1, p. 1925.

Abstract

What defines success and failure of river restoration measures is a strongly debated topic in restoration science, but standardized approaches to evaluate either are still not available. The debate is usually centered on measurable parameters, which adhere to scientific objectivity. More subjective aspects, such as landscape aesthetics or recreational value, are usually left out, although they play an important role in the perception and communication of restoration success. In this paper, we show that different perceptions of restoration success exist by analyzing data from 26 river restoration measures in Germany. We addressed both objective parameters, such as hydromorphological changes and changes in fish and benthic invertebrate assemblages, from field investigations, and subjective parameters, such as opinions and perceptions, from water managers via an online survey. With regard to the objective hydromorphological and biotic parameters, our results agree with many studies that have reported improvements in the hydromorphology following restoration; however, there is no similar agreement between results concerning changes in the benthic invertebrate and fish assemblages. The objective results do not correspond to the subjective parameters because self-evaluation of the restoration projects by water managers was overly positive. Indeed, 40% of the respondents admitted that their evaluation was based on gut feeling, and only 45% of the restoration measures were monitored or occasionally checked. This lack of objectively recorded data meant that the water managers were not able to reasonably evaluate restoration success. In contrast, some self-evaluation responses reflected a different perception of the restoration success that was based on landscape aesthetic values or on benefit for the public; others adopted a general “condemned to success” attitude. Based on our data, we argue (1) that goals should be thoughtfully formulated prior to restoration implementation and (2) that it is necessary to monitor river restoration success from different perspectives.

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