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Functional organization and colonization of macroinvertebrates in a nature-like fishway with added habitat heterogeneity
Karlstad University, Faculty of Social and Life Sciences, Department of Biology. (River Ecology and Management group)
Karlstad University, Faculty of Social and Life Sciences, Department of Biology. (River Ecology and Management group)
Stiftelsen Lillehammer museum.
Department of Environment, Land and Infrastructure Engineering Politecnico di Torino.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Stream habitat lost due to hydroelectric development can be partly mitigated through the construction of nature-like fishways that facilitate passage and provide habitat. Such habitats will become increasingly important as river rehabilitation and connectivity issues are addressed, and information concerning trophic levels and habitat functions brings important knowledge for conservation incentives. In 2009, a nature-like fishway, termed the biocanal, with added habitat heterogeneity in the form of four habitat types (‘pools’, ‘floodplains’, ‘braided habitats’ and ‘riffles’), was constructed in River Västerdalälven, Sweden. The trophic state and colonization by macroinvertebrates in the biocanal was studied during five years. Densities of functional feeding groups changed over time and among habitats, and functional feeding group ratios indicated that the biocanal is a heterotrophic system, probably caused by influx of nutrient rich water from the main river. Most macroinvertebrate families were found in the pools and fewest were found in the riffles, showing that the added habitat heterogeneity influenced both function and biodiversity. The total number of macroinvertebrate families increased initially to level out two years after the biocanal was constructed. The densities of macroinvertebrates did however depict a constant increase during the period, indicating that stabilization of the system is still under progress. 

Keyword [en]
Benthic community, biocanal, functional feeding groups, habitat rehabilitation
National Category
Ecology
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-65012OAI: oai:DiVA.org:kau-65012DiVA: diva2:1153321
Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2017-10-30
In thesis
1. Habitat compensation in nature-like fishways: Effects on benthos and fish
Open this publication in new window or tab >>Habitat compensation in nature-like fishways: Effects on benthos and fish
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The construction of nature-like fishways has become an increasingly common measure to restore longitudinal connectivity in streams and rivers affected by hydroelectric development. These fishways also have the potential to function as habitat compensation measures when running waters have been degraded or lost. The habitat potential has however often been overlooked, and therefore the aim of this thesis was to examine the potential of nature-like fishways for habitat compensation, with special focus on the effect of added habitat heterogeneity.

This thesis examines the effects of habitat diversity on the macroinvertebrate family composition and functional organization in a nature-like, biocanal-type fishway. The biocanal contained four habitat types; riffle, pool, braided channel and floodplain. The effects of habitat diversity and large woody debris on brown trout habitat choice was also investigated in the biocanal. In addition, and prior to introduction of the threatened freshwater pearl mussel into the biocanal, the suitability of different brown trout strains as hosts for the mussel was examined.

The results show that the habitat heterogeneity in the biocanal contributed to an increased macroinvertebrate family diversity. The functional organization of the macroinvertebrate community suggests that it was a heterotrophic system and more functionally similar to the main river than to the small streams that it was created to resemble. Brown trout habitat choice studies showed that high densities of large woody debris increase the probability of fish remaining at the site of release. Testing of different brown trout strains as host for the freshwater pearl mussel revealed that both wild and hatchery-reared brown trout strains were suitable hosts. In summary, the results indicate that it is possible to create a fish passage with added value through its high habitat function and that nature-like fishways can be designed to reach multiple species restoration goals.

Abstract [en]

The construction of nature-like fishways has become an increasingly common measure to restore longitudinal connectivity in streams, but these fishways also have the potential to compensate for habitat degradation and loss associated with hydropower. The habitat potential of fishways has largely been overlooked, and therefore the aim of this dissertation was to examine the potential of nature-like fishways for habitat compensation, with special focus on the effect of added habitat heterogeneity.

I examined the effects of added habitat heterogeneity in a nature-like fishway on macroinvertebrate family composition and functional organization as well as on brown trout habitat choice. In addition, I studied the suitability of different strains of brown trout as hosts for the freshwater pearl mussel, one of the target species for this study.

I found that by relatively simple modifications to increase habitat diversity, including the addition of large woody debris, that one could not only accommodate specific target species, but also increase biodiversity in general. These results show that it is possible to build nature-like fishways with high habitat functionality that also include multiple species restoration goals.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2017. 33 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2017:46
Keyword
Biocanal, biodiversity, brown trout, freshwater pearl mussel, functional feeding groups, habitat heterogeneity, large woody debris, macroinvertebrates, PIT-tag, salmonids
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-65018 (URN)978-91-7063-823-7 (ISBN)978-91-7063-918-0 (ISBN)
Public defence
2017-12-15, 1B 306 Fryxellsalen, Karlstad, 13:00 (English)
Opponent
Supervisors
Available from: 2017-11-24 Created: 2017-10-30 Last updated: 2017-11-24Bibliographically approved

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