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Re-establishment of connectivity for fish populations in regulated rivers
Karlstad University, Faculty of Social and Life Sciences.
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The hydropower industry has altered connectivity in many rivers during the last century. Many fish species depend on both an intact longitudinal connectivity to be able to migrate between spawning, feeding and winter habitats, and vertical connectivity for development and survival of incubating embryos and larvae in the gravel. The objective of this thesis was to examine problems and remedial measures associated with disrupted longitudinal and vertical connectivity in regulated rivers. The issue of longitudinal connectivity was studied in the River Emån by evaluating the efficiency of two nature-like fishways for anadromous brown trout. Telemetry studies showed that the combined efficiency for the two fishways in 2001-2004 was 60.5%. The passage efficiencies of both fishways were high for trout (89-100%), but also for other species such as chub, perch, tench, burbot and roach (74%). The attraction efficiencies were largely dependent on power plant operation, and generally high for the fishway situated next to the tail-race and low for the fishway situated inside the former channel. More than half of the trout spawners were also observed using the fishways for downstream passage. The densities of brown trout yearlings upstream of the fishways were higher after the fishways were built than during pre-fishway years. Smolts produced upstream of the fishways were observed migrating downstream in 2003-2005. The percentage of smolts that passed both power plants in was 51%, with losses being attributed to predation (15%), turbine-induced mortality (16%) and other reasons (18%). Turbine-induced mortality was higher (40%) at the power plant with four small Francis runners, than at the power plant with one large Kaplan runner (12%). The issue of vertical connectivity was studied in three rivers in Värmland, one unregulated, and two regulated, one of which had no minimum flow requirements. In the unregulated river, temporal patterns in hyporheic water chemistry correlated to variation in surface water chemistry and discharge as expected. In the regulated rivers, the hyporheic water chemistry showed little correlation to discharge or surface water chemistry. The intra-gravel water chemistry conditions for brown trout eggs were more favourable in the unregulated river, characterised by high oxygen levels, than in the two regulated rivers. The regulated river with no minimum flow requirements had critically low oxygen levels at the end of the incubation period.

Place, publisher, year, edition, pages
Fakulteten för samhälls- och livsvetenskaper , 2005.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2005:56
Keywords [en]
Attraction efficiency, Connectivity, Flow regime, Hyporheic water quality, Nature-like fishway, Passage efficiency, Regulated river, Remedial measures, Salmo trutta
National Category
Biological Sciences
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-1400ISBN: 91-7063-028-3 (print)OAI: oai:DiVA.org:kau-1400DiVA, id: diva2:5274
Public defence
2006-01-27, Andersalen, 11D 121, Karlstads universitet, Karlstad, 13:00
Opponent
Supervisors
Available from: 2008-02-05 Created: 2008-02-05
List of papers
1. Evaluation of nature-like fishways for re-establishing connectivity in fragmented salmonid populations in the River Emån
Open this publication in new window or tab >>Evaluation of nature-like fishways for re-establishing connectivity in fragmented salmonid populations in the River Emån
2005 (English)In: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 21, no 9, p. 951-960Article in journal (Refereed) Published
Abstract [en]

We evaluated the function of two nature-like fishways for re-establishing connectivity for anadromous salmonids in the regulated River Emån. Between 90 and 100% of the salmonids that entered the fishways actually passed through them, with median speeds of 180–190mh  1. Only 50% of the anadromous brown trout that passed the first fishway also passed the second one, indicating that the fish might have had problems locating the upstream fishway. The fishways were also observed to function as a passage for downstream post-spawning migrants. The densities of brown trout yearlings upstream of the fishways were higher in 2002, after the fishways were built, than during pre-fishway years. In control sites in other parts of the river as well as in a nearby river, no changes in yearling densities were observed. Thus, the fishways are working for upstream spawners, albeit at a recolonization rate that is slower than expected.

Place, publisher, year, edition, pages
Chichester: John Wiley & Sons, 2005
Keywords
regulated river; connectivity; nature-like fishway; passage efficiency; passive integrated transponder; anadromous brown trout; remedial measure
National Category
Natural Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-1974 (URN)10.1002/rra.865 (DOI)
Available from: 2008-02-05 Created: 2008-02-05 Last updated: 2017-12-07Bibliographically approved
2. The pre- and postspawning movements of anadromous brown trout in relation to two low-head power plants
Open this publication in new window or tab >>The pre- and postspawning movements of anadromous brown trout in relation to two low-head power plants
(English)Manuscript (Other academic)
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-1975 (URN)
Available from: 2008-02-05 Created: 2008-02-05 Last updated: 2015-11-12Bibliographically approved
3. Survival and movement of wild brown trout smolts past two power plants
Open this publication in new window or tab >>Survival and movement of wild brown trout smolts past two power plants
(English)Manuscript (Other academic)
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-1976 (URN)
Available from: 2008-02-05 Created: 2008-02-05 Last updated: 2015-11-12Bibliographically approved
4. The use of two nature-like fishways by some fish species in the Swedish River Emån: Nature-like fishways
Open this publication in new window or tab >>The use of two nature-like fishways by some fish species in the Swedish River Emån: Nature-like fishways
2007 (English)In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 16, no 2, p. 183-190Article in journal (Refereed) Published
Abstract [en]

We studied the use of two nature-like fishways by 15 fish species (N ¼ 240) in the River Emån in southern Sweden. Use of the fishways for both passage and as a habitat was studied by electrofishing, trap catches and PIT telemetry. Of the 187 PIT-tagged fish, 52 individuals from 10 different species ascended one of the fishways for a total passage efficiency of 74%. For the five species that most frequently ascended the fishways, the passage efficiency was 100% for tench (Tinca tinca L.) and perch (Perca fluviatilis L.), 86% for chub (Leuciscus cephalus L.), 60% for burbot (Lota lota L.) and 50% for roach (Rutilus rutilus L.). Individuals that failed to pass the fishways were typically small cyprinids or species that were assumed to have taken up residence in the fishways, such as juvenile brown trout (Salmo trutta L.) and burbot. The nature-like fishways have re-established longitudinal connectivity for most of the studied species and also functioned as rearing and winter habitat for a number of species.

Place, publisher, year, edition, pages
Chichester: John Wiley & Sons, 2007
Keywords
nature-like fishways, passage efficiency, habitat function, cyprinidae, percidae
National Category
Natural Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-1977 (URN)10.1111/j.1600-0633.2006.00210.x (DOI)
Available from: 2008-02-05 Created: 2008-02-05 Last updated: 2017-12-07Bibliographically approved
5. Temporal and spatial variation in quality of hyporheic water in one unregulated and two regulated boreal rivers
Open this publication in new window or tab >>Temporal and spatial variation in quality of hyporheic water in one unregulated and two regulated boreal rivers
2007 (English)In: River research and applications, ISSN 1535-1459, Vol. 23, no 8, p. 829-842Article in journal (Refereed) Published
Abstract [en]

This study describes the temporal and spatial variations in hyporheic water quality in three boreal rivers, the River Tobyälven, an unregulated river, the river Mangälven, a regulated river with a minimum discharge requirement and the river Järperudsälven, aregulated river without any minimum discharge requirements. A total of 43 permanent piezometers were used to measure dissolved oxygen (DO), temperature, electrical conductivity, pH, NO3 and NHþ4in the hyporheic water at 150mm and 300mmdepth, at monthly intervals from October 2001 to October 2002. Another seven piezometers were installed in brown trout redds and monitored during the incubation period, from December 2001 to April 2002. In the river Tobyälven, temporal patterns in hyporheic water chemistry correlated to variations in surface water chemistry and discharge. In the river Järperudsälven, the hyporheic water chemistry did not correlate to discharge or surface water chemistry. In the river Mangälven, the water chemistry was dominated by releases from a large upstream lake, and there were weak correlations between surface water chemistry and hyporheic water chemistry at some sites. The incubation conditions for brown trout eggs were most favourable in the unregulated river, characterized by high DO levels that remained high throughout the incubation period. In the river Järperudsälven the DO levels were variable during spawning, and then gradually declined to critically low levels during incubation, whereas in the river Mangälven the DO conditions were intermediate and stable. Thus we observed a stronger coupling between surface water conditions and hyporheic conditions, i.e. vertical connectivity, in the unregulated river than in the regulated river with minimum flow requirements, which in turn was stronger than in the river without minimum flow requirements.

Place, publisher, year, edition, pages
Chichester: John Wiley & Sons, 2007
Keywords
flow regulation; hyporheic water chemistry; flow requirements; incubation; vertical connectivity
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-1978 (URN)10.1002/rra.1015 (DOI)
Available from: 2008-02-05 Created: 2008-02-05 Last updated: 2017-12-06Bibliographically approved
6. Impact of short-term regulation on hyporheic water quality in a boreal river
Open this publication in new window or tab >>Impact of short-term regulation on hyporheic water quality in a boreal river
2008 (English)In: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 24, no 4, p. 407-419Article in journal (Refereed) Published
Abstract [en]

Water regulation may alter hydraulic head gradients with consequences for the exchange of water between the river and the hyporheic zone. The objective of this study was to investigate the effect of discharge on hyporheic water quality in a regulated Swedish boreal river during a 10-day experimental period with a sequence of alternating high- and low-flow episodes. A 250 m reach was instrumented with 28 piezometers placed at 150 and 300 mm below the river bed or below the mean groundwater level in the floodplain, and these piezometers were used to measure temperature, oxygen, electric conductivity and pH. High daily variation in air temperature during the first 3 days was transmitted vertically through the stream water into the hyporheic zone within hours. An oxygen saturation of 100% in the river water corresponded to 60–70% saturation at 150 mm depth and 30% at 300 mm depth. The hyporheic oxygen concentration at 150 mm depth decreased during the experimental period, falling into a range that is potentially harmful to incubating salmonid eggs. This was interpreted as a long-term response to the overall regulation regime, rather than a response to short-term water regulation during the experiment. Even though the effect of short-term regulation on the quality of hyporheic water in the river bed was limited, there was a more pronounced effect on the quality of floodplain hyporheic water. Most of the driving forces for temporal variation of water quality in the river bed came vertically from the river water, rather than from the lateral exchange.

Keywords
Flow regulation, hyporheic water, spawning habitat, floodplain, temperature, oxygen, conductivity, pH
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-1979 (URN)
Available from: 2008-02-05 Created: 2008-02-05 Last updated: 2017-12-07Bibliographically approved

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