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Indirect effects of river regulation: consequences for landbirds of reduced numbers of aquatic insects
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [sv]

Abstrakt: Jag har undersökt hur älvreglering påverkar mängden knott (Tvåvingar: Simuliidae) längs flera norrlandsälvar och vilka konsekvenser denna påverkan får för den landlevande fågelfaunan. Studien visar att utbyggnad av älvar har en negativ effekt på mängden knott. Det fanns sju gånger högre tätheter av knott längs "orörda älvar" jämfört med utbyggda älvar.

Skillnaden i antal knott mellan älvtyperna var mycket större för knotthanar än för knotthonor, vilket förklaras av att honorna är rörligare eftersom de flyger och letar efter blod. Knott lever av blod från ett flertal däggdjur och fåglar och visar en stor variation i värd-specificitet mellan olika arter. Jag fann en högre frekvens av haemosporida blod parasiter (Leucocytozoon) i fåglar längs "orörda" Vindelälven jämfört med den reglerade Umeälven. Detta mönster stämmer väl överens med tätheten fågelparasiterande knott som är lägre längs Umeälven. Knott attackerade främst värdar som var stora och vanliga. Fågelsamhällets sammansättning skiljde sig mellan orörda och utbyggda älvdalar. Tätheten av icke insektsätande fåglar tenderade att minska, efter häcksäsongen, längs orörda älvar medan den ökade längs utbyggda älvar. Den insektsätande fågeln svartvit flugsnappare (Ficedula hypoleuca Pallas) uppvisade större häckningsframgång längs orörda älvar jämfört med utbyggda älvar. Detta är förmodligen en effekt av den större mängden insekter som finns längs orörda älvar.

Abstract [en]

The effects of river regulation on blackfly (Diptera: Simuliidae) abundances and consequences for the avifauna in terrestrial environments were studied along multiple rivers in northern Sweden. I found that impoundment of rivers has detrimental effect to blackfly abundances. The densities of large-river breeding blackfly species were several-fold higher along free-flowing than along regulated rivers. The difference in abundances was much larger in males than blood-seeking females. Blackflies attacked a variety of mammalian and avian hosts and showed different levels of host-specificity between species. I found higher prevalence of haemosporidian blood parasites (Leucocytozoon) in birds along the free-flowing Vindel River in comparison to the regulated Ume River, where the lower densities of ornithophilic blackflies were reduced. Blood-seeking blackflies predominantly attacked large and/abundant hosts.

Assemblages of birds differed between valleys of regulated and free-flowing rivers. Densities of noninsectivorous birds tended to decrease along free-flowing rivers in the post-breeding season, but increased along regulated rivers at the same time. Insectivorous European pied flycatcher (Ficedula hypoleuca Pallas) showed greater fledging success along free-flowing than regulated rivers, which probably reflects the higher insect abundances found along freeflowing rivers.

Place, publisher, year, edition, pages
Umeå: Ekologi, miljö och geovetenskap , 2007. , 31 p.
Keyword [en]
Boreal region, Simuliidae, Leucocytozoon, pied flycatcher, aquatic insects, breeding success, blood parasites, bird communities, river regulation, impoundment
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:umu:diva-1107ISBN: 978-91-7264-291-1 (print)OAI: oai:DiVA.org:umu-1107DiVA: diva2:140223
Public defence
2007-05-25, Lilla hörsalen, KBC, Umeå Universitet, Umeå, 13:00
Opponent
Supervisors
Available from: 2007-05-03 Created: 2007-05-03Bibliographically approved
List of papers
1. Transfer to terrestrial ecosystems of an important aquatic insect prey and parasite vector decreases following human impact
Open this publication in new window or tab >>Transfer to terrestrial ecosystems of an important aquatic insect prey and parasite vector decreases following human impact
(English)Manuscript (Other academic)
Identifiers
urn:nbn:se:umu:diva-2286 (URN)
Available from: 2007-05-03 Created: 2007-05-03 Last updated: 2016-02-25Bibliographically approved
2. Are avian blood parasites reduced because of degraded vector-breeding habitats?
Open this publication in new window or tab >>Are avian blood parasites reduced because of degraded vector-breeding habitats?
(English)Manuscript (Other academic)
Identifiers
urn:nbn:se:umu:diva-2287 (URN)
Available from: 2007-05-03 Created: 2007-05-03 Last updated: 2016-02-25Bibliographically approved
3. Vertebrate host specificity of wild-caught blackflies revealed by mitochondrial DNA in blood
Open this publication in new window or tab >>Vertebrate host specificity of wild-caught blackflies revealed by mitochondrial DNA in blood
Show others...
2004 (English)In: Proceedings of the Royal Society Biology Letters Supplement, ISSN 0962-8452, Vol. 271, no Supp. 4, S152-S155 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-2288 (URN)
Available from: 2007-05-03 Created: 2007-05-03 Last updated: 2016-02-25Bibliographically approved
4. Influences of river regulation on upland bird assemblages in northern Sweden.
Open this publication in new window or tab >>Influences of river regulation on upland bird assemblages in northern Sweden.
(English)Manuscript (Other academic)
Identifiers
urn:nbn:se:umu:diva-2289 (URN)
Available from: 2007-05-03 Created: 2007-05-03 Last updated: 2016-02-25Bibliographically approved
5. Does river regulation reduce fledging success of European pied flycatchers via changed aquatic insect resources?
Open this publication in new window or tab >>Does river regulation reduce fledging success of European pied flycatchers via changed aquatic insect resources?
(English)Manuscript (Other academic)
Identifiers
urn:nbn:se:umu:diva-2290 (URN)
Available from: 2007-05-03 Created: 2007-05-03 Last updated: 2016-02-25Bibliographically approved

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