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Do Trichoptera in running water fly upstream?

Drift moves aquatic insects downstream, risking depopulation of upstream reaches. However, the necessity and exist-ence of an upstream flight to compensate for drift has not been undisputed. I analysed a sample of approximately 70 000 Trichoptera from a stream in northern Sweden collected during one season in 1974. The overall flight direction was upstream. Females had a stronger upstream flight than males and species varied in both flight direction and strength of the preference. Flight direction was not affected by wind or trap type. Upstream flight varied during the season and with different larval behaviours. Upstream flight increased with the size of the imago and with the abun-dance in flight. A colonisation cycle might be in effect but even though upstream flight occurs, it might not be neces-sary to sustain populations in upstream reaches.

Identiferoai:union.ndltd.org:UPSALLA1/oai:DiVA.org:liu-130870
Date January 2015
CreatorsLarsson, Malin
PublisherLinköpings universitet, Institutionen för fysik, kemi och biologi
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeStudent thesis, info:eu-repo/semantics/bachelorThesis, text
Formatapplication/pdf
Rightsinfo:eu-repo/semantics/openAccess

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