Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2021
Erindi/veggspjald / Talk/poster E4
Höfundar / Authors: Gísli Már Gíslason1), Erling Ólafsson 2) Matthías S. Alfredsson 2)
Starfsvettvangur / Affiliations: 1) University of Iceland, Institute of Life and Environmental Sciences, Reykjavik, Iceland 2) Icelandic Institute of Natural History, Gardabaer, Iceland
Kynnir / Presenter: Gísli Már Gíslason
During the 20th and 21st century two species of caddisflies (Trichoptera) have colonized Iceland. One species is Potamophylax cingulatus and the other is Micropterna lateralis. Potamophylax cingulatus is widely distributed in streams in Europe and is dominant at higher latitudes and elevations. The larvae feed on detritus in the streams and to some extent on invertebrates. In Iceland, it is a predator of the Holarctic caddisfly larvae Apatania zonella, which has become extinct in streams recently colonized by P. cingulatus, probably due to predation. P. cingulatus was not found in several extensive surveys before WWII, conducted by several entomologists and published in 1942. During a survey in streams in 1974 – 1978 the species was found to be common in eastern and north-eastern part of Iceland, but the Trichoptera species A. zonella was absent from the same streams, where it was common before WWIIl. Searching earlier collections of unidentified Trichoptera, a single specimen was found in East Iceland in 30 July 1959. The survey was repeated in 2004 - 2006, and the species had colonized most streams and rivers in Iceland, and A. zonella has disappeared from many of them. M. lateralis was found in a single light trap at Mógilsá near Reykjavik in 2008. The annual catch has since grown from 2 specimens to 73, but the species has been found in Hvalfjördur and Hvanneyri, but the larvae have not been found, but they presumably occur in running waters. It is possible to conclude from this that when species establish a population on a large island like Iceland, the population builds up and when it has established itself, it disperses fast. For P. cingulatus, the dispersal rate was about 7 km/year, but the dispersal rate for the more recent settler M. lateralis 4 km/year.