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Effects of an extraordinarily harsh winter on macroinvertebrates and fish in boreal streams.
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
2003 In: Archiv für Hydrobiologie, ISSN 0003-9136, Vol. 157, 505–523- p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2003. Vol. 157, 505–523- p.
URN: urn:nbn:se:umu:diva-2724OAI: diva2:140977
Available from: 2003-11-07 Created: 2003-11-07Bibliographically approved
In thesis
1. Rarity in boreal stream: patterns, causes and consequences
Open this publication in new window or tab >>Rarity in boreal stream: patterns, causes and consequences
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Patterns of site occupancy among boreal stream insects were studied in central Sweden with focus on sparsely distributed species and the role of dispersal and niche limitations.

In the study of dispersal limitation, I found that effects of an extraordinarily harsh winter in small to medium-sized streams were strongest in sites located in small streams and far from lake outlets. Species richness and the total abundance of macroinvertebrates and trout returned to pre-disturbance levels after three years. However, some species showed slow recolonization and the proportion of holoaquatic taxa was still reduced after three years. In a second study, I found a positive correlation between site occupancy in stream caddisflies and morphological traits associated with fast and energy-efficient flight, whereas specialized spring caddisflies showed a negative correlation to these traits compared to stream species. This suggested that streams, but not springs, select for strong dispersal ability in caddisflies. In a survey of springs in central Sweden, hydrogeology was found to be a useful predictor of the occurrence of spring specialists. Two of these, Crunoecia irrorata Curtis and Parachiona picicornis (Pictet), were found exclusively in glaciofluvial springs, characterized by a stable discharge and temperature. Less specialized members of the spring fauna (i.e. species also occurring in streams, ponds or lakes) also occurred in moraine and limestone springs characterized by more unstable conditions.

Niche limitations were studied by contrasting large-scale distributions of closely related rare and common stoneflies. Differences in temperature requirements in the juvenile stages and life cycles suggested that the rare species, Isogenus nubecula Newman, was restricted by a limited tolerance to low stream temperatures, whereas the two common species, Isoperla grammatica (Poda) and Diura nanseni (Kempny), appeared to have a broader tolerance to climatic conditions in the study area. In a second study of niche limitations, macroinvertebrate assemblages in 88 streams in Central Sweden showed a nested distribution pattern. Most species deviating from expected distributions occurred in small streams, indicating competitive exclusion from species-rich sites, predator avoidance, or specialization to unique habitat features of small streams. In the last paper, the longitudinal distribution of filter-feeding caddisflies in a lake-outlet stream demonstrated patterns concordant to feeding specialization.

23 p.
Ecology, Central Sweden, site occupancy, dispersal limitation, natural disturbances, recolonization, flight-morphology, metapopulation, habitat stability, spring specialists, Crunoecia irrorata, niche limitation, Isogenus nubecula, nestedness, longitudinal distribution, Ekologi
National Category
Research subject
Animal Ecology
urn:nbn:se:umu:diva-142 (URN)91-7305-529-8 (ISBN)
Public defence
2003-11-28, Lilla hörsalen, KBC-huset, Umeå, 13:00
Available from: 2003-11-07 Created: 2003-11-07Bibliographically approved

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