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Substitution of top predators: effects of pike invasion in a subarctic lake
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
Visa övriga samt affilieringar
2007 (Engelska)Ingår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 52, nr 7, s. 1271–1280-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

1. Invasions of top predators may have strong cascading effects in ecosystems affecting both prey species abundance and lower trophic levels. A recently discussed factor that may enhance species invasion is climate change and in this context, we studied the effects of an invasion of northern pike into a subarctic lake ecosystem formerly inhabited by the native top predator Arctic char and its prey fish, ninespined stickleback.

2. Our study demonstrated a strong change in fish community composition from a system with Arctic char as top predator and high densities of sticklebacks to a system with northern pike as top predator and very low densities of sticklebacks. A combination of both predation and competition from pike is the likely cause of the extinction of char.

3. The change in top predator species also cascaded down to primary consumers as both zooplankton and predator-sensitive macroinvertebrates increased in abundance.

4. Although the pike invasion coincided with increasing summer temperatures in the study area we have no conclusive evidence that the temperature increase is the causal mechanism behind the pike invasion. But still, our study provides possible effects of future pike invasions in mountain lakes related to climate change. We suggest that future pike invasions will have strong effects in lake ecosystems, both by replacing native top consumers and through cascading effects on lower trophic levels.

Ort, förlag, år, upplaga, sidor
John Wiley & Sons, Inc , 2007. Vol. 52, nr 7, s. 1271–1280-
Nyckelord [en]
Arctic char, cascading effects, climate change, lake ecosystems, ninespined stickleback, northern pike, top predator invasions
Identifikatorer
URN: urn:nbn:se:umu:diva-6187DOI: 10.1111/j.1365-2427.2007.01763.xOAI: oai:DiVA.org:umu-6187DiVA, id: diva2:145855
Tillgänglig från: 2007-12-07 Skapad: 2007-12-07 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Ingår i avhandling
1. Invasion of top and intermediate consumers in a size structured fish community
Öppna denna publikation i ny flik eller fönster >>Invasion of top and intermediate consumers in a size structured fish community
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Invasion av toppredatorer och intermediära konsumenter i ett storleksstrukturerat fisksamhälle
Abstract [en]

In this thesis I have investigated the effects of invading top and intermediate consumers in a size-structured fish community, using a combination of field studies, a lake invasion experiment and smaller scale pond and aquaria experiments.

The lake invasion experiment was based on introductions of an intermediate consumer, ninespine stickleback (Pungitius pungitius L.), in to allopatric populations of an omnivorous top predator, Arctic char (Salvelinus alpinus L.). The invasion experiment was performed in two tundra lakes and in two birch forest lakes to investigate the effect of climate on the invasion success. I found that the effect of sticklebacks on char was size dependent. Small char suffered reduced growth from resource competition with sticklebacks whereas the maximum size of adult char increased from the addition of a larger prey resource, stickleback. The negative effect of sticklebacks on the growth of small char suggests that sticklebacks may be a better resource competitor than char, which was also supported by the pond and aquaria experiments. The pond experiments also suggested that char were more efficient cannibals than interspecific predators on sticklebacks. Cannibalism in char may limit the recruitment of char and decrease both their predatory and competitive effect on coexisting species and thereby also promote the coexistence of char and sticklebacks. The successful invasion by sticklebacks and their subsequent increases in density suggest that the absence of sticklebacks in char lakes in this region is not caused by biotic interactions with char. Instead, it may be suggested that co-occurrence of sticklebacks and char in the region is limited by dispersal.

The char – stickleback system resembles an intraguild predation system with char as the top consumer and stickleback as the intermediate consumer. The effects of the stickleback invasion is also contrasted with a field study of a northern pike (Esox lucius L.) invasion into a system with coexisting char and stickleback, where pike can be viewed as the top consumer and char as the intermediate consumer both feeding on sticklebacks. In this case pike excluded char. The identity of the invading species and the relative strength of the predatory and competitive interactions in the two contrasting systems are discussed in relation to coexistence in intraguild predation systems. I found that the identity of the invading species is of crucial importance for the response at the ecosystem level, and that the inherent size dependency of competitive and predatory interactions in fish communities is important for attaining a mechanistical understanding of the effects of invasive species in lake ecosystems.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2010. s. 27
Nyckelord
Invasion, intraguild predation, size-structure, cannibalism, climate, temperature, Arctic char, ninespine stickleback
Nationell ämneskategori
Ekologi
Forskningsämne
biologi
Identifikatorer
urn:nbn:se:umu:diva-37995 (URN)978-91-7459-119-4 (ISBN)
Disputation
2010-12-17, KBC-huset, KB3B1, Umeå Universitet, Umeå, 11:03 (Engelska)
Opponent
Handledare
Tillgänglig från: 2010-11-26 Skapad: 2010-11-22 Senast uppdaterad: 2018-06-08Bibliografiskt granskad

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Byström, PärKarlsson, JanNilsson, PerAsk, Jenny

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Freshwater Biology

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