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Detecting whitefish divergence using remains of Cladocerans in lake sediment: Tracking shifts in the predation regime on Bosmina by measuring defense structures
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2014 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

Predation by northern pike is believed to have initiated a divergence in whitefish into several different morphs, differing in size, habitat use and growth rate.  The development of a small pelagic zooplankton feeding morph is expected to have large impacts on the zooplankton community. In this study the effect of a changing predation regime on Bosmina, before and after introduction of pike in Valsjön, was investigated.  By looking at the change in carapace length (and indication of the level of predation pressure from fish) and mucro index (an indication of the level of invertebrate predation) of Bosmina remains in lake sediment the changing predation pressure from invertebrates and fish could be investigated. These features proved to be good proxys for the level of defense against fish and invertebrate predation.  However, other species than whitefish, and unknown interactions seems to have affected the zooplankton community. This makes it hard to tell which effect is due to diversification in whitefish and which is not. Also it is not clear that it is pike that has induced the divergence in the whitefish population. Other species like brown trout might also have been involved.

Place, publisher, year, edition, pages
2014. , 17 p.
Keyword [en]
Bosmina, Leptodora, Bythotrephes, pike, whitefish, predation, resource polymorphism, divergence, competitive release, lake sediment
National Category
URN: urn:nbn:se:umu:diva-92248ISRN: urn:nbn:se:umu:diva-92248OAI: diva2:740377
Educational program
Bachelor of Science in Biology and Earthscience
Available from: 2016-01-07 Created: 2014-08-25 Last updated: 2016-01-07Bibliographically approved

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Swärd, Anna
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Department of Ecology and Environmental Sciences

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