Change search
ReferencesLink to record
Permanent link

Direct link
Effects of enrichment on protist abundances and bacterial composition in simple microbial communities
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
2006 (English)In: Oikos, Vol. 114, no 1, 15-26 p.Article in journal (Refereed) Published
Abstract [en]

We experimentally investigated effects of nutrient enrichment and trophic structure in a microbial food web consisting of mixed bacteria, two bacterivorous ciliates (Tetrahymena sp. and Colpidium sp.) and an omnivorous ciliate (Blepharisma sp.) feeding on both trophic levels. We assembled all possible food webs including one or more of the ciliate species and cross-classified them with four levels of enrichment of the bacterial medium. The qualitative outcome of food web interactions was independent of enrichment and always the same: Tetrahjrmena strongly depressed or excluded Colpidium, and Blepharisma strongly depressed or excluded both bacterivores. Consequently, in all sub-webs only the dominant ciliate species responded positively to enrichment. The total density of bacteria increased with enrichment irrespective of food web composition. In contrast, the response of singlecelled bacteria to enrichment depended on food web composition and was only weakly positive in most food webs with the omnivore. Enrichment had a positive effect on the relative success of (presumably more defended) bacterial aggregates. The outcome of interspecific interactions among ciliates could not be predicted from monoculture experiments and deviated from earlier experiments in which each bacterivore coexisted separately with the omnivore. As a potential explanation we suggest that changes in experimental protocol reduced spatial heterogeneity and increased attack rates. A simple, dynamical model shows that increased attack rates can indeed greatly decrease the upper limit and range of enrichment over which intermediate consumers can coexist with omnivores.

Place, publisher, year, edition, pages
2006. Vol. 114, no 1, 15-26 p.
National Category
URN: urn:nbn:se:umu:diva-31476ISI: 000239563300003ISBN: 0030-1299OAI: diva2:293184
Liess, Antonia Diehl, SebastianAvailable from: 2010-02-10 Created: 2010-02-10 Last updated: 2010-02-10

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Diehl, S.
By organisation
Ecology and Environmental Science

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 42 hits
ReferencesLink to record
Permanent link

Direct link