Composition of hard-bottom communities in a frequency-gradient of mechanical disturbance.

Spindler, Gitta (2005) Composition of hard-bottom communities in a frequency-gradient of mechanical disturbance. (Diploma thesis), Christian-Albrechts-Universität, Kiel, 67 pp.

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Species are lost with accelerating speed all over the world. (Edwards and Abivardi 1998). Each species that is lost reduces the diversity of the global ecosystem. However, diversity is known to be important for the functioning of ecosystems (Giller and O'Donovan 2002).
The IDH (intermediate disturbance hypothesis) and a model developed by Kondoh (2001) predict the influence of disturbance on diversity (IDH) and of the interactive effect of disturbance and productivity on diversity (Kondoh 2001). Although the IDH is one of the most frequently used models to explain the disturbance-diversity-relationship, there has been little evidence for its validity (Mackey and Currie 2000). In order to test the validity of both models, the influence of disturbance and productivity on the diversity of marine hard-bottom communities was investigated at two sites at the north-west coast of Italy in an experimental in-situ approach. Seven levels of disturbance frequency, i.e. removal of biomass, were fully crossed with three levels of nutrient concentration in an orthogonal design.

Species richness was significantly influenced by the interaction between the two factors, but the disturbance-productivity-diversity-relationship that is predicted by Kondoh (2001) was not observed. Neither productivity, nor disturbance, nor their interaction influenced total cover or evenness of the communities. Separately analysed taxa proved that disturbance influenced their abundance, while productivity had no measurable influence.
In conclusion, due to the results of this study and to the results of eight twin experiments conducted all over the world, neither the IDH, nor the model developed by Kondoh (2001) are sufficient to explain the ecological processes that influence diversity.

Document Type: Thesis (Diploma thesis)
Thesis Advisors: UNSPECIFIED
Keywords: Benthic Ecology; GAME; biodiversity
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-B Experimental Ecology - Benthic Ecology
Refereed: No
Projects: GAME
Date Deposited: 08 Dec 2008 22:01
Last Modified: 06 Jul 2012 14:53

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