Effects of disturbance on the diversity of hard-bottom macrobenthic communities on the coast of Chile .

Valdivia, Nelson, Heidemann, Astrid, Thiel, Martin, Molis, Markus and Wahl, Martin (2005) Effects of disturbance on the diversity of hard-bottom macrobenthic communities on the coast of Chile . Open Access Marine Ecology Progress Series, 299 . pp. 45-54. DOI 10.3354/meps299045.

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The intermediate disturbance hypothesis (IDH) predicts maximal diversity at intermediate levels of disturbance, but the validity of this hypothesis is controversially discussed. In this study, results of a field experiment, which was conducted on the northern-central Chilean coast, are presented. Fouling communities on artificial settlement substrata were studied. A total of 7 disturbance frequencies were applied to previously established communities, and a single disturbance event resulted in a removal of ~20% of the biomass. Species cover was estimated at the end of the experimental period, and it was found that diversity was strongly affected by disturbance frequency. With high disturbance frequencies the composition of the community was changed, with a decrease in the solitary ascidian Pyura chilensis (Molina 1782). The decrease of P. chilensis resulted in an increase of the colonial ascidian Diplosoma sp. A unimodal relationship between disturbance frequency and species richness was found, supporting the IDH. The results suggest that disturbance sustains diversity by reducing the abundance of the dominant species (e.g. P. chilensis), preventing competitive exclusion of the subordinate species, thus allowing subordinate species to re-emerge when competition is alleviated by disturbance. The results also suggest that these species show a trade-off between competitive and colonizing abilities, pointing to the existence of a competitive hierarchy. Therefore, the presence of competitive exclusion and disturbance-induced suppression of the dominant species remains a crucial mechanism, permitting species coexistence in the context of the IDH in the system studied.

Document Type: Article
Keywords: Benthic Ecology; Ecology; Marine Biology; Disturbance–diversity relationship; Intermediate disturbance hypothesis; Disturbance; Competitive exclusion; Frequency; Sessile; Hard-bottom; Pyura chilensis
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-B Experimental Ecology - Benthic Ecology
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.3354/meps299045
ISSN: 0171-8630
Date Deposited: 03 Dec 2008 16:51
Last Modified: 31 May 2018 11:37
URI: http://oceanrep.geomar.de/id/eprint/5906

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