Helber, Stephanie B. and Hoeijmakers, Dieuwke J. J. and Muhando, Christopher A. and Rohde, Sven and Schupp, Peter J. (2018) Sponge chemical defenses are a possible mechanism for increasing sponge abundance on reefs in Zanzibar. PLOS ONE, 13 (6). e0197617. ISSN 1932-6203

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Official URL: http://dx.doi.org/10.1371/journal.pone.0197617

Abstract

Coral reefs are experiencing increasing anthropogenic impacts that result in substantial declines of reef-building corals and a change of community structure towards other benthic invertebrates or macroalgae. Reefs around Zanzibar are exposed to untreated sewage and runoff from the main city Stonetown. At many of these sites, sponge cover has increased over the last years. Sponges are one of the top spatial competitors on reefs worldwide. Their success is, in part, dependent on their strong chemical defenses against predators, microbial attacks and other sessile benthic competitors. This is the first study that investigates the bioactive properties of sponge species in the Western Indian Ocean region. Crude extracts of the ten most dominant sponge species were assessed for their chemical defenses against 35 bacterial strains (nine known as marine pathogens) using disc diffusion assays and general cytotoxic activities were assessed with brine shrimp lethality assays. The three chemically most active sponge species were additionally tested for their allelopathic properties against the scleractinian coral competitor Porites sp.. The antimicrobial assays revealed that all tested sponge extracts had strong antimicrobial properties and that the majority (80%) of the tested sponges were equally defended against pathogenic and environmental bacterial strains. Additionally, seven out of ten sponge species exhibited cytotoxic activities in the brine shrimp assay. Moreover, we could also show that the three most bioactive sponge species were able to decrease the photosynthetic performance of the coral symbionts and thus were likely to impair the coral physiology.

Item Type: Article
Additional Information: Publiziert mit Hilfe des DFG-geförderten Open Access-Publikationsfonds der Carl von Ossietzky Universität Oldenburg.
Subjects: Science and mathematics > Life sciences, biology
Science and mathematics > Plants (botany)
Divisions: Faculty of Mathematics and Science > Institute for Chemistry and Biology of the Marine Environment (ICBM)
Date Deposited: 12 Sep 2019 07:25
Last Modified: 17 Sep 2019 10:46
URI: https://oops.uni-oldenburg.de/id/eprint/4155
URN: urn:nbn:de:gbv:715-oops-42369
DOI: doi:10.1371/journal.pone.0197617
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