Title
Effects of estimated herbivory on the reproductive potential of four East African algal species - A mechanism behind ecosystem shifts on coral reefs?
Author(s)
Nordemar I., Sjoo G.L., Mork E., McClanahan T.R.
Published
2007
Publisher
Hydrobiologia
Abstract
The aim of this field study was to investigate effects of estimated fish- and sea urchin herbivory on the reproductive potential of four species of macroalgae; Halimeda macroloba (Decasine), H. renschii (Hauck), Turbinaria ornata (Turner) and Padina boergesenii (Allender et Kraft). Fish and sea urchin herbivory were calculated based on reported consumption rates for their biomass estimates. We hypothesized that reduced herbivory would increase algal size and the reproductive potential, which may promote algal recruitment and be one of the driving mechanisms behind algal shifts and persistent algae-dominated reefs. Algae were investigated in field sites where the estimated fish- and or sea urchin herbivory differed. Our results suggest that algal fecundity of T. ornata and P. boergesenii are positively correlated to their size. Fecundity of T. ornata was higher and individuals grew larger in areas where estimated fish herbivory was lower. The two species of Halimeda grew larger and had higher fecundity in areas where estimated sea urchin herbivory was lower. P. boergesenii responded ambiguously to patterns in herbivory. Due to species-specific responses to different herbivores, it is difficult to generalize about effects of overfishing on algal fecundity. © 2006 Springer Science+Business Media B.V.
Keywords
Algae; Biomass; Ecosystems; Fisheries; Reefs; Coral Reefs; Ecosystem change; Herbivory; Macroalgae; Marine biology; coral reef; echinoderm; ecosystem dynamics; feeding behavior; fish; herbivory; macroalga; reproductive potential; Africa; East Africa; Sub-Saharan Africa; algae; Anthozoa; Echinoidea; Halimeda; Halimeda macroloba; Halimeda renschii; Padina boergesenii; Turbinaria ornata
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