Characteristic adaptations to grazing among algal turfs on a Caribbean coral reef

Hackney, J.; Carpenter, R.; Adey, W.

Tropical reef algal communities are dominated by a component frequently referred to as algal turfs. To study the composition of this turf assemblage, carbonate settling plates were placed in an area of intense herbivory on a shallow Caribbean reef and sampled after 15, 18, 22, and 24 months to analyze percent relative abundances of algal taxa. For all sampling dates, coverage was dominated by blue-green algae (Cyanophyta), with remaining taxa approximately equally divided between crustose and simple filamentous eukaryotes. The noncrustose taxa sampled from the plates were identified as representing the sparse algal turf assemblage. The persistence of turf species in this habitat was interpreted through a model that fits different components of shallow reefbenthic algae to particular ranges along a continuum of herbivore grazing pressures. Species within each algal component are characterized by adaptations that result in their persistence within a range of grazing intensities. Turf species persist in zones of intense grazing and commonly display adaptations for rapid growth. Algal crusts survive greater grazing intensities than turfs and possess adaptations for grazing resistance. Macroalgae display adaptations that enable avoidance of grazing through successful competition in grazing refugia. This model is proposed to explain the distributions of species within these benthic algal components across shallow coral reefhabitats and to predict the transitions that occur between algal components as grazing pressures shift in space or time.

Characteristic adaptations to grazing among algal turfs on a Caribbean coral reef

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