John M Pandolfi 1, Brigitte Sommer 2, Maria Beger 3, Eugenia M. Sampayo 4, Sun Wook Kim
1 Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of
Queensland, Brisbane QLD 4072 Australia, j.pandolfi@uq.edu.au, @JohnPandolfi
2 Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of
Queensland, Brisbane QLD 4072 Australia, brigitte.sommer@optusnet.com.au
3 Centre for Biodiversity and Conservation Science, The University of Queensland, Brisbane, QLD 4072, m.beger@uq.edu.au,
@mariabeger
4 Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of
Queensland, Brisbane QLD 4072 Australia, e.sampayo@uq.edu.au,
5 Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of
Queensland, Brisbane QLD 4072 Australia, sun.w.kim@uq.edu.au,
The capability of species to move across biogeographic transition zones depends on the magnitude and
rate of environmental change, species traits and life histories, dispersal limitation, evolutionary response,
and biotic interactions. The combination of these factors will undoubtedly shape the communities of the
future, many of which are predicted to be novel. We take an ecosystem level approach in examining the
potential mechanisms driving new species combinations across numerous taxa along the eastern Australian
coastline. Macroalgae, coralline algae, hard and soft corals, sea urchins and other invertebrates, and
benthic fish assemblages exhibit contrasting patterns of abundance and diversity along the latitudinal
gradient. Hard and soft coral abundance decreases whereas encrusting coralline algae abundance
increases with latitude. Macroalgae abundance remains relatively constant, resulting in an overall inverse
relationship with coral abundance. Sea urchin and encrusting coralline algal abundance increases with
latitude, whereas herbivorous fish show a bell‐shaped curve with a dip in fish herbivory in the middle range
latitudes. Since macroalgae decrease with urchin abundance, sea urchin herbivory may be a stronger driver
of community structure on high latitude reefs than fish herbivory, which may be more sensitive to declining
coral cover. Herbivores may indirectly facilitate higher abundance of corals, by reducing competition from
macroalgae and by fostering encrusting coralline algae where rugosity is sufficiently developed. Our
ecosystem level approach contributes to improved understanding of the potential impacts of anticipated
climate change on marine communities along latitudinal gradients and the processes driving community
assembly at the margins of biogeographic transition zones.
Twitter: @JohnPandolfi
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