A functional analysis of herbivory on Ningaloo Reef, Australia

Ningaloo Reef, despite being relatively unimpacted by human activity, exhibits high natural densities of sea urchins and macroalgae, challenging the conventional indicators of reef degradation. A study analyzing herbivory from 2009 to 2012 revealed that while grazing rates were high on the back reef and slope, bioerosion rates by fishes were low due to the absence of large excavating parrotfishes. Sea urchins, particularly Echinometra mathaei, played a significant role in bioerosion, comparable to that of dominant parrotfish species. The study also found marked cross-shelf variations in herbivorous fish functional groups and identified labrids as the primary sea urchin predators, contrasting with global patterns where balistids dominate. Additionally, small excavating and scraping parrotfishes showed a strong dependency on live coral cover for survival and foraging, highlighting potential vulnerabilities in high-energy habitats.

Johansson, C. L. (2012). A functional analysis of herbivory on Ningaloo Reef, Australia [James Cook University]. https://doi.org/10.25903/SM50-MK24