A Critique of a Method to Determine Long-Term Decline of Coral Reef Ecosystems

The supposedly already-degraded state of coral reef ecosystems is sometimes claimed to be a reason why anthropogenic global warming will have a major impact on the reefs, i.e. they are already close to extinction and can easily be tipped over the edge. Recently published work by Pandolfi et al . (2003) in Science has outlined a method for measuring the decline of coral reef ecosystems throughout the world according to which the outer and inner Great Barrier Reef (GBR) are claimed to be 28% and 36% respectively, down the path towards ecological extinction. This is a highly significant claim given the important status of the GBR, so the result deserves attention and objective scrutiny. This paper sets out to scrutinise the methodology used by Pandolfi et al . (2003) under four headings: (i) the guilds are poorly weighted and focus largely on human target species, rather than species that are ecologically important to reefs; (ii) the numerical scale used to “measure†the state of the reefs is not well-founded and hence distorts the result; (iii) the analysis fails to recognize that the GBR is of relatively recent origin and therefore never existed in the pre-human/pristine cultural period as defined by PAN; and (iv) in many cases it is doubtful that the literature cited demonstrates the claimed decline in ecological state. It is concluded that the work of Pandolfi et al . (2003) cannot be used as justification that the Great Barrier Reef has lost significant resilience, or that it is particularly susceptible to global warming because of its present supposedly degraded state.