Coral Reefs

, Volume 30, Issue 2, pp 521–531

Assessing loss of coral cover on Australia’s Great Barrier Reef over two decades, with implications for longer-term trends

Report

DOI: 10.1007/s00338-010-0715-1

Cite this article as:
Sweatman, H., Delean, S. & Syms, C. Coral Reefs (2011) 30: 521. doi:10.1007/s00338-010-0715-1

Abstract

While coral reefs in many parts of the world are in decline as a direct consequence of human pressures, Australia’s Great Barrier Reef (GBR) is unusual in that direct human pressures are low and the entire system of ~2,900 reefs has been managed as a marine park since the 1980s. In spite of these advantages, standard annual surveys of a large number of reefs showed that from 1986 to 2004, average live coral cover across the GBR declined from 28 to 22%. This overall decline was mainly due to large losses in six (21%) of 29 subregions. Declines in live coral cover on reefs in two inshore subregions coincided with thermal bleaching in 1998, while declines in four mid-self subregions were due to outbreaks of predatory starfish. Otherwise, living coral cover increased in one subregion (3%) and 22 subregions (76%) showed no substantial change. Reefs in the great majority of subregions showed cycles of decline and recovery over the survey period, but with little synchrony among subregions. Two previous studies examined long-term changes in live coral cover on GBR reefs using meta-analyses including historical data from before the mid-1980s. Both found greater rates of loss of coral and recorded a marked decrease in living coral cover on the GBR in 1986, coinciding exactly with the start of large-scale monitoring. We argue that much of the apparent long-term decrease results from combining data from selective, sparse, small-scale studies before 1986 with data from both small-scale studies and large-scale monitoring surveys after that date. The GBR has clearly been changed by human activities and live coral cover has declined overall, but losses of coral in the past 40–50 years have probably been overestimated.

Keywords

Coral coverGreat Barrier ReefLong-term monitoringAcanthasterDisturbance and recovery

Supplementary material

338_2010_715_MOESM1_ESM.pdf (457 kb)
Supplementary material 1 (PDF 458 kb)

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.Australian Institute of Marine ScienceTownsville MCAustralia
  2. 2.Australian Centre for Evolutionary Biology and Biodiversity, School of Earth and Environmental SciencesThe University of AdelaideAdelaideAustralia