Publication Abstract

A 1200 year paleoecological record of coral community development from the terrigenous inner-shelf of the Great Barrier Reef

Chris T. Perry, Scott G. Smithers, Suzanne E. Palmer, Piers Larcombe*, Kenneth G. Johnson

Various environmental factors may drive these changes, but elevated sediment and nutrient yields from anthropogenically-modified coastal catchments are commonly implicated. Within the Central Great Barrier Reef (GBR) lagoon, where water quality has reportedly declined as a result of increased sediment and nutrient inputs since European settlement (since ~1850AD), inner-shelf reef condition has purportedly deteriorated5. However, the link between reef decline and water quality change remains highly controversial, primarily because of a lack of pre-European period ecological baseline data against which to assess contemporary ecological states.

Recent global assessments of coral reef condition report widespread deterioration of ecosystem structure and functioning.  Here we present a high-resolution, 14C date-constrained, long-term (~1200 years BP) taxonomic record of turbid-zone coral community composition that is used to test whether inner-shelf coral communities have responded to reported post-European changes in water quality. The results demonstrate not only the potential for coral communities to initiate and persist in settings dominated by fine-grained terrigenous sediments, but also that a temporally persistent suite of corals has dominated these reef-building communities for at least the past millennium. The coral assemblages exhibit no evidence of community shifts attributable to post-European water quality changes and, indeed, the sedimentary records indicate that levels of terrigenous sediment accumulation are presently reduced on these reefs compared to the pre-European period.

These findings not only question widespread perceptions about the inherent negative effects of terrigenous sedimentation on coral community development, but also raise important questions about community thresholds levels and species adaptability to poor water quality conditions. 

Reference

Chris T. Perry, Scott G. Smithers, Suzanne E. Palmer, Piers Larcombe*, Kenneth G. Johnson (2008) A 1200 year paleoecological record of coral community development from the terrigenous inner-shelf of the Great Barrier Reef. Geology, 36 (9) 691-694