One Tree Reef lagoon, a relic of the pre-colonial Great Barrier Reef

Coral reefs are in decline worldwide due to local/regional (e.g., water quality and fishing) and global stressors (e.g., ocean warming and acidification). Palaeoecological studies help differentiate the effects of anthropogenic versus natural stressors, assist ecological interpretations of fluctuations in dynamic systems, and decipher the impact of future changes. Benthic Foraminifera are valuable proxies for monitoring coral reef condition. This project utilises Foraminifera preserved in a sediment core from the One Tree Reef (OTR) lagoon on the southern Great Barrier Reef (GBR) to quantify potential ecological changes associated with European colonisation (late 1700's) and industrialisation of Australia (1950's). Previous work focuses on foraminiferal assemblages from near shore reefs, but analysis of outer reef systems is lacking. OTR is located some 100 km from the mainland, removed from most local and regional stressors likely to drive changes in the foraminiferal assemblages. Richness, diversity and changes in foraminiferal assemblages over time using standard ecological indices and foraminifera specific metrics indicate that there has been no discernible trend or shift in OTR lagoon Foraminifera assemblages over the last four centuries. These Foraminifera assemblages suggest that the OTR lagoon may contain a living example of a pre-colonial GBR lagoon ecosystem.