Australia’s Great Barrier Reef has undergone numerous changes since 1928 due to global and local environmental changes, a study has revealed.
Led by Prof. Maoz Fine
of Bar-Ilan University, the study – the longest coral reef study to date – provided an in-depth focus on the reef over the past 91 years.
The Great Barrier Reef Committee and the Royal Society of London sent an expedition to study the reef in 1928. Members of the expedition – pioneers in coral biology and reef studies – lived on the Low Isles for over a year, during which time they were able to document – through the pioneering usage of diving helmets – environmental conditions surrounding the reefs as well as the community structure of tidal and subtidal communities.
“This is a unique opportunity to look at long-term changes on an inshore reef system,” said one of the researchers from the University of Queensland. “Most studies are only a few decades in length; this one is just short of 100 years of study.”
Members of this expedition produced highly accurate aerial photography mapping of the island. This enabled the researchers in the current study to follow in their footsteps, revisiting and sampling the exact intertidal and subtidal locations that were previously explored in 2004, 2015 and 2019, thereby forming the longest ecological survey to date.
In the latest investigation, the researchers concluded that the intertidal communities underwent significant phase-shifts. Species richness and diversity of these communities systematically declined for corals and other invertebrates. Specifically, massive corals have replaced branching corals, and soft corals have become much more numerous.
Coral reefs are very sensitive to any environmental change. Multiple stressors can lead to dramatic deterioration that can result in loss of reefs and their ecological services for years.
It is unlikely that the reefs
will ever return to their initial state.
“The degree to which reefs may shift from one state to another following environment change was overwhelming,” said Fine.
“The long-term implications of these changes highlight the importance of avoiding phase-shifts in coral reefs which may take many decades to repair, if at all.”
According to Fine, the study also illustrates the importance of considering multiple factors in the decline and potential recovery of coral reefs, as well as the importance of tracking changes in community structure and coral abundance over long periods.
“This study went much beyond pure scientific work,” Fine added. “Following in the footsteps of the pioneers of coral reef biology and ecology was an incredible and inspirational experience for us.”
In the future, the researchers hope to use the same methods to reconstruct data from other parts of the world, where historical expeditions accurately documented similar communities.
The study was published in the scientific journal Communications by scientists from Bar-Ilan, the Interuniversity Institute for Marine Sciences and the University of Queensland.