(CN) – In oceans across the globe, coral reefs have acted as a living record of changes to the environment, and nowhere in the world is that unique relationship more on display than in Australia’s Great Barrier Reef.
In a study published on Friday in the scientific journal Nature Communications, researchers reviewed over 90 years’ worth of data on the world’s largest reef system that stretches more than 134,634 square miles.
Researchers from Bar-Ilan University and Interuniversity Institute for Marine Sciences in Israel and the University of Queensland in Australia were provided a special experience – they revisited the site of a 1928 expedition and compared how the reef reacted to major changes in the environment.
“This is a unique opportunity to look at long-term changes on an inshore reef system,” said author Ove Hoegh-Guldberg, professor from the University of Queensland. “Most studies are only a few decades in length – this one is just short of 100 years of study.”
Researchers measured major phase-shifts in the reef, which are often caused by coral bleaching, outbreaks of harmful coral-eating species and storm damage.
Nearly 100 years ago, researchers from the Great Barrier Reef Committee and the Royal Society of London lived on Low Isles for over a year and documented environmental conditions surrounding the coral reefs, along with the structure of tidal and subtidal communities of coral reef. That expedition also marked another exciting breakthrough for the coral biology community – the first use of a diving helmet.
This latest expedition took place in three phases – in 2004, 2015 and 2019. Over the last 91 years, species richness and diversity declined for corals and other invertebrates living in the region, according to the study. Branching corals have given way to massive corals and soft corals have become much more prevalent.
Hard corals, also referred to as reef-building corals and branching corals, are much more susceptible to breakage in strong storms. The study’s findings show an overwhelming change due to the environment and these types of shifts take decades to repair, if at all, said lead author Maoz Fine from Bar-Ilan University.
“The degree to which reefs may shift from one state to another following environment change was overwhelming,” Fine said. “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 the Scripps Institution of Oceanography, coral reefs provide coastal protection that buff the force of strong waves and play host to a wide range of aquatic life that feed, live and mate in these unique ecosystems.
Because coral reefs are sensitive to environmental changes, more reef destruction could just as easily occur due to climate change and take years to bounce back.