Ice Age Slowed Warned Great Barrier Reef

It's no secret that the Great Barrier Reef is in danger as climate change and ocean acidification diminish coral populations, but now new research suggests that an ancient slowdown that occurred after the Ice Age warned this iconic ecosystem of its bleak future.

Research led by the University of Sydney reveals that environmental factors similar to those affecting the present day Great Barrier Reef have been linked to a major slowdown in its growth 8,000 years ago.

"Poor water quality, increased sediments and nutrients - conditions increasingly being faced by the modern day reef - caused a delay in the Reef's growth of between seven hundred and two thousand years duration," lead author Belinda Dechnik said in a statement.

"It took hundreds more years then we would have expected to establish itself and even longer to attain the complex level of biodiversity that much of the Reef has become famous for," she added.

The Great Barrier Reef has been around for about 700,000 years. And while it may not seem like a big deal that for just between 700 and 2,000 years of its history it experienced a slowdown, researchers say even a decade of such delayed growth would have a rapid impact on today's reef.

During the study, the team sampled 15 reef cores from the Southern Great Barrier Reef, using radiocarbon dating to determine their ages. Species of reef corals were also identified to establish any coral community changes over the past 8,000 years.

The findings show that after the Ice Age, when the global sea level rose due to ice melt and the Great Barrier Reef started its current regrowth, it was acutely sensitive to the turbulent conditions. The increase in sediments and nutrients following the flooding of the pre-existing reefs is likely to have been responsible for the poor water quality, according to the study.

"Not only was there a lag in reef growth of up to two thousand years following the flooding of the previous reef platforms but the reef communities that grew there were much less complex than those inhabiting those areas of the reef today. It took another two to three thousand years for the rich diversity that we see in those reef areas today to become established," Dechnik explained.

The findings, published in the journal Marine Geology, not only shed light on the reef's past but also have important implications for the future health of the Great Barrier Reef. As port expansions and high nutrient runoff is expected to increase over the coming decades, it's possible that this ecosystem may see a similar slowdown in the near future.

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