The End of the Ice Age May Have Slowed Down Reef Growth

Scientists may have found evidence for a slowdown in coral growth 8,000 years ago that included environmental factors that are impacting reefs today. In fact, the evidence may point out that the decline in the Great Barrier Reef today means hundreds of years of recovery.

"Poor water quality, increased sediments and nutrients-conditions increasingly being faced by the modern reef-caused a delay in the reef's growth of between seven hundred and two thousand years duration," said Belinda Dechnik, lead author of the new study, in a news release. "It took hundreds more years than 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."

In this latest study, the researchers sampled 15 reef cores from the Southern Great Barrier Reef. The cores were radiocarbon dated to establish their ages. Species of reef corals were also identified to establish any coral community changes over the past 8,000 years.

So what did they find? It turns out that the Great Barrier Reef started its current regrowth following the sea level rise when the ice sheets last melted 8,000 years ago. The reef was actually acutely sensitive to the turbulent conditions.

"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," said Dechnik. "It took another two to three thousand years for the rich diversity that we see in those reef areas today to become established."

The findings have important implications for the future health of the Great Barrier Reef. As nutrient runoff increases over the years, it could greatly influence the growth of the reef and its existence.

The findings are published in the journal Marine Geology.

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