Maui Coral Reef Holds Secrets Of The Past – And The Future

A 253-year-old coral sample from Olowalu, Maui, has unveiled unprecedented insights into the island's environmental past and future. Scientists studied the two-century-old core, finding that the reef's growth mirrored terrestrial conditions. The period examined, from 1760 to 2013, encompassed the precolonial era, the sugar plantation economy's rise and fall, and Maui's growth as a tourist destination.

Published in the September issue of "Coral Reefs," the findings offer the first long-term baseline for understanding ridge-to-reef connectivity on Maui.

The study, led by Sam Kekuewa of Hawaii Sea Grant College Program, revealed that the reef's growth rate plummeted in the late 1960s, coinciding with the booming sugar plantation economy. Researchers discovered that land-use patterns significantly impacted the reef's health. Kekuewa, a chemical oceanographer, connected chemical signatures in the coral's skeleton to terrestrial changes, noting sharp increases in barium-to-calcium, phosphorus-to-calcium, and iron-to-calcium ratios during the 1900s, primarily during the sugar plantation era.

The Olowalu reef, spanning nearly 1,000 acres off Maui's southwestern coast, is often dubbed a "mother reef" due to its prolific coral larva production that fertilizes neighboring islands. It's also a Mission Blue Hope Spot, highlighting its critical role in ocean health. However, the reef faces numerous threats from climate change, including increased storm frequency, runoff, sedimentation, and coastal development.

The severe storms and fires, exacerbated by climate change, could suffocate the reef and further degrade its health. Understanding the reef's past is crucial for guiding future management decisions and protecting this vital marine ecosystem for future generations.