生物学：グレートバリアリーフで最も幅の広いサンゴ

An exceptionally large coral – a structure made up of small marine animals and calcium carbonate – discovered in the Great Barrier Reef is described in Scientific Reports this week. It is the widest and sixth tallest coral measured in the Great Barrier Reef.

The coral was discovered by snorkelers off the coast of Goolboodi (also known as Orpheus Island), part of the Palm Island Group in Queensland, Australia. It has been named Muga dhambi (Big coral) by the Manbarra people, the traditional custodians of the Palm Islands. Adam Smith and colleagues surveyed Muga dhambi and found that it is hemispherical, 5.3 metres tall and 10.4 metres wide, which makes it 2.4 metres wider than the next-widest coral measured in the Great Barrier Reef. Using calculations based on coral growth rates and annual sea surface temperatures, the authors estimate that Muga dhambi is between 421 and 438 years old and predates European exploration and settlement of Australia. A review of the environmental events that have occurred in the past 450 years indicates that Muga dhambi may have survived up to 80 major cyclones and centuries of exposure to invasive species, coral bleaching events, low tides and human activity. The researchers report that Muga dhambi is in very good health with 70% consisting of live coral, the rest being covered with the green boring sponge, Cliona viridis, turf algae and green algae.

The authors recommend monitoring of this rare and unusually resilient large coral and comment that restoration may be needed in the future to minimise the potential negative impacts of climate change, declining water quality, overfishing and coastal development