Researchers study coral recovery at Lord Howe Island

The ability of coral to recover from a significant bleaching event is the subject of an ongoing research project at the world’s most southerly coral reef at Lord Howe Island.

With support from the Northern Rivers Catchment Management Authority and the Lord Howe Island (LHI) Marine Park Authority, a team of coral experts from Southern Cross University and University of Western Sydney will return to the island this September to document coral recovery following a significant bleaching event in the summer of 2010.

The coral-bleaching (whitening of hard coral due to the loss of the marine microalgae that lives inside the coral tissue) resulted in a decline in hard coral cover of many dominant corals species at the world’s most southerly coral reef.

These corals were further exposed to higher than normal ocean temperatures in 2011, which caused further coral stress, but normal seawater temperatures this summer provided the opportunity for stressed coral to recover.

According the Ian Kerr, manager of the LHI Marine Park, normal colouration has returned to most corals following these successive bleaching events.

“With normal ocean temperature, good cloud cover and adequate water mixing throughout the LHI lagoon this summer, little to no corals showed any signs of bleaching stress this year and there appears to be higher than normal coral growth and recovery,” Mr Kerr said.

Dr Steve Dalton, from Southern Cross University's National Marine Science Centre, said information collected during the trip would help to predict the level of reef stability and the level of resilience and resistance in marginal coral reefs to combat future predicted more frequent thermal stress.

“This funding and field support from the authorities will enable us to determine the ability of bleached coral species to shift to microalgae that are tolerant to higher ocean temperatures,” he said.

Genetic information from coral samples collected during and following the two successive bleaching events will be studied in Dr Madeleine van Oppen’s laboratory at the Australian Institute of Marine Science to understand coral mechanisms to combat ocean warming in the future.

The team will also assess the influence freshwater discharge has on coral recovery following bleaching and make recommendations to reduce local stressors.

Photo: A coral reef community in the Lord Howe Island Marine Park.