As the largest international gathering of coral reef experts comes to a close, scientists have written to the Australian prime minister, Malcolm Turnbull, calling for action to save the world’s reefs.

The letter was sent to Turnbull on Saturday imploring his government to do more to conserve the nation’s reefs and curb fossil fuel consumption.

The letter, signed by past and present presidents of the International Society for Reef Studies on behalf of the 2,000 attendees of the International Coral Reef Symposium held in Honolulu this week, urged the Australian government to prioritise the Great Barrier Reef.

“This year has seen the worst mass bleaching in history, threatening many coral reefs around the world including the whole of the northern Great Barrier Reef, the biggest and best-known of all reefs,” the letter said. “The damage to this Australian icon has already been devastating. In addition to damage from greenhouse gasses, port dredging and shipping of fossil fuels across the Great Barrier Reef contravene Australia’s responsibilities for stewardship of the reef under the World Heritage Convention.”

Leaders from the scientific community at the convention in Honolulu said on Friday the letter was critical to the conservation of the fragile reef habitat.

Scientists were not known for their political activism, said James Cook University professor Terry Hughes, but they felt this crisis warranted such action.

“We are not ready to write the obituary for coral reefs,” said Hughes, who is also the president of the ARC Centre of Excellence for Coral Reef Studies in Australia.

Messages seeking comment from Turnbull on Saturday were not returned.

A call to action from three Pacific island nations whose reefs are suffering from the largest and longest-lasting coral bleaching event on record was presented on Friday at the conclusion of the symposium.

The heads of state from Palau, Micronesia and the Marshall Islands attended the conference and provided a plan to help save their ailing reefs, which are major contributors to their local economies and the daily sustenance of their people. The call to action, signed by the three presidents, asked for better collaboration between scientists and local governments.

“If our coral reefs are further degraded, then our reef-dependent communities will suffer and be displaced,” the letter said. They also called for more integration of “traditional knowledge, customary practices and scientific research” in building a comprehensive coral reef policy.

In response conference participants pledged to work with the governments to curb the continued loss of reefs.

In the northern third of the Great Barrier Reef, close to half of the corals had died in the past three months, said Hughes, who focuses his research there. The area of the reef that suffered most was extremely remote, he said, with no pollution, very little fishing pressure and no coastal development.

“That’s an absolute catastrophe,” Hughes said. “There’s nowhere to hide from climate change.”

Last year, the United Nations expressed concern about the state of the Great Barrier Reef and urged Australia to boost its conservation efforts.

The panel of scientists in Hawaii emphasised the progress they have made over the past 30 years in helping improve the health of coral reefs and stressed that good research and management programs for coral reefs were available. The scientists said they just needed the proper funding and political will to enact them.

The researchers focused on the economic and social benefits coral reefs contribute to communities across the globe, saying the critical habitats generated trillions of dollars annually but conservation efforts were not proportionately or adequately funded.