The Great Barrier Reef Marine Park Authority “committed suicide” when it permitted millions of cubic metres of dredge spoil to be dumped near the reef, a coral reef expert says.

Former Australian Institute of Marine Science chief scientist Dr Charlie Veron also says the authority no longer has the expertise to protect the reef after $2.8m was cut from its budget, leading to the loss of 17 staff, including five directors.

“We’ve lost our prime place in the world as leaders of reef research; we’re no longer able to provide the science that is needed to protect it,” he told ABC Radio.

“It lost its credibility allowing the dumping and now it’s gutting its most effective staff.

“We’re not able to provide the science that is needed to protect [the reef].”

Veron, considered one of the world’s leading coral reef scientists, says GBRMPA lost its credibility and “committed suicide” when it gave North Queensland Bulk Ports the nod to dump dredged spoil in the marine park as part of a project to expand Abbot Point coal port.

The federal environment minister, Greg Hunt, is considering a new onshore disposal plan, meaning it is now unlikely any spoil will be dumped at sea.

Veron says he is now the only person in Australia who is tracking the loss of coral species along the entire reef.

Some of the staff who accepted redundancy packages as a result of the funding cut say there was a drop in morale within GBRMPA after the Abbot Point dredge disposal plan was approved.

They say some within the organisation disagreed with the decision.

One of those who took a redundancy, Paul Marshall, a former GBRMPA climate change director, told the ABC there was once eight to 10 people working on climate change but now there was no one entirely focused on the issue, which a federal government report this year named the most serious threat to the reef.

GBRMPA chairman Russell Reichelt said the organisation was going through an “evolutionary change” but he was confident he had a “very good team” despite losing five directors under the restructure.

“I do come with a lot of support from the staff and I feel confident that I can lead the agency in the right direction,” he told the ABC.

Reichelt said he acknowledged about a third of staff were unhappy with the Abbot Point decision.

The Australian Marine Conservation Society and WWF-Australia have both called for assurances the authority remains independent and properly resourced to ensure the reef is protected.

AMCS reef campaign manager Dr Lissa Schindler says the authority plays an important role in ensuring the world heritage committee doesn’t list the reef as a site “in danger” when it meets in June.

Comment has been sought from the state and federal environment ministers.