A board director of the Great Barrier Reef Marine Park Authority has resigned following reports of a potential conflict of interest over the allocation of publicly-funded contracts to control crown-of-thorns starfish.

Margie McKenzie told the environment minister, Melissa Price, of her plan to resign late last week over “perceived concerns of a conflict of interest”.

It followed reports by the ABC that McKenzie’s diving company Gempearl, which she owns with husband Col McKenzie, was subcontracted to perform crown-of-thorns starfish removal work by two not-for-profit companies.

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The authority spent more than $20m in taxpayer money on the pest control program. The not-for-profit agencies were selected through a tender process.

Col McKenzie is the executive director and company secretary on one of the winning agencies, the Association of Marine Park Tourism Operators, and is a board member on the other, the Reef and Rainforest Research Centre.

Margie McKenzie declared her interest in Gempearl to the marine park authority in 2015, two years after joining the board, and told the ABC she had left the room during any discussions about crown-of-thorns starfish.

In a statement, Price said she was examining the authority’s governance structures before proposed changes to its governing legislation, which stem from an independent review of the authority released by the federal government last year.

“It is extremely important that real or perceived conflicts of interest are declared and managed appropriately,” she said.

“Due to concerns about perceived conflicts of interest, Ms McKenzie has advised she will tender her resignation to the governor general.”

Guardian Australia has contacted McKenzie for comment.

Price said managing crown-of-thorns starfish, which prey on coral, was “critically important”. She supported a statement made by the authority on Wednesday, which said it did not have the power to make procurement or funding decisions related to the crown-of-thorns starfish control program.

“My department, with the authority, is examining the adequacy of the processes the authority has in place for managing conflicts of interest, and whether those processes will be adequate for managing conflicts when the authority’s new legislated board arrangements take effect in the coming months,” she said.

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The independent governance review made 24 recommendations, including separating the roles of chairperson and CEO, ensuring the chairperson is independent of any interests on the reef, and changing the authority’s governing legislation to ensure that board members are not also the member of a governing body of any relevant group in order to reduce the potential for conflict of interest.

The Great Barrier Reef Amendment (Authority Governance and Other Matters) Act 2018 passed parliament in February, but the schedule governing conflict of interest will not take effect until March 2019.

The Australian Conservation Foundation chief executive, Kelly O’Shanassy, said the legislated governance reforms should be enacted “straightaway”.

“The Great Barrier Reef must be managed properly for all Australians and for the fundamental ecological health of this amazing ecosystem,” she said.