The decision to enlarge the marine preserve around the Northwestern Hawaiian Islands is a momentous one — primarily for the long-range conservationist thinking it represents, a move that was justified in an era of global and regional concerns about climate change.

But it’s also a giant step in resource management, one that will rely on coordination among the federal, state and Native Hawaiian authorities called to oversee the Papahanaumokuakea Marine National Monument.

In advance of his trip to Hawaii this week, President Barack Obama on Friday announced that the federal government would quadruple the area covered by the monument, first established by his predecessor, President George W. Bush, a decade ago. Papahanau- mokuakea will be the world’s largest marine reserve.

Obama’s announced expansion is well-timed to both the Pacific Islands Conference of Leaders and to the IUCN World Conservation Congress, which convenes in Honolulu on Thursday.

It’s also been the subject of a contentious debate among its supporters and its critics. Ardent advocates included environmental groups and Hawaii’s congressional delegation, led by U.S. Sen. Brian Schatz, who formally proposed the expansion in June and was singled out by the Obama administration for his role.

Opponents included a range of commercial interests and community leaders — former Gov. George Ariyoshi among them. The fact that the debate has been such a passionate one underscores the importance of fisheries and access to all the people of Hawaii, including the indigenous population.

It is, without doubt, an enormous preserve — nearly four times the size of California — and setting aside such a large area of the ocean represents a sacrifice for the fishing industry. But on balance, the advocates have made the most persuasive case that the long-term benefits will be a healthier marine habitat that can withstand the strains global warming has placed on it.

Now the task is to weave a system of management that marries the concern for science and environmental protection with the stewardship of cultural resources. The official mechanism for doing that, unveiled in the announcement, is adding the state Office of Hawaiian Affairs as a co-trustee of the monument.

The monument incorporates state waters out to three miles as well as the waters in federal jurisdiction. The state Department of Land and Natural Resources has represented the state in the co-trusteeship established at the birth of the monument. The federal partners have been the federal National Oceanic and Atmospheric Administration and the U.S. Fish and Wildlife Service.

Prohibited activities within the bounds of the monument include commercial fishing, mining, the use of explosives and other activities that damage the environment.

But research, cultural practices and educational activities will carry on, through permits the trustees will issue after review.

OHA already has been a consultative partner for the past 10 years, said Suzanne Case, DLNR director, so it’s not a stranger to the management process.

There is reasonable concern about whether they can provide oversight that’s consistent without becoming bogged down in interagency bureaucracy.

But both Case and Kamana‘o Crabbe, the chief executive officer of OHA, do seem to agree on the mission, and that’s a good sign. The administration of Gov. David Ige has supported elevating OHA’s role to become a co-trustee, and that impetus should be helpful.

Further, Crabbe said, all the parties are resolved to become advocates for all shared concerns. This means preserving environmental quality as well as enabling cultural practices, guarding what he described as the “realm of the gods.”

Case said the strength of co-trusteeship is that federal and state stakeholders have an equitable voice in decisions, regardless of whether the activity happens within the state’s 3-mile marginal waters. “You all band together to protect an important resource without regard to boundaries,” she said.

This collective stewardship is precisely what the World Conservation Congress seeks to promote on a global scale. The onus is now on Hawaii to demonstrate how well it can work in Papahanaumo- kuakea.