The ancient Hawaiians had it right.

They knew that what happened on land affected the sea — one of the underlying principles of their land division system.

Under that system, an ali'i or local chief oversaw a wedge-shaped area (called an ahupua'a) that stretched from the mountains to the ocean, with the understanding that activities upslope could affect important resources downslope.

That same ridge-to-reef stewardship concept is central to many modern-day efforts in Hawai'i to combat the problem of land-based pollution and its effects on coral reefs.

That marriage between tradition and modern science has especially taken hold in recent years, with the formation of public-private partnerships and other initiatives to protect Hawai'i's watersheds and coastal resources.

Much of the focus is on reducing sediment runoff into the ocean, probably the most significant pollution problem affecting Hawai'i's reefs.

But scientists and others say it is too soon to show with data whether those efforts are working. Making changes on land, they say, can lead to improvements at sea that may not become evident for years.

Bob Richmond, a University of Hawai'i marine biologist, is among those who believe such traditional ridge-to-reef approaches can serve as models for communities trying to restore degraded reefs.

Richmond recently spoke at a Smithsonian Institution symposium in Washington, D.C., about several efforts he is studying in the Pacific.

In Palau, for instance, traditional leaders, with help from Richmond and other scientists, led the push to protect mangrove forests, which help keep sediment from reaching the ocean. Developers were clearing mangroves to make way for housing developments, but such clearing was banned about seven years ago.

In areas where sediment runoff was harming the Palau reefs, the moratorium has stopped the damage from worsening, Richmond said. But he is continuing his research to determine whether the moratorium contributes to improved reefs.