If you’ve been on a boat, pretty much anywhere in the tropics, you’ve seen mangrove forests.

There are at least 75 species of these small trees, evolved to live in harsh tidal conditions, their roots in sand, their trunks often submerged in saltwater.

There, they can form dense thickets that protect the coast from ravaging waves and storm surges. And that’s just one of their benefits.

Mangroves’ arching root networks trap and stabilize sediment to help build up the coast. In the process, they filter and clean coastal water.

Those same roots serve as nurseries, sheltering the young of many fish and crustacean species. While the forests provide timber for local human populations, and store carbon.

But mangroves are in peril -- from coastal development, agriculture, and especially aquaculture.

Shrimp farmers in Asia are responsible for a third of global mangrove destruction, as they clear forests to build their ponds.

Early efforts to replant the forests had failed. Until an innovative Florida ecologist realized that mangroves thrive best when their roots are wet only 30% of the time and dry the rest, as the tide comes and goes.

He used a backhoe to regrade the coastline to encourage those conditions. Within three years, the resilient mangroves had returned. His methods proved so successful, they’ve been adopted globally, in a preservation program that intends to bring 20% of mangrove coverage back within the decade.