Mangroves are the nursery for the reef and the sea. Shrimps, crabs and around 3,000 species of fish grow up in the protection of their root maze before the juveniles leave the underwater forest.

Mangroves are survivors. They grow as if on stilts where nothing else can, between land and sea in the intertidal zone on the coasts and estuaries of tropical Asia, Africa, America and Oceania, storing more CO2 per acre than rainforests. Salt, glittering on their leaves in the sun, does not bother them in normal concentrations.

The Mangrove Maniacs of Bonaire, led by Dr. Sabine Engel, are working with fishermen, volunteers and students to research and preserve the Lac Bay lagoon, a nearly 250-acre nursery in the island’s southeast region.

It’s arduous work: The group digs and cuts through overgrown and blocked waterways, removing seaweed so fresh water can flow into the forest again. Engel’s work is supported and financed by the Bonaire National Park Foundation, the Netherlands and the European Union; local dive shops provide tools.

The proliferation of plant life that can choke the mangroves happens naturally, but humans are not entirely innocent here. On windy Bonaire, goats and donkeys eat plants, increasing erosion, and a single change of water flow—say, from a construction project—can disrupt the entire ecosystem. Without that natural exchange, the salt content of the water increases, and rotting seaweed blocks oxygen and suffocates life. Then, only the mangroves’ white skeletons remain.