Warming waters hurt Zanzibar's seaweed. But women farmers have a plan.

Zanzibar’s streets are serene in the dark moments before sunrise, and an amber glow tints the beach. The tide is out, and the air is fresh. A few women head to work, toting sticks on their heads and empty sacks in their hands as they walk toward the sea. They cross acres of damp white sand before reaching the warm, clear waters that shelter their farms: seaweed growing on dozens of neat, parallel ropes staked to the Indian Ocean floor.

“Seaweed farming in our area is only done by women,” says Mwanaisha Makame, a 20-year veteran of the business, as warm little waves lap at her long, flower-print skirt.

Ms. Makame’s family didn’t have money for higher education when she was young, so she went to the ocean to farm. These macroscopic marine algae changed her life.

“I used the money to build a house, I used the money to school my children,” she says of her son and daughter, now in their early 20s. “I’m like a father.”

And that’s a bold statement in Zanzibar: a semi-autonomous archipelago off the coast of Tanzania, where women typically have lower employment, pay, education, and decisionmaking power than the men in their

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