By Daniel Dickinson
BBC News, Pemba, Tanzania
Fatima Hamidi is one of Tanzania's new seaweed farmers.
Seaweed is used in cosmetics, cheese, fertilizer and shampoo
Cultivating her new crop at Vumawimbi beach on the northern tip of Pemba island, she hopes it will supplement the meagre income she earns from other sources.
"We don't yet know how successful it will be as we have not sold any yet," says Fatima.
"But we think it will help us to earn a little money, which we can invest in other small businesses. We are not rich, sometimes we don't even have the money to buy enough food, so selling seaweed will help."
Fatima is one of an estimated 5,000 farmers who are cultivating seaweed on the small island of Pemba.
All along the Tanzanian coast and around its many islands, other farmers are doing the same.
They are meeting a worldwide demand for seaweed, which is being used as an ingredient in everything from cosmetics to cheeses, and fertilizers to shampoos.
All you need to start cultivating seaweed is two wooden pegs which are driven into the seabed 10 metres apart, rope joining the two pegs, and seeds which are attached to the rope.
"It's not difficult, but it is hard work. Sometimes it is hard to find the rope, or there is not enough rope," Fatima says.
"And recently I have lost a lot of seaweed because of high winds and strong currents."
Looking out to sea, I could see small groups of men and women bent over, tending their lines of seaweed.
These farmers have hitherto eked out a living earning a few dollars a month selling fish and fruit; they are not going to get rich on seaweed, but it may help them to ease them out of poverty.
The seaweed takes about two months to grow.
When it is harvested, it is laid out in the sun to dry.
Ali Hamadi is one of the main seaweed buyers on Pemba.
His firm dries out the seaweed, packs it and sends it for export around the world.
Seaweed growers have to compete with farmers from across the world
He pays farmers about seven US cents a kilogramme.
In a good harvest, farmers can make about $7 in two months.
Because Mr Hamadi has supplied the materials to the farmers, they are obliged to sell to him.
"Production is too low and sometimes there is problem in the sea," he says.
He says the farmers are not always happy, especially at the prices, but says these are determined by the world market.
Farmers on Pemba have willingly but perhaps unwittingly become part of this global business.
The seaweed produced here will be exported as far afield as China and the Philippines, as well as Europe, but inevitably the farmer's livelihood will depend on what other farmers in other parts of the world are producing and at what price.
Competition too tough
But now farmers are being helped to work independently, and thereby lessen the impact of fluctuating world prices.
Aid agency Care International is providing the basic start up materials costing just $10.
"It is very paining to see that the price is controlled and dictated by the buyers," says Care's Amour Bakari Omar.
"The farmers don't have time to negotiate. So we are trying to avoid that. We are supporting the farmers. We are providing the basic seaweed equipment for growing.
"In that case they are not forced to sell to particular agents. They can sell to anybody."
Nevertheless, some farmers in Tanzania have found the competition too tough and have given up seaweed cultivation and returned to other crops.
Back at Vumawimbi beach, Fatima Hamidi still has a couple of weeks to wait before her first crop of seaweed is ready to harvest.
She's hoping she'll get a good price - a price which will enable her to compete with farmers from across the world.