If you go to the cinema to see the Nelson Mandela biopic Long Walk to Freedom you will see one scene, set on Robben Island, when Mandela and the other political prisoners are working on the seashore, with Cape Town and Table Mountain visible in the distance, across the water.
In the book on which the film is based, Mandela explains what they were doing:
“We were instructed to pick up the large pieces of seaweed that had washed up on the beach, and wade out to collect weed attached to rocks or coral. The seaweed itself was long and slimy and brownish-green in colour. Sometimes the pieces were six to eight feet in length and thirty pounds in weight. After fishing out the seaweed from the shallows, we lined it up in rows on the beach. When it was dry, we loaded it into the back of the truck. We were told it was then shipped to Japan where it was used as a fertiliser.”
The seaweed sounds like Ecklonia maxima, or possibly a species of Laminaria, which are harvested for a variety of purposes, not just as fertiliser (see Of Sea bamboo, split-fan kelp and bladder kelp). There is a huge literature on the commercial exploitation of seaweeds, with the prospect of using them as “biofuels” being just the latest of many trends. Mandela’s experience, however, illustrates a recurring theme: that the theoretical potential of the huge quantities of algae in nearshore waters is difficult to convert into profit. On Robben Island, for example, the prisoners provided free labour to make the enterprise economically viable. The biofuel debate is, similarly, as much about economics as it is about algae. It is only as other fuels become more expensive that the costs of harvesting algae start to look attractive.
Harvesting seaweed seems, from Mandela’s account, to be one of the few bright points in his time on Robben Island. Part of this was because the co-lateral of seaweed harvesting was a plentiful supply of seafood which they popped into a pot of boiling water sitting on an open fire on the seashore:
“When it was ready, the warders would join us and we would all sit down on the beach and have a kind of picnic lunch. In 1973, in a smuggled newspaper, we read about the wedding of Princess Anne and Mark Phillips, and the story detailed the bridal luncheon of rare and delicate dishes. The menu included mussels, crayfish and abalone, which made us laugh; we were dining on such delicacies every day.”