Underwater treasure

Growing seaweed promises rich dividends for farmers, our environment and our health.

- ANDREA GRAVES

Seaweed is an unrecognised resource for most of us, spotted only when it peeks out of the water at low tide or gets cast up on beaches. But we may be seeing more of our oceanic algae because there’s increasing interest in farming it.

Most seaweed is edible, and our waters grow about 1000 species. Māori and other indigenous peoples traditionally ate seaweed, and New Zealand has embraced it in the form of the nori that wraps sushi. It is rich in protein, fibre, vitamins and minerals often associated with animal food sources.

The World Health Organisation predicts farmed seaweed will soon be a pillar of sustainable food security and our relatively clean waters may provide a natural advantage.

Food provision is just one of the hopes for Aotearoa’s nascent seaweed farming sector – alongside environmentally friendly animal feed, beauty and nutritional supplements, crop biostimulants and alternative materials for construction products. Seaweed farms could boost employment while restoring coastal environments currently in sub-par shape. And there is keen international interest in using it to sequester carbon.

One of seaweed’s most useful features is that it needs no freshwater or land. It also absorbs large quantities of nitrogen and phosphorus, which are commonly present at high levels in coastal waters. Seaweed feasts on these nutrients, incorporating them into its tissues and leaving water with lower, healthier levels.