How2Day: Seaweed Farming Methods

People eat seaweed in Asian cusine such as sushi. Water and Seaweed image by Mr Shemp from Fotolia.com
People around the world eat seaweed, creating a need for seaweed --- also known as macroalgae --- farmers. Mostly cultivated in Asian countries, seaweed includes different species such as Gelidium, Eucheuma and Porphyra. Seaweed farmers carefully choose strong and healthy seedlings from the wild or other farms then cultivate the plants in open or closed systems.

Seaweed farmers in Indonesia, the Philippines and Western Central Pacific Islands still use one of the earliest seafood farming methods, the fixed bottom monoline. Inexpensive and easy, this method requires farmers to string seedlings along twine, then tie the twine to mangrove stakes in a shallow area of the sea floor. Successful farms have a moderate water current, sandy or coral bottom and lie far from the mouth of a river.

While this method protects the seaweed from surface weather conditions, it won't shield the harvest from hungry animals. Farmers inspect their lines every day, cleaning the lines and plants of sediment. After 40 or 50 days when each plant weighs around 500 grams, it's time for the harvest.

The floating raft monoline method consists of a bamboo raft strung with twine that holds the seedlings. To successfully cultivate seaweed, a farmer must anchor his raft in clear water at least five fathoms deep with a moderate current.

This cultivation system will yield its first harvest between 40 and 50 days when the seaweed weighs 500 grams. While this floating method protects the seaweed from bottom-grazing creatures, it leaves the crops vulnerable to surface weather conditions.

A self-contained system, the algae photobioreactor allows seaweed to grow while controlling its light supply, nutrients, carbon dioxide, pH levels, air and temperature. This closed system protects the seaweed from changing weather conditions and contamination such as bugs or invasive species of algae.

While this seaweed farming method costs more than open systems, it produces more seaweed per liter of water. Photobioreactors grow seaweed in batches consecutively or in a concurrent cycle of growth and harvest.

How2Day