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  • Writer's pictureAnna Luna Rossi

Nusa Lembongan, the island living off seaweed farming

Updated: Jan 23, 2023

Wandering around the coast of Nusa Lembongan and Nusa Ceningan (the smaller island connected to Lembongan), it is impossible to miss the large canvas sheets covered with seaweeds: next to the beach, to people's houses, and even to some restaurants. The algae are left there to dry in the sun, various shades of green and purple and even blue.

There is something quite mesmerizing in the way seaweed farmers work for hours on the sea, boats sliding over the still water in a composed silence, and then come back with baskets filled to the brim, ready to be sorted.

Seaweed farming, an old practice

Seaweed aquaculture (or farming) has been a wildly developed practice around the world for centuries, especially in many Asian countries. Actually, there are records of people using seaweeds for various medicinal and alimentary properties as old as Prehistoric times. We may not realize it, but Indonesia is one of the three largest producers of seaweed in the world. Often, this type of culture finds its roots in the need to find economic alternatives to fishing where fish stocks are overexploited.

In Indonesia, seaweed farming was introduced to local people in the 1980s. Before travelers discovered the beauty of the beaches (and surfing spots) of Nusa Lembongan, this small island located south east of Bali, it used to be the first source of income for the islanders.

The planting and harvesting process

Seaweed farms are built along the beach, but also farther from the shore: as long as the ocean space chosen is not too deep and accessible during low tide. They are made of several "boxes" separated with rope and wooden supports in order to delineate cultivated parcels. The seedlings are attached to other ropes in several rows.

When it comes to habitat conditions, several parameters are important in order to ensure good production. The current and intensity of the waves can influence the way algae absorb nutrients, and the quantity of light reaching the crops influences the photosynthesis potential of the seaweeds. Water depth, temperature and salinity are also going to influence the growth of the algae species selected.

Harvesting can be done thirty days after planting: algae have a fast growth rate. It takes place during low tide (usually in the morning) and can take up to two weeks. The harvested pieces of seaweed are then laid out to dry in the sun, a process usually taking three days. Farmers sell their products to what we call "seaweed collectors", in charge of export trade for cosmetic or pharmaceutical uses.

Choosing the right species

Seaweed is an extensive term: it is used to describe many different species of marine plants and algae. But the ones cultivated in the context of seaweed farming most usually include Eucheuma cottonni (called Katoni in Indonesia).

Eucheuma cottonni is the species from which carrageenan, used as an ingredient for cosmetics and food processing, is extracted. Scientists also discovered that Eucheuma species have therapeutic properties, such as an anti-asthmatic and anti-inflammatory potential.

Just like rice farming, seaweed farming is a difficult labor requiring to adapt to the rhythm of nature and be tenacious: not all species grow at the same speed and in the same quantity, and not all are worth the same. Farmers have to choose what's more profitable: less value but faster growth, or more value but slower growth.

Seaweeds to regulate climate change

More than a prospering activity, seaweed farming is sustainable. Cultivating the algae species doesn't require the use of pesticides, or fertilizers of any kind. No fresh water is necessary for the crops, which gives this industry a significant advantage in the context of the global water stress.

Seaweeds also have a high buffer potential in the way they absorb carbon dioxide. Algae actually act as the most effective natural way of sequestering greenhouse gas and absorbing carbon dioxide, and their growth rate is way faster than trees. So no, it is not forests, but rather the ocean that plays a bigger role in regulating global warming.

Algae has recently been used more and more as a way to create biofuel, but also renewable plastics. As for their role in the ecosystem, seaweeds increase the oxygen level in the sea through their photosynthesis potential and play a role in reducing ocean's acidification.

What about today?

As of today, more and more farmers turn to tourism-related activities, and the practice is not as popular and lucrative as it could be in the 1990s. But in the light of the recent sanitary crisis, and the important decline of tourism, seaweed farming knows a resurgence on the islands.

As a takeaway, I would greatly encourage you to take the time to learn about Balinese agriculture. If Bali is known to be a destination with a high tourism flow, some local families have been working the land for centuries and will continue to do so as long as there is a land to work on. The relationship locals maintain with nature is so special that I cherish with all my heart the conversations I had about this during my trip. Nature and culture are intertwined in a way that makes you want to keep learning about Bali until you've pierced all its secrets - which is most certainly impossible!


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