Case Study Part 2: Marine Protected Areas in West Bali - Algae aquaculture as a solution

Part Two: Algae farming - method and specifications

1. Introduction

Algae farming was introduced to Sumber Kima in 2003, but the first attempts were more or less failures, as the seaweed would not thrive in their particular bay.

Different species of red algae were tested, among them Eucheuma Catonii. Finally, a species brought in from Maumere, Flores - another Rodophyte species called Kappaphycus Alpharezi - proved to be suitable for that area. (Maumere, in turn, got it from the Phillipines: the species is not native to the Indonesian seas).

Red algae are known for their high contents of the gelling agent carrageenan, which has many commercial applications in the food and cosmetics industry, for example in dairy products, pet foods, or toothpastes. Red algae high in carrageenan, as the species mentioned above, are therefore the major types of algae to be commercially cultivated in SE Asia.

"Hello, my name ist alvarezii"

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Seaweed farming is actually not an ancient practice in Indonesia, and therefore the knowledge about suitability and adaptability of species still low. While Japan has a very ancient tradition of algae cultivation, the Philippines were pioneers in SE Asia, from where it spread to Indonesia. In Bali, the first algae culture was done in the area of Nusa Dua, South Bali, in the 90ies.

Certainly, wild seeweads have been harvested in Indonesia for decades, and used in a variety of dishes, as salads or as gelling agent (Agar).

2. The method

2.1 Planting

Algae farmers in Bali Barat employ the long-line cultivation method. The seedlings are attached to a very long sythetic rope, which floats close to the surface of the water, held up by little buoys every few meters.


this sketch is borrowed from here! Thanks!

The seedlings, which are simply cut-off branches from an older plant, are tied to the rope with a thinner rope with a loose knot, allowing for some movement with the currents, with spaces of approx. 20 cm between knots. The floaters, usually pieces of Styrofoam, plastic bottles or balls, do not only keep the line at a more or less constant depth of 30-40cm and make it easier to spot but also increase the amount of movement of each little segment.




"'field of' long lines and floaters, clearly visible from the shore"



The line itself is attached to a stong pole or frame which sits firmly in the ground on both ends. This method is suited for bays which are steep, but no too deep.

At Nusa Dua, for example, algae is grown it along the ground. The advantage of this is that it can be planted and harvested on foot at low tide. But this works only on a flat, plan coastline. The result is the same, but the environmental damage is probably higher because you walk on any existing coral. Floating method and harvest/planting by boat is pretty low impact. The only impact really are some runaway styrofoam floaties, but these are usually collected again because they are needed.

In fact the seaweed cultivation creates favorable environment for fish, and the seaweed farmers report that the fish have increased in the area of seaweed farming and are easy to catch.

2.2 Harvesting

After 35-45 days, the algae has grown enough to be harvested. For harvest, the line is lifted above the water and the algae cut off close to the knot.

The tips of some of the harvested plants are cut for use of re-planting. Planting and harvesting is thus done in a constant cycle. While harvesting the ‘field’ on one side, young seedlings are being replanted on the other.

While harvest is technically possible throughout the year, the growth rate of the algae is best during the rainy season. During the dry months, june-september, seedlings grow slowly and are more prone to deseases.

The reason for this is not known for sure, because the farmers don’t have the means to measure temperature/salinity or any other factors that might be influencing this. However, the observation implies that during hot months, the water gets too muddy/warm or salty. In other areas, it’s the other way around and it seems to depend strongly on the species. Here, the alage aquaculture could profit greatly from a scientific research partnership. Perhaps it could prove best to cultivate one species during the hot months and another during the rainy season to yield maximum profits?

2.3 Drying

After harvest, the seaweeds are spread out on flat thatched bamboo boards and these are put on top of wood or concrete stand, directly in the sun. They get sun and wind from top and sides and a little from underneath because of thatched board. They needs to be spread evenly and only one layer to avoid fouling. If it starts to rain, they need to be covered with a synthetic cloth immediately, it is simply thrown over the drying structure and held up by the wooden bar running along the middle. If it’s hot and sunny it will only take two days to dry. Hanging is also possible but is simply much more work and the results are the same.

"drying stands"




"spreading out the algae on the drying stand"



After drying, they will have lost 90% of their weight. In dried form, the algae can be stored for several months.

"wet product on the left and dried on the right"





inside the currently very empty storage room

The dried product is sold on the markets in Bali’s capital Denpasar, but the farmers don’t know much about what happens then.

3. Species, reproduction, diseases

As described in the introduction, the species cultivated in Sumber Kima, and all over SE Asia as a matter of fact, are red algae of the Kappaphycus or Eucheuma kind. Both are high in carrageenan and essentially very similar.

They are branched, have thick, fleshy thalli and are olive-brown to purplish-red in color.

Highly interesting is their capacity for vegetative regeneration, which essentially is the reason for the entirely asexual reproduction method employed by farmers in Sumber Kima (simply cutting off tips of older plants and regrowing from there, and so on). Thinking back to our visit to Kiel, this method really sets them off from the German alage farmers who were obtaining new generations of their brown algae from spores in each cycle.

Now I am not a expert (yet) but I came across this study which seems to imply that purely vegetative methods in algae farming may lead up to problems such as decrease in productivity after several ‘generations’, increased vulnerability to catch diseases and so on, which are precisely the problems Sumber Kima farmers were also reporting.

At the time of my visit, two types of diseases had been affecting the harvest: first something called Ice-Ice. The algae starts to turn white around the attachment area, and is prone to break off. It is not so fatal and can be diminished by cutting the stems above the white spot one by one and reattaching it – a lot of work, but can be done

The other disease is known as Karat (‘Rust’). It is some sort of fouling or infection of the seaweed and it spreads quickly. It does not kill the seaweed entirely but inhibits growth and results in an uglier, less-branched and rather rough-skinned plant. Karat is one of the diseases which befalls the algae during the already less productive dry season. Again, more scientific support could help in gaining a better understanding of the diseases and finding ways how to deal with them.



healthy vs. sick algae

Look out for Part 3 of my report: processing algae: candy, crackers and more