Eucheuma algae can double their biomass in two weeks

Nearly 27 million tonnes of algae and aquatic plants – a source of important ingredients for medicines, cosmetics and foods – were produced worldwide in aquaculture in 2013. Algae farming is work-intensive but not very lucrative. In some regions, however, it is one of the few possibilities for earning a living without having to make larger investments. For example on Lembongan, one of over 17,000 islands that make up Indonesia.

Sketch of the algae farms off Lembongan Island, Indonesia. The dark patches on the aerial photograph (bottom left) are plots with algae cultures.

Indonesia comes second to China in worldwide algae production and has more than quadrupled its production since 2000. According to FAO statistics, algae farms in the Indian Ocean’s island state produced nearly one third of the relevant global production volume in 2013, or 8,323,263 t. Indonesian production mainly consists of red algae of the species Eucheuma/Kappaphycus (8.323 m t) and Gracilaria (0.975 m t). The two species groups serve as raw materials for the production of gelatinous, swellable substances that are used as binding and gelling agents in the food industry and other fields. Carrageenan (E407) is isolated from Eucheuma and Kappaphycus species, and Gracilaria algae provide agar-agar (E406), another highly demanded ingredient. Both macro-algae, which are commonly often simply known as seaweed, grow fast and have very efficient photosynthesis, the process by which green plants, with the help of sunlight, convert carbon dioxide and water into chemical energy (glucose) and at the same time release oxygen. Because numerous seaweed species bind five times more CO2 than terrestrial plants of the same size some experts even see algae production as a useful way to reduce the CO2 induced greenhouse effect on our planet.

It is doubtful whether algae farmers on the tiny island of Lembongan which lies about 12 km southeast of the island of Bali are aware of the positive effect that their hard work has on global climate. A lot of the 5,000 inhabitants who live on the eight square kilometre island have no other means of earning themselves any money. Agriculture is hardly possible on Lembongan because most of the island – about 85% - consists of unproductive limestone rocks. There is no industry there and not even stable electricity supply. The little villages provide their own power using diesel generators which are, however, often not started until the evening. All of this makes the island a paradise for backpacker tourists who are looking for peace and relaxation far away from the hustle and bustle of Bali and find there secluded locations for diving and surfing. It is questionable, whether fishing will continue undisturbed for long. With the support of the Nature Conservancy Coral Triangle Center, a regional environmental NGO is currently trying to restrict fishing in some areas off the island. The coral reefs off Lembongan are considered valuable and particularly worthy of protection, with so far 247 coral species and over 560 reef fish species detected there. Anyone among the local inhabitants who does not find a job in the tourist industry or rents out private accommodation has to make do with the cultivation of red algae.


Optimal conditions for algae farming

Seaweed culture on Lembongan began in the 1970s when demand for agar-agar and carrageen rose strongly worldwide. It reached its peak in the year 2000. At that time nearly 100 hectares were used for growing seaweed. Together with the two neighbouring islands Ceningan and Penida total production area at that time even amounted to 310 ha. Since then it has declined significantly, however, and is today concentrated on an area of less than 50 ha, mainly in a shallow tidal water channel which separates Lembongan from Ceningan. The two islands are linked at the narrowest point of the channel by a wooden suspension bridge which is only for pedestrians and bicyclists.

The position of the individual plots is clearly visible in the crystal clear water. The boats are mainly used for transporting the algae.

This shallow water area offers optimal conditions for algae farming. The channel is shallow enough to be able to reach the algae cultures on foot at low tide but deep enough for the plants to be covered in water during this time and so not fall completely dry. The incoming waves are broken at the point of transition to deeper water so that the cultures are not exposed to too much mechanical stress. There are no freshwater inflows which keeps salinity almost constantly in an optimal range of 30 to 35 parts per thousand. It only sinks slightly lower due to heavy rainfall in the rainy season. The water temperature of 27 to 30°C also offers perfect conditions for seaweed growth. Apart from that, the light-coloured sandy sea bed in the area reflects the sunlight which additionally promotes the algae’s growth.

Nearly every family on Lembongan is involved in algae farming, some of them only as a sideline to supplement their income. For others, mostly older island inhabitants, it is often the only source of income. With the exception of civil servants hardly anyone in Indonesia gets a regular pension so a lot of people continue working well into old age to avoid being dependent on the charity of others. In the past algae farming was considered as work for the whole family, including the children. Today young people mostly move away to the big towns and tourist centres where they can get better paid jobs and where life is more colourful, more varied and less hard than on the small island. It is mainly old people that remain there, and they have to scrape along with seaweed farming.


Eucheuma and Kappaphycus species dominate the cultures

The cultivation plots in the shallow water off the coast are called “are” and measure 10 by 10 metres. They usually cost on average 5 million rupiah, or 350 euros, to buy. A family on Lembongan typically owns 3 to 5 are for seaweed cultivation, but some people can afford more plots. Although today by no means all of them are cultivated the citizens still hold the ownership rights. The system is based only on oral records and traditions for on Lembongan no one would be likely to hold deeds proving ownership or be able to present property registers recording sales and purchases.

The individual fragments weigh between 50 and100 grams. They are tied to the main line at intervals of 20 to 25 cm using soft plastic string.

Several red algae species such as Eucheuma cottonii, E. spinosum, Kappaphycus alvarezii and Gelidium amansii, of which some are intensely green, others sooners reddish to brownish in colour, are farmed. Because they grow at different speeds the algae farmers usually differentiate them by colour. “Brown seaweed” (E. spinosum) takes about two weeks to double its biomass. Green algae (E. cottonii) take at least twice as long before they are ready for harvesting but to make up sell for three to six times as much (12,000 rupiah/kg or about 0.84 EUR) for the dried product. Just how much money is actually paid depends on market demand and on the quality of the dried algae. It is particularly important that the seaweed is clean, all of the same species, and that it contains no foreign bodies. The algae farmers on Lembongan have another problem, however, for there is no processing plant for algae on the islands and only one buyer who dictates the prices. Hardly any of the small algae producers earn more than one to two million rupiah, 70 to 140 euros, per month.


Hard, badly paid work in the rhythm of the tides

Hard work for a pittance and no regular working hours. Algae farmers have to follow the tides. Because they can only reach and care for the algae cultures at low tide they sometimes have to go out at night and work by lamplight if low tide doesn’t start till dusk. Maintenance and care of the crops are necessary about every two days. The farmers work for hours on end in knee deep, even chest high water, bent over their algae to remove the proliferating growth of unwanted plans that rob the seaweed of light and so interfere with their development. They remove any diseased or dead plant parts, collect pests and parasites from the cultures and fix any lines that might have become loose. On Lembongan seaweed is cultivated using the fixed off-bottom monoline technique. This is based on the enormous vegetative regeneration capacity of Eucheuma species. A number of algae bodies are divided into small fragments or cuttings that will then grow again into large algae. To this purpose they are tied at 20 to 25 cm intervals like washing on a washing line that is drawn across the plot close to the bottom between stakes. This is simple, cheap and also offers the advantage that the algae cuttings can already be attached to the line on land. When necessary, for example, if the cuttings do not grow well or are hit by disease such as ice-ice or are ready for harvesting, the farmers can remove or replace the line quickly and easily.

After the farmers have completed their work in the marine plots there is still more to do on land. A particularly time-consuming job is attaching the algae fragments to the lines and the farmers mostly do this themselves to save money. Although there are some companies that have specialised in this task and offer prepared seed lines the service is usually too expensive for the small producers. A line with E. spinosum costs about 0.30 EUR, with W. cottonii even as much as nearly one euro, and that would immediately eat up the already meagre income. And it is hardly possible to recover vital, robust seedlings from wild algae stocks on Lembongan either, because the natural algae populations in the island environment are already strongly depleted and the effort of collecting them accordingly high. For that reason the farmers usually rely on their own cultures and use parts of particularly well growing algae as seed for the next cycle. About one tenth of every harvest is immediately used to this purpose.

The algae fragments that serve as cuttings for the cultures are fixed onto the lines on land by hand.


Dried algae are mainly used for carrageen production

The most important task after harvesting is drying the seaweed. To do this the algae are first taken from the lines, any unwanted growth sorted out and all damaged or diseased plant parts removed. The remaining algae parts are then spread out on plastic mats and left in the sun for 2 to 5 days. To accelerate the drying process a transparent plastic foil is sometimes placed over the algae to intensify the heat. Progress during drying is clearly visible for the seaweed becomes paler with increasing water loss. After the drying process little more than one kilogram remains of 10 kg fresh seaweed. As soon as the residual moisture in the plant tissue has reached a level of below 40% the dried algae are packed in sacks of 40 to 60 kg and then collected in warehouses. Later on the buyer takes them to the mainland for further processing.

Eucheuma seaweed can also be eaten directly as a salad. For this it just has to be briefly boiled, mainly to remove part of the salt it contains. Although Eucheuma is nutritious and contains a lot of important trace elements it is not liked very much due to its thick, hard parts. Usually it is only served when there is nothing else available.

It is easy to see how dry the algae are: on the left fresh seaweed shortly after harvesting, on the right dried seaweed.

The vast majority of Indonesia’s seaweed production is exported dried, mostly to Japan and Hong Kong but also to North America and Europe. There, a number of substances are extracted from the algae and used for cosmetics, nutraceuticals and beauty products. The most important industrial application field is the extraction of carrageenan, which belongs to the group of gel forming polysaccharides and serves as a full substitute for pectin or gelatine. Carrageenan accounts for nearly one quarter of the dry weight of algae and about 250,000 t are produced worldwide at present. It is used in a lot of industrially produced diet and light products as a stabilizer, thickener and binder. The product spectrum ranges from sausage and meat products such as cooked ham or turkey breast, to jams and desserts, ice-creams, herbal tea and various dairy products. It is of advantage that there are no known restrictions for carrageenan, for example for vegetarians, vegans or some religious groups (kosher, halal). Perhaps this substance will find even wider use in future for there are some indications that carrageenan could prevent some cancers.