Farming and Culture of Red Seaweed (Kappaphycus)

Kappaphycus is a red seaweed commonly called ‘guzo’ or ‘tambalang.’ There are three common strains which are appropriate for farming. These are brown, green and red strains. Kappaphycus is naturally found below 0 tide line on sandy-rocky to corally substrate in the tropical intertidal and subtidal waters. Farming of this seaweed started in southern Mindanao in the mid ’60s, and has expanded to other parts of the Philippines and to other countries like Indonesia, Fiji, Micronesia, Vietnam, China, and South Africa.

Kappaphycus forms 80% of the Philippine seaweed export and is one of the three marine-based export winners of the country. It is the raw material for the manufacture of kappa carrageenan which is an important food (e.g., jellies, ice cream, sauce, ham, sausage, chocolate drinks, etc.) and non-food (e.g., personal care, cosmetics and pharmaceuticals) additive.
The following environmental factors are required:

• Substrate: sand-rocky to corally
• Light: full sunlight
• Temperature: 29-34°C
• Salinity: >32 ppt
• Nutrients: nitrogen and phosphorus
• pH: 7-9
• Quality of water: clean. clear & pollution-free
• Water current: 20-40 m/min

Culture Techniques

Initial Investment (PhP/ha)

The planter is assumed to own a boat (either motorized or sailboat) and labor for the preparation and planting comes from the family. One cultivation line is 20 m long. If fund is insufficient, a fisherman may start ¼ to ½ ha and may expand later.

Crop Quality Management

• Growth period: 60 days
• Harvesting: total (¼ of the total harvest is allotted to seeding preparation for the next culture period)
• Drying time:  2-3 sunny days
• Drying technique:  hanging, spreading
• Drying device: fish net, bamboo slats
• Moisture content: 37-39%
• Impurities: 5%
• Storage: well ventilated place, stored in sacks

Physical Determinants

The interrelationship of light, water quality, water motion, and temperature determines the fertility of the farm site. However, water motion becomes the most critical factor
in farm productivity as farming progresses.

Human and other biological determinants for farming:

• dedication of the fisherfolk
• application of sound agronomic practices
• biological factors – control of pests as in:

• a. grazing – is the nibbling of herbivores like siganid, acanthurid, sea urchin and starfish on tips of branches; this is common in reef areas, limestone substrate and seagrass beds.

• b. epiphytism – is the attachment of undesirable seaweeds to the cultured species which are common
  among tropical seaweeds which usually occurs at the onset of monsoon brought by change in water temperature, tradewind and water motion; drift seaweeds caused by limited substrate contribute also to epiphytism which compete for space, nutrient and sunlight.

Health conditions of the seaweed:

• pitting – occurs at the cortical layer, a cavity is formed mainly due to mechanical wound; regenerative
• tip darkening – is due to senescence (old age) and cold water which result to loss of color and consequently disintegration. However, it has regenerative capacity
• tip discoloration – is due to aerial exposure and warm water; tip softening usually follows
• slowing of growth – this is mainly due to (1) appearance of epiphytes, (2) pigment loss, (3) tissue softening, (4) general decay, (5) poor season, (6) poor place of farming
• die-off – is initially manifested by discoloration which is mainly brought by freshwater run-off
• ice-ice – is a phenomenon caused by low salinity, temperature, and light intensity. When the plant is under stress, it exudes an organic substance which is mucilaginous in nature, and the presence of opportunistic bacteria in the water column aggravates the whitening of the branches or the so-called ‘ice-ice’ disease.

For more information, contact:

Seaweed Project
SEAFDEC Aquaculture Department
Tigbauan, Iloilo
Tel.: (033) 335-1009, 336-2965/2937
Fax:  (033) 335-1008, 336-2891
Email: aqdchief@aqd.seafdec.org.ph, d_chief@i-iloilo.com.ph
Web: www.seafdec.org.ph

photo from etawau.com