A preliminary summary on Kappaphycus farming and the impact of epiphytes

Abstract

The read seaweed Kappaphycus alvarezii (Doty) Doty ex. P.C. Silva, commonly called "cottonii" in the processing industry, is used as raw material for the production of the hydrocolloid kappa carrageenan. Through biotechnological advaces, certain carrageenan-producing seaweeds have been truly "domesticated" and are now successfully farmed as marine crops in a number of suitable areas of the world. Significant and sustainable employment opportunities are generated by these activities with few environmental impacts. In mid-2001, the incidence of very heavy epiphytism of cultivated raw material of K. alvarezii (cottonii) was reported for a production centre in the Philippines. This case of epiphytism was "unusual" in that it had been present for a considerable period of time and following epiphyte growth, the seaweed crop began to rot and fall off the cultivation lines (this was not the case of the disease "ice-ice"). The outbreak of the epiphyte infestation followed successional development of an epiphyte community and resulted in a climax population of the read seaweed Polysiphonia sp. This was observed to be preceded by heavy precipitation with consequent siltation reaching the farm site. The presence of the Polysiphonia sp. gave the plants a "hairy" appearance. Where the Polysiphonia was attached, the host plant seemed to produce "galls". The end result was that the Kappaphycus material rotted, fragmented and fell off the cultivation lines. The impact of this epiphyte attack was economically, socially and ecologically serious in that the farmers became disillusioned and either moved from the islands to other cultivation sites, leaving their families behind, or returned to the environmentally damaging practices of dynamite and or cyanide reef fishing. This paper outlines the events of epiphytic settlement and subsequent decomposition of the crop plants. The impact of Kappaphycus farming in the north-east Philippines is outlined as well as steps undertaken to improve the farming practice and enable farmers to return to the sustainable activity of seaweed farming.