Kappaphycus (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, habit; 2, longitudinal section of a thallus; 3, transverse section of a thallus; 4, detail of transverse section of the cortical region of a thallus; 5, detail of transverse section of the cortical region of a thallus with tetrasporangia.

Kappaphycus Doty

Protologue: In: I.A. Abbott, Taxon. econ. seaweeds 2: 171-172 (1988).

Family: Solieriaceae

Chromosome number: x= unknown, possibly 10

Major species and synonyms

Synonym for the genus Kappaphycus is Eucheuma J. Agardh section Cottoniformis Doty & J.N. Norris, in: I.A. Abbott & J.N. Norris, Taxon. econ. seaweeds 1: 58-59 (1985).

• Kappaphycus alvarezii (Doty) Doty ex P.C. Silva - see separate article.

• Kappaphycus cottonii (Weber Bosse) Doty ex H.D. Nguyen & Q.N. Huynh, in: I.A. Abbott, Taxon. econ. seaweeds 5: 234 (1995), synonyms: Eucheuma cottonii Weber Bosse (1913), E. okamurae Yamada (1936).

• Kappaphycus inermis (F. Schmitz) Doty ex H.D. Nguyen & Q.N. Huynh, in: I.A. Abbott, Taxon. econ. seaweeds 5: 233 (1995) (as K. inerme), synonym: Eucheuma inerme F. Schmitz (1895).

• Kappaphycus striatus (F. Schmitz) Doty ex P.C. Silva - see separate article.

Vernacular names

• Indonesia: "cottonii" (Java, Bali, Sulawesi, the common name for all Kappaphycus spp.), agar-agar, agar besar (both common names for Kappaphycus and Eucheuma spp.)
• Philippines: tamsao (northern Luzon, both for Kappaphycus and Eucheuma spp.), guso (Visayan, for species of both genera), tambalang, kanot kanot (Ilocos Norte, for species of both genera).

Origin and geographic distribution

Originally, Kappaphycus only occurred in the Indian Ocean (Kenya, Tanzania, Madagascar, as well as on some small islands in the central part of that ocean), in South-East Asia and in Japan. Recently several Kappaphycus spp. have been distributed by humans to many other regions, including the Caribbean for cultivation trials. K. inermis was described from East Africa (Tanzania) and has recently been found in Vietnam.

Uses

Kappaphycus seaweeds are generally used as a source of kappa carrageenan as indicated under K. alvarezii.

Production and international trade

World phycoculture production for all "Eucheuma" spp. (including Kappaphycus and Betaphycus spp.) for 1986 was 160 106 t (all data on wet-weight basis, except for Vietnam) and by 1994 it had been risen to 384 980 t. Indonesia produced 77 462 t in 1986 and 115 000 t in 1994 (however, this also includes Gracilaria Grev. and Gelidiales). In the Philippines production in 1986 probably amounted to 4627 t ("E. alvarezii") and 145 632 t ("E. cottonii"). By 1994 these figures had risen to 12 110 t and 347 300 t respectively. However, these estimates are not accurate, because the combined estimated production for Indonesia and the Philippines is higher than the given estimate for world production. Figures for Vietnam suggest that in 1995 about 10 t (dry weight) of K. cottonii were produced.

Properties

In all cases where Kappaphycus was tested, both tetrasporic and cystocarpic stages consistently produced kappa carrageenan. In K. inermis, however, the gel strength of the kappa carrageenan is only half that of the carrageenan obtained from other Kappaphycus spp. In both K. inermis and K. striatus the sulphate content of the carrageenan is higher than in the other species.

Description

• Thalli prostrate or erect, amorphous, compressed or composed of cylindrical branches. Branching usually irregular with few to numerous coarse, blunt or spinose branchlets, occasionally arranged in rows.
• In cross-section, centre of medulla at or near apex of branches consisting of large, rounded cells interspersed with small, thick-walled cells forming the axial core; inner cortex and axial region in apical segments producing secondary cell structures ("thylles") extending basally as hyphae in axial region of thallus; in some species no separate central axial region visible.
• Life cycle triphasic, diplo-haplontic and isomorphic.
• Tetrasporangia seriate, embedded in cortex.
• Gametophytes dioecious; cystocarps forming hemispheres directly on main axes; spermatangia in indefinite superficial sori.

K. cottonii.

• Thalli forming large, crust-like clumps of fused, prostrate branches, strongly attached to solid substrates by haptera arising from under surface of thallus or consisting of somewhat compressed irregular branches, attached to one another by undefined haptera forming slightly amorphous fronds; surface rough, warty, with numerous short, blunt, stubby spines or tubercles.
• Cross-section of thallus with medulla composed of large rounded cells without central core of rhizoidal or hyphal cells.

K. inermis.

• Thalli erect, composed of cylindrical branches, attached by thick, fleshy, discoid holdfast forming several fronds; branching usually irregular, open, indeterminate, flexed upward, inflated.
• In cross-section, centre of medulla with distinct axial core, persisting to at least 10 cm in branches less than 5 mm in diameter, consisting of large, rounded cells interspersed with small, thick-walled cells, often surrounded by rather regular border of nearly uniform medium-sized cells.

Other botanical information

In the early 1970s these algae were known as Eucheuma cottonii (usually shortened to "cottonii" by farmers and traders) because it was a member of the Eucheumoid algae producing "cottonii-like" carrageenan. The genuine Kappaphycus cottonii was always relatively rare in commercial shipments of wild seaweed and has never been farmed. In the early stages of "cottonii" farming, most of the material produced was what would be identified as K. striatus, which was used until better growing cultivars of Kappaphycus were generally adopted for cultivation.

The status of K. alvarezii as a species separate from K. striatus (and K. inermis) has been challenged on the basis of tetraspore progeny studies. It is suggested that the presence of both dichotomous and decumbent plants in the tetraspore progeny of K. alvarezii may represent the segregation of forms similar to ancestral parent plants, putatively of the very variable species K. striatus. It is not certain whether K. inermis and K. striatus are really species that differ from one another.

The genera Betaphycus Doty ex P.C. Silva and Kappaphycus have recently been separated from the broad and variable complex genus Eucheuma J. Agardh. The species of these new genera were previously separated within sections in Eucheuma. In the circumscription of Eucheuma section Cottoniformis Doty & J.N. Norris (1985), Eucheuma cottonii is excluded. It is, however, clearly included in the circumscription of Kappaphycus Doty (1988).

Ecology

Kappaphycus spp. are tropical seaweeds. They occur usually on rocks and corals in clear-water areas. K. cottonii grows especially on the reef edge, where it is exposed to very strong wave action. Most species are stenohaline.

Propagation and planting

Only K. alvarezii and small amounts of K. striatus are used in phycoculture.

Diseases and pests

The most persistent disease problem in Kappaphycus is "ice-ice". It occurs almost exclusively in phycoculture under unfavourable ecological conditions.

Harvesting

In natural Kappaphycus populations harvesting is by hand-collecting or by collecting specimens which have drifted onto beaches.

Handling after harvest

Kappaphycus is usually sun-dried after being collected.

Prospects

If disease problems in K. alvarezii persist and/or become even more severe, other Kappaphycus spp. might become more interesting for phycoculture.

Literature

• de Paula, E.J., Lima Pereira, R.T. & Ohno, M., 1999. Strain selection in Kappaphycus alvarezii var. alvarezii (Solieriaceae, Rhodophyta) using tetraspore progeny. Journal of Applied Phycology 11: 111-121.
• Dinh, N.H. & Nang, H.Q., 1995. Species of Eucheuma and Kappaphycus in Vietnam. In: Abbott, I.A. (Editor): Taxonomy of economic seaweeds 5. pp. 229-235.
• Doty, M.S., 1988. Prodromus ad systematica Eucheumatoideorum: a tribe of commercial seaweeds related to Eucheuma (Solieriaceae, Gigartinales). In: Abbott, I.A. (Editor): Taxonomy of economic seaweeds 2. pp. 159-207.
• Doty, M.S. & Norris, J.N., 1985. Eucheuma species (Solieriaceae, Rhodophyta) that are major sources of carrageenan. In: Abbott, I.A. & Norris, J.N. (Editors): Taxonomy of economic seaweeds 1. pp. 47-61.
• Santos, G.A., 1989. Carrageenans of species of Eucheuma J. Agardh and Kappaphycus Doty (Solieriaceae, Rhodophyta). Aquatic Botany 36: 55-67.
• Trono Jr, G.C., 1993. Eucheuma and Kappaphycus: taxonomy and cultivation. In: Ohno, M. & Critchley, A.T. (Editors): Seaweed cultivation and marine ranching. 1st Edition. Japan International Cooperation Agency, Yokosuka, Japan. pp. 75-88.

Sources of illustration

Trono, G.C. & Ganzon-Fortes, E.T., 1988. Philippine seaweeds. National Bookstore, Manila, The Philippines. Fig. 110A, p. 156 (habit); Xia, B. & Zhang, J., 1999. Flora algarum marinarum sinicarum, vol. 2, Rhodophyta, 5. Academiae Sinicae Edita, Beijing, China. Fig. 75, p. 128 (sections). Redrawn and adapted by P. Verheij-Hayes.

Authors

• W.F. Prud'homme van Reine