Turbinaria (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Turbinaria decurrens - 1, habit; 2, leaf and receptacle. T. ornata - 3, habit; 4, leaf and receptacle. T. conoides - 5, portion of erect axis with leaves; 6, leaf and receptacle.

Turbinaria J.V. Lamour.

Protologue: Fucacées in Bory Dict. class. hist. nat. 7: 71 (1825).

Family: Sargassaceae

Chromosome number: x= unknown

Major species and synonyms

• Turbinaria conoides (J. Agardh) Kütz., Tab. phycol. vol. 10: 24, pl. 66, fig. 2 (1860), synonym: T. vulgaris J. Agardh var. conoides J. Agardh (1848).

• Turbinaria decurrens Bory, in Duperrey, Voy. monde, cryptogamie: 119 (1828) [1826-1829].

• Turbinaria luzonensis W.R. Taylor, J. Linn. Soc. (London), Botany 58: 482, pl. 2, figs 13-17 (1964).

• Turbinaria ornata (Turner) J. Agardh, Spec. gen. ord. alg. 1: 266 (1848), synonym: Fucus turbinatus L. var. ornatus Turner (1807-1808).

Vernacular names

General:

• Indonesia: rumput laut (general name for seaweed)
• Malaysia: rumpair (general name for seaweed)
• Philippines: samô (Cebuano)
• China: la ba zao.

T. ornata

• Indonesia: kakarian
• Vietnam: rong loa gai.

Origin and geographic distribution

Turbinaria is circumtropical in distribution and has been recorded from the Indo-Pacific as well as the Carribean but is more diverse in the Indo-west Pacific. T. conoides and T. ornata are probably the most widely distributed of the Turbinaria spp., having been found throughout South-East Asia. T. decurrens has a more limited distribution and has been recorded in South-East Asia from Thailand, Malaysia, Indonesia, the Philippines and Papua New Guinea. T. luzonensis has only been recorded from the Philippines.

Uses

Various Turbinaria spp. are used as human food, fertilizer, pesticide and insect repellent. In Malaysia pickled specimens of T. conoides and T. ornata are used in salads. As a fertilizer or soil conditioner, a mixture of Turbinaria with Sargassum, Hormophysa and Dictyota brown algae is decomposed in a pit for 2-3 months before being used. To hasten the decomposition, fresh leaves of Gliricidia sepium (Jacq.) Kunth ex Walp. are added. In the Philippines, the algae are mixed and boiled with seagrasses and the steam is inhaled to serve as a cure for children's fever. In the northern Philippines, a mixture of Turbinaria and Sargassum spp. is used in vegetable gardens to keep insects away.

Production and international trade

In South-East Asia, Turbinaria may be harvested and mixed with other large brown algae such as Sargassum spp. and reported as brown algae, so no specific information on their production and trade is available. There is no known phycoculture production of Turbinaria. In India, however, Turbinaria spp. are commercially harvested.

Properties

Turbinaria contains fatty acids, tannins, phenols, alginic acid, laminarin, steroids, mannitol, minerals (including Ca, Cu, Fe, I, K, Mg, Na, Zn), phytohormones (auxin, cytokinin, gibberellin) and pigments (carotene, chlorophyll a, chlorophyll c and fucoxanthin). Cell walls of Turbinaria contain alginic acid, cellulose and sulphated polysaccharides. For T. ornata from the Philippines 46.8% alginic acid content (moisture-free basis) has been recorded. Specimens of T. conoides in Malaysia have an alginate content of 25.7% (dry weight), with highest values around December. Alginate and mannitol contents of T. ornata have been found to vary with growth and reproductive seasonality, and were highest before the reproductive period, decreasing during and after the reproductive season.

Crude extracts of Turbinaria have been shown to improve seed germination and seedling growth of pigeon pea (Cajanus cajan (L.) Millsp.) with maximum activity obtained at 1% concentration of the crude extract. Methanol and hexane extracts of T. ornata from Papua New Guinea exhibited positive antibacterial activity against gram-positive bacteria. Antibacterial activity was also detected in T. conoides from India.

Turbinaric acid, identified to be 4,8,13,17,21-pentamethyl-4,8,12,16,20-docosapentaenoic acid has been isolated from T. ornata. A 20-hydroxy-4,8,13,17-tetramethyl-4,8,12,16-eicosatetraenoic acid was also isolated from T. ornata and found to be a feeding deterrent against the herbivorous gastropod Omphalius pfeifferi, and a feeding inhibitor for the herbivorous green snail Turbo marmoratus.

Description

• Leaves turbinate, expanding at distal end, forming marginal blades crowned by rows of teeth.
• Vesicles in centre of marginal blades.
• Life cycle diplontic.
• Sexual structures contained in modified leaves (receptacles).
• Receptacular branches located on stalk of leaves at some distance from main axis; gametangia in cavities (conceptacles) on the surface of receptacles.

T. conoides.

• Thalli erect, up to 1.5 m tall, attached to substrate by coarse, ramifying holdfast.
• Main axes terete, muricate at base; branches loose, in all directions.
• Leaves triangular or irregularly rounded, up to 12 mm × 9 mm in surface view, consisting of stalk, vesicle and expanded distal marginal blade crowned by short coarse teeth, sometimes cut on one side with cut extending to vesicle.
• Receptacular branches in clusters, 3-10 mm long, located about one-fourth distance from base of leaves.

T. decurrens.

• Thalli erect, up to 7 cm tall, with coarse, ramifying holdfast.
• Leaves up to 18 mm long, often in compact, distinct rows, distally expanded to trigonous form giving an obpyramidal lateral view; distal end triangular in surface view; surface concave, with or without fine marginal teeth; centre with or without vesicle.
• Receptacular branches paniculate, up to 8 mm long, located at base of leaf stalk.

T. luzonensis.

• Thalli erect, up to 10 cm tall, attached to rocks by coarse, ramifying holdfast.
• Main axis terete, densely covered with small, stalked leaves less than 1 cm long.
• Leaves expanded distally giving a triangular lateral view, in upper part of thallus with marginal blades narrowed to undulating ridge being entire or with a few teeth; terminal portion with vesicle surrounded apically by marginal blade being coarsely dentate or deeply cut.
• Receptacular branches racemose, less than 1 cm long, located near base of leaf stalk.

T. ornata.

• Thalli erect, 20-30 cm tall, attached to rock by discoidal holdfast with dichotomously branched ramifying stolons tipped with adhering discs.
• Main branch cylindrical, with numerous branches in all directions.
• Leaves coarse, subpyramidal to turbinate, up to 20 mm long, 15 mm broad at distal end; distal end expanded forming rounded to triangular marginal blade surrounded by crown of short teeth; centre of blade concave, usually with vesicle encircled by row of coarse teeth.
• Receptacular branches racemose, located about one-third distance from base of terete leaf stalk.

Growth and development

All plants of Turbinaria are diploid and only the meiogametes are haploid. In bisexual conceptacles both male and female gametangia are formed. Antheridia, oogonia and paraphyses are developed from an epithelial layer in the conceptacles. In oogenesis, one of the cells lining the conceptacle cavity divides transversely, giving rise to an outer cell forming the oogonial mother cell and an inner cell that becomes the stalk-cell. The oogonial mother cell differentiates directly into the oogonium and the stalk-cell persists until the oogonium is released. Per conceptacle 6-9(-12) oogonia are produced. Phenolic bodies, polysaccharide granules and protein bodies accumulate in the cytoplasm of the oogonium during differentiation. Each released oogonium contains eight nuclei of which one will be the nucleus of the single functional egg. Antheridia are either sessile or stalked. Eggs and sperms are released about the same time and synchronous in different conceptacles. The sperms are released en masse, but the eggs remain attached to the inside of the conceptacle by means of a small stalk and are embedded in transparent mucilaginous substances. The outer wall layer of an antheridium lyses at or near the apex of the mature antheridium, discharging the sperms.

Only one phenological study on Turbinaria has been conducted in South-East Asia (in the Philippines) in two sites on T. ornata and T. luzonensis. Young T. ornata populations appeared from January to May, and T. luzonensis populations from March to July. Receptacular branches developed from October to December in both sites. In India, where most studies were carried out, the growth cycle of T. conoides commences in April, and young plants of T. ornata appeared in April. Reproductive plants could be found there throughout the year but peaked in November. For T. decurrens in India, young plants were observed in May and June, while reproductive plants were found in 11 out of 12 months of the year, peaking in the period from December to February. The standing crops of T. ornata in Moorea Island (French Polynesia) were the most abundant of the perennial algae, constituting 61-80% of the bulk biomass.

Ecology

Turbinaria is commonly found on lower intertidal reef flats and shallow rocky subtidal areas exposed to moderate to strong waves and can form a distinct zone. In Pasacao, Camarines Sur, southern Luzon (the Philippines) tidal levels, temperature, and water movement seem to be the causal factors influencing the seasonality, distribution, growth and reproduction of Turbinaria at one station, and tidal levels, salinity, pH and water movement at another one.

T. ornata was found to stimulate slightly the growth of ciguateric dinofagellates in Mayotte Island (South-West Indian Ocean). Turbinaria invaded reefs on which the corrals have been killed by Acanthaster planci (crown-of-thorn starfish) in Moorea, French Polynesia. It appeared that T. turbinata was not preferred by sea urchin grazers. Various Turbinaria spp. form a suitable habitat for hydroids, polychaetes and dinoflagellates.

Propagation and planting

Turbinaria spp. are not known to be propagated artificially nor used in any phycoculture in South-East Asia. There were some early attempts to culture them in India but their growth was not encouraging.

Harvesting

Turbinaria is not specifically targeted for harvest in South-East Asia although it is commercially collected along the coast of the Gulf of Mannar (India). In South-East Asia, it may be a by-catch in the harvesting of other algae like Sargassum spp. For Malaysia the best time to harvest T. conoides, based on alginate yields, is stated to be October.

Yield

A population of T. ornata from Tiahura Reef, Moorea Island (French Polynesia) yielded 93.8-1130.5 g/m² (wet weight), 3.9-13.8% of which was made up of stolons only.

Handling after harvest

If harvested together with Sargassum spp., samples of Turbinaria are air-dried. It has been found that the gel strength (viscosity) of alginate extracted from T. ornata may increase from 10-74.5 cps (at room temperature) to 475 cps if the samples are pretreated overnight with 2% formaldehyde solution before extraction.

Prospects

Although Turbinaria is a potential source of alginate and other chemicals, it does not usually form a substantial component of the reef and its standing crop is not large enough to support extensive harvesting. Hence, unless unusual chemicals associated with Turbinaria are proven to have pharmaceutical significance, large-scale harvesting or phycoculture development is unlikely in the forseeable future.

Literature

• Ganzon-Fortes, E., Campos, R.R. & Udarbe, J., 1993. The use of Philippine seaweeds in agriculture. SICEN Newsletter 4(1): 2-3.
• Laserna, E.C., Veroy, R.L., Luistro, A.H., Montaño, N.E. & Cajipe, G.J.B., 1982. Alginic acid from some brown seaweeds. Kalikasan 11: 51-56.
• Montaño, N.E. & Tupas, L.M., 1990. Plant growth hormonal activities of aqueous extracts from Philippine seaweeds. SICEN Leaflet 2: 1-5.
• Moreland, P.S., 1979. Edible seaweeds of Northern Luzon, Philippines: market prices, local taste preference, seaweed recipes, and other local uses. Philippine Journal of Science 108: 41-53.
• Payri, C.E., 1984. Variations biologiques et morphologiques en fonction du milieu chez Turbinaria ornata (Turner) J. Agardh (Phéophycées) du récif de Tiahura - Ile de Moorea - Polynésie Française [Biological and morphological variations related to the environment in Turbinaria ornata (Turner) J. Agardh (Phaeophyceae) of the Tiahura reef, Moorea Island, French Polynesia]. Botanica Marina 27: 327-333.
• Sokhi, G. & Vijayaraghavan, M.R., 1986. Oogonial release in Turbinaria conoides (J. Agardh) Kützing (Fucales, Sargassaceae). Aquatic Botany 24: 321-334.
• Umamaheswara Rao, M. & Kalimuthu, S., 1972. Changes in mannitol and algic acid contents of Turbinaria ornata (Turner) J. Agardh in relation to growth and fruiting. Botanica Marina 15: 57-59.

Sources of illustration

Trono, G.C., 1986. Philippine seaweeds. In: Guide to Philippine flora and fauna. Vol. 1. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines. Goodwill Bookstore, Manila, The Philippines. Fig. 68, p. 260 (T. conoides), fig. 69, p. 261 (T. decurrens), fig. 70, p. 261 (T. ornata). Redrawn and adapted by P. Verheij-Hayes.

Authors

• P.O. Ang