Caulerpa racemosa (PROSEA)

Plant Resources of South-East Asia
Introduction

Var. laetevirens - 1, habit; 4, fertile branchlet with liberation tube (arrow) and gametangial network. Var. corynephora - 2, habit. Var. racemosa - 3, habit; 6, fertile branchlets and gametangial network. Var. peltata - 5, fertile branchlets with liberation tube (arrow) and gametangial network; 7, macrogamete, with reddish eye-spot; 8, microgamete.

Caulerpa racemosa (Forssk.) J. Agardh

Protologue: Lunds Univ. Årsskr., Afd. Math. Naturv. 9(8): 35-36 (1873).

Family: Caulerpaceae

Chromosome number: 2n= unknown

Synonyms

Fucus racemosus Forssk. (1775),
Caulerpa clavifera (Turner) C. Agardh (1817),
Caulerpa uvifera C. Agardh (1817).

Major varieties and synonyms

var. corynephora (Mont.) Weber Bosse (1898), synonym: Caulerpa corynephora Mont. (1842).

var. laetevirens (Mont.) Weber Bosse (1898), synonym: Caulerpa laetevirens Mont. (1842).

var. lamourouxii (Turner) Weber Bosse (1898), synonym: Fucus lamourouxii Turner (1811-19).

var. macrophysa (Sond. ex Kütz.) W.R. Taylor (1928), synonyms: Chauvinia macrophysa Sond. ex Kütz. (1857), Caulerpa macrophysa (Sond. ex Kütz.) G. Murray (1887), C. clavifera var. macrophysa (Sond. ex Kütz.) Sved. (1906).

var. peltata (J.V. Lamour.) Eubank (1946), synonym: Caulerpa peltata J.V. Lamour. (1809).

var. racemosa , synonyms: Caulerpa racemosa var. uvifera (C. Agardh) C. Agardh (1823), C. racemosa var. clavifera (Turner) Weber Bosse (1898).

var. turbinata (J. Agardh) Eubank (1946), synonyms: Fucus chemnitzia Esper (1800), C. clavifera var. turbinata J. Agardh (1837), C. racemosa var. chemnitzia (Esper) Weber Bosse (1898).

Vernacular names

Seagrapes (En)
Indonesia: lelato (Lombok), lata (Bangka), lai-lai (South Sulawesi)
Philippines: ararusip (Ilocano, general and for var. peltata), kulinatnat, saluysoy (for var. peltata).

Origin and geographic distribution

C. racemosa is widely distributed in tropical waters and some varieties also occur in subtropical waters. It is common in South-East Asia, and has been recorded in Burma (Myanmar), Thailand, Vietnam, Malaysia, Singapore, Indonesia, the Philippines and Papua New Guinea.

Uses

In the Moluccas (eastern Indonesia) the fronds of C. racemosa are consumed fresh as a salad and eaten mixed with spices such as grated coconut, garlic, shallot, leaves of basil (Ocimum basilicum L.), salt and chilli. In Cagayan Province (the Philippines), the C. racemosa side dish is prepared by mixing clean fronds with salt and tomatoes or with tomatoes, onions and pepper. Var. racemosa and var. peltata in particular are used in the Philippines. These varieties are also used in Indonesia; in South Sulawesi var. corynephora is also much appreciated. In Thailand the varieties corynephora and macrophysa are commonly used as salad vegetables. In the Philippines C. racemosa is also used as fish feed and as a medicine for humans to lower blood pressure and to treat rheumatism. Antibacterial, antibiotic, antifungal and peroxidase activities are recorded.

Production and international trade

C. racemosa is only used locally.

Properties

Like other Caulerpa, C. racemosa produces secondary compounds, such as caulerpin, caulerpicin, caulerpenyne and other terpenoids. The neurotropic activity of caulerpicin is thought to be of clinical value. Both caulerpin and caulerpicin are apparently transferred along marine food chains and become concentrated in the process. In some areas this can result in toxicity to fish. C. racemosa is often especially rich in cholesterol and is cited as having antitubercular, haemagglutinic and hyposensitive activities.

Description

Plant stoloniferous; stolons terete to ovoid in cross-section.
Rhizoid bearing descending branches (pillars) arising at irregular distances.
Fronds mostly erect, up to 20 cm tall, crowded or rather sparse.
Branching simple or irregular, not more than to third order; branchlets (assimilators) basically consisting of stalk and head of varied form (club, rounded, ovate or compressed), alternate, opposite, multiseriate or imbricate.
Thalli holocarpic when fertile.

var. corynephora. Fronds robust, fleshy, simple; branchlets biseriate, (sub)opposite, large distance between branchlets, clubformed with hemispherical head; head 1-2.5 mm wide on cylindrical stalk 2-5 mm long.

var. laetevirens. Fronds robust, fleshy, simple, crowded; branchlets imbricate, mostly arranged in four rows surrounding the frond's axis, clavate with hemispherical head; head 1.5-3 mm wide.

var. lamourouxii. Fronds stiff, irregularly branched, compressed, on short terete stalk either entirely nude or with branchlets at one or both margins; branchlets irregularly scattered or opposite, pyriform or clavate, 1.5-3.5 mm wide on a short stalk.

var. macrophysa. Plant stout, fleshy; stolons richly ramified; fronds 2-4 cm long; branchlets irregularly placed, pyriform to (sub-)spherical, always with rounded head, (2-)4 mm in diameter, on unconstricted stalk, shorter than the diameter of the branchlets.

var. peltata. Plant stoloniferous, creeping, delicate to rather robust; branchlets arising directly from the stolon's surface or from short ascending axis, irregular or subopposite, peltate or depressed turbinate (shield-shaped); head 1.5-7 mm in diameter, on a relatively long cylindrical stalk.

var. racemosa. Plant rather fleshy; stolons richly ramified, often with long, thin rhizophorous pillars; fronds (2-)3-4 cm long; branchlets irregularly placed to crowded, pyriform to (sub-)globose, (2-)3-4 mm long, with inflated top, head (2-)3-4 mm in diameter, on unconstricted stalk 0.5-1.5 mm long.

var. turbinata. Plant stout, fleshy; stolons thick, terete, 3(-5) mm in diameter, with well-developed, short or long, branched or unbranched rhizophorous pillars; fronds generally simple, 4-8(-17) cm tall; branchlets radially or helicoidally arranged, broadly clavate, with blunt, flat or even convex head (trumpet-shaped), 4-12 mm long and 5-9 mm in diameter.

Growth and development

In aquarium culture, C. racemosa grows relatively fast. The stolon may grow 1.1-2.0 cm per day in the first week, while the ascending fronds grow about 1 cm in the first week. In culture, propagation is mainly by fragmentation, while in nature propagation may happen by vegetative fragmentation as well as by sexual reproduction. Sexual reproduction is believed to be similar to that of other Caulerpa, where most of them are considered to be monoecious and holocarpic, releasing their total content in the form of microscopic, mobile, biflagellated presumed anisogametes. These gametes are usually shed from siphonous liberation tubes, 1.2-2 mm long.

Other botanical information

Cross-gradient culture experiments were carried out on specimens in the C. racemosa/peltata complex originating from Japan. There the laetevirens type was formed under relatively low temperatures and high light intensities, while peltata type assimilators were formed under lower light intensities and low as well as high temperatures. The results were the same whether the inoculating stock was C. racemosa var. peltata or C. racemosa var. laetevirens. In nature, plants with only peltata-type assimilators grow on shaded rocks or in deep water, while plants with only laetevirens-type assimilators grow on sunny rocks in shallow water. An individual plant that extends from a shaded to a sunny habitat is often morphologically complex, showing peltata- as well as laetevirens-type assimilators on different parts of the same stolon. It has been suggested that these two different varieties should be considered as ecological growth-forms (ecophenes or ecads) of a single Caulerpa sp., while at least some growth-forms of C. racemosa var. turbinata, which are often mentioned as forms intermediate between var. peltata and var. laetevirens, are probably also ecads of this complex taxon. The relationship with other components of C. racemosa has not yet been experimentally clarified, however.

Ecology

C. racemosa is very commonly found in shallow water less than 5 m deep. Favourable environmental conditions for most varieties consist of calm, relatively clear water with weak to medium current and loamy or sandy bottom. C. racemosa is also associated with mangrove forest. Very often a C. racemosa meadow is found in the frontier areas of mangrove forest, and it grows very well on the dead trunks of mangrove trees or covers the wooden piles of harbour bridges. Some of the varieties of C. racemosa (e.g. vars lamourouxii, macrophysa and racemosa) are tolerant of the fluctuations in salinity found in intertidal ponds. During the blooming season (in eastern Indonesia between late May-early July), C. racemosa grows very thick and dense and may reach a height of up to 40 cm. The varieties racemosa and peltata also occur on rocky-corally substrates exposed to strong water movement. In these habitats the stoloniferous plants may cover reef edges with closely set short fronds. Heterotrophic activity (uptake of amino acids) has been demonstrated in C. racemosa var. occidentalis from Florida, the United States.

Propagation and planting

Replanting of C. racemosa (e.g. var. laetevirens and var. macrophysa) very often fails due to stress-accelerated reproduction. Stress may occur when C. racemosa is transported over long distances in polybags for more than seven hours, and directly planted afterwards. Reproduction will take place in large amounts 5-9 days after replanting. When grown in ponds small pieces of alga are planted in the sandy or muddy substrate.

Phycoculture

The principal method of cultivating C. racemosa is by planting it in ponds. Cultivation of this alga in hanging cages gives unsatisfactory results: it grows laterally giving very long stolons and short fronds.

Diseases and pests

Small Oxynoe and Elysia molluscs are often found foraging on cultivated C. racemosa.

Harvesting

C. racemosa is harvested by hand from natural populations or from culture in ponds.

Handling after harvest

Harvested C. racemosa must be washed several times with clean seawater to remove sand and attached organisms. Clean algae are placed in big plastic baskets or fine-plaited bamboo baskets, the bottom and top covered with layers of Sargassum seaweeds or banana leaves. The material is then transported to local markets and sold fresh.

Prospects

C. racemosa is a promising supplementary sea vegetable, especially for coastal and island villagers. In eastern Indonesia it is regularly sold on the market, but the price is lower than that of land vegetables.

Literature

Crawford, G.H. & Richardson, W.N., 1972. Heterotrophic potential of the macroscopic alga Caulerpa racemosa. In: Nisizawa, K. (Editor): Proceedings of the Seventh International Seaweed Symposium, Sapporo. University of Tokyo Press, Tokyo, Japan. p. 262.
Enomoto, S. & Ohba, H., 1987. Culture studies on Caulerpa (Caulerpales, Chlorophyceae). I Reproduction and development of C. racemosa var. laetevirens. Japanese Journal of Phycology (Sôrui) 35: 167-177.
Ohba, H. & Enomoto, S., 1987. Culture studies on Caulerpa (Caulerpales, Chlorophyceae) II. Morphological variation of C. racemosa var. laetevirens under various culture conditions. Japanese Journal of Phycology (Sôrui) 35: 178-188.
Ohba, H., Nashima, H. & Enomoto, S., 1992. Culture studies on Caulerpa (Caulerpales, Chlorophyceae). III. Reproduction, development and morphological variation of laboratory-cultured C. racemosa var. peltata. Botanical Magazine, Tokyo 105: 589-600.
Silva, P.C., Basson, P.W. & Moe, R.L., 1996. Discussion on Caulerpa peltata and Caulerpa racemosa in: Catalogue of the Benthic Marine Algae of the Indian Ocean. University of California Publications in Botany 79: 828-838.

Sources of illustration

Hatta, A.M. Orginal drawings of habits of var. corynephora and var. laetevirens; Trono, G.C. & Ganzon-Fortes, E.T., 1988. Philippine seaweeds. National Bookstore, Manila, The Philippines. Fig. 19, p. 35 (habit var. racemosa); Hori, T. (Editor), 1994. An illustrated atlas of the life history of algae. Vol. 1. Green algae. Uchida Rokakuho Publishing Company, Tokyo, Japan. Fig. 134, p. 272 (fertile branchlet of var. racemosa), fig. 135, p. 274 (fertile branchlet of var. laetevirens), fig. 136, p. 276 (fertile branchlet and gametes of var. peltata). Redrawn and adapted by P. Verheij-Hayes.

see also the genus page

Authors

A.M. Hatta