MACOI - Portuguese Seaweeds Website

Class:

Ulvophyceae (ex Bryopsidophyceae)

Genus:

Caulerpa J.V.Lamouroux

Species:

Caulerpa racemosa

Authority:

(Forsskål) J.Agardh

Description:

Caulerpa racemosa is a bright green seaweed that resembles long skinny vertical bunches of tiny grapes. It can be very similar in appearance to Caulerpa lentillifera, though the latter tends to produce more dense bunches (though this line can be smudged when Caulerpa racemosa grows in wave-exposed waters and develops shorter, stronger branches than normal). Caulerpa racemosa is quite variable in morphology and has many different growth forms that have been identified and named. A horizontal stolon which is attached to the sediment (usually sand) by descending rhizomes gives rise to erect branches every few centimeters. These branches can reach as much as 30 centimeters in height and produce a large number of stalked branchlets which are variable in shape from spherical to ovate to disk-shaped, sometimes flattening on top or forming ice cream cone type shapes. These plants are coenocytic, which means that the entire plant is made up of one giant cell with many nuclei and no cross-walls. Due mainly to this characteristic, any part of a Caulerpa racemosa plant that is fragmented, even tiny bits of tissue, can regenerate to form entirely new plants.

Link for Seaweed Industry Association

Caulerpa racemosa is an aggressive, highly invasive species throughout much of the world. This spread has had broad deleterious effects such as smothering native seagrass meadows, out-competing native algal species, transforming complex ecoystems into monospecific stands, and overgrowing corals, thereby seriously harming the health and function of reef systems. Efforts are in place to encourage bio-control of Caulerpa racemosa and stop the spread of this seaweed into additional non-native areas.

Name History

Adjective (Latin), with flowers borne in racemes.

Biogeography

Caulerpa racemosa is native to the Southern Hemisphere, thought to have originated in Australia, but is now found worldwide in shallow coastal waters of both temperate and tropical seas. It began spreading through the Mediterranean as an invasive species in the 1990's and is now prevalent throughout the Mediterranean, Europe, Africa, the Pacific and Indian oceans, Caribbean Sea, and the Gulf of Mexico.

Life Cycle

Caulerpa racemosa is an annual in most of its range, growing from April through December and going dormant over the colder winter months. Most reproduction is done vegetatively by fragmentation, though sexual reproduction is possible by holocarpy. This means that the entirety of the plant's cytoplasm is used up in creation of the gametes, leaving only an empty husk at the site of the original plant. Caulerpa racemosa is one of the three species of Caulerpa that has invasive characteristics.

Uses and compounds

Direct use as food - consumed whole

Caulerpa racemosa is grown commercially in the South Pacific, and harvested wild in other areas.

Caulerpa racemosa, like Caulerpa lentillifera, is used commonly in Asian and Island cuisines. It is often used fresh and raw as a salad vegetable and is desired for its peppery flavor which also makes it ideal for use in sauce making. This seaweed is common in the Phuket market of Thailand where 10-20 kilograms of fresh Caulerpa racemosa is sold per day.

Caulerpa racemosa also contains compounds which function as mild anesthetics, which gives the seaweed clinical value. Traditional medicine of the Philippines uses Caulerpa racemosa to lower blood pressure and to treat rheumatism.

References

Verlaque, M., Boudouresque, C.-F., Meinesz, A. & Gravez, V. (2000). The Caulerpa racemosa complex (Caulerpales, Ulvophyceae) in the Mediterranean Sea. Botanica Marina 43: 49-68, 18 figs, 3 tables.

Verlaque, M., Durand, C., Huisman, J.M., Boudouresque, C-F., & Le Parco, Y. (2003). On the identity and origin of the Mediterranean invasive Caulerpa racemosa (Caulerpales, Chlorophyta). European Journal of Phycology 38: 325-339.

Wang, H., Li, Y.-L., Shen, W.-Z., Rui, W., Ma, X.-J. & Cen, Y.-Z. (2007). Antiviral activity of a sulfoquinovosyldiacylglycerol (SQDG) compound isolated from the green alga Caulerpa racemosa. Botanica Marina 50(3): 185-190.

Zuljevic, A., Antolic, B., Nikolic, V., Despalatovic, M. & Cvitkovic, I. (2012). Absence of successful sexual reproduction of Caulerpa racemosa var. cylindracea in the Adriatic Sea. Phycologia 51(3): 283-286.

Habitat:

C. racemosa forms intertwined mats in tidepools and on reef flats. Horizontal runners tightly anchor mats to rocks and sand and in calm to moderately heavy surf areas.

Common names:

In English: Sea Grape; Green Caviar; Grape Caulerpa;

In Japanese: Sennarizuta;

Nama {Fiji};

Ar-arusip {Cagay};

Latu {Cebu}

Type information:

Basionym: Fucus racemosus Forsskål

Type locality: Suez, Egypt (Silva, Basson & Moe 1996: 832).

Type: C (Yoshida 1998: 101).

Notes: Leg. P. Forsskål (Lipkin & Silva 2002: 65).