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Caulerpa racemosa var. cylindracea Taxon Caulerpa racemosa var. cylindracea (Sonder) Verlaque, Huisman and Boudouresque, 2003 Family / Order / Class / Phylum Caulerpaceae / Bryopsidales / Bryopsidophyceae / Chlorophyta COMMON NAMES (English only) Grape algae SYNONYMS Caulerpa cylindracea Sonder, 1845 Ahnfeltia cylindracea (Sonder) Trevisan, 1849 Chauvinia cylindracea (Sonder) Kützig, 1849 Caulerpa racemosa var. laetevirens f. cylindracea (Sonder) Weber van Bosse, 1898 SHORT DESCRIPTION A green macroalgae with slender thallus, lacking large rhizoidal pillars, basal part of the upright axes slightly inflated immediately above the attachment to the stolon, clavate branchlets, uncrowded and radially to distichously disposed. BIOLOGY/ECOLOGY Dispersal mechanisms The rapid dissemination owes to vegetative propagation by random fragmentation, and by specialized propagules formed by detached Caulerpa racemosa var. cylindracea ramuli. The propagules/fragments may be dispersed by currents or by anthropogenic means Photo: Enric Ballesteros (vessels, nets, aquaculture products). Reproduction Sexual reproduction with a low production of planozygotes. Vegetative reproduction happens either after ramification and development of stolons, or after natural or anthropogenic fragmentation by man, hydrodynamic forces, or marine animals like sea urchins and crabs. The fragmentation may occur in any part of the alga. Another method is the specific fragmentation process involving detachment of ramuli which detach themselves from the fronds and form propagules consisting of fine coenocytic chlorophyllous filaments. Known predators/herbivores Grazing fish and invertebrates. Resistant stages (seeds, spores etc.) None. HABITAT Native (EUNIS code) A3: Sublittoral rock and other hard substrata, A4: Sublittoral sediments. Marine sublittoral hard and soft. Habitat occupied in invaded range (EUNIS code) A3: Sublittoral rock and other hard substrata, A4: Sublittoral sediments. Marine, soft and hard bottoms, polluted and unpolluted, intertidal to 70 m. Habitat requirements The growth rate is closely correlated to the seawater temperature: in winter, the growth rate decreases rapidly with the seasonal drop in the seawater temperature. The alga probably survives the winter seawater temperatures of the north-western Mediterranean Sea (10.5°C) in the form of zygotes and/or small fragments (rhizoids, stolons, propagules). In southern localities, like Sicily, no significant winter regression have been observed. DISTRIBUTION Native range Southwest coast of western Australia. Known Introduced Range Mediterranean: from Spain to Turkey; Atlantic: Canary Islands. Trend First record in the Mediterranean in the early 1990s in Libya. It was soon found in many other locations. At present extensive populations are found along much of the Mediterranean coastline (Albania, Balearic Islands, Corsica, Crete, Croatia, Cyprus, France, Greece, Italy, Malta, Sardinia, Spain, Turkey, Libya). MAP (European distribution) Known in country Legend Known in CGRS square Known in sea INTRODUCTION PATHWAY Aquarium trade and shipping. IMPACT Ecosystem Impact It is known to attain total coverage in certain areas within six months of entry, its fast growing stolons allowing it to overgrow other macroalgae, mainly turf and encrusting species, and to curtail species number, percent cover and diversity of the macroalgal community. This feat is achieved even in highly diverse, native macroalgal assemblages with dense coverage. Off Cyprus, where the alga was first sighted in 1991, it replaced the dominant P. oceanica community within six years. The drastic change in the composition of the phytobenthos brought about a modification of the macrobenthos: a proliferation of polychaetes, bivalves and echinoderms and a reduction in the numbers of gastropods and crustaceans, and though the total number of species increased, it was mainly due to the greater number of polychaete species. A study of meiofauna in a dead matte of P. oceanica invaded by C. racemosa var. cylindracea revealed an increase in meiofaunal average density but a significant decrease in diversity and profound change in the crustacean assemblage, where harpacticoid copepods proliferate at the expense of ostracods, cumaceans, isopods, amphipods and tanaidaceans. Health and Social Impact Unknown. Economic Impact It impacts fisheries by the obstruction of fishing nets by the uprooted alga. MANAGEMENT Prevention Unknown. Mechanical Covering colonies with black PVC plastic; manual removal by scuba divers or by suction pump were ineffective. Chemical Injecting liquid or solid chlorine or coarse sea salt to sealed off areas was tried. Off the Montenegrin coast copper-sulphate solution and lime were injected under the PVC foil – with no success. Biological Unknown. REFERENCES Piazzi L, Ceccherelli G, Cinelli F (2001) Threat to macroalgal diversity: effects of the introduced alga Caulerpa racemosa in the Mediterranean. Marine Ecology Progress Series 210:149-159 Verlaque M, Afonso-Carrillo J, Candelaria Gil-Rodríguez M, Durand C, Boudouresque CF, Le Parco Y (2004) Blitzkrieg in a marine invasion: Caulerpla racemosa var. cylindracea (Bryopsidales, Chlorophyta) reaches the Canary Islands (north-east Atlantic). Biological Invasions 6:269-281 Verlaque M, Durand C, Huisman JM, Boudouresque CF, Le Parco Y (2003) On the identity and origin of the Mediterranean invasive Caulerpa racemosa (Caulerpales, Chlorophyta). European Journal of Phycology 38:325339 OTHER REFERENCES Argyrou M, Demetropoulous M, Hadjichristophorou M (1999) The impact of Caulerpa racemosa on the macrobenthic communities in the coastal waters of Cyprus. Proceedings of the workshop on invasive Caulerpa species in the Mediterranean, Heraklion, Crete, Greece. MAP technical report series 125:139-158 Capiomont A, Breugnot E, den Haan M, Meinesz A (2005) Phenology of a deep-water population of Caulerpa racemosa var. cylindracea in the northwestern Mediterranean Sea. Botanica Marina 48(1):80-83 Ceccherelli G, Piazzi L (2005) Exploring the success of manual eradication of Caulerpa racemosa var. cylindracea (Caulerpales, Chlorophyta): the effect of habitat. Cryptogamie Algologie 26:319-328 Giaccone G, Di Martino V (1995) Le vegetazione a Caulerpa racemosa (ForsskåL) J. Agardh nella Baia di S. Panagia (Sicilia Sud-Orientale). Bollettino della Accaddemia Gioenia di Scienze Naturali in Catania 28:59-73 Piazzi L, Balata D, Cecchi E, Cinelli F (2003) Co-occurrence of Caulerpa taxifolia and C. racemosa in the Mediterranean Sea: interspecific interactions and influence on native macroalgal assemblages. Cryptogamie Algologie 24:233-243 Piazzi L, Meinesz A, Verlaque M, Açali B, Antolic B, Argyrou M, Baltana D, Ballesteros E, Calvo S, Cinelli F, Cirik S, Cossu A, d'Archino R, Djellouli AS, Javel F, Lanfranco E, Mifsud C, Pala D, Panayotidis P, Peirano A, Pergent G, Petrocelli A, Ruitton S, Zuljevic A, Ceccherelli G (2005) Invasion of Caulerpa racemosa var. cylindracea (Caulerpales, Chlorophyta) in the Mediterranean Sea: an assessment of the spread. Cryptogamie, Algologie 26:189-202 Renoncourt L, Meinesz A (2002) Formation of propagules on an invasive strain of Caulerpa racemosa (Chlorophyta) in the Mediterranean Sea. Phycologia 41:533-535 Ruitton S, Verlaque M, Boudouresque C-F (2005) Seasonal changes of the introduced Caulerpa racemosa var. cylindracea (Caulerpales, Chlorophyta) at the northwest limit of its Mediterranean range. Aquatic Botany 82(1):55-70 Author: B. S. Galil Date Last Modified: November 6th, 2006