Chemical defence of the Mediterranean alga Caulerpa taxifolia: variations in caulerpenyne production

Caulerpenyne (Cyn) is the major secondary metabolite involved in the chemic al defence of Caulerpa taxifolia. A fast chromatography technique for Cyn q uantification in algal samples of fronds and stolons collected monthly at C ap Martin (France), from depth of 5-30 m, is reported. Temperature influenc ed Cyn production in this alga of subtropical origin and the maximum concen tration was in fronds at 5 m depth in summer period when the water temperat ure rose above 19 degrees C. The amount of Cyn decreased at increasing dept hs and Cyn concentrations were always higher in fronds than in stolons. Var iations in Cyn concentration explained seasonal changes in (1) feeding beha viour of the sea urchin Paracentrotus lividus and (2) biomass of fouling or ganisms of C. taxifolia. Tropical strains of this alga always contain less Cyn than the mediterranean strain. Geographical, seasonal, depth and intrap lant variations of Cyn concentrations are discussed versus influences of bi otic and abiotic factors. (C) 1998 Elsevier Science B.V. All rights reserve d.