Effect of Caulerpa taxifolia on the productivity of two Mediterranean macrophytes

Abstract

The possible effect of Caulerpa taxifolia (Vahl) C. Agardh on 2 Mediterranean macrophytes (Cystoseira barbata f. aurantia and Gracilaria bursa-pastoris) was studied. The experiments were carried out with seasonal periodicity. Productivity of C. barbata f. aurantia placed in contact with C. taxifolia was lower in spring and summer. The resistance of G. bursa-pastoris to C. taxifolia appeared to be effective throughout the year. In the presence of C. taxifolia extracts, both species showed lower productivity, but C. barbata f. aurantia appeared to be more sensitive than G. bursa-pastoris. Productivity started to fall at lower concentrations in summer and autumn than in winter or spring, in agreement with the annual variability of the extracts' toxicity.