Published online by Cambridge University Press: 11 May 2009
In vitro short time experiments (a few weeks) show that daily ingestion by Pamcentrotus lividus (Echinodermata: Echinoidea) is weak (0–81 mg DW d-1 ind-1) for Caulerpa taxifolia (Chlorophyta), compared to the data recorded with an almost totally avoided brown alga, Cystoseira compressa (24–137 mg DW d-1 ind-1) and with a preferred brown alga, Halopteris scoparia (79–397 mg DW d-1 ind-1). There is no significant difference between spring (when the toxic metabolite content is at its minimum) and summer-autumn (when it is at its maximum). In contrast, the absorption rate of the sea urchin fed on Caulerpa taxifolia is significantly weaker in spring than in summer-autumn. Overall, the daily absorbed weight is negative in spring with C. taxifolia (compared with 18 mg DW d-1 ind-1 with Cystoseira compressa and 25 mg DW d-1 ind-1 with H. scoparia). It has also been demonstrated that P. lividus becomes accustomed to Caulerpa taxifolia, at least for short time experiments: the echinoid consumes greater quantities of this alga especially if it is fresh when it has already consumed it previously.