engleski

Reproduction of Caulerpa taxifolia in the Mediterranean Sea

The introduced tropical alga Caulerpa taxifolia (Vahl) C. Agardh has been rapidly spreading since the mid-1980s throughout the Mediterranean Sea. This expansion is a result of wide ecological range of substrates, habitats, light, temperature and nutrients, and the lack of preda-tory species, and extremely successful vegetative reproduction. Regeneration of a whole alga is possible from each part of the algae thallus: fronds and pinnules, stolons or hairlike tiny rhiz-oids. In nature, vegetative reproduction most often occurred due to cuttings of fronds. At 25°C, formation of a whole small plant including fronds, stolons and rhizoids, from a cutting, oc-curred within 10 days following a similar pattern of regeneration. The regeneration from small pieces of thalli becomes a great problem during eradication efforts, because such small frag-ments are almost impossible to find and collect in the field. In tropical regions, this monoecious species also reproduces sexually by producing both types of gametes inside the same plant. In the Mediterranean Sea, thalli of C. taxifolia became fertile. They are easily detected in the field due to reticulate depigmentation and development of papillae mostly on the frond axes. The gametes are released around 27 minutes before sunrise. After release of gametes, the parental plant dies. In the Mediterranean Sea, only male gametes (without pigmentation) were observed. Despite prolific release of male gametes, sexual repro-duction does not occur because female gametes are absent. The reason for the absence of female gametes remains unknown.

reproduction; Caulerpa taxifolia; Mediterranean Sea

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