Vegetative propagation of the carrageenophytic red alga Gigartina skottsbergii Setchell et Gardner:: Indoor and field experiments

The carrageenophytic red alga Gigartina skottsbergii presents several biological constraints for its cultivation such as restricted temporal availability and high spore mortalities that affect the development of its mass cultivation. For this reason, research to develop alternative propagation methods has been undertaken. Previous laboratory studies demonstrated that manipulating temperature, light and nutrients could enhance healing and regeneration of this seaweed. In this study nursery and field experiments were undertaken to establish the possibility to regrow G. skottsbergii in conditions similar to those applied in mass cultivation practices. Frond fragments and rhizoids were tested as alternative ways to obtain new plants. Our results indicate that regeneration occurs in the field, and can be managed in nursery conditions. The addition of a nitrogen source enhances the growth from 0.6 to 1.0% d(-1) of the healed fragments and the use of a photon flux density above 50 mu mol m(-2) s(-1) increases the growth rate but decrease the survival of the explants. Explants can be transferred to field conditions and grow at similar rates to those registered in the nursery (0.5% d(-1)). It is also possible to propagate rhizoids of G. skottsbeigii and it seems that the attachment of a frond portion to the substratum, enhanced its survival and regeneration capacity. Finally, this study demonstrated that rhizoids attached to rocks can regenerate complete plants in nature, a feature which could be a useful for developing a sustainable harvesting methodology. (c) 2006 Elsevier B.V. All rights reserved.