Culture of Gracilaria gracilis and Chondracanthus teedei from Vegetative Fragments in the Field and Carpospores in Laboratory

Abstract

Gracilarioids and Gigartinales are of great economic importance due to the phycocolloids they contain in their cell wall and are used in different industries worldwide. Field and laboratory cultures of two species of red seaweeds (Gracilaria gracilis and Chondracanthus teedei), confirmed after DNA analysis, were carried out to foster the increasing use of this species in Spain as a food source. Vegetative cultures carried out in an open-lock gate within a traditional salina in the ay of Cadiz (Southern Spain) rendered maximum growth rates in April (3.64% day(-1)) for G. gracilis and in November (4.68% day(-1)) for C. teedei, the latter showing significant differences between the months of the year. For laboratory cultures, samples of the two species used for sporulation were obtained from tidal creeks in several nearby locations of the Bay. In order to grow fertile carposporophytes from spores, Provasoli enriched seawater medium (ES medium), Miquel A + B and f/2 were used as culture medium at a temperature of 18 degrees C and irradiance of 30 mu mol m(-2) s(-1) in 12:12 h photoperiod. Both species developed a basal disc after 12-15 days in ES medium and Miquel A + B, and new microscopic seedlings were observed at 20-25 days in ES medium. With f/2 medium, no growth was observed after sporulation. The life cycle of G. gracilis was completed in ES medium over a period of 11 months with a mean growth rate of 3.28% day(-1). The present study is an important step towards the development of seaweed cultivation in the Bay of Cadiz, especially in integrated multi-trophic cultivation in salinas as part of the more sustainable use of the marine resources in coastal communities.