Growth rates,phycocolloid yield and quality of the red seaweeds, Gracilaria sp., Pterocladia capillacea,Hypnea musciformis, and Hypnea cornuta, in field studies in Israel

The agarophytes Gracilaria sp. and Pterocladia capillacea, and the carrageenophytes Hypnea musciformis and H. cornuta were cultured under field conditions. Specific growth rates appeared to be related to temperature and light intensity. Attached seaweeds had higher annual yields per m² than free-floating samples. The specific growth rate of all four seaweeds was positively related to phycocolloid content in the main growing season. In agar extracts high gel strength coincided with high 3,6 anhydrogalactose content, with high gelling and melting temperature, and with low sulfate content. In the carrageenan extracts low gel strength coincided with low 3,6 anhydrogalactose content, with low gelling and melting temperatures and with high sulfate content. Chemical composition and physical properties of cultured and natural seaweeds were almost the same.