Ecological studies of Floridian Eucheuma (Rhodophyta, Gigartinales). III. Seasonal variation of carrageenan, total carbohydrate, protein and lipid

Eucheuma isiforme, E. nudum, and a species designated as the Bahia Honda form, because of its unclear taxonomic status, were analyzed seasonally to determine their dry weight, protein, carbohydrate, 3,6 anhydro-D-galactose, and lipid contents. A fourth species, E. gelidium, was analyzed occasionally and compared with the other three. The highest protein levels and the lowest carbohydrate values were recorded during the period of rapid growth (March-June). Lipid concentrations were low (0-2 per cent) throughout the year. The percentage of 3,6 anhydro-D-galactose was lowest when the carbohydrate levels were highest. The ratio of protein to carbohydrate can be used as an indicator of the physiological state of Eucheuma. Protein-to-carbohydrate ratios of 1/10 to 1/15 occurred in rapidly growing plants, while plants exhibiting little growth had ratios of 1/25 to 1/30. Seasonal variations of 3,6 anhydro-D-galactose are discussed in relation to recent information on nutrients and light