MODIFICATION OF THE M G RATIO OF ALGINIC ACID FROM LAMINARIA-JAPINICAARESCHOUG CULTURED IN DEEP SEAWATER/

The M/G ratios of alginates in Laminaria japonica Areschoug cultured i n deep seawater (DSW) pumped continuously from a depth of 320 m off Mu roto, were compared with those of kelp cultured in the cold northern a nd warm southern open sea. The M/G ratios tended to be higher in the n ew blade than in the old one throughout the year, irrespective of cult ure procedure and site. Monthly M/G ratios of the new DSW kelp decreas ed gradually toward August, to values less than 1. The lower values in the DSW kelp suggest the involvement of factors such as a high phosph ate concentration and a low temperature. In the cold northern open sea they increased during these seasons to attain values higher than 2.5. The values for the new blade in the warm southern open sea were even higher at the end of April, close to 3.0. Hence the variation in M/G r atio seems to depend also on the state of kelp maturity besides phosph ate concentration and temperature.