Pigment changes and photosynthetic rates under selected wavelengths in the growing tips of Eucheuma isiforme (C. Agardh) J. Agardh var deudatum Cheney during vegetative growth

Abstract

Pigment extracts (phycoerythrin and chlorophyll) and apparent photosynthetic rates under selected wavelengths for the benthic marine alga Eucheuma isiforme var denudatum are presented. Plants were sampled from March to September during vegetative growth. The study shows that (a) total pigment content exhibits a three-fold increase from young to mature plants, (b) the concentration of phycoerythrin changes from 0·36 nm/mg dry wt to 1·07 nm/mg dry wt and the chlorophyll concentration changes from 0·03 nm/mg dry wt to 0·57 nm/mg dry wt and (c) an initial phycoerythrin/chlorophyll ratio of 20 : 1 decreased to 1 : 1 during the summer months. The September ratio increased to 3 : 1. E. isiforme var denudatum exhibited strong correlations between pigment concentration and apparent photosynthetic rates. Blue and red light exhibited correlations (0·9447 and 0·7915 respectfully) to chlorophyll. Green light exhibited the strongest correlation (0·4298) to phycoerythrin. Physical environmental fluctuations during the summer are viewed with respect to the correlations between pigments and apparent photosynthetic rates. These comparisons indicate that E. isiforme var denudatum may chromatically adapt to the benthic marine environment by changes in pigment concentration.