The effects of temperature, light intensity, salinity and nutrient concentration on the early stage of erect thalli of Cladosiphon okamuranus Tokida in laboratory culture

Abstract

The influence of temperature, light intensity, salinity and nutrient concentration (including NO₃^- and PO₄^-) on the early stage of the erect thalli of Cladoszphon okamuranus Tokida were investigated in laboratory culture. The erect thalli formed in the range of 20-30 °C,75-260 μmol m^-2 s^-1, 22-50 ‰, and at nutrient concentrations of 3.1-104 μM NO₃^- and 0.1-15.1 μM PO₄^-. The highest growth was observed at 22.5 °C, 260 μmol m^-2 s^-1, 34 ‰, and at nutrient concentrations of 16.2-44.2 μM NO₃^- and 1.9-6.0 μM PO₄^-. The color of the branches and shape of the thallus was darkened and crumbled with an increase in NO₃^- concentrations of over 56.8 μM and 7.9 μM PO₄^-. The thalli did not grow more than 1cm in length at those nutrient concentrations. From these results, C. okamuranus erect thalli was shown to have minimal adaptability to high nutrient concentrations in enriched seawater media. This is the first report of the affects of nutrient concentrations on the growth of the erect thallus of C. okamuranus.