Seasonal variations of agar extracted from different life stages of Gracilaria cliftonii (Gracilariales, Rhodophyta) from Western Australia

Abstract

Seasonality in yield, physical and chemical properties of the native agar from different life stages of Gracilaria cliftonii was investigated over a period of six seasons (autumn 2008–winter 2009). Agar yield and its properties varied as a function of seasons and life stages but there was no significant correlation between environmental factors and agar properties (p > 0.05). Native agar varied from 53.6% to 59.6% dry basis over the study period. Agar yield of the tetrasporophyte was significantly higher in autumn 2008 than spring 2009. Gelling temperature of agar varied between 34 and 36 °C, whereas melting point varied from 77 to 84.3 °C. Sulphate of the agar from different life stages of G. cliftonii varied from 5.9% to 6.6% dry basis but was not influenced by seasons (p > 0.05). The present study demonstrated that agar yield and its properties are influenced both by seasons and reproductive status of the thallus.