Effect of inland saline water ionic profiles on growth, chemical composition and agar characteristics of Gracilaria cliftonii (Withell, Miller and Kraft 1994) under laboratory conditions

Abstract

Increase in salinity of inland water sources is adversely affecting aquatic and terrestrial ecosystems around the world including Australia. Inland saline water (ISW) with similar ionic profile to ocean water has potential for culturing marine species. Gracilaria species are commercially important as they are a source of agar. One of the native species Gracilaria cliftonii has been reported for high agar yield of 52%dw. The aim of this research was to investigate the feasibility of culturing G. cliftonii in different ionic profiles of ISW under laboratory conditions. The growth rate of G. cliftonii under different ionic profiles ranged from 0.9 to 2.5%day-1. Gracilaria cliftonii carbohydrate content decreased while protein content increased in culture conditions as when compared to natural populations. Agar yield, gel strength and melting point decreased while gelling temperature and sulphate content increased in culture conditions as when compared to natural populations. Strong correlation (R2 >0.8, P <0.05) was observed between K+, Na+, Ca2+, and Mg2+ content in tissue and water indicating ionic regulation by G. cliftonii. This research provides basic information and presents supportive arguments for G. cliftonii as a potential species for inland saline water aquaculture.