Growth of red alga Gracilariopsis persica (Rhodophyceae) in desalination pools of Qeshm Island

Gracilariopsis persica is one of the most abundant red algae distributed in Persian Gulf, despite increasing use in medicine as a major source for natural biomaterials and bioactive compounds in recent years, the researches on growth parameters of this alga remains limited. The main aim of this research was to study the favorable conditions for G. persica growth. Also it was to find the suitable primary storage density for the establishment of algal thallus in the appropriate depth which causes increase in biomass in the concrete pool of Qeshm Island. Tall of G. persica were grown for ۴۵ days on polyethylene ropes with primary storage weight of ۱۰۰ and ۲۰۰ gm-۱ in two depths of ۱ and ۲ m. The effect of environmental factors such as temperature, salinity, pH, and nutrient absorption were investigated for different treatments. Growth rate during the cultivation period increased for both densities of ۱۰۰ g and ۲۰۰ g of G. persica at first but decreased then along with the time till sixth week. The highest growth rate (percentage of increase in fresh weight d-۱) was obtained for the density of ۱۰۰ g in ۱ m depth in ۴۵ days and the lowest growth rate was observed for the density of ۲۰۰ g in ۲ m depth. Relative growth rate (RGR) was measured weekly based on the changes in fresh weight and showed the highest efficiency in ۱ m depth and ۱۰۰ g density (۱۵.۴۷% d-۱). The results showed that nutrients, especially those containing nitrogen and affecting algae growth at low depth, were inversely related (Kendall and Spearman negative correlation coefficients) to growth rate at ۱ m depth. At depth ۲ m, alga growth showed negative correlation with NO۳- and NO۲-. Findings provide novel evidence concerning growth and culturing conditions of G. persica, which can aid in the development of cultivating protocols for commercial agar production by this alga.

کلیدواژه ها:

Biomass ، Algal density ، Depth of water ، Nutrient ، Salinity ، Temperature of water. ، زیست توده ، تراکم ، عمق ، مواد مغذی ، شوری ، دما