Abstract

The genus Tetraselmis is one of the most widely used microalga in mariculture for feeding marine herbivores, due to its ability to grow under a wide range of physical and chemical environmental conditions. The present study shows the effect of different concentrations of nitrogen and phosphorus on some metabolic activities of Tetraselmis chuii. The results revealed that the algal growth rate, chlorophyll-a content, total proteins, carbohydrates and lipids of T. chuii were affected by changes in concentrations of N and P at different culture ages. The cell growth increased significantly with treatment 2, 4 and 6 (2: 256 μM N and 16 μM P; 4: 256 μM N and 36 μM P; 6: 883 μM N and 16 μM P). The algal growth rates of T. chuii were decreased significantly in all treatment. Increasing of total lipids and carbohydrates were occurred with treatment 1, 3, and 5 (1: 64 μM N and 4 μM P; 3: 64 μM N and 36 μM P; 5: 883 μM N and 4 μM P) during the experimental period. Variations in protein content were much lower compared with the total lipid and carbohydrates. Statistical analyses showed that this effect was significant at P= 0.05. On the basis of these results, significant differences in the nutritional values (total protein contents, total carbohydrate contents and total lipid contents) of Tetraselmis chuii were dependant on N and P concentrations in the medium.

Key words: Tetraselmis chuii, Nitrogen, Phosphorus, Chlorophyll-a, Growth rate, Protein, Carbohydrate, Lipids.