Effect of nutrient medium on growth of blue-green algae (<em>Phormidium chlorinum</em>) and its potential harm to the survival rate of whiteleg shrimp

Abstract

The study was conducted to determine the effects of media on the growth of blue-green algae (Phormidium chlorinum) and to determine the blue green algae density that causes 50% mortality of whiteleg shrimp under laboratory conditions. The study included two experiments. In experiment 1, algae were cultured in 5L plastic tanks with a light intensity of 3,000 Lux, using white LED light and continuous aeration; each treatment was triplicated. Blue-green algae were cultured with a medium of Walne, F/2, AGP, and NPK (30:10:10). The results showed that the F/2 medium was favorable for the growth of blue-green algae with the highest density (200,741 ind. mL^-1^). In addition, the dry weight (0.364 g L^-1^) and chlorophyll-a content (3,305.7 µg L^-1^) were the highest on the 7th day. Experiment 2 was set up with 7 treatments: a control treatment (no algae added) and 6 treatments with different algae densities of 5,000 ind. mL^-1^; 10,000 ind. mL^-1^; 15,000 ind. mL^-1^; 20,000 ind. mL^-1^; 25,000 ind. mL^-1^ and 30,000 ind. mL^-1^. Each treatment was triplicated. The LC50 value causing 50% mortality of whiteleg shrimp with blue-green algae density was 26,432 ind. mL^-1^ after 14 days of the experiment. To summarize, P. chlorinum algae developed well in F/2 medium. Treatments added to higher algae density had lower survival rates of whiteleg shrimp.