Maria Clara A. Barbasa (August 2009)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Ascorbic acid, commonly known as Vitamin C, is said to be toxic to red-tide dinoflagellates and can eliminate external dinoflagellates, however, it has not been tested yet. This study tested the toxicity of different concentrations of ascorbic acid to the red- tide dinoflagellate Amphidinium carterae for 1 hour, 2, 6, 12 and 24 hours. Batch cultures of Amphidinium carterae obtained from the University of the Philippines – Marine Science Institute were exposed to different concentrations of ascorbic acid (0, 0.0010, 0.0020, 0.0040, 0.0080, 0.0160, 0.0320, 0.0640, 0.128, 0.256, 0.512, 1.024 and 2.048 g L-1) and dinoflagellate mortalities were counted after 1 hour, 2, 6, 12 and 24 hours of exposure. The median lethal concentrations (LC50 values) obtained via probit analysis (with 95% confidence intervals) were 0.17211, 0.10938, 0.03737, 0.022666, and 0.00077 g L-1 respectively. A toxicity curve was obtained to relate the LC50 values and the exposure times. The results indicated that Amphidinium carterea could be killed or controlled by ascorbic acid in the concentration range of 0.00077-017211 g L–¹ within 1-24 hours.