Laboratory Studies on Chemical Control of Red Tide Phytoplankton (Chattonella marina and Heterosigma akashiwo) for Black Tiger Shrimp (Penaeus monodon) Culture

Abstract

Laboratory cultures of red tide organisms, Chattonella marina and Heterosigma akashiwo, were maintained under a light intensity of 2,000 luxes at 28 °C and salinity of 30 ppt. Growth rates of C. marina and H. akashiwo were 0.792 and 0.872 divisions/day, respectively. Calcium hypochlorite (66 ppm), benzalkonium chloride (0.3 ppm) and hydrogen peroxide (39 ppm) completely disintegrated 50% (24-h LC50) of cultured C. marina within 24 hours. The 24-h LC50values of H. akashiwo were 35, 0.1 and 15 ppm, respectively. Acute toxicities (24-h LC50) of these chemicals to post larvae (PL-30) of black tiger shrimp in the C. marina treatment were 52, 0.2 and 42 ppm, respectively, while in the H. akashiwo treatment were 51, 0.2 and 62 ppm, respectively. The chemical that gave the best control of both phytoplankton species was hydrogen peroxide. During the chemical treatment procedures, water quality showed little variation.