Mortality on zoea stage of the Pacific white shrimp Litopenaeus vannamei caused by Cochlodinium polykrikoides (Dinophyceae) and Chattonella spp. (Raphidophyceae)

Cochlodinium polykrikoides and Chattonella spp. are responsible for harmful algal blooms along the Mexican coasts. These microalgae have the ability to produce toxic compounds such as reactive oxygen species, brevetoxin-like compounds, nitric oxide, and free polyunsaturated fatty acids, which can be harmful to marine fauna. However, scarce information exists about the effect of these harmful phytoplankton species on potential zooplankton grazers. In this study, the effect of microalgae Cochlodinium polykrikoides and Chattonella spp. isolates from the Gulf of California were evaluated on larval stages of the shrimp Litopenaeus vannamei. Several bioassays were performed from nauplii to zoea stages. Nauplii of Litopenaeus vannamei were placed (1 well⁻¹) in microdilution plates, and in each well 1 mL of different cell concentrations (0.5, 3, and 6 × 10³ cell mL^{− 1}) of Cochlodinium polykrikoides, Chattonella subsalsa, C. marina var. marina, and C. marina var. ovata was added. Nontoxic Chaetoceros calcitrans and Tetraselmis suecica were used as controls. Higher mortalities were observed when L. vannamei larvae reached the zoea stage. Sudden increase in mortality was caused by C. polykrikoides at the beginning of the zoea stage, followed by C. marina var. ovata (LT₅₀ ~ 1 day), C. subsalsa (LT₅₀ 1 day 19 h), and C. marina var. marina (LT₅₀ ~ 2 days). This study showed that L. vannamei larvae could be affected by C. polykrikoides and Chattonella spp. causing mortalities close to 100% during the zoea stage, when they start feeding on phytoplankton.