Temperature dependence of toxin production in a dinoflagellate strain

Ocean temperatures are increasing at a critical rate, altering the geographic distribution and likely the frequency and severity of toxic algal blooms. Hence, understanding how temperature influences toxin production in toxic algal species is critical for predicting future toxic bloom dynamics under climate change scenarios. In this study, we investigated the temperature dependence of the production of okadaic acid (OA) and dinophysistoxins (DTX1 and DTX2) in the marine dinoflagellate Prorocentrum lima CCAP 1136/11. Experiments were conducted to determine toxin production under rapid and gradual exposure to a temperature gradient from 5°C to 25°C in 5°C increments. LC-MS/MS analysis confirmed the presence of OA, DTX1, and DTX2, suggesting toxigenicity of this dinoflagellate strain. Temperature had a significant effect on the cellular content, relative composition, and cellular production rates of OA and DTX1. Rapid temperature changes resulted in higher OA/DTX1 ratios compared to gradual exposure, highlighting the complex temperature-dependent dynamics of toxin production. Furthermore, these findings support the hypothesis that toxin production is a stress response mechanism, uncoupled from growth, and is triggered by suboptimal temperatures. The results underscore the importance of incorporating acclimation effects in models forecasting harmful algal bloom toxicity, particularly in the context of increasing thermal variability under climate change.