A recent study funded by the National Centers for Coastal Ocean Science investigated the role of specific phosphorus and nitrogen compounds in determining the amount and composition of Paralytic Shellfish Poisoning-causing toxins in cultures of two harmful algal bloom (HAB)-forming dinoflagellates from Hong Kong, Alexandrium catenella and Alexandrium tamarense. Growth and toxicity of even these two closely related HAB species differed, and depended on the nutrient type, nutrient availability and the growth phase.
Improved waste water treatment systems and new fertilizers are increasing the relative amount of organic forms of nutrients in water bodies (e.g. urea nitrogen). These changes will require HAB prediction systems that are more accurate regarding different species. Knowledge of how different HAB species respond to organic vs. inorganic nutrients and knowing the environmental conditions leading to high or low toxicity blooms will assist in predicting the toxicity of blooms and likely impacts. Results from Hong Kong are transferable to U.S. waters as the same species occur here.