Short-term and long-term effects of the toxic dinoflagellate Alexandrium minutum on the copepod Acartia clausi

Several experiments were performed to determine the effects of cell toxin concentration, composition and toxicity of Alexandrium minutum on ingestion rate, egg production, hatching success and naupliar fitness of the copepod Acartia clausi. A combination of A. minutum and nontoxic algae (Prorocentrum micans, Tetraselmis suecica and Isochrysis galbana) was used as food. Copepods ingested a higher amount of A. minutum cells as the concentration of these toxic dinoflagellates increased, and also in response to decreasing total food concentration available for the copepods. A positive relationship was obtained between A. minutum cells ingested by copepods and total toxin concentration per copepod. Hatching success and naupliar production were lower when copepods ingested a higher amount of toxic dinoflagellates. This negative effect could has been due to the accumulated toxins in the egg and copepod tissues, and was higher when A. minutum had a higher cell concentration of GTX1. Finally, the results obtained from nauplii incubated with T. suecica and I. galbana showed that nauplii hatched from females fed non-toxic food (T. suecica and I. galbana) reached copepodite stage earlier than those nauplii hatched from females fed with a combined of toxic (A. minutum) and non-toxic (T. suecica and I. galbana) food.