Copepod responses to CCMP isolate 1708 in exponential growth phase
Grazing experiments
There were no significant differences in mean ingestion rates in both experiment 1 (100% ISO, 50:50 Aa:ISO and 100% Aa) and experiment 2, which replicated the treatments of experiment 1, where Acartia tonsa nauplii were provided with A. anophagefferens as a sole food source (Fig. 1a–e; ANOVA, P > 0.05). However, ingestion rates on A. anophagefferens (578 and 247 ng C nauplius−1 h−1 for experiments 1 and 2, respectively) were approximately two times greater than in treatments when I. galbana was provided as the single food source (Figs. 1a–d). Mean ingestion rates for mixed diets were below the reference line for naupliar ingestion on all but one occasion (Fig. 1a and b). Four of six mixed diets had positive electivity indices for I. galbana and negative indices for A. anophagefferens (Table II).