ABSTRACT Phosphorus (P) is a chemical element essential for life that can drive dynamics of microorganisms in marine environments. Nutrient acquisition by parasitic organisms is mainly done through infection. In the case of micro‐parasites, how host diet limitations affect parasite stoichiometry and parasite–host interaction has not been thoroughly studied yet. This study focused on the free‐living stage of Amoebophrya ceratii , a micro‐parasite (Syndiniales, Dinoflagellates) of marine dinoflagellates. It aims to examine how host P limitation prior to infection affects parasite stoichiometry and infection cycle. To this end, Scrippsiella acuminata was used as a host and cultivated under P‐replete or P‐limiting conditions. Infection and parasite production were monitored, and elemental quotas and stoichiometry of the freshly produced dinospores were determined. In P‐replete conditions, elemental quotas and ratios of the parasites were similar to their host, showing a strong need for P. While the host's stoichiometry was greatly impacted by P limitation, parasites were able to maintain stoichiometric homeostasis and elemental cell quotas. Finally, host P limitation mainly affected the dinospore production, exhibiting a trade‐off between dinospores quotas, stoichiometric homeostasis, and production. These findings have implications for host–parasite interactions and biogeochemical cycling in coastal waters.
Rodríguez et al. (Thu,) studied this question.