Toxic marine phytoplankton, zooplankton grazers, and pelagic food webs

Interactions between toxic phytoplankton and their zooplankton grazers are complex. Some zooplankters ingest some toxic phytoplankters with no apparent harm, whereas others are deleteriously affected. Phycotoxins vary in their modes of action, levels of toxicity and solubility, and affect grazers in different ways. Beyond effects on direct grazers, toxins may accumulate in and be transferred through marine food webs, affecting consumers at higher trophic levels, including fish, seabirds, and marine mammals. Grazers of toxic phytoplankton include protists as well as metazoans, and the impact of zooplankton grazing on development or termination of toxic blooms is poorly understood. In most interactions of toxic phytoplankters with grazers and other marine food‐web components, outcomes are situation‐specific, and extrapolation of results from one set of circumstances to another may be inappropriate.