Predicting the population dynamics in Amoebophrya parasitoids and their dinoflagellate hosts using a mathematical model

Abstract

Free-living, photosynthetic marine dinoflagellates are frequentlyinfected by microparasites of the genus Amoebophrya. Attacks byAmoebophrya can contribute to the termination of dinoflagellate bloomsand have been suggested to influence the geographical distribution ofcertain host species. Because infection terminates with the killing ofthe host (i.e. Amoebophrya behaves like a parasitoid), the interactioncan be considered, from a modeling point of view, similar to the processof predation, with the difference that it takes a longer time for theparasitoid to kill the host as compared to typical predator-preyinteractions. In the present work, we explored the population dynamicsin Amoebophrya and their dinoflagellate hosts using theRosenzweig-MacArthur modification of the traditional Lotka-Volterrapredation model. The model was parameterized for 3 systems, Akashiwosanguinea, Gymnodinium instriatum, and Karlodinium micrum, and theirrespective Amoebophrya parasitoids, using published experimental data.Parameter validation was possible for parasitoid search rate andmortality. The potential for host control by Amoebophrya and theprobability for host extinction were studied with respect to carryingcapacity, a parameter that is influenced by e. g. eutrophication. Themodel may be useful to predict conditions under which Amoebophrya cancontrol populations of its dinoflagellate hosts.