Viruses are known to impact blooms of phytoplankton in the ocean, in some cases causing the
bloom to crash. And yet the impact of viruses is not taken into account in conventional models of
the marine ecosystem. Part of the problem is little is known about the interactions between the
host (phytoplankton) and the virus. Here, using a simple population model that includes viral
infection, we investigate the conditions under which the presence of a virus significantly impacts
the population dynamics. A major focus is how spatial variability influences the spread of an
epidemic in a stirring and mixing fluid flow. The combination of viral infection and diffusion can
cause waves of the epidemic to sweep through the domain, with the epidemic lasting much
longer than in the homogeneous case. Stirring by the fluid flow can greatly increase this effect
causing an increase in the fraction of the bloom that is affected and in certain circumstances
(high diffusion and stirring) can totally suppress the bloom.
To begin viewing slides, click on the first slide below. (Or, view as pdf.)