Viruses play important roles in population dynamics and as drivers of evolution in single-celled marine phytoplankton. Viral infection of the marine alga Ostreococcus tauri causes cell lysis, however two spontaneously arising resistance mechanisms occur: resistant cells that cannot become infected and resistant producer cells that are infected but not lysed, and which may slowly release viruses. Little is known about how consistent the effects of viruses on their hosts are across different environments. We compared the growth and survival of susceptible, resistant and resistant producer O. tauri cells under five environmental conditions with and without exposure to Ostreococcus tauri virus. In the absence of virus, we did not detect a cost of resistance in any environment, as measured by growth rate. In fact, the opposite appears to be the case, with populations of resistant producer cells having the highest growth rates across all environments except low phosphate. Increased knowledge of algae-virus interactions will allow us to better understand the evolutionary responses of marine microorganisms to future environmental change in the oceans.