The role of Oxyrrhis marina as a model prey: current work and future directions

Protozoa hold a key trophic position in pelagic food webs. Primary and bacterial production is consumed by them; their role as consumers is well established. Not as fully explored is their fate, by predation from upper trophic levels and through viral lyses. Impacts of this are: reduced trophic transfer efficiency; nutrient recycling and increased respiration (CO2 generation). Studies that examine the loss of protozooplankton via predation often employ model species in lab-based experiments, rather than attempting to follow populations in natural samples. Such model species are rarely ideal representatives of natural systems, but various attributes (e.g. easy of culture and manipulation) facilitate experimentation and, in many cases, provide more precise data. Oxyrrhis marina is one such model. Most studies on the fate of O. marina are incidental, using it as a convenient prey and not focusing on it as a model to assess general questions or recognizing the breadth of its application. We have assembled the dispersed works that uses O. marina as prey and synthesized their findings to assess its utility as a model; our premise is that O. marina is a versatile and useful model prey that should be adopted in future planktonic studies, ranging from those that examine nutrition to feeding behaviour. To this end, we provide guidance for future work. However, we also recognized that O. marina is a valuable food for maintaining laboratory species and have augmented our study with a brief assessment of the pragmatic nature of using it to help maintain its predators.