Fast and slow swimmer: a consequence of nutrient source

GASTÓN L. MIÑO; NICOLE KING; MIMI A. R. KOEHL; ROMAN STOCKER

Villa Carlos Paz

Congreso; XIII Latin American Workshop on Nonlinear Phenomena (LAWNP 2013); 2013

Protozoans play an important role in aquatic food webs. The ability to locate and exploit patches becomes particularly important in environments where background resource availability is low, such as in the ocean, where planktonic microorganisms regularly experience background concentrations of limiting nutrients and prey that are below the critical limits required for optimum growth. However, dissolved nutrients and bacteria are patchily distributed in the water column. To succeed within heterogeneous environments, organisms must possess movement and search behaviors that maximize exposure to limiting resources. To understand how such environmental heterogeneity aects the ecology of populations, it is imperative to explore foraging behavior at environmentally relevant spatiotemporal scales.The flagellated protozoan Salpingoeca rosetta is one of the closest relatives of multicellular animals. This cell uses a single agellum to drive a ow of water and captures bacterial prey. This cell can produce colonies, fast and slow swimmer and theca cell depending on the environmental conditions. Fast and slow swimmers are morphological dierent. Slow swimmers have a long feeding collar and rounded cell body. Fast swimmers, in contrast, have a reduced or absent feeding collar. The transition on how a cell decides to become a fast swimmer it is not well understood.In this work we try to elucidate on how the environment can produce a selection in the mode of swimming. Preliminary results suggest that the depletion of prey bacteria may activate certain mechanisms, showing the apparition of fast swimmers in the suspension.