Predator Field and Colony Morphology Determine the Defensive Benefit of Colony Formation in Marine Phytoplankton

Colony formation in marine phytoplankton can be modified by the presence of grazers, but effect colony size and shape on feeding behavior grazers is still relatively unknown. To explore defensive role formation, we examined response three differently sized (copepodites, copepod nauplii, two heterotrophic dinoflagellates) colony-forming phytoplankton, using both direct video observations bottle incubations. We found a dramatic increase capture clearance rate with for copepodites, up to 140% higher largest diatom chains relative their solitary cells. This was part facilitated mechanism – described here first time which copepods efficiently detect colonies antennules, thereby increasing radius. Prey handling copepodites increased size, did not limit prey ingestion. Larger diatoms were handled consumed whereas larger spherical Phaeocystis globosa rejected subsequent capture. In contrast, colonial better protected against microzooplankton nauplii examined, since these only managed consume smaller equivalent few find that value depends foraging grazer colony. Thus, benefit therefore function composition community. argue bloom chain-forming efficient protection rapidly responding micro-grazers lagged numerical grazers.