title: Growth, Grazing, and Starvation Survival in Three Heterotrophic Dinoflagellate Species.
abstract: To assess the effects of fluctuating prey availability on predator population dynamics and grazing impact on phytoplankton, we measured growth and grazing rates of three heterotrophic dinoflagellate species-Oxyrrhis marina, Gyrodinium dominans and Gyrodinium spirale-before and after depriving them of phytoplankton prey. All three dinoflagellate species survived long periods (> 10 d) without algal prey, coincident with decreases in predator abundance and cell size. After 1-3 wks, starvation led to a 17-57% decrease in predator cell volume and some cells became deformed and transparent. When re-exposed to phytoplankton prey, heterotrophs ingested prey within minutes and increased cell volumes by 4-17%. At an equivalent prey concentration, continuously fed predators had ~2-fold higher specific growth rates (0.18 to 0.55 d-1) than after starvation (-0.16 to 0.25 d-1). Maximum specific predator growth rates would be achievable only after a time lag of at least 3 d. A delay in predator growth poststarvation delays predator-induced phytoplankton mortality when prey re-emerges at the onset of a bloom event or in patchy prey distributions. These altered predator-prey population dynamics have implications for the formation of phytoplankton blooms, trophic transfer rates, and potential export of carbon.
authors: Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, 02882.
authors: Sean R
authors: SR
authors: Anderson
authors: Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, 02882.
authors: Susanne
authors: S
authors: Menden-Deuer
mesh_terms: D000818:Animals; D018533:Biomass; D048429:Cell Size; D004141:Dinoflagellida / Q000145:classification / Q000254:growth & development* / Q000502:physiology*; D004435:Eating / Q000502:physiology; D005247:Feeding Behavior; D020387:Food Chain; D052836:Heterotrophic Processes; D010839:Phytoplankton / Q000469:parasitology; D011157:Population Dynamics; D011235:Predatory Behavior; D013045:Species Specificity; D013217:Starvation
keywords: Starvation; food web; ingestion; phytoplankton patchiness; population dynamics; predation; protist