MIXOTROPHY IN MARINE SPECIES OF CHRYSOCHROMULINA (PRYMNESIOPHYCEAE) -INGESTION AND DIGESTION OF A SMALL GREEN FLAGELLATE

Species of Chrysochromulina (Prymnesiophyceae) were screened for their ability to ingest inert material and live cells of a small green flag ellate. The species C. brevifilum showed a marked preference for the s mall green flagellate over carmine particles and the rate of ingestion of the flagellate was proportional to its concentration and inversely proportional to light intensity. Ingestion was also higher by phospha te-starved Chrysochromulina, and a clear predator/prey relationship wa s demonstrated with C. brevifilum clearly benefiting, in terms of grow th rate, from the ingestion of the small green flagellate. Electron mi crographs confirmed that digestion occurs. Mixotrophy in Chrysochromul ina appears to be a complex mode of nutrition, dependent on environmen tal parameters and on nutritional status. Some species take up dissolv ed organic carbon as well as particulate prey and other species are pu re autotrophs. As yet there does not appear to be a pattern to phagotr ophic behaviour in Chrysochromulina that would allow general conclusio ns to be drawn on the factors controlling modes of nutrition.