Ecology of Heterotrophic Microflagellates. II. Bioenergetics and Growth

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Abstract
The bioenergetics of growth of 6 spp. of heterotrophic (bacterivorous) microflagellates [Paraphysomonas vestita, Pseudobodo tremulans, Actinomonas mirabilis, Ochromonas sp., Monosiga sp. and Pleuromonas jaculans] was studied in batch cultures. Maximum growth rates varied between 0.15 and 0.25 h-1 among the species, but growth as slow as 0.028 h-1 could be maintained. Yield (gross growth efficiency) was .apprx. 30% (volume) or, in 2 cases, 34% and 43% (C basis), respectively; net growth efficiency (C) was 60%. Respiratory and growth rates were directly proportional to consumption rate within the range of growth rates studied. Clearance (volume of water cleared for bacteria per unit time and measured in fractions of cell volume) ranged from .apprx. 5 .times. 104 to .apprx. 106 h-1; this large variation can in part be explained as a consequence of specialization to different food particle sizes. The type of flagellates studied may grow on and possibly control the concentration of bacteria found in marine plankton.