Chapter 11 



Nutritional Characteristics of 

 Some Chrysomonads 



I. J. PiNTNER and L. Provasoli 

 INTRODUCTION 



Di 



'iatoms and dinoflagellates, because of their conspicuous 

 blooms, were considered the most important components of the 

 phytoplankton. However, the chrysomonads, often neglected be- 

 cause they are too small to be caught by fine-mesh nets or too 

 fragile to withstand the usual fixatives, appear to be as important. 

 The /'-flagellates seem to constitute a good part of the primary 

 producers in the sea around England (8). Rodhe (11) employing 

 fractionated Ci4 filtration, demonstrated that in Swedish Lakes, 

 the net-plankton algae (retained by the finest net) represent in 

 most cases, only 10 to 20 per cent of the total primary production; 

 the nannoplankton ( less than 70/j. ) constituting the bulk. A similar 

 situation apparently exists in the warm seas (Mediterranean, 

 Atlantic, Indian Oceans ) where flagellates, coccolithophorids and 

 blue-green algae seem the predominant crop (3). Bernard and 

 Lecal (3) often found phytoplankton maxima well below the 

 photic zone; Coccolithus fragilis in the Mediterranean gi-ows in 

 the non-photic zone as well as in the photic zone — an implica- 

 tion that this photosynthetic organism has a functional heterotro- 

 phy. The freshwater chrysomonads Ochromonas malhamensis and 

 O. danica (1, 6) are photoautotrophs with a very well developed 

 heterotrophic ability, but little if anything is known of the nutri- 

 tional versatility of the marine species; Pnjmnesium parvum, 

 which is a brackish organism (9) is endowed with some hetero- 

 trophy. As a preliminary to studying nannoplankton chiysomo- 



* This work was supported in part by contract NR 104-202 with the Office of 

 Naval Research and part by grant G- 10783 from the National Science Founda- 

 tion. 



114 



