NUTRITIONAL FACTORS IN SALINITY AND TEMPERATURE 

 TOLERANCE OF SOME PHYTQFLAGELLATEsT ^ 



by 



Stanley Scher 

 Haskins Laboratories 



and 



Edwin T. Moul 

 Rutgers University 



Apparent tolerance to extreme ecological conditions in tidal -marsh pools 

 probably reflects observable physiological adaptations. To study the biochem- 

 ical requisites of euryhalinity and thermotolerance, phytoflagellates were 

 isolated from pannes where temperature rose to 35 - 36° C. and salinity to 

 56 - 57°/00 during summer months. The development of artificial media for 

 marine algae has permitted an attack on nutritional problems of ecological 

 significance via bacteria -free cultures under controlled laboratory conditions. 



That chlamydomonads grow over a much wider range of salinities when 

 minimal media is supplemented with a balanced mixture of amino acids, sug- 

 gests a relationship between euryhalinity and heterotrophy in these photosyn- 

 thetic forms. 



When fresh water euglenids and other algal flagellates are cultivated 

 above 35° C. , they have augmented requirements for vitamins B]^2 ^^'^ 

 thiamine. This raises the issue of whether these growth factors ever limit 

 the thermal tolerance of such auxotrophs in nature. Parallel assays of tidal 

 marsh mud extracts with Euglena and Ochromonas indicate the presence of 

 physiological concentrations of pseudo-Bi 7 but very low true cobalamin. Does 

 the B]^2 specificity pattern of some phytoflagellates restrict their distribution 

 in natural waters? The absence of true B]^2 ^"^ these pannes provides a rare 

 opportunity to predict the ecological consequences of a nutritional factor being 

 limiting: that organisms requiring this vitamin will be absent. That chryso- 

 monads are indeed scarce or missing from the tidal-pool microflora reflects 

 a certain nutritional poverty of this niche, and exemplifies the use of sensitive 

 phytoflagellates as indicator species for growth-limiting vitamins in nature; 

 an extension here of Clement's early ideas on plant indicators. 



1) Aided by grant B-4043 from National Science Foundation 



69 



