Chapter 8 



Laboratory Experhnents on Uptake 



81 



done on the mineral metabohsm of marine or- 

 ganisms relative to sex. The data that will be 

 presented were collected either at the Fishery 

 Radiobiological Laboratory of the United States 

 Fish and Wildlife Service (R.L.F.W.S.) or 

 the Hawaii Marine Laboratory, University of 

 Hawaii (HML). 



First trophic level 



Experiments performed at the R.L.F.W.S. 

 very clearly show that different species of 

 planktonic algae have remarkably different abili- 

 ties to concentrate a particular element from the 

 sea water medium. Algae were grown in the 

 presence of radiostrontium obtained from Oak 



TABLE 1 The Differential Uptake of Radio- 

 active Strontium and Yttrium By Algae 



Percentage Percentage 



activity activity 



from from 



Species strontium yttrium 



Carteria sp 100.0 0.0 



Thoracomonas sp 50.4 49.6 



Amphora sp 10.0 90.0 



Navicula sp 8.5 91.5 



Chromolina sp 8.2 91.8 



Chlamydomonas sp 6.5 93.5 



Nitzschia dosterium 6.0 94.0 



Nannochloris atomus 5.7 94.3 



Chlorella sp 5.3 94.7 



Porphyridium curentum . . . 4.4 95.6 



Gymnodinium splendins . . . 4.1 95.9 



Gyrodinium sp 2.3 97.7 



Ridge. The material used contained both Sr^^ 

 and Sr«»; the latter decays to form Y^^. By 

 counting the algal samples immediately after 

 they were removed from the culture medium, 

 and again after several weeks, in order to allow 

 the secular equilibrium of the Sr^^-Y^" pair to 

 be reached, it was possible to determine what 

 percentage of the original radioactivity was due 

 to strontium. Table 1 shows that Carteria sp. 

 accumulated strontium 89 and 90 from the iso- 

 topic mixture, and that Gyrodinium sp. removed 

 almost no strontium 89 or 90, but instead ac- 

 cumulated yttrium 90. It was found that Nitz- 

 schia closteriujn under an apparent steady state 

 condition concentrated strontium 17 times over 

 its concentration in sea water (weight of algae/ 

 weight of water) . The concentration factor for 

 strontium Carteria sp. was found to vary with 

 condition of culture but was much greater than 

 for Nitzschia dosterium. 



Experiments using cesium^^^ show that while 

 different species concentrate cesium to different 

 degrees (Table 2) none of the nine species 



TABLE 2 Concentration of Cesium By Marine 

 Algae 



Concentration 

 Algae factor ^ 



Bacillariaceae 



Nitzschia dosterium 1.2 



Amphora sp 1,5 



Nitzschia sp 1.7 



Chlorophyceae 



Chlamydomonas sp 1.3 



Carteria sp 1.3 



Chlorella sp 2.4 



Pyramimonas sp 2.6 



Nannochloris atomus 3.1 



Rhodophyceae 



Porphyridium curentum 1.3 



1 The concentration factor is reported as the ratio 

 of Cs"^ in the algae (wet weight) to that in an 

 equivalent weight of sea water at an apparent steady- 

 state condition. 



tested from three families showed any marked 

 concentration of this element from sea water. 



The effect of the concentration of an element 

 on its uptake by Nitzschia cells is shown in 

 Figure 1. Nitzschia cells were grown in sea 

 water to which had been added labelled zinc at 

 three different concentrations. From the graph 



0. 1 mg./^ 



• 5 irig./i. 



m 80- 



40 60 



HOURS 



Figure 1. Uptake of Zinc®^ by Nitzschia Cells 

 from Culture Medium Containing Different Concen- 

 trations of Zinc. 



O 0.1 mg./l 



O 1 mg./l 



• '5 mg./l 



