sity of gross photosynthesis is determined, may be a very distinct indica- 

 tor of preservation of toxic substances in the water (Table 3). 



In water containing herbici 

 algae, including the filamentou 

 for visual detection of substan 

 is performed in vessels with sm 

 weight), which, in a toxic medi 

 become covered with bubbles of 

 pended in water and actively li 

 performed on a glass slide with 

 concave slide with a suspension 

 the presence of toxic factor is 

 the bubbles of oxygen. 



des, photosynthesis is inh 

 s forms which may be used 

 ces inhibiting photosynthe 

 all lumps of filamentous a 

 urn, settles to the bottom, 

 oxygen, but in the control 

 berate oxygen. This test 

 solitary filaments of Cla 

 of any planktonic algae, 

 indicated by the absence 



ibited in all 

 as indicators 

 sis. The test 

 lgae (5-10 g wet 

 and does not 

 they remain sus- 

 may be also 

 dophoia, or in a 



In both cases, 

 of formation of 



The most useful indicator organisms are aquatic invertebrates since 

 they are more sensitive to toxicants than algae. Cladocerans, rotifers, 

 larvae of mayflies and chironomids, garmarids, isopods, copepods, ostra- 

 cods, bivalvia and gastropod molluscs are routinely used. Each of these 

 organisms have their own specific features of behavior, biology, and 

 reactions to toxic materials which must be taken into account when per- 

 forming experiments. 



TABLE 3. GROSS PHOTOSYNTHESIS IN A WATER-BODY TREATED WITH DIURONE 

 AT THE TIME OF A BLUE-GREEN ALGAL BLOOM. 



Days of Temperature 

 Experiment °C 



Experiment 

 (Diurone 0.2 mg/1 



O2, Percent of Photosynthesi s 

 Saturation mg/1 hr-1 



Control 

 O2, Percent of 

 Saturation 



111.8 



57.2 

 

 

 

 

 

 

 



12.0 





 

 

 

 

 

 

 



224.2 



124.5 

 152.8 

 165.2 

 71.8 

 66.0 

 109.8 

 154.0 



106 



