BIOLOGICAL SURVEY OF THE UPPER MISSISSIPPI RIVER 



159 



Table 10. — Number of zodplanktonic organisms per liter of water 

 [S = shore; C=channel] 



Zooplankton 



Sta. 1, 

 Aug. 14 



Sta. 1 

 Sept. 7 



Sta. 2, 

 Aug. 14 



Sta. 2, 

 Sept. 7 



Sta. 3, 

 Aug. 12 



Sta. 3, 

 Sept. 8 



Sta. 4, 

 Aug. 17 



Sta. 5- 

 S, Aug. 

 20 



Sta. 5- 

 S, Sept. 

 15 



Sta. 5- 

 C, Aug. 

 20 



Sta. 5- 

 C, Sept. 

 15 



Nauplii. 



0.8 

 .8 



0.4 

 .2 





0.8 





0.4 

 .3 



30 



91 

 18 



16 

 4 



5.4 

 1.2 





0.8 



Cvclops 



.0 







Moina 

























4 









Chydorus 













. 1 











Ceriodaphnia 



2 





















Noteus 



.2 









.6 



.4 



23 

 81 



1.2 

 90 



1.2 



8 

 8 

 78 

 4 



.4 



14 

 15 

 36 

 1.2 







Anuraea 











55 

 100 



.8 

 2.4 



Rotifer — 



.8 



.2 







3 



Polyarthra 









Triarthra 



















Distyla.. 









.4 







1.2 







Asplanchina. 













1.2 





























Zooplankton 



Sta. 6- 

 S, Aug. 

 18 



Sta. 6- 

 C, Aug. 

 18 



Sta. 6- 

 C, Sept. 

 16 



Sta. 7- 

 S, Aug. 

 18 



Sta. / - 

 S, Sept. 

 16 



Sta. 7- 

 C, Aug. 

 18 



Sta. 7- 

 C, Sept. 

 16 



Sta. 8, 

 Aug. 19 



Sta. 8, 

 Sept. 16 



Sta. 9- 

 S, Aug. 

 27 



Sta. 9, 

 S, Sept. 

 17 



Sta. 9- 

 C, Aug. 

 27 





36 

 60 



3 



1.2 



0.2 



22 

 40 



13 



.8 



10 

 11 



12 



8 



2. 4 



9 



5.2 



17 



.8 



8 



2.8 



Cyclops- 



Dioptomus 







.6 





Bosmina 









1.6 

 2 



2 



.8 



183 

 3 



2.4 

 1.6 













.4 





Ceriodaphnia._ 



















.4 

 1.8 

 4.4 



.8 

 .8 



1.4 

 3.2 

 3.2 



Noteus 









6 

 5 

 33 





12 

 11 



46 



.6 





6.4 

 5.2 

 9 



Anuraea 







.4 



16 







Rotifer-.. 



408 

 4 



83 



184 



.8 







Polyarthra.. 









Triarthra. _ 





.2 



2.4 



2.4 







.8 





Distyla 















2.4 























.4 



























Zooplankton 



Sta. 9- 

 C, Sept. 

 17 



Sta. 10, 

 Aug. 27 



Sta. 11- 

 S, Aug. 

 28 



Sta. 11- 

 S, Sept. 

 18 



Sta. 11- 

 C, Aug. 

 28 



Sta. 11, 

 C, Sept. 

 18 



Sta. 12, 

 Aug. 28 



Sta. 12, 

 Sept. 18 



Sta. 14- 

 S, Aug. 

 31 



Sta. 14- 

 S, Sept. 

 19 



Sta. 14- 

 C, Aug. 

 31 



Sta. 14- 

 C, Sept 

 19 



Ostracoda 







4.8 

 32. 4 

 24' 



1.8 

 30 

 13 



.6 

 2.4 



















Nauplii 



11.2 

 .4 



0. 4 



39 

 9 



1.6 



16 

 4.8 

 .8 



0. 4 

 '.i 



.4 



25 

 4 

 3 



7.2 

 2.4 

 1.2 



19 

 7.7 

 1.2 



1 2 

 2. 4 



Cyclops __ 



Diaptomus. 





Simocephalus 















Bosmina 







4.8 



.4 



.8 









1 



.6 





.6 

 4.8 





Daphnia 



















Chydorus 







20 



.6 







1.6 



.6 



.6 



Ceriodaphnia 



.8 

 5.6 

 7.2 

 14.8 





.4 



.4 

 7.2 

 .4 







1.2 





Noteus 





1.2 

 2.4 







.4 











Anuraea 



.4 





1.2 



1.2 

 .8 



1 





1.8 





Rotifer 











Monostyla _ 







1.4 

 .6 















Polyarthra 



1.6 

 .4 





1.2 

 2.2 















1.2 





Triarthra 









.4 











Distyla 





.6 

 .6 

















Asplanchina 

















































In an attempt to determine whether the character of the zooplankton changes 

 with the varying degrees of pollution, the same procedure employed for the phyto- 

 plankton (p. 157) was followed here. Table 11 lists the five most abundant zodplank- 

 tonts for each of the three groups of stations selected (the groups of stations are 

 described on p. 157). From this table it may be seen that four of the five planktonts 

 that are most abundant in the grossly polluted waters occur also among the five 

 that are most abundant in the unpolluted waters. My inadequate material shows 

 that the zooplankton in the unpolluted sections of the river and tributaries is not 

 markedly different in quality from the zooplankton of the polluted sections of the 

 river, and that, with the exception of Rotifer, the species taken by me can not be 

 employed as indices of the degree of pollution in the Mississippi River. 



