154 



BULLETIN OF THE BUREAU OF FISHERIES 



Table 7. — Total number of plankton organisms per liter of water 

 [S=shore; C=channel] 



Station 



Date, 1926 



Number 

 of 



organisms 



Station 



Date, 1926 



Number 

 of 



organisms 



1 ■ ... . 



Aug. 14 

 Sept. 7 

 Aug. 14 

 Sept. 7 

 Aug. 12 

 Sept. 18 

 Aug. 17 

 Aug. 20 

 Sept. 15 

 Aug. 20 

 Sept. 15 

 Aug. 18 

 do 



79, 202 

 19, 061 

 59.511 

 57. 381 

 30. 535 

 25, 513 



670, 214 



121, 138 

 67, 318 



281, 115 

 82, 344 



140, 908 

 45, 617 

 43. 602 



356, 678 

 60, 486 

 31,585 

 73, 603 



8 



Aug. 19 

 Sept. 16 

 Aug. 27 



Sept. 17 

 Aug. 27 

 Sept. 17 

 Aug. 27 

 Aug. 28 

 Sept. 18 

 Aug. 28 

 Sept. 18 

 Aug. 28 

 Sept. 18 

 Aug. 31 

 Sept. 19 

 Aug. 31 

 Sept. 19 



33, 494 

 186, 920 

 49, 844 

 92, 420 

 65, 691 

 98, 462 

 24, 596 

 23, 783 

 47, 551 

 11, 529 



8, 518 

 48, 081 



9,078 

 34, 865 

 17, 977 

 62, 756 

 26, 380 



1 - 



8... 



2 



9-S 



2 - - 



9-S 



3- - 



9-C ... 



3 - 



9-C _ 



4 



10 



5-S 



11-S 



5-S 



11-S 



5-C 



11-C 



5-C...- 



11-C 



6-S 



12 



6-C... 



12 _ 



6-C... 



Sept. 16 

 Aug. 18 

 Sept. 16 

 Aug. 18 

 Sept. 16 



14-S_._. 



7-S 



14-S 



7-S 



14-C 



7-C 



14-C 



7-C 





RESULTS AND DISCUSSION 



Table 7 gives, for two dates (August and September), the number of plankton 

 organisms — plants (Table 3) and animals (Table 10) combined — per liter of water 

 at each station. The figures show that the quantity of plankton varies with the 

 different stations (from 8,518 to 670,214 per liter). The data show also that the 

 amount of plankton at one station varies with the date of collection. For example 

 at station 5-C, on August 20, the number of plankton organisms per liter was 281,115; 

 on September 15 it was 82,344; again, at station No. 8 the number per liter on 

 August 19 was 33,494, but on September 16 it increased to 186,920. 



Investigations have shown that plankton abundance can not be correlated with 

 pollution, but to satisfy the skeptical an attempt has been made here to correlate 

 the distribution of plankton with the varying degree of pollution. The average 

 number of plankton organisms per liter for stations 1, 4, 8, 10, and 12 (waters at 

 which, as shown by the dissolved-oxygen determination and a study of the bottom 

 fauna, were not polluted) were compared with the average number for stations 

 3, 5, 6, 7, and 9, waters which the data on dissolved oxygen and bottom fauna had 

 shown to be polluted. The average number for the unpolluted waters of the first 

 group of stations was found to be 133,830; that for the polluted waters of the second 

 group of stations was 98,050, a difference of 35,780. This difference at first may 

 seem significant, but when one considers the great difference in the number of 

 plankton organisms at the various stations of each of the above groups (Table 7), 

 the differences between the shore and channel counts at the same station (Table 7), 

 and the differences in numbers at the same station for August and September 

 (Table 7), these differences between the above averages probably lose their signifi- 



