the sample was taken, and the series of bottles 

 was then lowered to incubating depths. 



9. Samples were allowed to incubate for 

 4 hours at the selected depths, 



10. In the same sequence as incubation 

 was started, bottles were picked up at the 

 end of 4 hours and immediately placed in the 

 dark sample box. 



11. Samples were rushed back to the 

 laboratory, and 100 ml. of each were vacuum- 

 filtered through millipore filters again in the 

 same order as originally set out. 



12. Very dilute Janus Green B dye (2 ml.) 

 was added to the sample being filtered to detect 

 leaks in the vacuum system. 



13. Ten ml, 0,003 HCL (normal) were 

 pipetted onto the filter to remove residual 

 carbonate or organisms adhering to the funnel 

 surface. 



14. Ten ml, 3 percent formalin were 

 pipetted onto the filter to preserve organisms 

 and prevent bacterial activity, 



15. The millipore filters were placed in 

 individual shallow aluminum sample pans to 

 dry. 



16. Millipore filters were glued to shallow 

 sample pans, on the back of which were in- 

 scribed the station, date, depth, and ml. of 

 sample (if different from 100 ml. normal). 



17. Sample pans were mailed to the Uni- 

 versity of Michigan where radiation of each 

 was later measured. 



An example of one series of comparative 

 data between Naknek and Brooks Lakes demon- 

 strates a typical situation (fig. 36). Produc- 

 tivity is measured in terms of beta radiation 

 counts per second. Highly turbid Naknek Lake 

 is much more productive than clear Brooks 

 Lake in the upper 10 m., but below that depth, 

 because of deeper light penetration. Brooks 

 Lake is the more productive. The striking 

 differences shown are all the more significant 

 when one considers that Brooks Lake tempera- 

 tures were higher (which would increase 

 production) and that the Brooks experiment was 

 on a bright day, while that for Naknek Lake 

 was on a cloudy day. This example served to 



10 



a. 20 

 u 



a 



25 



30 

 35 



10 



IS 



20 



25 



30 



35 

 5 10 15 20 25 30 35 « 50 55 



BETA COUNTS PER SECOND TEMPERATURE (* F.) 



Figure 36.--Relative primary productivity and tem- 

 perature of Brooks and Naknek Lakes on 2 days in 

 July 1957. 



show how great differences may be in primary 

 productivity between adjacent lakes in the same 

 system. 



Summary of Water Quality Analysis 



The following may be concluded from the 

 water analyses studies: 



1. None of the qualities measured were 

 in short supply nor did they fluctuate greatly, 

 indicating that lack of these essential nutrients 

 is not the primary cause of current low pro- 

 duction of sockeye salmon in Brooks Lake. 



2. The entire water mass is in constant 

 circulation with no stratification (except pos- 

 sibly thermally for short periods). 



3. Compared withother lakes of the world. 

 Brooks Lake would be classified as a mod- 

 erately productive, soft-water, oligotrophic 

 lake, supplied with all essential nutrients and 

 able to support a healthy fish population. 



The three points above are based on data 

 taken between July and October during the 

 summer growing season. Measurements of the 

 same water qualities should be made periodic- 

 ally throughout the year to establish the 

 validity of my conclusions. Ruttner (1953: 

 p. 55) says, "Only those dissolved substances 

 which are either of no importance for life 

 or are present in amounts in excess of those 

 necessary do not undergo a marked change 

 in their amounts and states." If the same 

 uniformity of distributions and amounts of 

 dissolved substances which characterized the 



60 



