42 COXSERVATIOX DEPARTMENT 



The field program consisted of : 



Physical Observations : 



1. Sounding for depth and bottom sample— to determine 

 the character of bottom throughout the region and the dis- 

 tribution of silt deposits. 



2. Temperature — horizontal and vertical range throughout 

 the season ; also diurnal fluctuations. 



3. Currents — rate and direction of the movements in the 

 Avater mass. 



4. Transparency — degree of turbidity due to organic and 

 inorganic matter in suspension. 



5. Effect of storms on physical, chemical, and biological 

 conditions in the eastern part of the lake. 



*Ch€mical and Bacteriological Observations: 



1. Free ammonia, albuminoid ammonia, nitrates, dissolved 

 oxygen, dissolved carbon dioxide, calcium carbonate, calcium 

 bicarbonate, and hydrogen ion test to determine 



(a) Normal chemistry of the lake. 



(b) Extent and concentration of pollution. 



2. Bacterial test to determine quantitative distribution of 

 bacteria and of the B. coli-aerogenes group. 



Biological Observations : 

 Limnological cruise — 



*1. Liter samples from surface and bottom centrifuged for 

 nannoplankton. 



*2. Fifty liters from the surface and bottom taken with 

 pump and filtered through No. 20 silk for quantitative 

 distribution of phytoplankton. 



3. Horizontal five-minute hauls at surface and near bottom 

 with No. 20 silk foot net for a qualitative check on the pump 

 collections. 



4. Horizontal five-minute hauls at surface and near bottom 

 with jMichael 8ars meter net of No. oxx and No. ooxx silk for 

 quantitative and qualitative macroplankton and young fish 

 collections. (Depth at which loAver net fished was deter- 

 mined from the angle of the dredging wire and length of line 

 out.) 



Fisliiiig Cruise — 



^. Five-minute ])ott()m liauls witli a Helgoland trawl for 

 demersal fish eggs, small fry, and the macroplankton com- 

 munity adjacent to the bottom. 



*2. Fifteen-minute hauls with a Petersen young fish trawl 

 (Vi inch s(|uare mesh) fishing at all levels. 



Observations omitted on Xavette stations. 



