192 HUMMON et al. 



thermometer. Light transmission was measured in stream water with 

 a Beckman EV-4 Envirotrans meter. Conductivity and pH were 

 measured in stream and interstitial water with YSI 33 S-T-C and 

 Orion 404 Specific Ion meters. Water samples from both stream and 

 hole were placed in plastic bottles and BOD (biochemical oxygen 

 demand) bottles for further chemical analysis in the laboratory. The 

 azide modification of the Winkler technique was used on site for 

 preliminary fixation of dissolved oxygen, A tvdg, meterstick, and 

 stopwatch were used to measure flow rates in shallow zones having 

 rather even depths, A tape and level were used to make a 

 bank-to-bank stream and channel profile along the transect line. 



Samples were returned to the laboratory within 3 hr of 

 collection, where fauna were narcotized with 1% MgCl2 and 

 extracted from one jar into an identical jar by multiple decantation, 

 using 1% MgCl2 as the decantation fluid throughout. Samples were 

 fixed with enough 100% Formalin containing rose bengal to make a 

 10% final solution, capped with the numbered cap from the original 

 jar, and mixed thoroughly by swirling. Sieving was omitted, since 

 even a 38-)um sieve results in a serious loss of small animals, including 

 rotifers, nematodes, and gastrotrichs. 



Concurrently with the extraction and fixation of faunistic 

 samples, bottles for BOD determination were placed in a constant- 

 temperature chamber without light at 20° C. Duplicate titrations 

 were made for methyl orange (total) alkalinity with bromocresol 

 green— methyl red indicator and for dissolved oxygen. As soon as 

 time allowed, tests for manganese, iron, and sulfates were conducted 

 with Hach chemical tests modified for use with a Bausch and Lomb 

 Spectronic 20, Calcium and total hardness were determined with 

 unmodified Hach chemical tests. After 5 days, BOD samples were 

 fixed and titrated for residual dissolved oxygen. 



Extracted and fixed faunistic samples were analyzed under a Wild 

 M-8 stereomicroscope at 50 and lOOx magnification using multiple 

 Sedgwick— Rafter (S— R) cell counts. Eight whole-cell counts were 

 used for split samples and twelve were used for grouped samples. 

 Material was prepared for the S— R cells by first decanting about 

 two-thirds of the supernatant fluid. The residual material was swirled 

 to determine its suspended load of organic material, silt, and clay. If 

 the suspended load was great enough to impede counting efficiency, 

 fluid was added back to dilute the suspended load and increase the 

 counting efficiency. The fluid was swirled to randomize its contents; 

 then the S— R cells were filled by a large-bore pipette, and the 

 remaining fluid volume was noted. Fauna were enumerated to major 

 taxon, and the resulting number of organisms in each taxon was 



