MEIOFAUNAL ABUNDANCE 193 



multiplied by a correction factor to convert to organisms per cubic 

 centimeter of sediment: 



(Organisms per cm^ sed.) = (organisms counted from S— R cells) 



X (total fluid, ml, from which S— R 

 cells were filled) 



X [(amount of sediment, cm^ , 

 represented by sample) 



X (number ml counted in S— R cells)] ~"^ 



Parenthetically, the procedure provides generous flexibihty for use 

 with any predominately sandy sediments. Under light suspended 

 loads it allows for the actual counting of 70 to 90% of the fauna 

 contained in the sample. The procedure also gives reliable results 

 with meiofauna of marine sandy sediments, requiring only two alter- 

 ations: (1) the concentration of MgCl2 should be increased to 6 to 

 7% and (2) the observation magnification can be reduced by one-half 

 owing to the generally larger sizes of the marine meiofauna. 



Faunistic abundance per 10 square centimeters of surface 

 (x 10^ = abundance per squ£ire meter of surface) was estimated sep- 

 arately for each taxon and coring station. Density per cubic centi- 

 meter of sediment for individually analyzed samples or subsamples was 

 multiplied for each depth fraction analyzed by an appropriate factor 

 (0 to 1 cm depth by 1.0, 1 to 2 cm depth by 1.5, 3 to 4 cm depth by 

 2.5, and 6 to 7 cm depth by 3.5) to convert estimate from partial to 

 complete cores, and then by 10 to convert from 1 to 10 square centi- 

 meters of surface. The sum of taxon abundances at a given coring 

 station was taken as the abundance of total meiofauna at that 

 station. 



Geometric mean abundance per station and 95% confidence 

 limits were then calculated for each taxon and site, using log (X) or 

 (X + 1) transformations as appropriate. The resulting values were cor- 

 related with a provisional three-parameter index of the physical- 

 chemical environment. Of the three pgirameters in the index — 

 noncarbonate conductivity tempered by high oxygen saturation and 

 stream flow — the first two represent faunally weighted means of 

 stream- water and interstitial-water values. For the faunal weighting 

 factor, the fauna in the upper centimeter of sediment was thought to 

 be most responsive to stream-water values and the fauna of the re- 

 maining depths to be most responsive to interstitial- water values. 

 Hence, for a given site, stream- water values were multiplied by the 

 decimal fraction of abundance occurring in the upper centimeter of 



