The nutrient medium for determining the general aerobic bacterial population 
consisted of 10 
Bacto-peptone 5.0 gm 
Ferric phosphate 0.1 gm 
Yeast extract 1.0 gm 
Seawater (aged) 1,000 ml 
Bacto-agar 20 gm 
pH U9) 
To determine the general anaerobic bacterial population, the above medium was 
then treated with sodium formaldehyde sulfoxylate (1.0 gm/I) to lower the redox poten- 
tial, and with resazurin (0.001 gm/I) to serve as an indicator of anaerobiosis. 
The nutrient medium for determining the presence of sulfate-reducing bacteria 
consisted of:!0 
Potassium phosphate dibasic 0.2 gm 
Magnesium sulfate hydrated 0.2 gm 
Sodium sulfite 0.1 gm 
Ferrous ammonium sulfate 0.1 gm 
Calcium lactate 3.5 gm 
Ascorbic acid 0.1 gm 
Bacto-peptone 1.0 gm 
Yeast extract 1.0 gm 
Bacto-agar 3.0 gm 
Seawater 1,000 ml 
The pH was adjusted to 7.5, and the medium (agar excluded) was placed in test 
tubes with screw caps and sterilized. The screw caps were tightened when the medium 
was still warm to exclude atmospheric oxygen. Small samples of bottom sediment from 
various depths were placed in these test tubes and incubated for several days at 15°C. 
The sediment samples obtained with a scoop sampler were washed through a 
plastic screen to collect mud-dwelling organisms. The animals were bottled and pre- 
served in a 5-percent glycerol - alcoho! solution aboard ship for laboratory analysis. 
A variety of animals were found in these sediment samples. Annelid worms were the 
most abundant marine organisms collectedin the vicinity of STU I-1 (Figure 6). Other 
mud dwellers collected were nemertean or round worms, holothurian or sea cucumbers, 
(Figure 7), molluscans, and Foraminifera tests, The Foraminifera tests found in the 
sediment samples have been classified and reported in Reference 1. 
