with retaining rods welded across its lower end was employed for collecting rocks 

 from the ocean floor. The pipe dredge was lowered to the ocean floor from on 

 oceanographic vessel, USNS Davis, and the area was dredged for rock specimens. 

 Several passes were made across the area of Test Site I at a depth of 6,000 feet, 

 and rocks of various sizes were collected. Various organisms were attached to the 

 collected rock specimens (Figure 5), and these are listed in Table 3. 



Several rocks had deep holes bored by pholads; neither live pholads nor their 

 empty shells were found, so it is not known whether these rock borers are active at 

 this depth. There was a deposit (as great as 1/4 inch thick) of manganese oxide on 

 the rock specimens. Chemical and instrumental analyses of these deposits were made 

 by U. S. Bureau of Mines, Tiburon, California. The results of these analyses are 

 presented in Table 4. Further information on the manganese deposits on the floor of 

 the Pacific is given in Reference 4. It is believed that bacteria play a major role 

 in the formation of nodules, for it is reported in Reference 5 that 36 pure bacterial 

 species were found and isolated from inside surface-sterilized manganese nodules. 



Sediment Samples 



Marine bacteria are among the major biological agents in the deterioration 

 and fouling of various materials submerged in the sea. To determine the type and 

 activity of bacteria in the deep sea, sediment samples were obtained and analyzed 

 in the laboratory by means of standard microbiological methods. Samples were also 

 obtained to determine the type of marine animals found in the sediment. 



Table 3. Fouling Organisms on Rocks From 6,000-Foot Depth 



Organisms 





Remarks 



Bryozoa . . . 





. . Six or more different species of encrusting 

 and erect forms; one encrusting form covered 

 about 1 square inch of rock surface 



Foraminifera 





. . Many different species 



Glass sponges 





. . Several different deep-sea species 



Serpulid worm 



tubes . . 



. . Numerous large and small; the longest was 

 over 4 inches 



Brittle stars . 







Chiton. . . . 





. . One 1/2-inch long 



