INTRODUCTION 



As part of a research program to determine the effects of the deep-ocean 

 environment on various engineering materials, the U. S. Naval Civil Engineering 

 Laboratory in March 1962 placed the first of a series of Submersible Test Units, 

 designated STU 1-1, on the ocean floor in 5,300 feet of water at Test Site I. Since 

 then three additional Submersible Test Units, designated STU's 1-2, 1-3, and 1-4, 

 have been placed on the ocean floor at Test Site I (Figure 1). In February 1964 

 after 4 months in the sea, STU 1-3 was retrieved for study. It was loaded with 

 1,324 test specimens of 492 materials. The effects of deep-sea marine fouling and 

 boring organisms upon these materials has been reported in Reference 1. 



STU's ll-l and 11-2 were placed on the ocean floor at Test Site II (lot 34°06' N, 

 long 120 42' W), (Figure 1). Figure 2 shows the STU ll-l complex emplaced.2 

 STU ll-l was recovered in December 1964 after 197 days on the ocean floor. This 

 report presents the materials and methods employed for attracting, collecting, and 

 evaluating deep-sea fouling and boring organisms and the results of field and labora- 

 tory investigations of the materials recovered from STU II-l. A literature survey has 

 been published on fouling and boring organisms and their effects upon various materials 

 submerged in the deep ocean. ^ 



RESEARCH METHODS 

 Oceanographic Information 



Concurrently with the STU program, numerous oceanographic and biological 

 data-collecting cruises to Test Sites I and II have been conducted. These have pro- 

 duced information about the environmental parameters, such as salinity, temperature, 

 oxygen content, and biological activity. Such information is essential in evaluating 

 changes in the materials, especially corrosion of metals, exposed on the ocean floor. 

 The environments at both test sites are summarized in Table l.^/^ 



Because the rate of corrosion of certain metals and alloys submerged in the sea 

 are greatly influenced by the amount of dissolved oxygen concentration in sea water, 

 it was desired to also investigate the effects of the minimum oxygen zone upon these 

 materials. Test Site II was selected because at this site, at a depth of about 2,500 

 feet, the dissolved oxygen content in sea water falls to a relatively low value and is 



