The vinyl tubes were also damaged by the borers where they were in direct 

 contact with wood (Figure 28). A vinyl tube (NCEL No. 66) intended for low- 

 temperature use had a very heavy bacterial slime growth over the entire tube and 

 over the plastic, rubber, and burlap wrappings. When recovered, the tube was 

 quite rigid and had decreased in diameter by about 1/16 inch, perhaps because the 

 plasticizer or some other chemicals used in the tube's formulation may have been 

 lost as a result of bacterial slime activity or other effects of the deep sea environment. 

 The other three vinyl tubes listed in Table 4 had a light slime growth over the surface; 

 the diameter of these tubes remained unchanged except where marine borers had 

 penetrated the surface of the plastic under the area of the wood bait pieces. 



There were light to moderate amounts of hydroid growth and Tubularia growth 

 on the plastic rods and tubes. The heaviest hydroid growth was found over the 

 roughened surface of a nylon rod (Figure 29). No other types of attachment organisms 

 were found on these plastic specimens. 



Moisture absorption and hardness tests were conducted on the plastic rod and 

 tube specimens. From each of the 3-foot-long plastic specimens, which were stored 

 in a plastic bag aboard the ship, a section about 3 inches long was cut from one end. 

 After each piece was weighed and the hardness tested, the specimens were then dried 

 for 2 months in a room in which the relative humidity was kept at 20% and the 

 temperature was kept at 23° C. When the weight remained constant after this drying 

 period, the specimens were then reweighed and the hardness was tested again. From 

 these tests, it was found that Teflon absorbed the least amount of moisture and 

 cellulose acetate absorbed the most amount of moisture during exposure in the deep 

 sea environment. 



The information about the moisture absorbed by the plastics and their hardness 

 when wet and when dry is presented in Table 8. 



The 1/16x3 x3-inch cellulose acetate plastic films which were used as spacers 

 between the wood bait pieces and the aluminum bio-rack frame were riddled by 

 borers (Figure 30). These plastic films were in direct contact with the wood so that 

 the borers hod attacked the wood first and then continued into the plastic material. 



Wrappings Around Plastics. The burlap wrappings around the plastic rods, 

 tubes, and pipe and around a rubber vacuum hose were severely deteriorated by 

 bacterial action (Figure 31), and the material could easily be torn apart by hand. 

 A nylon fishing line, which was used to secure the burlap wrappings to the plastic, 

 wcjs not damaged. 



Severe surface cracking was found over the entire rubber electrical tape 

 wrappings (Figure 32). In some areas for some specimens the wrapping had failed 

 completely, and the underlying plastic was exposed. The damage to the rubber 

 tope was probably caused by the effects of the deep sea environment; however, 

 microorganisms may have been responsible for the deterioration to some extent. 



35 



