It is highly unlikely that the surfaces of the wooden panels were infested with 

 borers during descent aboard the STU because (1) the wooden panels were dry when 

 initially submerged and (2) the rate of descent to the sea floor was probably too 

 rapid (100 to 150 ft/min) for any borer attachment. In order to eliminate any doubt 

 about this matter, several panels were covered with a clean, white, bonded paper 

 and sealed with a plastic adhesive tape to prevent any borers present near the surface 

 from attaching themselves to the wood during descent (see Figure 6). 



It is not known whether the paper coverings were detached from the wood 

 during descent to the bottom or at the sea floor. When the panels were recovered 

 and examined, they were also found to be riddled by borers identical to those found 

 on uncovered test panels. 



The wood panels which were exposed about 0.5 feet above the sediment layer 

 were much more severely damaged by the borers than the set of panels exposed 3 to 

 4 feet above the sediment layer. This indicates that the deep-sea marine borers are 

 very active in large numbers immediately above the sediment layer and their number 

 tends to decrease in seawater as the distance from the sediment layer increases. A 

 similar phenomenon has been reported in Reference 10. It is possible that these 

 borers may not be present in seawater about 25 feet above the deep-sea floor. 



The greatest borer population was found in the 2x4x30-inch bait pieces 

 (untreated fir) fitted over the plastic rods and tubes (Figure 12). Some borers, about 

 3/16 inch in diameter, had penetrated about 1-1/2 inches into the center of the 

 wood from the cut end (Figure 13), Because of the deteriorated condition of the 

 wood, the 2 x 4-inch bait pieces could easily be broken apart by hand (Figure 14). 

 Numerous white deep-sea sponges (Figure 9) were found attached to the surfaces of 

 these woods. Numerous amphipods (Figure 15) were found between the wooden 

 layers, and over 50 of the crustaceans were found trapped inside a plastic container. 



The molluscan borers (Figure 16) in these wooden bait pieces have been 

 identified as Xylophaga washingtona Bartsch and Xylophaga duplicata Knudsen. 

 Complete descriptions of Xylophaga washingtona and Xylophaga duplicata are pre- 

 sented in References 11 and 12, respectively. 



Marine bacteria and fungi were also responsible for the deterioration of the 

 wood. The surfaces of the test panels were softened by the action of bacteria and 

 fungi. Microscopic examination of sections through the wood revealed two types 

 of deterioration of wood cells: 



1. Irregular tiny cracks and channels in the cell walls caused by bacteria. 

 This type of deterioration was the most commonly found on the surface of 

 the wood. 



2. Wide channels in the secondary cell walls of the wood caused by higher 

 marine fungi. This type of deterioration is known as "soft rot" and was 

 less commonly found on the surface of the wood. 



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