FOREWOED 



Every year millions of dollara' worth of marine structijres are 

 damaged "by marine "borers of various. Mnds. They "bore into and may 

 eventually destroy not only tiaiber, "but also low-grade concrete, soft 

 stone, and other nonmetallic materials in salt water. No salt-water 

 port in the world is entirely safe from their depredations, except 

 perhaps where the water is extremely diluted with fresh water or is 

 heavily polluted with acids, oils, or other industrial wastes. Even 

 heavily creosoted wood is not immune from Limnoria , the most widely 

 distrihuted genus of crustacean horer. 



Since ahout 1920, various types of marine "borer traps and test i 

 hoards have "been designed and systematically siibmerged in harhors all 

 over the world for the purpose of determining the type and extent of 

 marine horer attack to which shoreside structures may "be suh jected. 

 Exsimining these indicators at regular intervals led to the accumulation 

 of much valuable data concerning the density of horer attack, rate of 

 destiniction, "breeding seasons, distribution of the various species, length 

 of life, rate of growth, and other significant factors relative to marine 

 "borer activity and destructiveness . 



Test "board data are now considered indispensable in the design of 

 marine structures. When kept up to date, these data serve as continuous 

 warnings against sudden borer invasions or a large increase in the borer 

 popiilatlon. They are of basic value in the preparation of wharf speci- 

 fications and in the study of the fouling of intake tunnels, sMps' 

 bottoms, and ships' service pipe lines. They form the basis for accurate _ 

 decisions as to the borer resistance of various woods, and the relative 

 effectiveness of various treatments of piling and structviral timbers 

 subject to borer attack. 



The extensive program, of research now under way is an outgrowth of 

 the initial investigations by the National Eesearch Council in 1922 and 

 1925. These studies proved of such eccaiomic value that 'they were later 

 organized on a continuing basis, and the present program conducted by the 

 William F, Clapp Laboratories is being carried on at more than 500 loca- 

 tions along the United States coasts. 



From 19h2 to 19'<-7, the Bureau of Yards and Docks of the "Dnited States 

 Navy sponsored marine "borer studies at 56 important harbors. The results 

 are summarized in Sections 2 to 57 in PART A of this report, which com- 

 prises a narrative analysis of the data from each of the 56 harbors. These 

 locations are widely distributed along our Atlantic and GvLLf coasts; in 

 Canada and Alaska; in various Caribbean islands; in Brazil, North Africa, 

 Sicily, and Italy; and in the Pacific as far as Australia and New Zealand. 

 Each analysis identifies the marine borers which attacked the test boards ^ 

 at a given station, summarizes the intensity of borer attack, and describes 

 the kind and number of fouling organisms present. The depth of the test 

 board and various hydrographic data also are reported. Additional data 

 for 19k& and 19^9^ where available, are sumnoarized under the heading 

 "Recent Addenda. " 



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