siderable progress has been made in determining the nutritional 

 requirements and mechanisms of digestion of crustacean marine 

 borers. It has been ascertained that a specific enzyme is required 

 for the utilization of cellulose by the wood gribble -- an organism 

 which is responsible for much of the marine borer damage. In the 

 course of efforts to evaluate a number of compounds as enzymie in- 

 hibitors in the wood gribble, it was discovered that a silver com- 

 pound was extremely effective in preventing attack by the wood 

 gribble and the shipworm. The results of a 3-year field evaluation 

 program conducted both in temperate and semitropical waters in- 

 dicate that this compound has provided 100 percent protection during 

 this period. 



The progress in physiology and biochemistry just presented is 

 cited to show the broad spectrum of scientific research encompassed 

 within the Hydrobiology Program. Hydrobiology, like the closely 

 related field of oceanography, is not a single scientific discipline. 

 It is a multidisciplinary effort extending from taxonomy and the des- 

 criptive biological sciences, through ecology and so-called "bio- 

 logical oceanography, " well into physiology, biochemistry, biophy- 

 sics, and the other modern disciplines of quantitative biology. Also, 

 hydrobiological research relies heavily upon modern chemistry, 

 physics, mathematics, and the earth sciences for assistance. 



In addition to the progress already cited, the Navy continues 

 to obtain a body of data regarding the worldwide distribution and 

 population fluctuations of marine organisms responsible for deter- 

 ioration and fouling. This information is of direct benefit to the Navy 

 in the design and construction of waterfront structures and outboard 

 equipnnent, and in the planning of naval operations. Finally, research 

 data is being obtained relevant to the control of marine borer damage 

 and fouling on a number of classified high priority naval projects. 



2. Prediction and control of biological particulates interfering 

 with the propagation of acoustic signals underwater: Ever since it 

 was discovered during World War II that the false bottom echoes 

 or deep scattering layer being picked up on sonar was due to marine 

 organisms, the Navy has been vitally concerned with learning more 

 about the role of marine biological particulates in the transmission 

 ^nd reception of sound underwater. The Hydrobiology Program has 

 yielded basic information implicating marine biological particulates 

 in a number of ways as follows: Marine organisms, even very 

 small ones ranging in size from a few millimeters to less than one 

 millimeter in length, may cause sound reverberation or attenuation 

 if present in sufficient numbers. Larger marine animals may ex- 

 hibit acoustic target characteristics similar to the characteristics 

 of operational targets, i.e., the so-called "false target" problem. 



254 



