10. Bioluminescence recorders 



No instruments are in use by the Hydrographic Office at the 

 present time for measuring bioluminescence. Displays are reported 

 when observed in the field with a brief description of type (sheet, spark, 

 or globe), intensity (can you read a newspaper by it?), and areal extent. 

 It is understood that a project was begun at another agency to develop 

 a continous bioluminescence recorder that would consist of a tube with 

 light baffles and a photoelectric cell to measure the bioluminescence 

 produced by turbulence in the towed tube. However, this project has 

 since been cancelled. 



C. CONCLUSIONS AND RECOMMENDATIONS 



In quantitative plankton research, no instrument will obtain a fully 

 representative sample of the organisms present in the water; most 

 samplers are selective in one way or another. They may be selective 

 as to size due to the loss of smaller organisms or the avoidance of the 

 sampler by the larger and more agile ones. The selection may result 

 from mechanical limitations of the gear or the methods employed 

 in its operation. In addition, sampling reliability may be affected by 

 the irregular distribution (patchiness) of the plankton. 



The Clarke- Bumpus plankton sampler has received wide acceptance 

 and is considered to perform well within its limitations. It is very 

 useful when only small amounts of sample are required. The Hardy 

 continuous plankton recorder and the Isaacs high-speed sampler also 

 offer many attractive features. 



The use of fouling plates for biological fouling studies is a widely 

 accepted technique, and no recommendation for instrument purchase 

 or development is made at this time. 



The equipment currently available to the Hydrographic Office is 

 considered to be adequate for reliable animal sound measurements. 



Little information exists concerning bathypelagic organisms, and any 

 detailed analysis of the Deep Scattering Layer will require sampling 

 this group. 



Accurate and reliable measurement of biolumine scent displays is 

 impossible with present day methods. Development of a photoelectric 

 luminescence recorder is currently feasible, if warranted. 



IX- 5 



