A-9 



faunal constituents estimates of the number of square meters 

 viewed were made. The method that was used is described in 

 Grassle et al., (1975) and employs the use of a Canadian 

 (perspective) Grid. Construction of the perspective grid 

 requires knowledge of the elevation of the camera, the angle 

 of the optical axis of the lens with respect to the image, 

 and the focal length and acceptance angles of the lens in 

 water. These parameters were then used to calculate the 

 number of square meters of the bottom viewed on each slide. 

 Prior to January, 1976 the ALVIN external camera was an 

 EG&G camera which covered a viewable area of approximately 

 6 m^ per frame. ALVIN now uses a Benthos 35 mm camera which 

 covers a viewable area of approximately 9 m^ . The fore- 

 ground of the field which is obstructed by the sample basket, 

 and the edges of the frame which are rather dark were not 

 used. For the DIAPHUS dives estimates of approximately 3 m^ 

 viewed per slide were used (based on actual measurements) . 



Each slide was projected on a scaled up replica of the 

 calculated grid and examined. The depth, area viewed, sub- 

 strate, and species and their abundance was noted for each 

 slide. This data compilation was aided by use of the data 

 sheets given in Appendix 1. Species identification from 

 photographs is extremely tentative. It is virtually impos- 

 sible to positively identify all the fauna seen in the 

 photographs to the species level. At present, the state of 

 the art of taxonomy of much of the fauna found below the 



