10. 



change in elevation, substantially alters the size of the 

 field viewed. In such instances estimates of the area were 

 made in relation to the size of organisms or various topo- 

 graphic features. The viewable area for the 35 mm camera 

 was approximately 11 m^ , while the area for the 70 mm camera 

 was approximately 4 rtr . 



Each slide was projected on the tracing of the area grid 

 and examined. The time, area viewed, substrate, and species 

 and their abundance was noted for each slide. This informa- 

 tion was recorded in coded form on Opscan sheets (Appendix 

 D) . Depth for each photograph was obtained from the Aandera 

 current meter, which, among other things, measured pressure 

 depth in relation to time. Absolute species identification 

 from photographs is exceedingly tentative. It is virtually 

 impossible to identify each organism, seen on the photographs, 

 to the species level. At present, the taxonomy of some major 

 groups found below the photic zone is sketchy at best. This 

 problem is compounded by the fact that the characteristics 

 separating closely related species are frequently too fine to 

 be discernable in a photograph. In many coelenterates the 

 problem is further compounded by contraction of collected or 

 disturbed organisms, such that their appearance in an 

 undisturbed state is radically different. Within these 

 constraints every effort was made to obtain as precise an 

 identification as possible for each organism seen. The 



