Aooordingly, one mile square encompassing this type of bottom was 

 chosen within the Disposal Area* The area in the Mud Hole, too, 

 was similarly reduced to this dimension. Then a series of photographic 

 and bottom sampling stations were laid out at one-sixth mile intervals, 

 but only nine pictures resulted from this operation because of the 

 failxire of the camera to function properly. 



To determine the number and kind of animals and Tegetative growth 

 visible for each unit area a comprehensive study was made of enlarge- 

 ments of satisfactory bottom exposures from both cruises. The area 

 covered by each photograph was calculated by -caking vinder-water tank 

 pictures of a framework marked off at 6-inoh intervals, using focal 

 distances and lens apertures adopted for the investigations. From these 

 observations it was found that 246 square feet of bottom were covered 

 in the Disposal Area, of which 154 square feet were of the muddy 

 portion; and 40 square feet were covered in the Mud Hole. The 

 combined results of the two cruises are summarised in table 1. 



The bottom samples wer« utilised by counting and identifying the 

 animals contained in them. Table 2 shows the results of 37 samples 

 taken in the Disposal Area (29 in muddy-type bottom) and 8 samples 

 in the Mud Hole. 



A second underwater photographic and bottom sampling survey of 

 the same 1 -mile -a qua res in the Disposal Area cmd Ifud Hole took place 

 November 1 and 2 during cruise 12 of the Albatross III « On this 

 cruise, station procedure was changed slightly. It was decided that 

 the best method under existing conditions, instead of running from 

 one station to another, was to drift slowly aoross the area, lowering 

 and raising the camera and bottom sampler as rapidly as possible. 

 Then when the vessel reached the opposite boundary, it steamed back 

 to the windward boundary several hundred yards to the southward of the 

 first station, with the process being repeated as many times as necessary. 



During this particular cruise the taking of bottom photographs 

 was greatly facilitated by using a better camera (Robot), plus an 

 improved routine of operations t 72 negatives and 26 bottom samples 

 were obtained in less than two days despite adverse weather conditions. 

 Thirty-five negatives and thirteen samples were obtained from the 

 Disposal Area and 37 negatives ajid 12 samples fron the Mud Hole. 

 Enlargements were made from the negatives, the area covered was cal- 

 culated, and bottcwi ssunples were examined as in the earlier study. 

 The summarization of these results are shown in tables 3 and 4. 



Discussion 



These two photographic sunreys (tables 1 and 3) show a marked decrease 

 in the numbers of marine organisms visible on the bottom between the 

 spring of 1948 and November 1948. There were 27 animals per-one -hundred- 



