The NEL photographs have revealed similar environ- 

 mental relationships in microrelief separated by hundreds 

 of miles. Comparable microstructures also exist at dif- 

 ferent depths, presumably due to a depth-range toleration 

 by many benthonic organisms. 



Random sampling of irregularly distributed bottom 

 targets makes it difficult to obtain accurate distribution 

 counts. The photos revealed a range of distribution of 

 small visible targets for all environments from less than 

 1 per square meter of sea floor to 5 or more. Tracks, 

 markings, scratches, plow trails, impressions, pits, and 

 mounds resulting from benthonic sediment churning did not 

 vary greatly in magnitude and horizontal distribution con- 

 sidering the vast size of the oceans. 



In shoal depths, organisms are normally plentiful be- 

 cause of rich food supplies. With greater depth there appears 

 to be a linear decrease of the number of visible organisms, 

 with a corresponding decrease of food. As an example of 

 the numbers of organisms, Beagles and Shumway 7 reported 

 high concentrations of clams (400 /m 3 ) in depths of 5 meters 

 or less in Alaska waters. Worm mounds up to 5 cm high 

 in the same area indicated concentrations up to 10 animals /m 3 

 In other nearshore shallow areas in Alaska, Beagles and 

 Shumway reported concentrations of worm mounds at 

 20/m 2 . On the other hand, many photographs taken in deep 

 abyssal areas indicate benthonic organism populations of 

 less than 1/m 2 . Number of benthonic fauna and amount of 

 churning of sea floor sediments are closely related, as is 

 to be expected. 



There does not appear to be a close relationship 

 between bedrock outcrops and manganese nodule formation, 

 but further investigation will probably show considerable 

 manganese encrustation on the harder surfaces such as 

 bedrock and coral boulders that exist on topographic highs. 

 Table 2 indicates a distinct relationship between physical 

 disturbances such as wave or current-formed ripple marks 

 and outcrops of rock. Photographs have repeatedly shown 

 that coarser sediments such as Globigerina ooze and coral 

 sands are rippled in the vicinity of bedrock. 



31 



