the sampling stations were located on either side of the canyon, while 

 the third station was in the center of it. Twelve of the 13 species 

 collected occurred at all three stations. A total of 1,416 fish were 

 taken from the station in the center of the canyon; only 207 were taken 

 from the station closest to the New Jersey coast; 484 were taken from 

 the station furthest away from it. The significantly higher number of 

 fish taken at the canyon by SHL suggested that this is an area important 

 to local fish populations. It is not known, however, whether greater 

 numbers of fish frequent this area throughout the year or whether it is 

 a seasonal occurrence. The role of Hudson Canyon as an important habitat 

 for finfishes or as a spawning area should, therefore, be determined. 



b. Zooplankton . Zooplankton serve as link between phytoplankton 

 (primary producers) and the larger organisms of the sea. They are, 

 therefore, important in marine food chains. Extensive studies of 

 zooplankton populations within and outside the ocean dumping grounds of 

 the Bight were made by the Sandy Hook Laboratory. 



The samples of zooplankton were taken by SHL at different water depths 

 (surface, middepth and bottom) using 1/2-meter-diameter nets with #8 mesh 

 (.203 mm aperture) at different stations within and outside the waste 

 dumping grounds, as shown in Figure 42. It is not known, however, 

 whether the middepth samples were above, below or within the thermocline 

 or pycnocline (the vertical gradient of density) which are known to vary 

 in depth, seasonally. Flow meters were mounted in the mouths of the nets 

 to allow calculation of the volume filtering through. The plankton nets 

 were towed by SHL simultaneously at the three depths for 5-10 minutes, at 

 intervals of 2 weeks, at six stations for which the data are recorded. A 

 station in the sewage sludge disposal area and one in the acid-iron waste 

 disposal area were included. Some of the sampling procedures and analy- 

 tical methods used by SHL for this investigation have been questioned 

 in the SAC review report. One criticism by SAC was that the counting 

 technique used by the SHL, measured only a fraction of each of the total 

 samples, and therefore is not considered adequate. According to the SHL 

 method, a 1-milliliter subsample was counted and repeated until 300 cope- 

 pods were included. One has no idea of the fraction of the actual sample 

 counted. Many zooplankton specialists insist on counting the entire 

 sample because, only then, can diversity indices be calculated, some- 

 thing which was not done by SHL. Another criticism by SAC pertaining to 

 the SHL zooplankton study is that no analysis of variability of counts 

 was provided. Replicate sampling would have been important, because in 

 coastal waters zooplankton distributions are very patchy. The SHL count- 

 ing method therefore introduced additional variation, and one has no way 

 to judge the reliability of the data, nor the statistical significance. 



The zooplankton data were often reported in settled volumes. These 

 according to the SAC review are unreliable. The reason is that several 

 hours or days are required for adequate settling of zooplankton, and 

 not 5 minutes as in the SHL study. Furthermore, although the SHL method 

 for determination of displacement volumes was found acceptable by the SAC, 

 it is not the best method for biomass evaluation. Settled volumes are 



94 



