and Wishner, 1986; Noriki and Tsunagai, 1986; Wishner and Gowing, 

 1987) , it is technically difficult to conduct detailed sampling 

 in the BNL in order to examine horizontal, vertical, and temporal 

 variability. The data presented here and in Smith et al. (1987) 

 and Wishner and Gowing (1987) suggest considerable 

 spatial/temporal variability in the biological and chemical 

 constituents. Some of the variability between the stations can 

 be related to differences in hydrography and environmental 

 conditions at the two stations, i.e., the Mt. Desert Island 

 station is shallower, well mixed and has strong bottom currents. 

 The differences in the BNL between the two dates at Jordan Basin 

 could have been related to the occurrence of a fall bloom or 

 horizontal movement of patches. But the variation between 

 replicates taken within a short time and the lack of strong 

 gradients in biological and chemical measurements suggests that 

 processes in the BNL are quite complex. For example, the lack of 

 strong gradients could result because organically-enriched, 

 nutritionally-enhanced particles may be finer and suspended at 

 greater heights above the bottom than the rest of the larger 

 sediment grains (Muschenheim, 1987) . Accordingly, in our study 

 copepod numbers appeared to be higher at the top of the BNL than 

 at the bottom. 



Understanding the dynamic processes affecting the 

 nutritional quality, distribution of variables in general, and 

 mechanisms of formation of BNL will require technically 

 sophisticated sampling devices, probably deployed with a 

 submersible. It is necessary to sample very near the bottom and 

 to be able to take samples in the BNL and the overlying clearer 

 water simultaneously. 



Because the flux of organic material to the bottom is 

 greatest just after the spring bloom, the BNL in the spring and 

 early summer should be much more biologically enhanced than in 

 the late summer and fall periods reported here. Finally, more 

 physical measurements and more definitive methods of assessing 

 nutritional value and biological activity are necessary for 

 understanding dynamics in the BNL. In our 1987 field program in 

 the Gulf of Maine we were able to improve the sampling capability 

 through the use of the Johnson Sea-Link . Although some technical 

 problems remain, the methods of assessing biological enhancement 

 were improved. These results will be reported in the near 

 future. 



ACKNOWLEDGEMENTS 



This research was supported by NURP and by NSF grants OCE 

 8608808 and OCE 8616876. 



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