Characteristics of Particles in Each Particle Maximum 



Surface layer 



The surface is the source of particles at depth, although 

 not necessarily directly. It was hypothesized that the surface 

 waters at Mt. Desert Island would be more biologically enhanced, 

 i.e., productive, than the Jordan Basin station because of the 

 proximity to the coast and the hydrography. Although it was 

 suspected that a fall bloom occurred as a result of a storm just 

 prior to sampling in Jordan Basin, there were no significant 

 differences in the characteristics of the particles on the two 

 dates. In the surface layer at Jordan Basin there were 

 significantly higher chlorophyll concentrations and numbers of 

 autotrophic nanoplankton, a greater particle volume, but smaller 

 particles than at Mt. Desert Island. There was no significant 

 difference in protein, ATP or numbers of heterotrophic 

 nanoplankton and not enough data for the other analyses to make 

 comparisons. Because the differences between stations were 

 small, even when significant, all the data reported for the 

 surface layer are means for all dates and times. 



Intermediate particle maximum 



Most effort went into sampling the BNL, so there is little 

 information about the intermediate particle maximum. It 

 represents a protein maximum (Fig. 3) , but not a chlorophyll or 

 nanoplankton maximum (Fig. 3 and 4) . Despite the decreased light 

 transmission, the total particle volume was not appreciably 

 different from the water layers above and below, although the 

 slope of the particle size distribution indicates that particles 

 there were much smaller. More information is necessary before 

 this layer can be characterized. 



Bottom nepheloid layer 



Gradients above the bottom. 



The sharp increase in light transmission with distance away 

 from the bottom (Fig. 2) was related to a decrease in the number 

 and volume of particles suspended in the water. It was expected 

 that many of the biological and chemical properties of the BNL 

 would show a similarly steep gradient (Fig. 5-7) , but such 

 gradients were rare. 



Particulate carbon and nitrogen decreased with distance 

 above the bottom in Jordan Basin (Fig. 5) . At both stations 

 some large protozoans either increased ( Tintinopsis , 

 Parafavella . foraminif era ; Fig. 6) or decreased ( Sticholonche ; 

 Fig. 6) near the bottom. Finally all stages of copepods tended 

 to be more abundant at 10-20 m than at 2-5 m above the bottom. 

 The lack of a strong gradient in the other measurements could be 

 a result of the sampling method in combination with spatial and 

 temporal variability. The bottom tripping rosette sampled only 



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