o 



O) 



24 - 

 22 - 

 20 



18 



16 



14 



12 



10 

 8 

 6 

 4 



NO A A PROFESSIONAL PAPER 11 



1 1 1 1 



1 



Vertical Bars = 1 s.d. 



} 



i 



A^ 



O Sept 73 -Dec 75 



• Feb -March 76 



A Feb -March 76 w/o C. tripos 



A 

 A 



6 



9 Q 



■^ 



A -L 



M 











^0 



_L 



M 



M 



J J 



MONTH 



N 



FIGURE 9.1-15. — Temporal- variations in mean water column particulate organic carbon content of the Apex, September 1973 to March 1976. 



POM that settled to the bottom or washed out of the 

 system in previous years. Aggregation near the bottom of 

 the thermociine would be advantageous in that the pop- 

 ulation is in a region where POM tends to accumulate as 

 it settles through the water column. By metabolizing POM 

 in the water column, which was previously lost from the 

 system, a substantial increase in water column BOD would 

 be generated without necessarily increasing the input of 

 inorganic nutrients or POM. 



Presumably, the bloom's collapse in June and July was 

 a consequence of the exhaustion of nutrient supplies (in- 

 ternal or external) or parasitism. Based on the proportion 

 of C. tripos-C in the POC pool of the water column at the 

 end of March (64%), it is possible that as the discharge 

 of the Hudson River began to decline in May and June 

 (fig. 9.1-18) the population off the New Jersey coast suf- 

 fered mass mortalities due to limited food supplies. Graz- 

 ing is unlikely, since copepods have been shown not to eat 

 C tripos. 



CONCLUSIONS 



Although data were not collected synopticaily in time 

 or space, coastal observations correlated well with those 

 in the Apex and outer Bight (figs. 9.1-3, 9.1-5, 9.1-13, 

 and 9.1-14). Temporal variations in C. tripos cell density 

 at Fire Island Inlet reflect the early stages of the bloom 

 before stratification, and mean cell densities along the 

 New Jersey shore appeared to reflect at least the latter 

 stages of the bloom during the period of thermal strati- 

 fication. 



The C. tripos bloom apparently began throughout the 

 New York Bight in January; maximum cell densities de- 

 veloped in the midshelf to shelf break region in late March 

 before the onset of thermal stratification. The temporal 

 and spatial distributions of cells indicate that the popu- 

 lation was increasing most rapidly in the outer Bight dur- 

 ing March or that the outer Bight received a larger initial 

 inoculum of cells than the inner Bight. The large area over 



212 



