Q8 = ZP'i.8 ~^8,3 " R 8 " H 8» Q9 : SHRIMP 

 Q9 = SP'1,9 "^ p 9,j - R9 " H9 - B, Q 9 : GROUNDFISH 

 QlO ■ ^ p 'i,10 -^ P 10,j " R 10 ~ H 10» QlO : MIGRATORY PELAGICS 

 Qll = SP'i.H -^ p ll,j " R ll» Qn : MARINE MAMMALS 

 Q 12 = lP' ± 12 + cB -IP12 i " r 12> Ql2 : LARGE SCAVENGERS 

 where 



i is a number from 2 to 12 representing food compartments, 



j is a number from 5 to 12 representing predator compartments, 



Jk are flows into the system from outside, 



Hi are nitrogen release and remineralization rates, 



L is the rate of loss of inorganic nitrogen in currents, 



Pj a are flows of energy between compartments, most of which represent 

 feeding , 



P'i a are the assimilated portion of food intake, 



F^ are flows of unassimilated food to organic compartments from animal 

 compartments , 



B is the bycatch rate, 



R.» are respiration rates, 



Hj are harvest rates. 



Flows indicated in the equations but not represented by connecting lines in the 

 model diagram can be assumed to be null flows. 



J I and J3 are constants representing nitrogen and low-nitrogen organic 

 matter flows into the system. J 2 , gross primary productivity (GPP), is a 

 variable that is a product of S2, GPP at saturation, multiplied by a Michaelis- 

 Menten equation, with nitrogen as the substrate (controlling factor): 



J 2 = 82(01/1011! + Qi). 

 ?l 2 is the rate of uptake of organic nitrogen by phytoplankton: 



p l,2 " n 2< J 2 " R 2>» 

 where n2 is the nitrogen concentration in phytoplankton. 



185 



