MOdel Shopping Tool ( MOST )
"mesozooplankton budget module" from PISCES v1 Equations
Same equation in other models :
Equation Description :
Mesozooplankton budget in PISCES depends on growth efficiency, grazing on multiple sources and losses to exudation and mortality. The parametrization for the grazing on multiple resources differs from the one adopted for microzooplankton (link below) (e.g., Frost, 1987; Moloney and Field, 1991).
This parameterization implies that mesozooplankton always predominantly grazes on the most preferred prey (no-switching parameterization). It avoids the maintenance of high-standing stocks of mesozooplankton in the case of small-cells dominated ecosystem (for instance, in oligotrophic regimes) which would happen with the parameterization adopted for microzooplankton. In addition to the conventional concentration-dependent grazing described for microzooplankton, flux-feeding is also accounted for in PISCES. This type of grazing has been shown to be potentially very important for the fate of particles in the water column below the euphotic zone (Dilling and Alldredge, 2000; Stemmann et al., 2004). Flux feeding depends on the flux and thus, on the product of the concentration and of the sinking speed. In PISCES, only the largest particles experience this type of grazing as they are the fastest sinking material.
In the equation for mesozooplankton, the term with a square dependency to mesozooplankton does not depict aggregation but grazing by the higher, non-resolved trophic levels. All terms in the equation driving the temporal evolution of mesozooplankton depend on temperature using a Q10 of 2.14 (Buitenhuis et al., 2005).
Parameters definitions and typical values in PISCES:
D = diatom concentration micro mol C l-1;
e M = 0.35 (mesozooplankton growth efficiency);
g M = 0.7 d-1 (max grazing rate);
I = phytoplankton groups mesozooplankton can graze on, P, D and Z;
K G M = 20 micro mol C l-1 (half-saturation k for grazing);
K M = 0.1 micro mol C l-1 (half-saturation k for excretion);
m M = 0.03 (micro mol C l-1)-1 d-1 (mesozooplankton mortality rate)
P = nanophytoplankton concentration micro mol C l-1;
p D M (or gamma D) = 1.0 (mesozooplankton preference for diatoms);
p N M = mesozooplankton preference for species N (eg P, D, Z, POC);
p P M (or gamma P) = 0.2 (mesozooplankton preference for nanophytoplankton);
p POC M (or gamma POC) = 0.2 (mesozooplankton preference for POC);
POCs = small POC concentration;
POCb = big POC concentration;
r M = 0.008 d-1 (excretion rate);
Z = microzooplankton concentration micro mol C l-1;
References:
Buitenhuis, E., et al, 2005. Global Biogeochemical Cycles Vol 20, doi: 10.1029/2005GB002511;
Dilling, L., and A. L. Alldredge, 2000. Deep Sea Res. Part I, 47, 1227-1245;
Frost, B. W. 1987. Mar. Ecol. Prog. Ser., 39, 49-68;
Moloney, C. L., and J. G. Field, 1991. J. Plankton Res., 13, 1003-1038;
Stemmann, L., G. A. Jackson, and G. Gorsky 2004. Deep Sea Res. Part I, 51, 885-908;
