Linking a lower trophic level
biogeochemical model with an upper
trophic level ecosystem model
Kelly Kearney, Jorge Sarmiento,Villy Christensen, Anand
Gnanadesikan, Charles Stock, Sylvie Guenette
Ecosystem and biogeochemical models
Ecosystem models
Biogeochemical models
• Focus on upper trophic levels
• Focus on lower trophic levels
• Forced by changes in
• Forced by changes in climate,
predation, i.e. top-down
i.e. bottom-up
The Ecosim Model
! aνBk Bi
!
aνBi Bj
dBi
rBi
=
+ ge
−
− (M0 + F + e) Bi
dt
1 + hBi
2ν + aBi
2ν + aBj
k=prey
j=predators
"
#$
% "
#$
%
IN
OU T
Predator
Primary
production
Fleet
Group
Other
mortality
Prey
The Ecosim Model
! aνBk Bi
!
aνBi Bj
dBi
rBi
=
+ ge
−
− (M0 + F + e) Bi
dt
1 + hBi
2ν + aBi
2ν + aBj
k=prey
j=predators
"
#$
% "
#$
%
IN
OU T
Predator
Primary
production
Fleet
Group
Other
mortality
Detritus
Prey
The Ecosim Model
! aνBk Bi
!
aνBi Bj
dBi
rBi
=
+ ge
−
− (M0 + F + e) Bi
dt
1 + hBi
2ν + aBi
2ν + aBj
k=prey
j=predators
"
#$
% "
#$
%
IN
OU T
aνBi Bj
aVi Bj =
2ν + aBj
Predator Bj
aViBj
ν(Bi - Vi)
Unavailable prey
Bi - Vi
Available prey
Vi
νBi
The Topaz Model
The Topaz Model
•
N: NO3, PO4, SiO4,
Fe, DOM
•
P: large, small,
diazatrophs
•
•
Z: implicit grazing
D: particle ballast
(CaCO3, opal,
lithogenic)
The Topaz Model
•
N: NO3, PO4, SiO4,
Fe, DOM
•
P: large, small,
diazatrophs
•
•
Z: implicit grazing
D: particle ballast
(CaCO3, opal,
lithogenic)
The Topaz Model
•
N: NO3, PO4, SiO4,
Fe, DOM
•
P: large, small,
diazatrophs
•
•
Z: implicit grazing
D: particle ballast
(CaCO3, opal,
lithogenic)
The Topaz Model
•
N: NO3, PO4, SiO4,
Fe, DOM
•
P: large, small,
diazatrophs
•
•
Z: implicit grazing
D: particle ballast
(CaCO3, opal,
lithogenic)
The Topaz Model
•
Phytoplankton production
•
•
Light limitation
Nutrient limitation
The Topaz Model
Nlim = N O3 ·
1+
kN O3
"
!
N H4
· 1+
+ N O3
kN H4
N H4
kN O3
Plim =
Silim =
SiO4
kSiO4 + SiO4
P O4
kP O4 + P O4
F elim =
Fe
kF e + F e
The Topaz Model
•
Phytoplankton production
•
•
•
Light limitation
Nutrient limitation
Grazers
•
•
Assumed to maintain steady state with respect to phytoplankton
Grazing is function of phytoplankton biomass and temperature
Integrating the two models
1. Run Topaz in ocean model
2. Sum phytoplankton biomass and implicit
grazing over the area where an Ecosim
model is defined
3. Force the
phytoplanton
biomass and
zooplankton
grazing variables
within the
Ecosim model