Role of zooplankton in marine ecosystems and modellinggp p ...NCAR).pdf · Role of zooplankton in...
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Role of zooplankton in marine ecosystemsand modelling perspectivesg p p
Tom AndersonNational Oceanography Centre, Southampton, UK
ASP Researcher Workshop NCARASP Researcher Workshop, NCARAug 6-10th 2013
Role of zooplankton in marine ecosystemsp yand modelling perspectives
Introduction: bottom up (BU) vs top down (TD) control of marine ecosystems
Zooplankton control of phytoplankton blooms Zooplankton control of phytoplankton blooms
Zooplankton control of plankton community structure
Modelling zooplankton: state-of-the-art
Role of zooplankton in marine ecosystemsRole of zooplankton in marine ecosystemsand modelling perspectives
Introduction: bottom up (BU) vs top down (TD) control of marine ecosystems
Zooplankton control of phytoplankton blooms Zooplankton control of phytoplankton blooms
Zooplankton control of plankton community structure
Modelling zooplankton: state-of-the-art
evapotranspiration
NPPtree PFT2
fluxesCH2O
NPPtree PFT1
grasses
NPP
soilrespirationdecomposition
precipitation
soil
pp
uptakeuptake
Sea surface temperature Chlorophyllp p y
http://earthobservatory.nasa.gov
16 most abundant organized by “functional group”
Prochlorococcus Prochlorococcus analogsanalogs
SynechococcusSynechococcus & small eukaryotes& small eukaryotes
DiatomsDiatoms.
Other large eukaryotesOther large eukaryotes
Plant animal warsPlant-animal wars
spinesspinescoloniestoxinstoxins
Daksalov (2002): “Overfishing drives a trophic cascade in the Black sea”( ) g p
Change in dominance across the pelagic food chain since the depletion oftop-predators after 1970: model results
trophic level before 1970 after 1970
top predators
planktivores
resource limited
consumer controlled
-
resource limitedp
zooplankton
phytoplankton
resource limited
consumer controlled
consumer controlled
resource limitedphytoplankton consumer controlled resource limited
Mar. Ecol. Prog. Ser. 225, 53-63
Green world hypothesis
The “Biological Pump”The “Biological Pump”The Biological PumpThe Biological Pump
Export
No simple relationship with primary production
Much export occurs during bloom events
Is related to ecosystem structure
Active flux
Bianchi et al. (2013)
Detritus turnover
A d d T (2010)Anderson and Tang (2010)
Role of zooplankton in marine ecosystemsRole of zooplankton in marine ecosystemsand modelling perspectives
Introduction: bottom up (BU) vs top down (TD) control of marine ecosystems
Zooplankton control of phytoplankton blooms Zooplankton control of phytoplankton blooms
Zooplankton control of plankton community structure
Modelling zooplankton: state-of-the-art
Plankton stocks are a balance of opposing forces :accumulation and degradation, consumption and regenerationaccumulation and degradation, consumption and regeneration
(Riley, 1941)
Pgrowth grazing Gordon Riley
Ph (1 k z )L LpI0
= (Ph – R – G)PdPdt
Ph = (1-e-k.zeu)LNLVpI0kzeu
TR = R0erT
photosynthesis grazingG = gZ
Riley (1946)
respiration
Riley (1946)
Georges Bank simulationg
P ZP, Z
monthmonth
maximum growth and grazing rates
MEDUSA
0.5 d-1
2.0 d-1
1 7 d 11.7 d-11.6 d-1
Yool et al. (2010, 2013)
Annual cycle of mixed layer depthAnnual cycle of mixed layer depth
India 60N 20W
KERFIX 50S 68E
India 60N 20W
KERFIX 50S 68E
60N 20W planktondiatoms mesozooplankton
60N 20W planktonnon-diatoms microzooplankton
plankton biomassl N
m-3
mm
ol
growth60N 20W plankton
g
grazingd-1
non-diatoms diatoms
60N 20W planktondiatoms mesozooplankton
no grazing planktonnon-diatoms microzooplankton
plankton biomassl N
m-3
mm
ol
India 60N 20W
KERFIX 50S 68E
Kerfix planktondiatoms mesozooplankton
Kerfix planktonnon-diatoms microzooplankton
plankton biomassl N
m-3
mm
ol
growth
Kerfix planktong
grazingd-1
non-diatoms diatoms
Kerfix planktondiatoms mesozooplankton
Kerfix,no grazing
planktonnon-diatoms microzooplankton
plankton biomassl N
m-3
mm
ol
grazingplankton
no grazing
grazing
non diatoms it tnon-diatoms nitrate
ol N
m-3
mm
o
Role of zooplankton in marine ecosystemsRole of zooplankton in marine ecosystemsand modelling perspectives
Introduction: bottom up (BU) vs top down (TD) control of marine ecosystems
Zooplankton control of phytoplankton blooms Zooplankton control of phytoplankton blooms
Zooplankton control of plankton community structure
Modelling zooplankton: state-of-the-art
PlankTOM5
li h hmixed
coccolithophores diatomsphytoplankton
dissolveddissolvedorganic matter PO4 Fe SiO3
microzooplankton mesozooplanktonsmalldetritus
largedetritus
1 0
0.8
1.0 BS
IvMM
ntak
e, d
-1
0 4
0.6MM
in
0.2
0.4
0 1 2 3 40.0
prey densityprey density
diatoms mg chl m-3diatoms, mg chl m
March MayMM March-May B
0 60.6
0
S IV
(Anderson at al., 2010)
Rosie Fisher (yesterday):
“The juxtaposition of numerous complex models createsTh i l f h l i l b h i ”The potential for pathological behaviour”
coccolithophores mg chl m-3coccolithophores, mg chl m
March MayMM March-May B
0.4
0
S IV
(Anderson at al., 2010)
microzooplankton mmol C m-3microzooplankton, mmol C m
March MayMM March-May B
0.8
0
S IV
(Anderson at al., 2010)
mesozooplankton mmol C m-3mesozooplankton, mmol C m
March MayMM March-May B
5
0
S IV
(Anderson at al., 2010)
Primary production g C m-2 d-1Primary production, g C m d
March MayMM March-May B
0.5
0
S IV
(Anderson at al., 2010)
export g C m -2 d-1export g C m d
March MayMM March-May B
0.2
0
S IV
(Anderson at al., 2010)
Role of zooplankton in marine ecosystemsRole of zooplankton in marine ecosystemsand modelling perspectives
Introduction: bottom up (BU) vs top down (TD) control of marine ecosystems
Zooplankton control of phytoplankton blooms Zooplankton control of phytoplankton blooms
Zooplankton control of plankton community structure
Modelling zooplankton: state-of-the-art
Trophic transferingested
substrates
assimilationcosts
pelletsassimilation CO2
assimilated digestionsubstrates
moultmaintenance CO2 PO4
basal metabolism
maintenance
remainingsubstrates
protein turnover
t f
newbiomassproduction CO2
release
costs ofgrowth
growth (incl. reproduction)
excess C,P CO2 orDOC
PO4 orDOP
Nit C b
pelletsCO2,NH4
Anderson & Hessen 95 ERSEM Anderson & Hessen 95 ERSEM
Nitrogen Carbon growth
1
0
frac
tion
Pahlow 03 Pahlow 03
0
1
n
0
frac
tion
Anderson et al. 05 HadOCC Anderson et al. 05 HadOCC1
on
food C/N4 20 food C/N4 20 food C/N4 20 food C/N4 200
frac
tio
food C/N4 20 food C/N4 20 food C/N4 20 food C/N4 20
Anderson et al. (in press)
Anderson et al. (in press)
1.0 B
-1
0.8
BS
IvMM
inta
ke, d
-
0.4
0.6i
0.2
0 1 2 3 40.0
prey density
Loss terms and closure
Complex models
ocean surface
Complex models
zooplanktongrazing
phytoplankton
ocean surface
euphotic zone NPP
microzooplankton mesozooplankton
g g
defecation
coccolithophores diatomsmixed
phytoplankton
“messy isinking
nutrients non-living organic matter
excretiondefecation,mortalityuptake
remineralisation
messyfeeding” grazing
mortality
sinking
PO4 Fe SiO3dissolved
organic mattersmall
detrituslarge
detritus
deep ocean mixing mixing sinking
Poorly understood ecology
ingestedsubstrates
assimilation
pelletsassimilation CO2
costsassimilatedsubstrates
digestion
basal metabolism
moultmaintenance CO2
remaining
PO4
protein turnovergsubstrates
p
newbiomassproduction CO2
costs ofgrowth
biomassproduction
growth (incl reproduction)release
excess C,P CO2 orDOC
PO4 orDOP
growth (incl. reproduction)
Aggregation
Simplification
Calanus finmarchicus life history
All in the interactions
coccolithophores mg chl m-3coccolithophores, mg chl m
MM March-May B
S IVV
Lack of validation
Insufficient data
Too many free parameters
“What little validation is undertaken will always tend to overstate the case for belief in the model results”
(Wainwright, 2003)
Conclusions
BU and TD combine to determine ecosystem structure andassociated fluxes such as export
The key is to understand the coupling of phytoplankton andl k di d b h i l izooplankton as mediated by physical environment
M d l k bl i i h i i f Models are remarkably sensitive to the parameterisation of zooplankton
The parameterisation of zooplankton in models is fraught withdifficulty, especially in complex models