Download Frank et al. 2005

Open Pelagic Ecosystems
Brad deYoung
Roadmap
 Ecosystem structure – considerations of the issues and how to think
about them
 Regime shifts in the ocean – examples of some observed behaviour
that we do not quite understand
 Variability and modelling of marine ecosystems, some examples
Food web structure, and model structures?
Simplified life history
model or data
Top down view
more life history
driven >> structured
models
Challenge : With a
target species focus
coupleare
structured
All to
models
wrong,
(even ifare
not
butmodels
some models
IBM) and
predators
useful.
George
Box
and prey below
which may have
different model
structures
or data
Bottom
up view
more process
driven – represent
metabolism, massbalance
Structured population
model
Mass balance models
–NPpZzD …
Nutrient Pool
What criteria do we use to simplify our
ecosystem food web? Selection of target
species
A mixture of theory, observation and pragmatism
 Functionally important/ecologically significant
 Extensive data sets (spatial and temporal)
 Choose a food web in which the first PCA contains relatively few
species
 Concurrence with other relevant data sets
 Understanding of life history
 Widely distributed/across the basin
 Economic and societal importance
 Well resolved taxonomy
 …
Modelling can be driven by

data exploration (see right)

process exploration

forecast simulations
Low frequency changes are
more important than we once
thought
The long-period changes lead
to larger spatial scales >>
basins
Shifts in physical (temperature,
mixed layer depth, …) and
biological properties
(phytoplankton,
zooplankton,…)
Chavez et al. Science (2002)
Trophic complexity – maintaining fidelity to life history as it becomes
more complex and also more difficult to model
Predation
Trophic level
Top predators
Key
taxa
Bacteria
Feeding
Probable number
of species
Number of state
variables
Detail of resolution
ICES - Report of the Study Group on spatial and temporal integration, University of Strathclyde, Glasgow,
Scotland, 14-18 June 1993. ICES CM 1993/L:9, (1993).
Physical Ocean
Trophic level
Predators
Zooplankto
n/fisheries
focus
Life History
Without
Life History
Phytoplankton/
nutrient focus
Chemistry
Functional Complexity
deYoung et al. Science. 2004
Zooplankton
Focus
Top-down predation
Challenge lies
in coupling the
structured and
unstructured
models and
data
Fish - myctophids, redfish,
herring, blue whiting;
Zooplankton - gelatinous,
euphausiids
Fish - sandlance, capelin,
herring, sprat, mackerel,
Norway put, blue whiting;
Zooplankton - gelatinous,
euphausiids
Zooplankton – Structured population
representations of key basin
distributed species – variously,
particularly congeneric Calanus spp.,
euphausiids
Unstructured
competitors
for structured
zooplankton
Food for zooplankton: Microzooplankton,
diatoms, non-diatoms, Phaeocystis
Physics and chemistry – high resolution large scale
circulation, coupling between global, basin and shelf models
Coupling with the
structured
components will
likely be one-way
First Order Horizontal
Structure
Low frequency ‘cycles’ are not likely as linear as they may appear
 linear shifts, i.e.
nothing special
happening
 abrupt shifts but
reversible in principle
 non-linear shifts that
are not easily
reversible
 how linear is the
fundamental behaviour
that we are trying to
represent?
Anderson et al. TREE 2008
deYoung et al. Prog. Ocgy. ( 2004), TREE 2008
DEFINITION OF THE REGIME SHIFT
Working definition : a regime shift is a relatively abrupt
change between contrasting persistent states in an ecosystem
Environmental state
Erosion of resilience
Erosion of resilience
Environmental driver
Review of a few examples of regime
shifts in pelagic ecosystems
• Scotian Shelf – driven primarily by fishing, cascading
trophic impacts
• North Sea – combined drivers: natural=biogeographic
shift and human=fishing
• North Pacific – complex natural state change(s)
Explore characteristics of the drivers and response of
differing examples – time and space scales, trophic
structure, predictability
-30%
+30%
Scotian Shelf – Frank et al. 2005
Colour display of 60+ indices
for Eastern Scotian Shelf
Grey seals - adults
Pelagic fish - #’s
Pelagic:demersal #’s
Pelagic:demersal wt.
Inverts - $$
Pelagics - wt
Diatoms
Grey seals – pups
Pelagics - $$
Greenness
Dinoflagellates
Fish diversity – richness
3D Seisimic (km2)
Gulf Stream position
Stratification anomaly
Diatom:dinoflagellate
Sea level anomaly
Volume of CIL source water
Inverts – landings
Bottom water < 3 C
Sable winds (Tau)
SST anomaly (satellites)
chlorophyll – CPR
Temperature of mixed layer
NAO
Bottom T – Emerald basin
Copepods – Para/Pseudocal
Shelf-slope front position
Storms
Bottom T – Misaine bank
Groundfish landings
Haddock – length at age 6
Bottom area trawled (>150 GRT)
Cod – length at age 6
Average weight of fish
Community similarity index
PCB’s in seal blubber
Relative F
Pollock – length at age 6
Calanus finmarchicus
Groundfish biomass – RV
Pelagics – landings
Silver hake – length at age
Condition – KF
Depth of mixed layer
Condition – JC
Proportion of area – condition
RIVSUM
Sigma-t in mixed layer
Oxygen
Wind stress (total)
Wind stress (x-direction)
Wind stress amplitude
SST at Halifax
Groundfish - $$
Salinity in mixed layer
Ice coverage
Wind stress (Tau)
Number of oil&gas wells drilled
Nitrate
Groundfish fish - #’s
Shannon diversity index –fish
Seismic 2D (km)
Grey seals, pelagic fish
abundance, invertebrate
landings, fish species
richness, phytoplankton
Red –
below
average
Green –
above
average
Bottom temp., exploitation,
groundfish biomass &
landings, growth-CHP, avg.
fish weight, copepods
1970
1975
1980
1985
1990
1995
2000
Scotian
Shelf – top
down story
Top Predators
+
(Piscivores)
Forage (fish+inverts)
-
(Plankti-,Detriti-vores)
Zooplankton
+
(Herbivores)
Phytoplankton
Frank et al. 2004/2005
Science et al.
(Nutrivores)
North Pacific regime shift – Hare and
Mantua (2000)
Physical
forcing – air
temperature but there are
dozens, and
dozens of
other such
time series
The technique of Hare and Mantua has been
criticized as being subject to false positives –
taking the normalized variance anomalies of many
different time series with red spectra can lead to
‘apparent’ shifts
The lack of sufficient clear data is one problem
The time series are too short
The regimes are likely never completely in
equilibrium
Many different possible states are likely
Anderson et al. Reviewed the different
approaches, and confirm the basic result of Hare
and Mantua
North Sea regime shift – a mixture of
biogeography, environmental change and fishing
Line in black: warm-temperate species
Line in red: temperate species
60
55
50
-10
-5
Before 1980
12
11
M 10
North Sea
O 9
8
N 7
France
T 6
5
0
10
H 5
S 4
3
2
After 1980
1
5
4.5
4
3.5
3
2.5
2
1.5
1
Mean number of species
per CPR sample
58 62 66 70 74 78 82 86 90 94 98
Years
Mean number of calanoid
species per CPR sample
Second principal
component (31.36%)
3
2
1
0
-1
-2
-3
3
Gadoid species (cod)
4
2
Flatfish
0
-2
-4
plankton change
plankton change
1
No match for any of the
calanoid copepod assemblages
0
-1
-2
2
SST
2
Mean umber of
species per assemblage
Second principal
component (31.36%)
Mean umber of
species per assemblage
2
salinity
3
2
1
0
-1
-2
-3
3
2
1
0
-1
-2
2
SST
(central North Sea)
1
0
-1
-2
NHT anomalies
0.8
0.4
0
-0.4
SST
(central North Sea)
58
66
70
74 78 82 86 90
Years (1958-1999)
94
98
1
1
0
0
-1
-1
-2
-2
0.8
NHT anomalies
62
NHT anomalies
Westerly wind
2
0.4
1
0
0
-1
-0.4
58 62 66 70 74 78 82 86 90 94 98
Years (1958-1999)
-2
58 62 66 70 74 78 82 86 90 94 98
Years (1958-1999)
Standard deviate
1.6
1.2
0.8
0.4
0
-0.4
-0.8
-1.2
-1.6
-2
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
Beaugrand G (2004) Progress in Oceanography
Standard deviate
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2
1.6
1.2
0.8
0.4
0
-0.4
-0.8
-1.2
-1.6
-2
-2.4
Calanoid copepods
Beaugrand & Ibanez (in press, MEPS)
Fi sh tota l biomass (5 species)
Calanoid copepods
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
Standard deviate
2
1.6
1.2
0.8
0.4
0
-0.4
-0.8
-1.2
-1.6
-2
-2.4
Beaugrand G (2004) Progress in Oceanography
1.6 Fish tota l biomass (5 species)
1.2 Ca la no id copepods (17 i ndicato rs)
0.8
0.4
0
-0.4
-0.8
-1.2
-1.6
-2
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
Standard deviate
Beaugrand & Ibanez (in press, MEPS)
Long-term changes in the abundance
of two key species in the North Sea
80%
C. finmarchicus
60%
40%
20%
0%
C. helgolandicus
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
Percentage of
C. helgolandicus
100%
Reid et al. (2003)
Consequences of plankton changes on higher
trophic level
Mismatch between the timing of calanus prey and larval cod
Abundance of C. finmarchicus
1.4
1.2
1.0
0.8
0.6
0.4
0.2
Gadoid Outbu rst
60 65 70 75 80 85 90 95
12
11
10
9
8
7
6
5
4
3
2
1
Ga doid Outburst
60 65 70 75 80 85 90 95
Beaugrand, et al. (2003) Nature. Vol. 426. 661-664.
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
Abundance (in log 10(x+1))
1.6
Abundance (in log 10(x+1))
12
11
10
9
8
7
6
5
4
3
2
1
Abundance of C. helgolandicus
1
0.8
0.6
0.4
0.2
300
1960
biomass ('000T)
But there is also a
significant
influence of
fishing – how
much??
250
200
150
1970
1980
Year
1990
Propn. of eggs from ag
Fishing mortality rate (
North Sea - dynamics
Biogeographic shift
Meteorological/oceanographic
forcing
Fishing
Ecosystem status
and function
Seasonal sea surface temperature anomalies over
the North Atlantic for 2006
From the NOAA Optimum
Interpolation SSTv2
dataset, provided by the
NOAA-CIRES Climate
Diagnostics Center, USA.
The anomaly is calculated
with respect to normal
conditions for the period
1971–2000. The data are
produced on a one-degree
grid from a combination of
satellite and in situ
temperature data. Regions
with ice over for >50% of
the averaging period are
left blank.
ICES Report on Ocean Climate 2006. Prepared by the Working Group on Oceanic
Hydrography Sarah L. Hughes and N. Penny Holliday, Editors. ICES cooperative research
report no. 289 special issue September 2007 (from Figure 4).
Biological consequences expected under climatic warming
Or changes in water mass structure.
• Changes in the range and spatial distribution of species.
• Shifts in the location of biogeographical boundaries, provinces,
and biomes.
• Change in the phenology of species (e.g. earlier reproductive season).
• Modification in dominance (e.g. a key species can be replaced by
another one).
• Change in diversity.
• Change in other key functional attributes for marine ecosystems.
• Change in structure and dynamics of ecosystem with possible
regime shifts.
Expected Result: Major impact for marine exploited resources and biogeochemical processes (e.g. sequestration of CO2 by the ocean).
Long-term changes in the mean number of species per assemblage
based on three periods: 1958-1981, 1982-1999, and 2000-2002.
Warm-water
species have
extended their
distribution
northwards by
more than 10° of
latitude, while
cold-water species
have decreased in
number and
extension.
(Beaugrand, G. ICES Journal of Marine Science, 62: 333-338 (2005)
Calanus finmarchicus in the North Atlantic
- open ocean, deep and shallow, spreads out onto shelf, for some species some
evidence for genetic separation, copepods key organisms for food web, coupled
with circulation
Diapause depth – how deep do they
go?
70
65
60
55
50
-60
-50
-40
-30
-20
-1800
Heath et al. (2004)
-10
-1400
0
-1000
10
-600
-200
Median depth (m below sea surface)
Calanus in the Labrador Sea
Biological model – with a lot of
detail on copepod development and
growth – in this case the numerical
organism eats satellite (SeaWifs)
chlorphyll data
Non-diapausing
individuals
The physical model represents the
seasonal circulation in the Labrador
Sea and the organisms are carried
around in it
In the vertical the zooplankton
behaviour determines their position
 Population achieves maximum
growth rate when emergence is
1 month prior to the spring
bloom
 Timing of population peaks is
closely matched observations
Diapausing
individuals
Phytoplankton
Temperature
Tittensor et al. Fish. Ocgy. 2004
Advection

Latitudinally
dependent
emergence, starting in
South (March) and
later to the North
(May)

only start out in water
> 1000m deep (none
on the shelf)

results in a peak in
the centre of the
Labrador Sea

some Calanus move
up onto the shelf

Locally sustainable
population
January
July
May
November
Tittensor et al. Fish. Ocgy. 2004
Model design for the North Atlantic Calanus
problem – Heath, Speirs, Gurney et al. (2005)
Use the model to test different hypotheses of diapause – a process for
which we have no direct process model
Entry
Exit
H1
Low food
Development at
depth
H2
Low food
Photoperiod
OWS Mike - hypothesis test
Surface
Copepodites
Diapausers
H1
H1
H3
H3
Newly surfaced
overwinterers
Sharp drop at
awakening
No diapausers
in spring
Long-term spatial structure and advection through
the basin
 Preliminary conclusion is hat
biology dominates over
circulation
Year 1
 Requires some ‘adjusting’
different parts of the basin
Year 3
 Is able to reproduce the
population dynamics at the
basin scale – for the first
time.
Year 6
Speirs et al. Fish. Ocgy. (2005)
If god had consulted me before embarking on the creation, I would
have suggested something simpler.
Alfonso of Castile (15th century)