Delft3D Phytoplankton modelling: Concepts of BLOOM€¦ · Delft3D Phytoplankton modelling:...
Transcript of Delft3D Phytoplankton modelling: Concepts of BLOOM€¦ · Delft3D Phytoplankton modelling:...
Delft3D Phytoplankton modelling:
Concepts of BLOOM
Hans Los
Deltares Webinar
March 2016
Overview of Webinar
1. Role of primary producers
2. Position of BLOOM in Delft3D modeling suite
3. Concepts of BLOOM (overview)
4. Competition principle (detail)
5. Existing knowledgebase
6. Some validation results
7. Summary and advise for further reading
Aquatic Ecosystem
Aquatic Ecosystem
• Physical processes
• Exchange atmosphere
• Sedimentation, resuspension
• Horizontal water movement
• Possibly stratification
• Seasonality
Aquatic Ecosystem
• Physical processes
• Exchange atmosphere
• Sedimentation, resuspension
• Horizontal water movement
• Possibly stratification
• Seasonality
• Foodweb (eating and being
eaten)
Aquatic Ecosystem: driven by Primary Production
• Physical processes
• Exchange atmosphere
• Sedimentation, resuspension
• Horizontal water movement
• Possibly stratification
• Seasonality
• Foodweb (eating and being
eaten)
• Main driver: primary production
by phytoplankton using Solar
energy and CO2 giving sugar and
O2
Trophic state depends on nutrients
Trophic state depends on nutrients
DELWAQ - BLOOM: nutrients and primary production
• For historic reasons, many different names circulate in papers and
reports such as
• DBS (fresh water mode)
• GEM (marine mode)
• ECO
• DWAQ
• DELWAQ – BLOOM
• DELWAQ(D3D)-BLOOM consists of one generic code for fresh
and marine applications.
• Some differences in selected processes and coefficient values
particularly in definition of phytoplankton species
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
6. The mathematical method employed in the model prevents
numerical oscillations or instabilities under all circumstances
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
6. The mathematical method employed in the model prevents
numerical oscillations or instabilities under all circumstances
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
• Competition between phytoplankton types is the guiding principle in BLOOM
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
• Competition between phytoplankton types is the guiding principle in BLOOM
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
• Competition between phytoplankton types is the guiding principle in BLOOM
• BLOOM selects the optimum composition based on the ratio of the net growth rate and the requirements for each environmental resource
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
• Competition between phytoplankton types is the guiding principle in BLOOM
• BLOOM selects the optimum composition based on the ratio of the net growth rate and the requirements for each environmental resource
• Trade-off between growth and requirement:
• Relatively high potential growth rates may compensate a relatively large requirement
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
• Competition between phytoplankton types is the guiding principle in BLOOM
• BLOOM selects the optimum composition based on the ratio of the net growth rate and the requirements for each environmental resource
• Trade-off between growth and requirement:
• Relatively high potential growth rates may compensate a relatively large requirement
opportunistic species win when light is high…
Process formulations BLOOM (1): competition
• BLOOM is a multi-species phytoplankton model
• Competition between phytoplankton types is the guiding principle in BLOOM
• BLOOM selects the optimum composition based on the ratio of the net growth rate and the requirements for each environmental resource
• Trade-off between growth and requirement:
• Relatively high potential growth rates may compensate a relatively large requirement
…efficient species win when there is little light
opportunistic species win when light is high…
Process formulations BLOOM (2): general
• BLOOM considers various (3 to 20) algal species (groups), including some nuisance algae
Process formulations BLOOM (2): general
• BLOOM considers various (3 to 20) algal species (groups), including some nuisance algae (e.g. Phaeocystis,
Process formulations BLOOM (2): general
• BLOOM considers various (3 to 20) algal species (groups), including some nuisance algae (e.g. Phaeocystis, Microcystis
Process formulations BLOOM (2): general
• BLOOM considers various (3 to 20) algal species (groups), including some nuisance algae (e.g. Phaeocystis, Microcystis or Ulva)
Process formulations BLOOM (2): general
• BLOOM considers various (3 to 20) algal species (groups), including some nuisance algae (e.g. Phaeocystis, Microcystis or Ulva)
• Every species (group) has its own:
• growth response to light conditions
Process formulations BLOOM (2): general
• BLOOM considers various (3 to 20) algal species (groups), including some nuisance algae (e.g. Phaeocystis, Microcystis or Ulva)
• Every species (group) has its own:
• growth response to light conditions
• growth response to temperature
Process formulations BLOOM (2): general
• BLOOM considers various (3 to 20) algal species (groups), including some nuisance algae (e.g. Phaeocystis, Microcystis or Ulva)
• Every species (group) has its own:
• growth response to light conditions
• growth response to temperature
• growth response to available nutrients
• stochiometry (composition in C, N, P,
Chlorophyll)
• Depending on environmental conditions
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
6. The mathematical method employed in the model prevents
numerical oscillations or instabilities under all circumstances
Process formulations BLOOM (3): types
• Variability of stochiometry is modelled as a distinction of the species in 3 types:
• a nitrogen limited type
• a phosphorus limited type
• an energy limited type
Process formulations BLOOM (3): types
• Variability of stochiometry is modelled as a distinction of the species in 3 types:
• a nitrogen limited type
• a phosphorus limited type
• an energy limited type
• Every type has a constant stochiometry
• The model computes the optimal combination of types
• Different types of same species may be present at the same time (any linear combination of types is possible: variable stochiometry)
• Types can instantaneously convert into each other, (groups of) species can’t (adaptation occurs rapidly, succession takes more time: days or weeks)
Process formulations BLOOM (4): energy
• At sufficient (= not limiting) availability of nutrients, light and temperature become the limiting factors
• Analogous to nutrients the available ‘amount’ of light is
calculated
• A ‘critical light efficiency’ is reached when growth averaged over
depth equals all losses:
Process formulations BLOOM (4): energy
• At sufficient (= not limiting) availability of nutrients, light and temperature become the limiting factors
• Analogous to nutrients the available ‘amount’ of light is
calculated
• A ‘critical light efficiency’ is reached when growth averaged over
depth equals all losses:
• This threshold varies:
• per species
• in time and space
TiTiIcrTi RespMorteffPPmax ,,,, *
Process formulations BLOOM (4): energy
• Blue line: growth vs depth
• Green line: mortality + respiration
vs depth
Process formulations BLOOM (4): energy
• Blue line: growth vs depth
• Green line: mortality + respiration
vs depth
• Low extinction
Positive net growth
Surplus Energy
Process formulations BLOOM (4): energy
• Blue line: growth vs depth
• Green line: mortality + respiration
vs depth
• Critical extinction
Positive net growth
Surplus Energy
Zero net growth
Energy Limitation
TiTiIcrTi RespMorteffPPmax ,,,, *
Process formulations BLOOM (4): energy
• Blue line: growth vs depth
• Green line: mortality + respiration
vs depth
• Extinction too high
Positive net growth
Surplus Energy
Zero net growth
Energy Limitation
Negative net growth
Energy shortage
Process formulations BLOOM (4): energy
• Blue line: growth vs depth
• Green line: mortality + respiration
vs depth
• Extinction too high
• Note: Under stratified conditions,
depth gets smaller, hence higher
potential biomass
Positive net growth
Surplus Energy
Zero net growth
Energy Limitation
Negative net growth
Energy shortage
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
6. The mathematical method employed in the model prevents
numerical oscillations or instabilities under all circumstances
Time averaging in BLOOM
• Growth (= biomass increase) has a characteristic time of about 24
hours
• Note that this is not photosynthesis (= production of energy stored
as sugar), which reacts quickly to changes in light
• Photosynthesis is an instantaneous process
• Growth is a time-averaged process
• The light response curves of photosynthesis and growth are not
the same
• So apart from computational aspects, there is also a fundamental
argument to use a relatively long 1 day time step as the default for
BLOOM
Depth averaging in BLOOM
• 2D (vertically averaged) models:
mixing depth = actual depth
• 1Dv / 3D models:
mixing depth ≠ segment depth: during 24 hours algae
usually visit several vertical layers
• This conflicts with DELWAQ’s usual procedure to
compute process rates in segments independently from
other segments during ∆t
• To deal with this, tracers are introduced in every
vertical layer at the start of the BLOOM time step
• The probability distribution of these tracers is computed
for each layer based on vertical transports
• Based on the mixing pattern of the tracers, the depth
averaged light regime is computed
dep
th
Fate of tracers tropical reservoir model (1)
Vertical distribution tracer layer 4 in a 7 layer model after 24 hours
Fate of tracers tropical reservoir model (2)
Vertical distribution tracer layer 1-7 in a 7 layer model after 24 hours
Graph for location STN.3 (1), STN.3 (2), STN.3 (3), STN.3 (4), STN.3 (5), STN.3 (6), STN.3 (7)
FRACTIME01 05 Jul 05 00:00
FRACTIME02 05 Jul 05 00:00
FRACTIME03 05 Jul 05 00:00
FRACTIME04 05 Jul 05 00:00
FRACTIME05 05 Jul 05 00:00
FRACTIME06 05 Jul 05 00:00
FRACTIME07 05 Jul 05 00:00
STN.3 (1)
STN.3 (2)
STN.3 (3)
STN.3 (4)
STN.3 (5)
STN.3 (6)
STN.3 (7)
FRACTIME01
1
0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
Fate of tracers tropical reservoir model (3)
3 year simulation of all tracers in layer 1
Graph for location STN.3 (1)
FRACTIME01 STN.3 (1) FRACTIME02 STN.3 (1) FRACTIME03 STN.3 (1) FRACTIME04 STN.3 (1) FRACTIME05 STN.3 (1)
FRACTIME06 STN.3 (1) FRACTIME07 STN.3 (1)
DecNovOctSepAugJulJunMayAprMarFebJanDecNovOctSepAugJulJunMayAprMarFebJanDecNovOctSepAugJulJunMayAprMarFebJan
FR
AC
TIM
E01
1
0
Fate of tracers tropical reservoir model (3)
Little mixing
Graph for location STN.3 (1)
FRACTIME01 STN.3 (1) FRACTIME02 STN.3 (1) FRACTIME03 STN.3 (1) FRACTIME04 STN.3 (1) FRACTIME05 STN.3 (1)
FRACTIME06 STN.3 (1) FRACTIME07 STN.3 (1)
DecNovOctSepAugJulJunMayAprMarFebJanDecNovOctSepAugJulJunMayAprMarFebJanDecNovOctSepAugJulJunMayAprMarFebJan
FR
AC
TIM
E01
1
0
Fate of tracers tropical reservoir model (3)
Strong mixing
Graph for location STN.3 (1)
FRACTIME01 STN.3 (1) FRACTIME02 STN.3 (1) FRACTIME03 STN.3 (1) FRACTIME04 STN.3 (1) FRACTIME05 STN.3 (1)
FRACTIME06 STN.3 (1) FRACTIME07 STN.3 (1)
DecNovOctSepAugJulJunMayAprMarFebJanDecNovOctSepAugJulJunMayAprMarFebJanDecNovOctSepAugJulJunMayAprMarFebJan
FR
AC
TIM
E01
1
0
Depth profile phytoplankton species deep region
Simulated actual depth profile also depends on other factors!
Depth profile phytoplankton species deep region
Simulated actual depth profile also depends on other factors!
Insufficient
nutrients
Insufficient
light
Current development
• Present tracer approach confined to vertical excursions, which
results in some inaccuracies in
• Systems with tidal flats
• Deep lakes with confined, shallow areas (near beaches)
• We now have a beta model version considering both horizontal
and vertical tracer movements
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
6. The mathematical method employed in the model prevents
numerical oscillations or instabilities under all circumstances
Competition: 2 types, 1 nutrient
• X-axis: biomass Alg1
• Y-axis: biomass Alg2
Competition: 2 types, 1 nutrient
• X-axis: biomass Alg1
• Y-axis: biomass Alg2
• DIN requirement per unit
of biomass (first
competition criterion:
Alg2 is more efficient):
• Alg1 = 0.07
• Alg2 = 0.05
Competition: 2 types, 1 nutrient
• X-axis: biomass Alg1
• Y-axis: biomass Alg2
• DIN requirement per unit
of biomass (first
competition criterion:
Alg2 is more efficient):
• Alg1 = 0.07
• Alg2 = 0.05
• Green: sufficient DIN
Competition: 2 types, 1 nutrient
• X-axis: biomass Alg1
• Y-axis: biomass Alg2
• DIN requirement per unit
of biomass (first
competition criterion:
Alg2 is more efficient):
• Alg1 = 0.07
• Alg2 = 0.05
• Green: sufficient DIN
• Orange line: DIN = 0
(limiting)
Competition: 2 types, 1 nutrient
• X-axis: biomass Alg1
• Y-axis: biomass Alg2
• DIN requirement per unit
of biomass (first
competition criterion:
Alg2 is more efficient):
• Alg1 = 0.07
• Alg2 = 0.05
• Green: sufficient DIN
• Orange line: DIN = 0
(limiting)
• Orange: insufficient DIN
Competition: 2 types, 1 nutrient
• Equal growth rate 0.5
per day (second
competition criterion)
• Grey line: growth rates
• Alg1 = Alg2 = 0.0
Competition: 2 types, 1 nutrient
• Only Alg1 present, not
yet optimal
Competition: 2 types, 1 nutrient
• Competition criterion:
Growth divided by
requirement so
• 0.5/0.05 > 0.5/0.07
• Alg2 (= small nutrient
requirement) wins
Competition: 2 types, 1 nutrient
• Growth rate (Alg1 rapid
grower):
• Alg1 = 0.8 d-1
• Alg2 = 0.5 d-1
• Angle grey line shifted
• DIN requirement per unit
of biomass (Alg2 is more
efficient):
• Alg1 = 0.07
• Alg2 = 0.05
• Alg1 = Alg2 = 0.0
Competition: 2 types, 1 nutrient
• Only Alg2 present, not
yet optimal
Competition: 2 types, 1 nutrient
• Competition criterion:
0.5/0.05 < 0.8/0.07
• Alg1 (= fastest growing)
wins
• Potential biomass Alg2 >
Alg1
Competition: 2 types, 2 nutrients
• DIN requirement:
• Alg1 < Alg2
• PO4 requirement:
• Alg2 < Alg1
• Green: sufficient DIN
and PO4
• Orange line: DIN = 0
Blue line: PO4 = 0
• Other areas: insufficient
DIN or PO4 or both
Competition: 2 types, 2 nutrients
• Equal growth rate 0.5
per day (second
competition criterion)
• Alg1 = Alg2 = 0.0
Competition: 2 types, 2 nutrients
• Only Alg2 present, PO4
limiting, not yet optimal
Competition: 2 types, 2 nutrients
• Only Alg1 present, DIN
limiting, not yet optimal
Competition: 2 types, 2 nutrients
• Alg1 present and limited
by DIN
• Alg2 present and limited
by PO4
• Two most efficient types
win
Transient conditions in BLOOM
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
• So far resource
limitations
Transient conditions in BLOOM
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
• So far resource
limitations
• It takes about 2 weeks to
get growth started
Transient conditions in BLOOM
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
• So far resource
limitations
• It takes about 2 weeks to
get growth started
• And another 2 weeks to
reach nutrient limited
spring bloom
Transient conditions in BLOOM
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
• So far resource
limitations
• It takes about 2 weeks to
get growth started
• And another 2 weeks to
reach nutrient limited
spring bloom
• How does BLOOM deal
with this?
Growth and mortality as limitations
•At the beginning of the
growing season,
• Alg1 = Alg2 = 0.0
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
Growth and mortality as limitations
•After 1 week
• Alg1 > 0.0
• Alg2 > 0.0
•Maximum biomass increase
over time is restricted
•We call this ‘growth’ limitation
•BLOOM records growth (and
mortality) limitations per
individual species
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
Growth and mortality as limitations
•After 3 weeks biomasses of
both algae have further
increased
•Still growth limitation
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
Growth and mortality as limitations
•After 4 weeks resource
limitation
•Alg1 present and limited by
DIN
•Alg2 present and limited by
PO4
Graph for location NZR9TS135
Chlora NZR9TS135
19-May12-May05-May28-Apr21-Apr14-Apr07-Apr31-Mar24-Mar17-Mar10-Mar03-Mar24-Feb17-Feb10-Feb03-Feb27-Jan
Chlo
ra
8
7
6
5
4
3
2
1
0
Growth and mortality as limitations
• Mortality limitations delimit the
disappearance rate similar to
growth
Growth and mortality as limitations
• Mortality limitations delimit the
disappearance rate similar to
growth
• Growth and mortality limitations
also occur as a result of spatial
gradients in depth, nutrients etc.
Growth and mortality as limitations
• Mortality limitations delimit the
disappearance rate similar to
growth
• Growth and mortality limitations
also occur as a result of spatial
gradients in depth, nutrients etc.
Preferred
Alg1 Alg2
Growth and mortality as limitations
• Mortality limitations delimit the
disappearance rate similar to
growth
• Growth and mortality limitations
also occur as a result of spatial
gradients in depth, nutrients etc.
• Mixing between spatially diverse
areas operates like time: it
extends the necessary period
for reaching resource limited
conditions
Preferred
Alg1 Alg2
Growth and mortality as limitations
• Mortality limitations delimit the
disappearance rate similar to
growth
• Growth and mortality limitations
also occur as a result of spatial
gradients in depth, nutrients etc.
• Mixing between spatially diverse
areas operates like time: it
extends the necessary period
for reaching resource limited
conditions
• Similarly (heavy) grazing by
shell fish also results in
prolonged growth limitations
Preferred
Alg1 Alg2
Practise
•In practise BLOOM considers all
types and all limitations
simultaneously
•More difficult to visualize
•But same principle
Limitations and types in practise
• At station Noordwijk 10 (North Sea)
• Energy is limiting during the winter
half year
Limitations and types in practise
• At station Noordwijk 10 (North Sea)
• Energy is limiting during the winter
half year
•Accordingly BLOOM selects E
limited types in winter
Limitations and types in practise
• At station Noordwijk 10 (North Sea)
• Energy is limiting during the winter
half year
•Accordingly BLOOM selects E
limited types in winter
•Phosphorus and silicate are main
limitations in summer half year
Limitations and types in practise
• At station Noordwijk 10 (North Sea)
• Energy is limiting during the winter
half year
•Accordingly BLOOM selects E
limited types in winter
•Phosphorus and silicate are main
limitations in summer half year
• In summer half year P types are
dominant
• Usually various species are present:
there is a high species diversity
Limitations and types in practise
• At station Noordwijk 70 (North Sea)
• Energy is limiting during the winter half
year
Limitations and types in practise
• At station Noordwijk 70 (North Sea)
• Energy is limiting during the winter half
year
•Accordingly BLOOM selects E limited
types at beginning spring bloom
Limitations and types in practise
• At station Noordwijk 70 (North Sea)
• Energy is limiting during the winter half
year
•Accordingly BLOOM selects E limited
types at beginning spring bloom
•Nitrogen and silicate are main limitations
in summer half year with some P limitation
late summer
Limitations and types in practise
• At station Noordwijk 70 (North Sea)
• Energy is limiting during the winter half
year
•Accordingly BLOOM selects E limited
types at beginning spring bloom
•Nitrogen and silicate are main limitations
in summer half year with some P limitation
late summer
•In summer half year N types are dominant
with some P types end of summer
• Less diversity compared to NW10
Limitations and types in practise
• At station Noordwijk 70 (North Sea)
• Energy is limiting during the winter half
year
•Accordingly BLOOM selects E limited
types at beginning spring bloom
•Nitrogen and silicate are main limitations
in summer half year with some P limitation
late summer
•In summer half year N types are dominant
with some P types end of summer
• Less diversity compared to NW10
• Notice that strong increase in plankton C
in summer is hardly reflected in chlorophyll
levels due to intrinsic adjustment C /
Chlorophyll ratio by BLOOM
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
6. The mathematical method employed in the model prevents
numerical oscillations or instabilities under all circumstances
Phytoplankton characteristics (1)
• Freshwater model version considers a subset of:
• Diatoms
• Micro flagellates
• Green algae
• Aphanozomenon (optionally as N-fixer)
• Microcystis
• Oscillatoria (Planktotrix)
• Anabaena
• Nodularia
• Cylindrospermopsis (N-fixer)
• Pseudoanabaena
• Chara
• Data on characteristics of many individual species have been obtained from lab cultures of UvA in the 1980s + other literature sources
• Adjustments from numerous model applications
Phytoplankton characteristics (2)
• Marine model version considers a subset of:
• Diatoms
• Micro flagellates
• Dinoflagellates (optionally mixotrophic)
• Phaeocystis
• Ulva
• Benthic diatoms
• Data on characteristics of individual species particularly for
Phaeocystis and diatoms have been obtained from lab cultures
• Some adjustments from model applications North Sea
Phytoplankton characteristics (3)
For each species the database contains type-specific information on:
• Stoichiometric ratios (nutrients; chlorophyll)
• Specific extinction coefficient
• Maximum growth rate
• Light requirement
• Dependency diurnal light pattern
• Mortality rate as a function of temperature and salinity
• Partitioning mortality to autolysis (dissolved nutrients), labile and refractory detritus
• Respiration rate
• Sedimentation rate
BLOOM Highlights
1. It is a true multi species competition model based on an easy
to understand biological principle
2. Phytoplankton species are represented by different types
which allows BLOOM to vary their characteristics as a function
of the environment
3. BLOOM has been applied and validated world wide in a very
large number of fresh, transitional and marine waters
4. The result is a huge knowledge database with default species
characteristics available to every user
5. BLOOM typically operates on a 24 hour time step, which is
characteristic for phytoplankton but it does include diurnal
variations in light even across vertical layers
6. The mathematical method employed in the model prevents
numerical oscillations or instabilities under all circumstances
Calibration & Validation
• First application fresh water model more than 35 years ago,
marine version more than 20 years ago
• Both model versions have been applied very extensively
(worldwide)
• Initially mainly in temperate regions, but many (sub)tropical
application in later years
• The user selects species / types to be included in application
• Usually default coefficients will do, no local tuning required
Validation DBS Lake Veluwe
Simulated species composition Lake Veluwe
Diatoms Greens
Cyanos
Noordwijk 20km 2002 Validation
NZR6NW020 SiO2
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
j f m a m j j a s o n d
[mg/m3]
Mean Median Model Obs2002
NZR6NW020 OPO4
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
j f m a m j j a s o n d
[mg/m3]
Mean Median Model Obs2002
NZR6NW020 NO3
0
0.2
0.4
0.6
0.8
1
1.2
j f m a m j j a s o n d
[mg/m3]
Mean Median Model Obs2002
NZR6NW020 Chlorophyll
0
5
10
15
20
25
30
j f m a m j j a s o n d
[mg/m3]
Mean Median Model Obs2002
Simulated species composition North Sea
Diatoms Phaeocystis
Terschelling transect 2002 March chlorophyll
Chlorophyll TerschellinS
0
2
4
6
8
10
12
14
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380
[mg/m3]
Model Obs2002 Mean Median
Venice Lagoon - Year 1987 - Ulva (gC.m-2)
Simulated Observed
DO summer 1987 Venice Lagoon
Sea of Marmora Phytoplankton result September
Upper layer
Intermediate layer
Lower layer
Tropical reservoir
Han Hongjuan et al in prep
Tropical reservoir
Han Hongjuan et al in prep
Summary
• DELWAQ-BLOOM is a phytoplankton competition model that …
• has been developed and applied for over 35 years now
• and is generic for both fresh water, marine and transitional
(estuarine) systems
• has many applications worldwide
• requires little time for calibration
• and is documented in a large number of peer reviewed papers
• Water quality is often very much dependent on hydrodynamics,
and ideally the two should be modelled in close cooperation!
Additional references
Further reading: • Los, F.J., Mathematical Simulation of algae blooms by the model BLOOM II, Version 2, T68, WL
| Delft Hydraulics Report, 1991.
• Van der Molen, D.T., F.J. Los, L. van Ballegooijen, M.P. van der Vat, 1994. Mathematical
modelling as a tool for management in eutrophication control of shallow lakes. Hydrobiologia,
Vol. 275/276: 479-492.
• Ibelings, Bas W., Marijke Vonk, Hans F.J. Los and Diederik T. v.d. Molen and Wolf M. Mooij,
2003. Fuzzy modelling of Cyanobacterial waterblooms, validation with NOAA-AVHRR satellite
images, Ecological Applications, 13(5): 1456-1472
• Los, F. J., M. T. Villars, & M. W. M. Van der Tol, 2008. A 3- dimensional primary production
model (BLOOM/GEM) and its applications to the (southern) North Sea (coupled physical–
chemical–ecological model). Journal of Marine Systems, 74: 259-294.
• Blauw, Anouk N. , Hans F. J. Los, Marinus Bokhorst, and Paul L. A. Erftemeijer., 2009. GEM: a
generic ecological model for estuaries and coastal waters. Hydrobiologia, 618:175–198
• Los, F. J., M. Blaas, 2010. Complexity, accuracy and practical applicability of different
biogeochemical model versions. Journal of Marine Systems 81: 44-74.
• Los, Hans, 2009. Eco-hydrodynamic modelling of primary production in coastal waters and
lakes using BLOOM, PhD Thesis Wageningen University, ISBN 978-90-8585-329-9.
• Los, F.J., T. A. Troost, J.A. v. Beek, 2014. Finding the optimal reduction to meet all targets -
Applying Linear Programming with a nutrient tracer model of the North Sea Journal of Marine
Systems 131: 91-101
• Troost, T.A., A. de Kluijver, F. J. Los, 2014. Evaluation of eutrophication thresholds in the North
Sea in a historical context - a model analysis. Journal of Marine Systems 134: 45-56
Thank You!