carrying capacity as an ecosystem management tool,

GEM – Geochemical and Ecological Modelling

http://www.ecowin.org/Address

http://www.ecowin.org/smile/

Carrying Capacity as an Ecosystem Management tool,



• Hydrodynamic model – simulates the circulation and phytoplankton productivity. Used to generate water exchange and boundary conditions to implement ecological models

• Shellfish model – Growth predicted by ShellSIM of individual shellfish species is used in the EcoWIN ecological model to simulate the population dynamics of cultivated oysters and mussels

• EcoWIN2000(E2K) is an ecological model that provides a platform for integration of the other models and adds functionality of its own. Runs for multi-year periods



Modelling frameworkRun Delft 3D for large domain (Western Irish Sea and four

loughs) using a fine grid (each lough has hundreds of cells)

Define larger boxes (<50) within the loughs with GIS for

E2K using (I) current and bathymetry data (ii) WFD (iii)

aquaculture distribution

Use D3D to calculate water fluxes across these larger

boxes at 30m intervals, and at the seaward boundary of the lough domain – supply these

offline as spreadsheets

Hydrodynamic transport simulated in E2K by reading

these spreadsheet files during an E2K model run

Prepare a water quality database including both the individual lough and inputs from freshwater and ocean boundaries

(measurements)

Enter larger box areas, volumes

etc from GIS into E2K

Run full E2K model, calibrate

and validate

Simulate individual shellfish physiology

using a raceway model

Use results to conceptualise an

energy budget model for individual growth

Implement and validate individual growth model in Stella or other simple

modelling package

Measure individual shellfish growth rates in the field

Implement individual growth model in E2K,

test, and then add population dynamics

Extract E2K initial conditions for state variables in each box,

boundary conditions and calibration data

Delft3D

EcoWin2000

ShellSim2006

Management scenarios



SMILE is an ecosystem model, a series of interconnected boxes

34 boxes, 2 layers

Criteria for boxes:

Water framework DirectiveTopographyBiogeochemistry



Strangford Lough

340 boxes8 layers

34 boxes2 σ layers

EcoWin2000ecological model

A much coarser grid is used in biogeochemical models than in hydrodynamic models.

Delft3DDelft3DHydrodynamic modelHydrodynamic model



So far!• Developed growth models for Modiolus modiolus,

Ostrea edulis and Pecten maximus in addition to existing species

• Growth models integrated into software to check that individual growth can be accurately scaled up for ecosystem models

• SMILE model framework changed to deal with three new species

• Now in position to simulate growth in certain areas at varying densities



Objectives

• Examine growth of Modiolus

• Simulate growth

• Investigate growth at varying stocking densities for Modiolus

• Determine optimal locations for restoration

• Examine knock-on effects



ShellSIM – simulation of shellfish growth

Real time feeding experiments required to measure Modiolus

feeding rates. Experiments show how temp and food availability

effect feeding. Allowing us to model how changes in the

lough (or different areas) will effect Modiolus feeding and hence

growth

With the addition of population dynamics to the individual model,

shellfish stocks can be modelled over mutil-year periods (E2K)



• Simulated temperature, illustrating northern and southern trends. Matches well with measured values.



Simulated temperature graph

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Box 21

Box 22Year 1 Year 2



J F M A M J J A S O N D J F M A M J J A S O N D

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Strangford LoughBox 22 - Lough entrance

Phytoplankton (µg Chla l-1) SPM (mg l-1)

POM (mg l-1)DIN (µmol l-1)

J F M A M J J A S O N D J F M A M J J A S O N D



Simulated growth curve for Pecten maximus

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0 365 730 1095 1460 1825 2190 2555 2920 3285 3650 4015 4380 4745 5110 5475 5840

Julian Days over 15 years

Sh

ell

len

gth

(m

m)

Observed growth

Simulated growth



M. modiolus growth

y = 25.058Ln(x) + 13.677

R2 = 0.6814

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shell length

Log. (shell length)



Modiolus individual growth

size refuge/ sexual maturity

match to measured growth, 10y mean length of 7cm

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0 500 1000 1500 2000 2500 3000 3500 4000

Box 27

Box 28

Box 29

Year 5 Year 10



Possible factors

POM at 50

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2900 3000 3100 3200 3300 3400 3500 3600 3700

Box 27

Box 28

Box 29

Phytoplankton biomass at 50

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2900 3000 3100 3200 3300 3400 3500 3600 3700

Box 27

Box 28

Box 29

NB. Important to remember, only modelling Mytilus, Crassostrea and Modiolus at present, need to turn on wild species and additional aquaculture species



• Food does not seem to be limiting!

• Other factors, including:

• Suitable habitat

• Predation pressure

• Brood stock availability…..



Next step

• Integrate Wild species

• Turn on new Aquaculture species

• Invite scenarios



.

Operate at Eunis level three or four;

Rather than worrying about individual species use broadscale habitat layers;

Assign loss rates or or “feeding” rates based on top five keystone species;

Each habitat will be assigned a feeding type – i.e deposit, suspension feeder;

carrying capacity as an ecosystem management tool,

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