Update on the Ecological Model:

Box Model Version

Mark Brush (VIMS)CHRP October 8, 2009

Officer Box Model

Current Activities

• Expanding from 2001 – 2008

• Improved salinity functions around the bay: NuShuttle data

Alternate S functions:- Cosine functions- Insomniacs + NuShuttle- Supplement with buoy data when available

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

Cosine functionInsomniacs / NuShuttleBullocks Reach buoy

Relating Model Daily Average Results to Management Criteria

Mark Brush (VIMS)CHRP October 8, 2009

One potential problem re: management use of the model:

• RI O2 criteria focus on instantaneous values

• Our eco model simulates daily mean O2

• Models can simulate diel O2 variations, but …

Rhode Island DO criteria:

Surface Waters (and waters without a pycnocline):

“Waters with a DO concentration above an instantaneous value of 4.8 mg/l shall be considered protective of Aquatic Life Uses.”

Bottom Waters (waters with a pycnocline):

As above, plus …

“When instantaneous DO values fall below 4.8 mg/l, the waters shall not be:

1. Less than 2.9 mg/l for more than 24 consecutive hours during the recruitment season; nor

2. Less than 1.4 mg/l for more than 1 hour more than twice during the recruitment season; nor

3. Shall they exceed the cumulative DO exposure presented in Table 3.A.”

Concept for GEMBox / GEM-OBM:

• daily mean DO• instantaneous minimum DO • time with DO below 2.9 mg/l• time with DO below 1.4 mg/l

Use buoy O2 data to look for relationships between:

DO mean

DO NCP CR?

2.9DO

Inst. min

2.91.4

t2.9

t1.4

Test sites:

• North Prudence• Conimicut Point• Bullocks Reach• Greenwich Bay

2003, 2005-07

y = 0.6496x + 1.1152R² = 0.7014

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 1.005x - 0.9433R² = 0.9399

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Test sites:

• North Prudence

2003 SURFACE

BOTTOM

Test sites:

• Conimicut Point

2003 SURFACE

BOTTOM

y = 0.6281x + 0.6985R² = 0.6692

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 1.0939x - 1.2177R² = 0.9206

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Test sites:

• Bullocks Reach

2003 SURFACE

BOTTOM

y = 0.6679x + 1.2682R² = 0.4423

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 1.0719x - 1.1773R² = 0.9379

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Test sites:

• Greenwich Bay

2003 SURFACE

BOTTOM

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Need a change-point regression?

All years together …

2003, 2005-07

y = 0.7406x + 0.7954R² = 0.706

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 0.9813x - 0.9535R² = 0.9032

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Test sites:

• North Prudence

2003, 2005-07 SURFACE

BOTTOM

Test sites:

• Conimicut Point

2003, 2005-07 SURFACE

BOTTOM

y = 0.7325x + 0.2965R² = 0.7139

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 0.9784x - 0.7465R² = 0.909

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Test sites:

• Bullocks Reach

2003, 2005-07 SURFACE

BOTTOM

y = 0.8193x - 0.2138R² = 0.6508

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 1.057x - 1.1834R² = 0.9093

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Test sites:

• Greenwich Bay

2003, 2005-07 SURFACE

BOTTOM

y = 1.1415x - 2.6697R² = 0.8635

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 1.0947x - 2.239R² = 0.8783

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

All sites & years together …

Test sites:

• All Sites

2003, 2005-07 SURFACE

BOTTOM

y = 0.9352x - 1.093R² = 0.7565

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MinO2surf, mg/l

TIMEsurf<2.9 mg/l

TIMEsurf<1.4 mg/l

y = 1.0215x - 1.2893R² = 0.8609

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MinO2bott, mg/l

TIMEbott<2.9 mg/l

TIMEbott<1.4 mg/l

Predicting DO Criteria Attainment:

• Inst. min. DO and time below DO thresholds appears predictable directly from daily mean DO

• Addition of terms for metabolism does not appear to help

• Fit is especially good in bottom waters, which is good news

• Relationship appears robust across years, and to a lesser degree across sites

• PROPOSAL: fit statistical distribution functions by site (years aggregated) with all available buoys to predict criteria attainment/violation from modeled daily mean DO