Benthic Ecology from Space

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Benthic Ecology from Space

• Heidi Dierssen, Univ. CT
• Richard Zimmerman, Old Dominion

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Acknowledge

• Univ. CT
• Chris Buonassissi
• Dirk Aurin
• Alison Branco
• Old Dominion Univ.
• David Burdige
• Lisa Drake
• Victoria Hill
• David Ruble

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Questions

• How much do the shallow carbonate sediment banks
  contribute to NPP?
• How do seagrasses on these banks influence the
  carbon cycle (carbonate dissolution) and heat
  budgets?
• What are the mechanisms underlying seagrass
  distributions?

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Moving Beyond Qualitative

• Qualitative maps
• Presence or absence of benthos
• cover
• Quantitative maps
• Leaf area index (LAI) m2 m-2
• LAI or standing crop to NPP
• LAI to Carbonate dissolution
• Bottom albedo for heat budgets

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Biomass to benthic NPP
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Carbonate Sediment Geochemistry

• Seagrasses oceanic sink for carbon
• Shallow water biological pump
• Decomposition in sediments
• Carbonate sediment dissolution
• Burdige Zimmerman, Limnol. Oceanogr. 2002. 47
  1751-1763

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Comparing two sites

• 1) Bahamas Banks
• Little anthropogenic influence
• Constant water column IOPs
• Primarily ag, whitings
• 2) Florida Bay
• Anthropogenic disturbance
• CDOM, sediment, and phytoplankton

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Seafloor Measurements

• Bottom reflectance
• DOBBS
• Seagrass quadrats
• Seagrass primary productivity
• Digital camera/strobe
• Sediment cores
• Reflectance
• Particle size spectrum
• Chl, PP
• Seagrass blades
• Morphometrics
• Reflectance

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Water column

• ac-9 package, eco-VSF, CTD, fluorometers (Chl,
  CDOM, phycoer.)
• Hydroscat 6
• LISST 100X, particle size analyzer
• Irradiance
• Planar, Ed (2 depths), Eu over substrate
• Scalar Eod (2 depths), Eou
• Filtered for TSM, Chl, CDOM

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Sea surface interface

• Remote sensing reflectance
• HyperPro
• Analytical Spectral Devices (ASD)
• Data available at http//colors.uconn.edu

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Intensive Field work
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Field Work
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24 ft. boat
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Lesson 1 Sediment Reflectance is highly variable
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Lesson 2 Green color can be seagrass OR sediments
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Seagrass
Island Shadow Effect
LAI (m2 m-2) Land 0 0.38 0.75 1.1 1.9 gt2.6
NPP (gC m-2 y-1) Land 0 100 200 300 500 gt700
Area 78,000 km2 Mean 1.4, 360 g C m-2
y-1 Integrated 2.8 x 1013 g C y-1
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1998
1999
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Approaches

• Use known bathymetry
• Time as another variable
• More spectral channels

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Lesson 3 Need total ecosystem productivity
Above-ground NPP 2.8 x 1013 g C y-1
Benthic Microalgae (10-100 mg Chl m-2)
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Below-ground NPP
Leaf epiphytes
Phytoplankton, 1 (0.12 mg Chl a m-3)
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Lesson 4 Need to understand fate of production

• Carbonate dissolution
• Assumes seagrass blades decompose in sediments
• 2 of annual oceanic CO2 uptake

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FL Bay seagrass beds have little debris Export
Carbon out of system
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Lesson 5 Avoid hurricane season
Post-Hurricane Wilma 2005
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Jan 2006
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Atmospheric Correction
Atmospheric Correction
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Current Collaborators

• Atmospheric Correction
• TAFKAA model (Bo-Cai Gao)
• Hyperspectral imagery, Paul Bissett FERI
• Total suspended matter, GOBI Model, Mike
  Twardowski
• Air-Sea CO2 Flux, Wade McGillis
• Carbonate dissolution, David Burdige

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