Oceanography Oceanography Interdisciplinary approach Interdisciplinary approach for observing the water for observing the water column and benthic column and benthic interactions interactions Cruise on the R/V Savannah Cruise on the R/V Savannah Sampling sites and techniques Sampling sites and techniques
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Oceanography Interdisciplinary approach for observing the water column and benthic interactions Interdisciplinary approach for observing the water column.
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OceanographyOceanography
Interdisciplinary approach for Interdisciplinary approach for observing the water column observing the water column and benthic interactionsand benthic interactions
Cruise on the R/V SavannahCruise on the R/V Savannah
Sampling sites and techniquesSampling sites and techniques
Let’s Get PhysicalLet’s Get Physical
The Intellectual Upwelling The Intellectual Upwelling Group:Group:
John BallardJohn BallardKaren PuckettKaren PuckettSierra LynchSierra Lynch
GoalsGoals
Explain the structure of water Explain the structure of water masses observed during the cruise masses observed during the cruise (June 19-20, 2008)(June 19-20, 2008)
Examine physical influences of the Examine physical influences of the water column on the physical benthic water column on the physical benthic environmentenvironment
Station 1 Station 2
Station 3 (R2)
Station 4
Station 5
Station 1 Station 2
Station 3 (R2)
Station 5
Station 4
Station 1 Station 2
Station 3 (R2)
Station 5
Station 4
R2 Surface Temperature and Salinity Averages for each day from 1999-2007.
10
15
20
25
30
35
40
Date (m/d/year)
Sal
init
y (p
pt)
/ T
emp
erat
ure
(C
)
SalinityTemperature
Hypothesis: Potential Gulf Stream meander and eddy-induced upwelling
Lee et al 1991
Winds from the Winds from the SouthwestSouthwest
Blanton et al 2003
NutrientsNutrients• [NO[NO33]= 53.0 – 2.6T (Lee et al 1991)]= 53.0 – 2.6T (Lee et al 1991)• Colder water=Higher nitrogen Colder water=Higher nitrogen
(nutrients)(nutrients) Chlorophyll Chlorophyll
Onshore currents Onshore currents south of 30˚ latitudesouth of 30˚ latitude
Alongshore currents Alongshore currents 31˚ to 32˚ latitude31˚ to 32˚ latitude
Offshore currents Offshore currents after 33˚after 33˚
Beginning in June
Aretxabaleta et al 2007
Assumptions and LimitationsAssumptions and Limitations• TimeTime• Number of ProfilesNumber of Profiles
• DataData• Small Temperature Small Temperature
GradientGradient
Benthic and Water Column Benthic and Water Column InteractionsInteractions
Mid-shelf currents are wind driven (Blanton Mid-shelf currents are wind driven (Blanton et al 2003)et al 2003)
Does water movement affect ripple Does water movement affect ripple formation?formation?
Ripples are important for nutrient Ripples are important for nutrient circulationcirculation
Figure 1. The Effect of Wind Stress on Wave Height at R2 for 2007
y = 0.0159e0.1997x
R2 = 0.5548
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 2 4 6 8 10 12 14 16 18 20
Wind Stress (N/m²)
Wav
e H
eigh
t (m
)
Ripple Size 1
Ripple Size 2
Wave Height v Ripple Direction
0
0.5
1
1.5
2
2.5
3
3.5
4
Date
Wav
e H
eigh
t (m
)
0
1
2
3
4
Rip
ple
Dir
ectio
n
Wave Height
Ripple Direction
NW & SE
N & S
NE & SW
E & W
Stable Summer Winds
Ripple Size 1
Ripple Size 2
Wave Height v Ripple Size
0
0.5
1
1.5
2
2.5
3
3.5
4
Date
Wav
e H
eig
ht
(m)
0
1
2
3
4
5
Rip
ple
Siz
e
Wave Weight
Ripple Size
Advection in the Boundary LayerAdvection in the Boundary Layer
Huettel and Rusch 2000
•Low Pressure pulls nutrients up to water column
•High Pressure pushes POM and DOM down
•Advection stronger with increased ripple height, current strength, and grain size
Bringing it all togetherBringing it all together
Upwelling moving onshore bringing Upwelling moving onshore bringing nutrients from deep ocean nutrients from deep ocean
Wind driven mixing and potential Wind driven mixing and potential advection of sediment circulate advection of sediment circulate nutrients in the mid-shelfnutrients in the mid-shelf