Phytoplankton Entrainment and distribution in the Pelagic C. Reynalds, Chapter 2 Ecology of...
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Transcript of Phytoplankton Entrainment and distribution in the Pelagic C. Reynalds, Chapter 2 Ecology of...
Phytoplankton Entrainment and distribution in the Pelagic
C. Reynalds, Chapter 2Ecology of Phytoplankton
Paul Simonin
John Bisgrove
Physical Properties of Water
• Higher density• Higher viscosity• Higher melting point• Higher boiling point• Lower compressibility• Polar molecule• Aquo polymers• High specific heat
• Density is greatest at 3.98 Celsius
• Rate of density change increases as heated above
Viscosity and Turbulence
• Turbulent Intensity– Product of root mean
squares of time averaged fluctuations (u*)2
– Turbulent velocity (u*)
1
absolute viscosity
mild horizontal force
u horizontal velocity
z depth
dudz
Turbulent Dissipation
• Environmental grain– The size and velocities
decrease with transfer
-1
largest eddy size
m s
e
e
l
duu l dz
Wind
Velocities must equalor create heat
Total volumes must equal
2 3* * 1 2 -3
Rate of energy dissipation (E)
E= u u m sedu ldz
Turbulent Embedding of Phytoplankton
1Re w su d
Sinking and Floating
12 1
c
w
Stokes equation
18
sinking velocity
g gravity
d diameter
density of cell
density of water
absolute viscosity
s c w
s
w gd m s
w
Regulation of Density
• Densities of cellular components – Proteins ~1,300 kg m-3 – Carbohydrates ~1,500 kg m-3
(cellulose)– Nucleic acids ~1,700 kg m-3 – SiO2 ~2,600 kg m-3(diatom walls) – Lightest lipids ~860 kg m-3
– Average cell density is rarely less than ~1050 kg m-3
Form resistance
rs
grV
9
'2 2
Sinking and Entrainment in Natural Turbulence
• Tendency to sink or float (ws)
• Propulsion (us)
• Velocities of the water • Horizontal motion
increases distance traveled during fall
12 2/15[ ' ]sw w
Loss of Sinking Particles from Turbulent Layers
• 95% elimination te/t’=3.0
• 99% elimination te/t’=4.6
Mixing1( )( / )el u du dz
12
b w m wRi gh u
121 2
b m w m wW Ri Lh gh u L
1*
1*
0.2 time of travel in mixed layer, unconstained
2 time of travel in mixed layer, constained
m m
m m
t h u
t h u
Robustness of gradient
Resistance to mixing
Largest eddy size
Vertical Structure in the Pelagic
• diurnal time-scale
• wind time-scale
• seasonal time-scale
• compare to euphotic zone
• mixed layer
• thermocline
Spatial Distribution of Phytoplankton - Vertical
• non-motile, negatively buoyant planters
• positively buoyant plankters
• neutrally buoyant plankters
• motile plankters
( )c w
( )c w
( ~ )c w
( )su u
Spatial Distribution of Phytoplankton – Langmuir
circulation
Horizontal Spatial Distribution of Phytoplankton - Patchiness
• Sampling Issues• Ecological Reasons
– In fisheries patchiness leads to very reduced zones of high growth potential (Hobbie, 2000)
• Small scale patchiness– Langmuir circulation
• Small lake basins– Drift interrupted by
shallows, margins, islands
– Basin scale conveyer current
– Drift of buoyant organisms
– Patchiness as inverse function to wind speed
• Large scale patchiness– Horizontal mixing time– Diffusivity– Population change
Oceanic Circulation
Additional resources• General concepts: Inland waters and their ecology, by I. A. E. Bayly
and W. D. Williams; Textbook of limnology, by Gerald A. Cole; Wetzel texts…
• United States. Environmental Protection Agency. Ecological research series ; EPA-600/…
• Ecology of harmful algae, by E. Graneli, J.T. Turner (eds.)• The Algae and their life relations; fundamentals of phycology, by
Tilden, Josephine E (1935)• Local resources: ESF theses such as:The distribution and density of
phytoplankton of Jamesville Reservoir, by Pingel, Patricia A. • Estuarine Science: A Synthetic Approach to Research and Practice
Edited by John E. Hobbie, Island Press, Washington, D.C. (2000)