Transcript Life in Water - Cornell College

Water in the Ocean
Water properties
Organisms and water
Pressure
Temperature
Light
Chemistry
O2
CO2
CaCO3
Salinity
Life in the water
Water
Water molecule: electric dipole
Salinity: dissolved solids
35ppk: marine water
Residence times of elements
Na
K
Ca
Si
Mn
Fe
Al
Amt (g)
147 X 1020
5.3 X 1020
5.6 X 1020
5.2 X 1018
1.4 X 1015
1.4 X 1016
1.4 X 1016
Resid t
2.6 X 108
1.1 X 107
8.0 X 106
1.0 X 104
7.0 X 103
1.4 X 102
1.0 X 102
Not cumulative
Removal:
Sediments
Organisms
Mineral precipitation
Sea spray
Water
Liquid is fluid.
Fluid will change shape as force is applied
Gas is also fluid, but fills space; liquid has surface
Density 
How tightly packed are molecules
Pure H2O: 1.0 g/cm^3
Seawater: 1.02-1.03 g/cm^3
T, salinity affects
Water is unusual in  changes
Viscosity
Resistance to change in shape
Important to microorganisms
Organism Sizes and Water
Large size: control movement, food contact
Self-propelled: Buoyancy, swimming
Hunting, scavenging, grazing
Small size: water has huge effect
Viscosity
Ltd propulsion: Migration, currents, settling
Boundary layer: microorganisms, filter feeders
Pressure
Vertical variability: 1 atm per 10 m
Static variability: can change with tides
Stenobaric, eurybaric
May or may not effect benthos,
but have to deal with it!
Some fish limited by pressure
examples: coelocanth, deep sea fish
Temperature
Tropics: Constant: 30C
Deep water: Constant: 4C
0 5 10 15 20 25 30
0
Everywhere else, variable.
Polar
Equator
Fluctuations depend on:
mixing
Tropics
daily T flux
tides
Thermocline
Effects:
Oxygen
CaCO3
Nutrient uptake
Activity
4km
Eurythermal, stenothermal
Light
Very important to primary
producers, visual senses
Red end of spectrum
absorbed in upper 10m
Blue scattered
Photic zone: depends on
turbidity (suspended
particles, cloudiness)
Shoreline: <1m
Open ocean: ~60m
Tropical reefs: ~80
Absolute depth, clear
water: 1000km
Oxygen
Terms: Anoxic/anaerobic – no O2
dysoxic/dysaerobic – low O2
oxic/aerobic -- oxygenated
Oxygen saturation changes with T, t, D
3ppm: limiting
5ppm: “safe”
Oxygen continued
Sources:
Atmosphere
Plants
Sinks:
Decomposition
Respiration (animals and plants)
Chemical reactions
Mechanisms of O2 movement:
Diffusion
Convection
Chesapeake Bay
Diurnal surface O2 variation: T
Morning: 85%; afternoon: 115%
Seasonal variation
Shallow: April: 150% saturation
high photosynthesis + low decomp.
August: 42% saturation
Deep: T control, detrital rain
June: 24% saturation
Oct: 133% saturation
CO2 and CaCO3
(Carbon Dioxide and Calcium Carbonate)
H2O + CO2  H2CO3
Carbonic Acid
H2CO3  H+ + HCO3-
Bicarbonte ion
H+ + HCO3  2 H+ + CO32-
Carbonate ion
Calcite (Calcium Carbonate) and CO2
CO2 + H2O + CaCO3  Ca2+ + 2 HCOcarbon dioxide + water + calcium carbonate 
calcium + carbonic acid
Glacial Sea
Periods Level CaCO3 RCO2 Av global T
CaCO3
Quaternary
2 phases:
calcite (stable)
aragonite (unstable)
Acropora
modern
5
Tertiary
65
High frequency
sea-level
oscillation
Cretaceous
144
Jurassic
202
Triassic
248
Permian
286
Pennsylvanian
320
Syringopora
Carboniferous
Mississippian
360
Devonian
408
Silurian
438
Ordovician
504
Cambrian
540
Millions of
years ago
High frequency
sea-level
oscillation
age of
proposed
study
Salinity
Dissolved solids
Ocean water: 35 ppk
0-1ppk at fresh water input (hyposaline)
to 150 ppk in evaporative systems (hypersaline)
Sediments buffered
Variability from:
Tides
Seasonality: precipitation
Unpredictable storms
Salinity changes density
Animals:
Stenohaline vs. euryhaline
Direct effects: osmosis
Indirect effects: buoyancy
How does living on land differ from
living in the water?
Living in the Water
On land:
Need structure for gravity
Air less dense
Respiration, movement, heat loss/gain on land
Need water for respiration, reproduction
Vision, hearing
In water:
Buoyancy, support
Dense water
More O2; drag forces; heat loss/gain in water
Vision, hearing
Anableps dovii, the four-eyed fish
Fish Morphology
and Depth