1. Unit 10: Marine Life
Physical Factors

2. Physical Factors Affecting Marine Life
Most important factors (physical factors):
1. water transparency
2. salinity
3. dissolved nutrients
4. temperature
5. dissolved gases
6. acid-base balance
7. hydrostatic pressure

3. 1. Transparency
Sea water is relatively transparent allowing photosynthesis to take place at good distances from the surface.
The depth that light can penetrate is limited by the water molecules and particles suspended in the water.
These particles absorb and scatter light (particles absorb blues and reflect greens).

4. Light will penetrate:
A. 1,700 feet (measured by photometers)
B. 660 feet – human eye (blue light)
C. 130 feet – becomes dark to human perception
Photic zone – sunlit area at the oceans surface
Euphotic zone – upper ½ of the photic zone; area where organisms trap more energy than they use.

5. The light spectrum is well known. "ROY G
The light spectrum is well known. "ROY G. BIV" is an acronym used to remember the colors from one end to the other.
From left to right the letters stand for: Red, Orange, Yellow, Green, Blue, Indigo, and Violet. 
A mixture of all the colors makes white light.

6. Water acts as a selective filter.
If one were to suspend a white light above the surface of a tank of water that was 1000' deep, the colors from the white light would be GRADUALLY filtered out selectively one-by-one.
At 10’ most of the red is gone
At 25' most of the orange is gone.
At 35' most of the yellow is gone.
continues through the spectrum until all that is left is violet light and that fades out after hundreds of feet.
So, at the bottom of this 1000' tank of water there would be little or no light!

7. 2. Dissolved Nutrients
Nutrients are all needed substances an organism obtains from its environment except:
oxygen, carbon dioxide and water
Nutrients contain:
nitrogen
potassium
sodium
Calcium
silicon
manganese
phosphorus
sulfur
zinc
copper
cobalt
iodine

8. Some necessary nutrients are always present in seawater. Most are not.
2 main nutrients needed in primary productivity are:
1. Nitrogen in the form of nitrates (NO3-)
2. Phosphorus in the form of phosphate (PO4-)
These are in very short supply and must be recycled within the living system
Primary productivity is high when light is available
living mass can not increase until inorganic nutrients become available.
accomplished by recycling, upwelling and runoff from the land.

9. 3. Temperature Too much heat agitates and distorts large molecules.
Too little slows molecular movement so much that molecules no longer react.
optimum temperature and very wide range of “operating” temperature for most organisms.
Since agitation brings reactants together – warmer temps increase the rate at which chemical reactions occur.

10. The majority of marine organisms are:
metabolic rate - rate at which energy releasing reactions proceed within an organism.
The internal temperature of an organism is directly related to the rate at which it generates ATP, moves, thinks and lives.
The majority of marine organisms are:
Ectotherms – “cold blooded” – have an internal temperature very close to that of their surroundings.

11. Few marine animals (mammals and birds) are:
Endotherms : “warm blooded” – have a stable high internal temperature
The higher the temperature of the environment (within the limits of the ectotherms) the faster the metabolism.
Tropical fish will eat more, grow faster and to greater size (the upper limits of temp is often not much more than the optimum).

12. 4. Dissolved gases
Atmospheric gases can dissolve in water at the surface.
The proportions present in water are much different than their proportion in air.
There is 100x as much O2 in the air as in ocean water.
N2 & O2 do not easily dissolve.
CO2 is much more soluble – 1,000x as much CO2 can dissolve as N2 or O2.
(CO2 is critical to primary productivity)

13. CO2 builds up in deep water because:
Because of the ease at with it dissolves and its abundance, marine plants never run out of CO2.
CO2 builds up in deep water because:
colder water contains more gas at saturation
polar waters sink (temp. & density)
only heterotrophs live and metabolize in deep water ( no primary producers in deep water)
The levels of CO2 decrease and the levels of O2 increase at the surface due to rapid photosynthesis.

14. 5. pH The acidity or alkalinity of a solution
a logarithmic measurement of the concentration of hydrogen ions
The pH scale runs from 0 – 14
The closer to 0 the more acid something is.
The closer to 14 the more alkaline something is.
7 is neutral