1. Properties of the Ocean
Water, Salinity, Light, and Dissolved Oxygen

2. Water’s Unique Properties

3. Properties of Water
It is the only natural substance that is found in all three states of matter on Earth- solid, liquid, and gas
Also called the universal solvent- meaning many things can be dissolved in water
Has a high heat capacity, so water can absorb a lot of solar energy without its temperature increasing

4. Density of Water
Unlike any other substance, the density of water is the greatest at 4⁰C (as a liquid)
So, ice floats on water!

5. Composition of Seawater
pH 7.5 to 8.4
Salinity of oceans remain constant
Contains various salts, such as sodium, magnesium, and potassium chlorides
Contains organic carbon compounds
Contains dissolved gases- oxygen, carbon dioxide, and nitrogen

6. Composition of Seawater

7. Salinity
Why is the Sea Salty?

8. What is Salinity? Total amount of salt dissolved in sea water.
Typical salinity of:
Freshwater – 0 grams per 1000 mL of water
Saltwater – 35 grams per 1000 mL of water
Brackish – mixture of both
Hypersaline – over 39 ppt
Usually referred to as Parts Per Thousand or ppt

9. Depth vs. Salinity As depth increases salinity increases
Colder water pushes particles closer together – increasing the salinity
Halocline
A distinct depth at which salinity drastically increases. Typically starts at 100 meters and ends at 200 meters

10. Processes Affecting Sea Water Salinity
Precipitation – adds more water, decreases salinity
Runoff – adds more water, decreases salinity
Coastal waters are less salty
Icebergs melting – adds more fresh water, decreases salinity
Sea Ice Melting – adds more water and very little salt – decreases salinity
Sea ice forming – takes away fresh water – increases salinity
Evaporation – takes away fresh water – increases salinity

12. Salinity and Latitude
Highest salinities are recorded at 20 degrees North and 20 degrees South.
Highest amount of evaporation and the least amount of precipitation
Lower at the equator – more precipitation
Higher latitudes have lower salinities – less evaporation and melting of polar ice adds more fresh water to the ocean and decreases the salinity

13. Salinity and Latitude
Salinity and Ocean Currents
What Aquarius Found

14. Water Water everywhere
Drinking Sea Water?
Drinking sea water causes the water in your cells to diffuse out
The salt doesn’t go into your cells because the molecules do not fit through the membrane
Water Water everywhere
And not a drop to drink!

15. Osmoregulation
Ability of aquatic organisms to maintain proper balance of water and salt.
Osmosis – movement of water molecules from area of high concentration to low concentration
Both salt and fresh water fish have to deal with maintaining water balance!

16. Hypotonic Environment
When a cell is in a hypotonic environment, there is a higher concentration of salt inside the cell than outside
As a result, water moves into the cell, and it swells and bursts
When a fish is in freshwater, it continuously gains water by osmosis

17. Hypertonic Environment
When a cell is in a hypertonic environment, there is a higher concentration of salt outside the cell than inside
As a result, water diffuses out of the cell, and it shrivels and shrinks
When a fish is in salt water, it continuously loses water by osmosis

18. Osmoregulation Adaptations
Freshwater Fish
Gains water by osmosis
Special kidneys to get rid of excess water
Saltwater Fish
Loses water by osmosis
Must continuously drink to stay hydrated
Salt glands to remove excess salt

19. Light and Dissolved Oxygen

20. Why is Light Important?
Essential for photosynthesis, which produces oxygen
Sunlight is the primary source of energy for all living things (beginning of all food chains)
Sunlight also warms up the ocean

21. Relationship between Light and Color
Visible light is a form of radiant energy
This energy penetrates into the ocean at a maximum depth of 200 meters
Different colors are all absorbed and reflected differently

22. Why Does Water Appear Blue?
Blue wavelengths are absorbed the least by the deep ocean water and are scattered and reflected back to the observer’s eye
Particles in the water help to reflect blue light
Light and Color in the Sea

23. Relationship Between Wavelength, Frequency, and Energy
Shorter wavelengths = Greater Frequency = More Energy!
The more energy a wavelength of light has, the farther (and deeper) it can travel in the ocean!
Blue light has a very short wavelength, therefore it has a lot of energy, and can travel the deepest

24. What Reduces the Amount of Light Reaching the Bottom?
Suspended sediments within the water
Overabundance of zooplankton and phytoplankton
Cloudy waters are called turbid

25. What is Dissolved Oxygen? (DO)
Molecular oxygen O2 dissolves in water
Measured in parts per million or ppm
Ocean water can hold 1-12 ppm of DO.
Below 3 is not healthy
The oxygen molecule in DO is separate from the oxygen in H2O.

26. Why is Dissolved Oxygen Important?
Oxygen is required for respiration, a life process that all organisms must undergo in order to survive
Organisms use oxygen to produce ATP, an energy molecule used by every cell

27. How Does DO Get into the Water?
Most dissolved oxygen enters from the air!
Winds blowing over a body of water help DO to diffuse
Oxygen is also released by marine plants as a byproduct of photosynthesis
Most DO is produced from meters. Why?

28. What Factors Affect DO Levels?
Temperature – oxygen is more soluble in cooler temperatures (cold water molecules are close together, trapping in the gas and dissolving it
MORE DO in COLD water
Respiration – all aquatic plants and animals use up DO
Plants photosynthesize in the light but they also do respiration!
Overcrowding of organisms decreases DO
Decomposition – bacteria that decomposes dead and decaying material use DO to break these things down.

29. Temperature vs. Dissolved O2

31. Why is the Water in the Caribbean so clear?
The sediments in the Bahamas and Hawaii tend to be composed of heavier particles that are not as easily stirred up or suspended
There tends to be far less phytoplankton and zooplankton in the water due to very low nutrients in the Bahamas and Hawaii.
There is lower dissolved oxygen because the waters are warmer