1. The Waters of the Ocean

2. A. The Unique Nature of Pure Water
 All matter is made of atoms
 Elements are make from one kind of atom
 A molecule is two or more different atoms combined
 Water is a polar molecule; one end is positively
charged and
 the other is negatively charged

4. 1. The Three States of Water
 Only substance on Earth to naturally exist in three states
 Weak hydrogen bonds form between to the positive end
and
 the negative end of different water molecules
 Solid water molecules pack close together & locked in
fixed three dimensional pattern
 Becomes more dense until about 4°C (get less dense) &
expands
 When water freezes in fresh and marine water the ice
forms on top allowing organisms
 to live underneath the ice
 When marine water freezes it acts like an insulator to stop
freezing all the water

5. 2. Heat and Water
 Bonds must be broken before molecules can begin to
move around
 Melts at higher temperature & absorbs a lot of heat
when it melts (high latent heart of melting) and great
deal of heat must be removed to freeze it
 Melting ice, added heat breaks more hydrogen bonds
than increasing molecular motion
 Mixture of ice & water is 0°-adding heat goes into
melting the ice not raising temperature
 High heat capacity therefore marine organisms not
affect by temperature changes in atmosphere & latent
heat of evaporation

7. 3. Water as a Solvent
 Dissolve more things than any other natural
substance
 (universal solvent) especially salts
 Salts made of opposite charged particles and conducts
electricity
Single atoms or groups of atoms
 In water, strong ion charges attract water
molecule, water molecules surround the ions and pull
them apart (dissociation)

9. B. Seawater
 Characteristics due to nature of pure water &
materials dissolved in it
 Dissolved solids due to chemical weathering of rocks
on land & hydrothermal vents

10. 1. Salt Composition
 Sodium chloride account for 85% of all solids dissolved
 Salinity is total salt dissolved in seawater
 number of grams left behind when 1000 grams evaporated
 if 35 grams left then 35 parts per thousand or 350/00 or 35
psu (practical salinity units)
 Rule of constant proportions states that the relative
amounts of various ions in seawater are always the same
 Differences in salinity results from removal (evaporation)
and addition (precipitation) of water
 Rarely have to deal with changes in ratio of ions as result
easier to control salt & water balance
 Average salinity is 35 psu and between 33-37 psu in open
ocean
 Red Sea is 40 psu 7 & Baltic Sea is 7 psu
 Why is Red Sea salinity so high and the Baltic Sea so low?

11. 2. Salinity, Temperature, and Density
 Get denser as it gets saltier, colder, or both
 -2° to 30°C
 temps. below zero possible because saltwater freezes
at colder temps.
 Density controlled more by temperature than salinity
 There are exceptions therefore salinity & temp need to
be measured to determine density

12. 3. Dissolved Gases
 O2, CO2 and N2 in atmosphere & sea surface
 Gas exchange happens between the surface &
atmosphere
 Dissolved gas concentration higher in cold
water, lower in warm water
 Amount of oxygen in water is affected by
photosynthesis & respiration
 Most oxygen is released into the atmosphere
 More susceptible to oxygen depletion than
atmosphere
 80% of gasses is carbon dioxide

13. 4. Transparency
 Sunlight can penetrate, but it’s affected by the
material suspended in the water
 Important to the photosynthetic organisms
 Runoff makes coastal waters less transparent than
deep blue waters of open ocean

14. 5. Pressure
 On land, organisms are under 1 atm at sea level
 Marine organism have the pressure of the atmosphere &
water
 With every 10m increase depth another atm is added
 As atms increase gases are compressed
 Organism have air bladders, floats and lungs that shrink
and collapse
 Limits depth range, some organism are injured when
brought to the surface
 Submarines & housing must be specially engineered to
withstand pressure

16. Ocean Circulation
 Throughout depths currents move and mix ocean
waters and transport heat nutrients, pollutants and
organisms

17. A. Surface circulation
 Driven by the wind

18. 1. The Coriolis Effect
 Because Earth is rotating anything that moves over
the surface tends to turn a little rather in a straight line
 Deflects large-scale motions like winds and currents
to the right in Northern Hemisphere and to the left in
Southern Hemisphere

19. 2. Wind Patterns
 Winds driven by heat energy from sun
 Trade winds
 warmer at equator
 wind at equator becomes less dense and air from
adjacent areas gets sucked in to replace it creating
winds
 wind bent by Coriolis Effect
 approach equator at 45° angle where there is no land
 steadiest winds
 Westerlies at middle latitudes move in opposite
direction
 Polar easterlies at high latitudes
 most variable winds

21. 3. Surface Currents
 Winds push the sea surface creating currents
 Surface current moves off 45°
 Top layer pushes on layer below & again Coriolis Effect
come into play
 Second layer moves slightly to right and slower and is
repeated down the water column (Ekman spiral)
 lower waters move progressively at greater angles from
wind
 effect of wind decrease with depth
 100 m no wind is felt
 produces Ekman transport
 upper part of water column moves perpendicular to wind
direction to right N. Hemisphere & left in S. Hemisphere

23.  trade winds move toward equator the equatorial
current move parallel
 currents combine into huge gyres
 west side of gyres carry warm water to higher
latitudes while cold current flow on eastern sides
 giant thermostat warming the poles & cooling
tropics
 tropical organisms like corals tend to extend into
high latitudes on the west sides of the oceans
 cold loving organisms like kelp grow closest to
equator on eastern shores

24.  large-scale fluctuations can cause conditions like El
Nino
 current shift with season and weather
 near the continental shelf currents are effect by the
shape of the bottom & coastline

26. B. Thermohaline Circulation and the
Great Ocean Conveyor
 Ocean water stratified
 Cold more dense on the bottom & warmer less dense on
top
1. The Three-layered Ocean
 Surface layer or mixed layer 100 to 200m thick
 Mixed by wind, waves and currents
 Sometimes in summer & spring in temperate & polar
waters sharp transition to cooler water (theromoclines)
noticed by divers
 Intermediate layer depth of 1000 to 1500m
 Main thermocline rarely breaks down & in open ocean
 Deep or bottom layers
 Below 1500 m
 typically less than 4°C

27. 2. Stability and Overturn
 Water column with less dense water on top and dense
water on bottom with no mixing is stable
 Depends on the difference in densities between layers
 If difference is small not much energy is needed to
mix the water
 Downwelling occurs when top layers become more
dense & sinks
 The sinking water displaces and mixes with deeper
water (overturn)
 Density & temperature profiles are straight-lined
 Temperate and polar during winter

28.  Mixing layers extends greater into water column
 Important to productivity
 In intense downwelling, large volume of water may
leave without mixing
 Changes in salinity at surface
Precipitation, evaporation, freezing, and temp.
 Once water sunk it does not change in salinity and
temp. (water mass)
 Oceanographers can follow the circulation over large
distances
 Because it is driven by density (determined by temp
and salinity) the circulation is called thermohaline
circulation

30. 3. The Great Ocean Conveyer
 Only places where surface overturn reaches the
bottom is Atlantic south of Greenland & north of
Antartica
 The sinking water spreads though the Atlantic &
other ocean basins then eventually rise to surface
and flows back
 Recycles about every 4000 years
 Regulates climate and alterations have produced
rapid climate changes (ie ice ages)
 Bring dissolved oxygen to deep sea

32. 3.3 Waves and Tides
A. Waves
 Caused by wind
 Wave crest moves up & forward
 Trough moves down and back
 Water particles do not go anywhere
 Moves in a circle
 Faster the longer the wind the bigger the waves
 Fetch-span of open water
 Larger the fetch the bigger the wave
 Seas
 Sharp peaks stretch over trough
 Move away get faster than speed of wind

33.  Swells
 Once waves settle
 Surf
 Bottom forces water to move elongated ellipses
 Wavelength get shorter
 Waves “pile up” becoming higher & steeper until they
fall forward
 Water affected by mixture of waves
 Two crest adding to make a higher wave (wave
reinforcement)
As high as ten stories
 Trough & crest combine & cancel out the wave

36. B. Tides
 Influence marine organisms
 Organisms are exposed & submerged on shore
 Drive circulation of bays and estuaries, trigger
spawning

37. 1. Why Are There Tides? (if water
covered completely by water)
 Gravitational pull of sun & moon & rotation of
Earth, moon, & sun
 Moon’s influence
 gravity strongest on side of earth closest - pulls water in
ocean toward it
 Opposite side furthest from moon - pull is weakest
 earth’s rotation is like unbalanced tire (wooble) creates a
centrifugal force - makes the
 oceans bulge out toward the moon & away from moon
 2 high tides and 2 low tides in 24 hours and 50 minutes
 extra 50 min because for earth to catch up to moon

38.  Sun ½ as strong as moon because so far away
 Full & new moon (sun moon in line)
 Tidal range (difference between high and low tide) is
large
Spring tides
 First and third quarter
 Sun & moon at right angles partially cancel each other
out – tidal range small
 Neap tides

40. 2. Tides in the Real World
 Tides vary depending on location and the shape and depth
of the basin
 East coast of N. America & most of Europe & Africa have
semidiur West coast of USA & Canada mixed
 semidiurnal tide- successive tides of different height
 Diurnal ( 1 high and 1 low) rare on Antarctica and parts of
Gulf of Mexico, Caribbean, & Pacific
 Tide tables give predicted time and height of high and low
tides
 Determined by local geology
 Weather like strong winds can cause water to pile on the
shore creating higher tide than predictednal tides (2 highs
and 2 lows)