Characteristics of
Ocean Water
• Oceanography covers physical properties
of the ocean:
–Dissolved materials: minerals and salts
(salinity) and gases
–Properties that change with depth: light,
temperature and pressure
–Motion: Waves, tides, currents
Waters Unique Properties…
-Found in 3 states of matter on our
planet
-High heat capacity: ability of water
to hold heat energy and regulate our
climate
-Universal solvent: can dissolve
more things than any other solvent
Unique Properties of water are due to
Hydrogen Bondingattraction between water molecules because
of the unequal charges of O & H
• Charges on O and H help it dissolve things
like salts
• Attraction between water molecules- a lot
of heat is needed to increase water temp
and when water cools it release a lot of heat
Salinity
• Result of weathering of rocks on
land carried by rivers to the
ocean
• Materials from the earth’s
interior
– Hydrothermal vents
– Volcanic eruptions
Materials in Seawater
–Oceans have an average salinity
of 3.5% or 35 ppt (35 ‰)
– ppt= parts per thousand
–More than 70 elements in
seawater but the main ones are..
Chloride
Sodium
Sulphate
Magnesium
Calcium
Potassium
Dissolved Gases
• Oxygen, carbon dioxide and nitrogen
• Dissolve into the ocean from the
atmosphere through wave action
• Dissolve better in cold water
• Animal life can change the chemistry
of ocean gases
• Around 500 m water runs out of
oxygen
–Bacteria and other animals are
using it during decomposition and
respiration
• Animals in this region and lower have
large gills, modified hemoglobin
or are inactive
Pressure
• We are under 1
atmosphere (atm) of
pressure on land
• Water is heavier than
air so every 10 m deep
= 1 more atm of
pressure
Animal Adaptations and Pressure
• Ocean life has adapted to deep ocean
and 1000x our pressure with
lightweight skeletons, little
musculature, and reduced metabolic,
growth and reproductive rates.
• Diving mammals have rib cages that
collapse and expand in result to
changing pressure
Water Depth vs Light
• Photosynthetic organisms use light to
make sugars.
• Sunlit area (top 100 meters) contains 90%
of marine life
• Colors of penetrate thru water differently
– Red light filters out first and blue light
goes the furthest
– Red animals are essentially invisible in
deep waters
Energy in the Ocean
• Ocean takes
longer to heat
and cool than
land due to its
specific heat
• Water temp
decreases with
depth
Animal Adaptations and Temperature
• Colder temps reduce the metabolic rate
• In very cold waters fish have a special
protein like antifreeze to keep tissues
from freezing
• Lighter colored animals stay cooler than
darker colored animals and are found in
warmer waters
• Some marine life have thick layers of fat
to insulate their bodies
Motion in the Ocean…Tides
• Daily rise and fall of the ocean (high
and low tide)
• Range as small as 1 m & as high as
20m
• Some areas have 1 or 2 high & low
tides
• Caused by gravitational pull of moon
on our ocean basin
Moon/
Sun
TIDES
•Tides rise (FLOOD) to produce a
HIGH TIDE
• And fall (EBB) (LOW TIDE)
This side is pulled towards the
Sun and/or Moon by
gravitational attraction
This side bulges out because
of inertia
Therefore, there are two high tides on Earth at
any one time
Marine Life and Tides
• Some marine life time their
reproduction to the high or low tide
cycle
• Horseshoe crabs come ashore to
mate on the night of a high tide in
May
• Eggs hatch 2 wks later on a high tide
and are washed into the ocean
Motion in the Ocean…Waves
• Winds produce waves as it blows
across the ocean’s surface
• When waves enter shallow water they
drag along the ocean floor
• The wave top is moving faster than
the wave bottom so it topples forward
• Specialty waves: rogue waves, tidal
waves and tsunamis
At the shoreline
• Surf sequence of
breaking waves
• Swash - water
sliding up
beach
• Backwash water flowing
back down
beach to sea
Longshore drift
• Waves arrive at a
coast at an angle
(swash)
• Backwash returns
at 90 degrees
Sand is moved along the beach = longshore
drift or longshore current
Coastal
deposition
• Result of
longshore drift
and a lot of
sediment
• produces
extensions of
deposit from
the shoreline
spit = curved extension
• May grow
across a bay
(baymouth
bar)
• May link an
island to the
main land
(tombolo)
Motion in the Ocean-Currents
• Rivers of water moving through
the ocean
• Surface currents caused by major
wind belts
• Deflected by the Coriolis Effect
• Important in moving marine life
and nutrients around the oceans
Vertical Ocean Currents
• Differences in temperature and salinity
change the density of water.
• This causes sinking and rising of water in
the ocean
• Ocean conveyor belt- convection current
of water moving between the equator and
poles in the oceans
• Takes 1600 years to cycle