OCEAN WATER & OCEAN
LIFE

Total amount of solid material dissolved in water

Ratio of the mass of dissolved substance to the mass of the water
sample

Use parts per thousand because proportion of dissolved
substance is small number

Average salinity of ocean water is 3.5% or 35 parts per thousand
SALINITY

Where does the salt come from?

Chemical weathering of rocks on continents

Earth’s interior volcanic eruptions emit water vapor & gases
over the course of Earth’s history. Elements that make up salts
also emitted
SOURCES OF SEA SALTS

Oceans are well mixed

Relative concentrations are fairly constant around
the world

33ppt to 38ppt
PROCESSES AFFECTING SALINITY


Add large amounts of fresh water to seawater decrease salinity

Precipitation

Runoff from land

Icebergs melting

Sea ice melting
Remove large amounts of fresh water increase salinity

Evaporation

Formation of sea ice
PROCESSES AFFECTING SALINITY

Surface temperature varies depending on solar radiation

What pattern do you think you would find if you lowered a
thermometer from the surface into deeper waters?

Thermocline layer of ocean water between 300m to 1000m
where there is a rapid change in temperature with depth
OCEAN TEMPERATURE VARIATION

Salinity increase salinity, increase density

Temperature increase temperature results in decrease in
density

Which has a greater impact on ocean density and why?
OCEAN DENSITY VARIATION
Pycnocline what is it?
DENSITY VARIATION WITH DEPTH

Surface zone solar energy creates warmer waters, well mixed
because of waves and currents

Transition zone thermocline & pycnocline

Deep zone sunlight never reaches, water temperatures are
low, density is high
LAYERS ACCORDING TO DENSITY

Classified according to where they live & how they move

Plankton

Nekton

Benthos
OCEAN LIFE!
• Organisms that drift with
ocean currents
• Algae, animals, & plants
• Phytoplankton &
zooplankton…what’s the
difference?
Phytoplankton=plants
Zooplankton=animals
PLANKTON

Move independently of ocean currents
NEKTON

Live on or in the ocean bottom

Hydrothermal vents

Super-heated & saturated with minerals

Hot water comes in contact with cold minerals precipitate out

Support organisms not found anywhere else in the world

Chemicals are food for bacteria create sugars and other foods
other animals live off of these
BENTHOS

Photic zone sunlight penetrates upper part of ocean

Euphotic zone part of photic zone where light is strong enough
for photosynthesis

Aphotic zone no sunlight available
MARINE LIFE ZONESSUNLIGHT

Intertidal zone alternately covered and uncovered by
seawater with each tidal change

Neritic zone covers continental shelf, often shallow enough for
sunlight to reach the floor, entirely within photic zone, 90% of
words fisheries

Oceanic zone open ocean, lower nutrient concentration,
smaller populations
MARINE LIFE ZONES DISTANCE
FROM SHORE

Pelagic open ocean of any depth

Benthic zone sea-bottom surface

Abyssal zone subdivision of benthic zone, deep-ocean floor,
abyssal plains, high water pressure, sparse life, food “rains” down for
organisms living on the bottom
MARINE LIFE ZONES WATER DEPTH

Try to sketch a picture that models all of the zones that we
discussed 
SKETCH A PICTURE
It should look a little
something like this 
SOME SEA CRITTERS & THEIR HOMES
3 months of little to no
light during winter
3 months of all light
during summer
Why does May show
the height of
phytoplankton
(diatoms)?
Most sunlight
penetrating water= a
lot of photosynthesis
PRODUCTIVITY IN POLAR OCEANS
Why is there an
increase in
zooplankton right
after?
Feed on
phytoplankton.
If there is a lot
of food, there is
higher
productivity!
What is the limiting
factor for
phytoplankton?
Enough sunlight for
much photosynthesis
What is the limiting
factor in the
Why might productivity tropics?
be low?
Permanent
thermocline
prevents mixing
Barrier between
surface waters and
nutrient rich deeper
waters
PRODUCTIVITY IN TROPICAL OCEANS
Supply of
nutrients
considered
biological desert
Winter productivity=low,
solar energy is limited
Spring sun is higher=more photosynthesis,
spring bloom of phytoplankton, limited by lack of
nutrients because depleted very quickly
Summer strong thermocline so
limited mixture, nutrients depleted
from surface waters and cannot be
replaced by deeper waters
Fall summer thermocline
breaks down, nutrients return to
surface layer, waters mix,
sunlight becomes limiting factor
PRODUCTIVITY IN TEMPERATE OCEANS

Trophic levels feeding stages

Algae zooplankton & larger herbivores carnivores larger
carnivores

Energy transfer about 2% of the energy is transferred
OCEAN FOOD CHAINS

Approximately what percentage of Earth’s surface is covered by
oceans?

40

60

50

70
BEGINNING OF OCEAN ASSESSMENT
QUESTIONS 

Which ocean basin is the largest?

Atlantic

Pacific

Indian

Arctic

The use of sound waves to determine the depth of the ocean is
called

Submarine sounding

Sonar

Satellite altimetry

Submersible sounding

Bathymetry is

Depth of ocean

Distance from coast

Only focused on marine life

None of the above

The gently sloping submerged surface that extends from the
shoreline toward the ocean basin floor is the continental

Shelf

Rise

Slope

Margin

Submarine canyons are believed to have been created by

Rivers during the ice age

Earthquakes

Lost ships

Subduction

Calcareous ooze is an example of

Terrigenous sediment

Biogenous sediment

Hydrogenous sediment

A combination of hydrogenous and terrigenous sediment

Sediments that consist of mineral grains that were eroded from
continental rocks are called

Terrigenous

Biogenous

Hydrogenous

Hydrates

What could gas hydrates be used for

Landfill

To make concrete

Source of energy

Source of cobalt & copper

The most abundant salt in seawater is

Calcium chloride

Sodium chloride

Magnesium chloride

Sodium fluoride

Which process does NOT lead to a decrease in salinity of
seawater?

Runoff from land

Precipitation

Evaporation

Sea ice melting

Which term refers to the layer of water in which there is a rapid
change of temperature with depth in the ocean?

Pycnocline

Abyssal zone

Thermocline

Isothermal line

Which is NOT a zone in the 3 layered structure of the ocean
according to density?

Mixed zone

Deep zone

Transition zone

Intertidal zone

Organisms that drift with ocean currents are

Nekton

Plankton

Neritic

Pelagic

Which term describes the upper part of the ocean into which
sunlight penetrates?

Neritic zone

Intertidal zone

Oceanic zone

Photic zone

Phytoplankton are usually found in the

benthic zone

Photic zone

Abyssal zone

Aphotic zone

The use of light energy by organisms to convert water and
carbon dioxide into organic molecules is

Chemosynthesis

Decomposition

Photosynthesis

consumption

During which season does primary productivity reach its peak in
polar oceans

Spring

Summer

Fall

Winter

In temperate oceans, primary productivity is limited by

Nutrients and oxygen concentration

Nutrients and water temperature

Sunlight and oxygen concentration

Sunlight and nutrients

Why is salinity expressed in parts per thousand instead of
percent?

Parts per thousand expresses smaller units of measurements

Explain how salinity of water in polar regions varies seasonally

During winter sea ice forms & salinity increases because fresh
water is pulled out to form ice. During summer sea ice melts and
puts fresh water back into the ocean

Compare & contrast phytoplankton & zooplankton.

Both drift with waves & currents, limited mobility to vertical
motions, phytoplankton are plants zooplankton are animals

What factors may affect the depth of the photic zone in any
given area of the ocean?

How deep the sunlight penetrates