Aquatic Ecosystems
Chapter 19
Lesson 3
Types of Ecosystems
Water takes up more than 70% of the Earth’s
surface. That means that if you divided the Earth
into ten equal parts, seven of those equal parts
would be made of water.
The water on earth is categorized into two
groups: freshwater ecosystems and saltwater
ecosystems.
Saltwater is water that has a lot of salt in it.
Salinity is the amount of salt dissolved in water.
Freshwater is water that contains very little salt.
Freshwater Ecosystems
 rivers & streams,
Rivers and streams have moving water. The
water may be moving fast or slow.
Streams are often clear and form
underground.
Rivers form when streams run together.
Biodiversity
-Water-loving plants
-Species adapt to fast/slow
moving water
Human Impact
-People take out the water
-Hydroelectric dams stop water
-Runoff a source of pollution
Freshwater Ecosystem
Ponds & Lakes
Ponds are shallow and warm and
sunlight can usually reach the bottom
Lakes are larger and colder where
sunlight barely reaches the bottom
Biodiversity
-Plants surrounds ponds/lakes
-Fewer organisms live in
deeper, colder water of lakes
Human Impact
-Humans fill-in ponds/lakes
-Run-off washes pollutants
into water
Wetlands
Aquatic ecosystems that have a thin layer
of water covering soil that is wet most of
the time.
Contain freshwater, saltwater, or both
Wetland trap sediments and purify water.
Biodiversity
-Few trees live in saltwater
wetlands
-Insects are abundant
-More than 1/3 of NAm birds
species use wetlands
-alligators, turtles, frogs, snakes
Human Impact
-Once drain off and built on
-Now, major preservation
and focus on restoring
wetlands
Estuaries
Regions along coastlines where streams
or rivers flow into a body of saltwater.
Salinity depends on rainfall, freshwater
flowing from land and tides.
Protect coastal land
Filter out pollution
Biodiversity
-Many ocean animals lay their
eggs in estuaries
-Many species of birds depend
on estuaries for breeding,
nesting, and feeding
Human Impact
-Filled in for land and destroys
natural habitats.
-Exposed coastlines are prone
to coastal flooding and storm
damage
Ocean Zones
Oceans are the world’s largest ecosystem.
Water is deeper is some places than in
others and the water temperature also
changes.
The ocean is divided into three zones.
Sunlight Zone
Twilight Zone
Dark Zone
The deeper the water, the colder and darker
it becomes.
Most plants and animals can be found in the
areas closer to the surface.
Saltwater Ecosystems
Open Oceans: from continental shelf to
deep ocean.
Photosynthesis can take place only where
the sunshine reaches. Little in Twilight
Zone and none in the Dark Zone/sea floor
Decaying matter and nutrients float down
Biodiversity
-Microscopic algae and other
producers are the base of most
ocean food chains.
-Most animals live in light or
twilight zones
-Dark zones have lava eruptions
Human Impact
-Overfishing
-Trash discarded on cruise
ships and from the land
greatly impact ocean life
Saltwater Ecosystems
Ocean: Coastal Oceans/Intertidal Zones is
the ocean shore between the lowest low tide
and the highest high tide.
Sunlight reaches the bottom of shallow
coastal ecosystems
Nutrients washed in from rivers and
streams contribute to high biodiversity.
Intertidal species have adaptations for the
extreme living conditions of low tide and
heavy waves of high tide.
Oil spills can destroy all living organisms.
Saltwater Ecosystems
Coral Reef is an underwater structure
made from outside skeletons of tiny, softbodied animals called coral.
Most are in shallow tropical oceans
They protect coastlines from storm damage
Provide food and shelter for many animals
Pollution, overfishing, and harvesting
threaten coral reefs.
Animals Found in Saltwater Ecosystems
crustaceans
fish
sharks
sponges
penguins
whales
Animals Found in Freshwater Ecosystems
Grebe
Turtle
Trout
Puffer fish
Otter
Pelican
Bullfrog
The largest source of freshwater on earth is ice sheets,
glaciers, and icebergs.
The Great Lakes are the largest fresh water on the planet.