1. Aquatic Ecosystems
Lesson 4.4
Bodega Head, Sonoma Coast
M. Parker

2. Freshwater: flowing Freshwater = 3% of all surface water on earth
Flowing systems include
rivers, streams, creeks
Supports a large
variety of fishes, reptiles
and amphibians, as well
as their predators,
such as otters, bears,
eagles and raccoons.
Water flow is too fast
to support most
invertebrate life.

3. Fresh water: standing
Lakes and ponds are the most common standing water ecosystems
Water circulates within as well as in and out of the system (little currents)
This helps to distribute oxygen, nutrients and heat through the system
Habitat for “plankton,” or tiny, free-floating organisms
“Phytoplankton” are single-celled algae
“Zooplankton” are microscopic animals that feed mainly on the phytoplankton

4. Wetlands Water covers soil or is present at least part of year
Can be fresh water, salty
or “brackish,” which is a
mixture of fresh and salt
water (Shollenberger)
Very productive
ecosystems, many plant
and animal species
supported (over 170 spp
of birds alone at
Shollenberger Park)
Over 90% of SF Bay
wetlands gone due to
development and agriculture
165 acres of tidal wetlands, brackish water from Petaluma river, but also fresh water channels– different communities of plants and animals. Over 160 species of birds have been identified here.
Shollenberger Park, Petaluma

5. SF Bay wetlands 150 years ago and today
Bay Institute

6. Estuaries Wetlands formed where rivers meet the sea.
Mixture of fresh and salt
water, affected by rise and fall of
ocean tides
Many shallow, enough
light for photosynthesis, so lots
of plant life in estuaries
Most plant material is not consumed
by zooplankton, but forms
“detritus,” tiny particles that
provide food for bottom of the
food web such as clams, sponges,
and worms.
Breeding grounds for many fish
And shellfish that we eat

7. Continental slope and continental rise
Marine Ecosystems
Photic zone
Land
200 m
1,000 m
Intertidal zone
Coastal
ocean
Open
ocean
4,000 m
Aphotic zone
Benthic zone
6,000 m
The ocean can be divided into zones based on light penetration and into zones based on depth and the distance from shore. Each zone contains a characteristic assemblage of organisms.
Ocean
trench
Continental slope and continental rise
10,000 m
Continental
shelf
Abyssal
plain

8. Oceans can be divided into zones
based on amount of light, depth
and distance from shore.
Photosynthesis is limited to
“Photic” zone (200 meters deep)
“Aphotic” zone below is
permanently dark and cold.
Chemosynthetic organisms are
The only producers that can live
in aphotic zone.
They get their energy from
chemicals leaked from deep
sea vents in the ocean floor.
However, many different
consumers, such as
octopuses and giant squid can
live in the deep ocean.

9. Rocky Intertidal
Intertidal organisms are exposed to regular and extreme changes in their environment
Once or twice a day, submerged in water at high tide
At low tides, exposed to sunlight, air and
temperature changes, wave shock
Competition leads to “zones” of different
organisms living in particular habitats

10. Coastal ocean Extends from low tide mark to outer edge of
continental shelf
Shallow enough for
photosynthesis
Rich in plankton and many other
organisms
Kelp = giant brown algae
that can grow 50 cm/day!
Kelp forests provide habitat
for snails, sea urchins, sea
otters, many fish species, seals,
even whales.

11. Kelp forest at Monterey Bay Aquarium

12. Coral reefs Found in warm, shallow tropical coastal oceans
Among the most diverse and
productive systems on earth
Named for tiny coral animals
that have hard calcium
carbonate skeletons.
Live together in vast numbers and
feed on plankton with tentacles
Live symbiotically with algae in their
tissues. Algae do photosynthesis
and use coral waste as nutrients.
Algae also provide corals with carbon
compounds for growth.

13. Open ocean Largest marine zone, over 90% of the surface area of the
world’s oceans.
500 meters deep to
11,000 meters in the
deepest ocean trench
Deep ocean creatures are
subjected to high
pressure, frigid
temperatures and
total darkness
Fishes of all types
dominate, but also
many marine mammals,
jellies, octopus, etc.