Aquatic EcosystemsLesson 4.4

M. ParkerBodega Head, Sonoma Coast

Freshwater: flowing Freshwater = 3% of all surface water on earth

Flowing systems include rivers, streams, creeks

Supports a largevariety of fishes, reptilesand amphibians, as well as their predators,such as otters, bears, eagles and raccoons.

Water flow is too fastto support mostinvertebrate life.

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

WetlandsWater covers soil or ispresent at least part of year

Can be fresh water, saltyor “brackish,” which is amixture of fresh and saltwater (Shollenberger)

Very productive ecosystems, many plant and animal species supported (over 170 spp of birds alone atShollenberger Park)

Over 90% of SF Baywetlands gone due todevelopment and agriculture

Shollenberger Park, Petaluma

SF Bay wetlands 150 years ago and today

Bay Institute

EstuariesWetlands 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

Marine Ecosystems

200 m1,000 m

Aphotic

zone

Photic zone

Abyssalplain

Continental slope

and continental rise

Continentalshelf

Open ocean

Coastal ocean

Land

Oceantrench

Inter

tidal

zone

Benthic zone

4,000 m

6,000 m

10,000 m

Oceans can be divided into zonesbased 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 livein aphotic zone.

They get their energy from chemicals leaked from deepsea vents in the ocean floor.

However, many different consumers, such asoctopuses and giant squid canlive in the deep ocean.

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 andtemperature changes, wave shock

Competition leads to “zones” of differentorganisms living in particular habitats

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.

Kelp forest at Monterey Bay Aquarium

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.

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.