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CHAPTER 4.4
AQUATIC ECOSYSTEMS
 Aquatic ecosystems are dependent on abiotic factors
like light, nutrient availability, and oxygen.
 Aquatic ecosystems are determined mostly by
depth, flow, temperature, and chemistry of the
overlying water.
FRESHWATER ECOSYSTEMS
 There are 2 main types of freshwater ecosystems:
flowing-water and standing-water.
 Flowing-water ecosystems – rivers, streams, creeks,
and brooks are all examples. All organisms that lives
in these areas have ways of handling the flow of the
water.
STANDING-WATER ECOSYSTEMS
 Lakes and ponds are the most common. These systems usually have water that flows in and out and also have
water circulating within them.
 The water circulation helps distribute heat, oxygen, and nutrients throughout the lake or pond.
 Plankton is commonly found in standing-water ecosystems. Plankton are tiny, free-floating organisms that live in
both freshwater and saltwater environments.
 Phytoplankton (a type of plankton) is an algae that is the base of the aquatic food chain.
 Zooplankton (another type of plankton) feed on phytoplankton.
FRESHWATER WETLANDS

A wetland is an ecosystem that either covers soil or is present
at or near the surface of the soil for at least part of the year.
This water may be flowing or standing and fresh, salty, or
brackish (mix of fresh and salt water).

There are usually many insects, fishes, amphibians, and birds in
this area.

There are 3 types of wetlands: bogs, marshes, and swamps.

Bogs are usually dominated by moss and form in depressions
where water collects.

Marshes are shallow areas along rivers, usually cattails, rushes,
and tall grass like plants are found here.

Swamps – look like flooded forests. This area will have shrubs
and trees.
ESTUARIES
 Estuaries – wetlands that form where rivers meet
the ocean. This area will have a mix of fresh and salt
water and the amount of water here is affected by
ocean tides.
 The main source of food is detritus – tiny pieces of
organic material. Animals that feed on detritus are
clams, worms, and sponges.
 Salt marshes – temperate zone estuaries that have
salt-tolerant grasses.
 Mangrove swamps – coastal wetlands that are in
tropical regions. They have mangroves that grow
there (salt tolerant trees)
MARINE ECOSYSTEMS
 The marine ecosystem is divided into different zones:
photic zones are well-lit upper layer. Algae and
producers can grow here. Aphotic zone is
permanently dark. Chemosynthetic autotrophs are
the only producers here.
 Marine ecosystems are also divided based on the
depth and distance from the shore: intertidal zone,
coastal zone, and open ocean.
INTERTIDAL ZONE
 These have regular and extreme changes in
surroundings because of tides coming in and out.
 A good example is a rocky intertidal zone where
starfish, sea anemones, crabs, and mussels are
located.
 These areas have zonation – the horizontal banding
of organisms that live in a particular habitat.
COASTAL OCEAN
 This extends from the low-tide mark to the outer
edge of the continental shelf (the shallow border
that surrounds the continents).
 Usually part of the photic zone so photosynthesis
can take place here.
 Kelp forests – are found in coastal oceans and have
an enormous amount of brown kelp. There is a giant
kelp forest near Monterey. Life here includes snails,
sea urchins, sea otters, many fish, seals, and whales.
CORAL REEFS
 These reefs are in warm, shallow waters in tropical
areas. Coral reefs are named for the coral animals
that make up this area.
 These are areas that have very diverse life.
OPEN OCEAN
 Begins at the continental shelf and moves outward. It
also ranges in depth.
 Organisms in the deep ocean are exposed to high
pressure, very cold temperatures, and total darkness.
 There is usually not many nutrients in the water so
there is not a lot of photosynthesis that takes place.
 All different types of fish are found here.
BENTHIC ZONE
 This is the ocean floor. Animals that live here are sea
stars, sea anemones, and marine worms.
 Animals here do not move around much and usually
feed on dead organic material that come from
surface waters.