Aquatic EcosystemsChapter 7
Environmental Science
Section 7.1Freshwater Ecosystems
Freshwater EcosystemsTemperature, sunlight, oxygen, and
nutrients are factors that determine where organisms live.
A main factor is salinity.Salinity is the amount of dissolved salts the
water contains.
Characteristics of Aquatic EcosystemsPlankton are
organisms that cannot swim; they drift.
Phytoplankton are drifting plants that provide most food.
Zooplankton are drifting animals.
Aquatic OrganismsNekton Benthos
Are free-swimming organisms, like fish, turtles, and whales.
Are bottom-dwelling organisms, such as mussels, worms, and barnacles.
Life in a LakeLakes
Zones of Lake or PondLittoral Zone is near the shore and aquatic life is diverse and abundant.
Littoral Zone is where most plants are found: like reeds and cattails.
Benthic Zone is the bottom of the pond or lake which is inhabited by decomposers, insect larvae, and clams.
How Nutrients Affect LakesEutrophication: an increase in the amount
of nutrients in an aquatic ecosystem.Leads to algal blooms and reduced amounts
of oxygen.Other aquatic organisms suffocate and die.Eutrophication is accelerated by run-off.
Freshwater Wetlands Description of a wetland:Areas of land that are
covered with fresh water for at least part of the year.
They act as filters when they absorb and remove pollutants.
Environmental Functions:
They control flooding by absorbing extra water when rivers overflow.
They provide homes for many species and trap carbon.
Marshes Description of a
marsh:Occur on low, flat
lands and have little water movement.
Attract migratory birds
Salinity varies Adaptations: Organisms adapt to
the range of salinity
Swamps Description of a
swamp:Occur on flat, poorly
drained land, often near streams.
Mangrove trees are found in saltwater swamps.
Many amphibians in freshwater swamps
Alligators are the top predator of swamps
Human Impact on WetlandsMany wetlands were drained and filled in for
development.Example: Florida EvergladesLaws protect wetlands and prohibit wetland
destruction.
Rivers Description of a
river: Headwaters: cold and
full of oxygenFlows downward:
warmer, wider, slower, more vegetation and less oxygen.
Factors that impact a river:
Pollution is killing river organisms
Dams change the river ecosystem.
Time for a reading quiz
Section 7.2Marine Ecosystems
EstuariesDescription of an
estuary:An area in which fresh
water from a river mixes with salt water from the ocean.
It forms a nutrient trap making estuaries very productive.
Adaptations of organisms:
Plant and animals must be able to adapt to changing salinity and water levels.
Threats to Estuaries
Used as solid waste landfills.
Used for building sites
Sewage, industrial waste, and agricultural run-off
Salt Marshes vs. Mangrove SwampsSalt Marshes Mangrove Swamp
Are where rivers deposit their load of mineral-rich mud.
Clams, fish, birds.Nursery for shrimp,
crabs, fishAbsorb pollutants
Mangroves have above ground root systems.
Found in tropical and subtropical zones.
Protect coastline from erosion
Coral ReefsAre limestone ridges
built by tiny coral animals called coral polyps
Highly diverse ecosystems but fragile
Fish, snails, clams, sponges
Shallow, clear tropical seas
Threats to Coral ReefsCan’t get too cold or too hotCoral bleaching leads to coral deathGlobal warming, oil spills, run-off, over-fishing
leading to more coral reef destruction
OceansShallow, coastal
waters is where most ocean life is found
Open ocean is one of the least productive ecosystems (lacks sunlight)
Ocean floor consists of dead organisms, decomposers and filter feeders
Threats to OceansPollution Run-offOverfishingTrawl nets
Arctic and Antarctic EcosystemArctic Antarctic
North PoleMost food comes from
oceanPlankton, fish, birds,
whales, and seals
Only continent not colonized
South PolePlankton is base of food
web.Fish, whales, and
penguins.
Time for reading quiz
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