Transcript Aquatic Ecosystems

Aquatic Ecosystems
Chapter 7
Environmental Science
Freshwater Ecosystems
• Lakes and Ponds
• Wetlands
• Rivers
• Factors affecting which organisms live in
freshwater ecosystems
–
–
–
–
Temperature
Sunlight
Oxygen
Nutrients
Aquatic Ecosystem Organisms
• Plankton
– Organisms that float near the surface
– Two types
• Phytoplankton – produce most food for ecosystem
• Zooplankton – microscopic animals
• Nekton
– Free-swimming organisms
– Fish, turtles, whales
• Benthos
– Bottom-dwelling organisms
– Mussels, worms, barnacles
• Decomposers
– Break down dead organisms
Lakes and Ponds
• Layers of a Lake
– Littoral zone
• Top layer near the shore
• Nutrient rich
• Plants are rooted in mud
• Plants make energy from photosynthesis
– Depend on sunlight
– Benthic zone
• Bottom of the lake
• Bacteria lives here
• No sunlight reaches this layer
• Dead organisms are consumed by decomposers
Lakes and Ponds,
cont.
• Eutrophication
– Increase of nutrients
– Occurs when a large amount of plant growth
in a lake or pond
– Increases amount of bacteria
– Bacteria uses up oxygen
– Eventually not enough oxygen for organisms
– Runoff can accelerate eutrophication
• Sewage, fertilizers, animal wastes
Freshwater Wetlands
• Areas of lands covered in water for at
least part of the year
• Two types – marshes and swamps
• Environmental Functions
– Absorb and remove pollutants
– Control flooding by absorbing extra water
– Provide homes for wildlife
– Prevent against erosion
– Provide recreational areas for fishing, etc.
– Provide breeding grounds for fish and shellfish
Marshes
• Occur in low, flat lands
• Have little water movement
• Plants root in sediment under water
– Reeds, rushes, cattails
• Water birds have adapted to marshes
– Heron – spearlike beak to grab fish
– Ducks – flat beak to sift through water for fish
• Kinds of marshes according to salinity
– Brackish marshes – slightly salty water
– Salt marshes – saltier water
Swamps
• Flat, poorly drained land near streams
• Types of swamps
– Mangrove swamps
• In warm climates near the ocean (salt water)
– Freshwater swamps
• Ideal environment for amphibians
• Swamps attract birds and reptiles
– Wood ducks, alligators
Human Impact on Wetlands
• Wetlands were considered wastelands
where insects breed
– Humans drained the wetlands for this reason
• Important roles now recognized
– Purifiers for wastewater
– Flood prevention
– Habitats for wildlife
• Most states have laws against the
destruction of wetlands
Rivers
• Many begin from snow melt in mountains
– Cold, full of oxygen, fast moving
• River flows down the mountain
– Becomes wider, warmer, slower, less oxygen
• A river changes depending on the land
and climate it is flowing through
Rivers in Danger
• Industries polluting the water
– Kills organisms
– Makes fish inedible
• Runoff from land
– Puts pesticides in the river and sediment
• Dams
– Change the ecosystem in and around river
Marine Ecosystems
• Costal Wetlands
– Areas covered by salt water for all or part of
the time
– Many fish and wildlife live here
– Absorb excess rain
• Helps to avoid flooding problems
– Filter out pollutants and sediments
– Are recreational areas for boating, fishing, etc
Estuaries
• Estuary
– Area where fresh water from a river mixes
with salt water from an ocean
– Currents form here
• Cause mud and nutrients to fall to the bottom
• Marsh grasses will begin to grow here
– Constantly receiving fresh nutrients
• Makes it a very productive ecosystem
Plants and Animals of Estuaries
• Rooted plants
– Sunlight can reach the bottom since water is shallow
– Nutrient supply is always high
• Plankton live here
• Mammals feed on plankton
– Dolphins, manatees, seals
• Oysters, clams feed on the plants
• All organisms that live here can tolerate various
levels of salinity
Threats to Estuaries
• Ports are built over estuaries
– Provides easy access to oceans
• Usually populated areas surround an estuary
– Waste is dumped in the estuary
– Pollutants
• Sewage
• Industrial waste containing toxic chemicals
• Agricultural runoff containing pesticides, fertilizers
Salt Marshes
• Develop in estuaries where rivers deposit their
•
•
load of mineral-rich mud
Clams, fish, aquatic birds live here
Protects young animals when small
–
–
–
–
Shrimp
Crab
Fish
When older, they migrate to the sea
• Absorbs pollutants
• Protect inland areas
Mangrove Swamps
• Located along coastal areas of tropical and
subtropical zones
• Mangrove trees are the main plant
• Protects the coastline from erosion
• Reduces damage from storms
• Many animals use as a breeding grounds
• Sometimes filled with waste and destroyed
Rocky and Sandy Shores
• Rocky Shores
– Many plants anchor to rocks
– Many animals live on the rocks
• Anemones
• Mussels
• Sponges
• Sandy Shores
– Dry out when tide goes out
– Tiny organisms live off of plankton
– Barrier islands
• Land that runs parallel to the shore
• Protect the mainland and coastal wetlands
Coral Reefs
• Limestone ridges built by tiny coral animals
called polyps
– They secrete skeletons of limestone
• Calcium carbonate
• Thousands of plants and animals live here
– Most diverse ecosystem on Earth
• Live in clear, warm salt water
• Live in shallow water so sunlight can reach
• They are predators that never chase their prey
– Stinging tentacles to capture organisms that float by
Disappearing Coral Reefs
• Corals die if:
– Water becomes too hot or too cold
– Fresh water drains into the water near reef
– Water is too muddy, polluted or too high in nutrients
• Causes of coral reef destruction
–
–
–
–
–
–
–
–
–
Oil spills
Sewage
Pesticides
Silt runoff
Overfishing
Careless divers
Shipwrecks
Ships dropping anchor
People breaking off pieces
Oceans
• Animals
– Phytoplankton
• Live where light and nutrients are (shallow water)
• Have flagella to keep them from sinking deeper
– Zooplankton
• Feed on phytoplankton near surface
• Examples
– Jellyfish
– Tiny shrimp
– Larvae of fish, oysters, lobsters
– Decomposers
• Live on bottom of ocean
• Consume dead organisms
Threats to the Oceans
• Pollution
– Industrial waste
– Sewage
– Plant nutrients (fertilizers, etc.)
• Overfishing and nets
– Animals can get tangled in nets and die
Arctic and Antarctic Ecosystems
• North and South Poles
• Large population of plankton
• Many fish eat the plankton
• Birds, whales, seals feed on the fish
• Fish and seals feed the polar bears
• Antarctic is not populated by humans
– Mainly used for research purposes
Section 2 Assignment
• Page 185
• #1-5
Chapter 7 Review
• Pages 187-189
• #6-18, 20-26, 29, 34-35