Aquatic Ecosystems

1. Aquatic Ecosystems Chapter 9 Environmental Science

2. Freshwater Ecosystems • Lakes and Ponds • Wetlands • Rivers • Factors affecting which organisms live in freshwater ecosystems • Temperature • Sunlight • Oxygen • Nutrients

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. Life in a River • Mosses • Anchor to rocks with roots called rhizoids • Plankton • Live further down stream in warmer water • Trout and minnows • Live at the headwaters (strong current) • Plants • Some are rooted in the river’s sediment • Leaves will vary in shape depending on river’s current

12. 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

13. Assignment • Page 178 • Section 1 Review • #1-5

14. Marine Ecosystems • Coastal 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

15. 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

16. 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

17. 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 • Quick Lab • Page 180

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. Threats to the Oceans • Pollution • Industrial waste • Sewage • Plant nutrients (fertilizers, etc.) • Overfishing and nets • Animals can get tangled in nets and die

25. 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