Chapter 7: Aquatic Ecosystems

1. Chapter 7: Aquatic Ecosystems

2. Chapter 7 Goals • Describe the factors that determine where an organism live in an aquatic ecosystem • Describe the zones that make up lakes or ponds • Explain the environmental function of wetlands • Explain why estuaries are productive ecosystems • Describe threats against river ecosystems, coral reefs and ocean organisms

3. Aquatic Ecosystems (Wet Biomes) • 75% of Earth’s surface is covered by water.

4. Salinity: the amount of dissolved salt present in water • Ecosystems are classified as salt water, fresh water, or brackish depending on salinity • Photosynthesis is limited by light availability, which is a function of depth and water clarity • Aquatic ecosystems are either flowing, standing or wetlands • Aquatic ecosystem zones: • photic, aphotic, littoral, benthic

5. Aquatic Ecosystem Limiting Factors • Limiting factors include: • Salinity • pH • Sunlight • Dissolved oxygen • Temperature • Nutrients

6. Freshwater Ecosystems:Ponds, Lakes, Rivers, Streams, Wetlands Salinity is less than 0.5 ppt (parts per thousand)

7. Aquatic Ecosystem Organisms • Grouped by location & adaptations • Plankton – floaters • Phytoplankton • Zooplankton • Nekton – swimmers • Benthos – bottom dwellers

8. Ponds & Lakes • Littoral – • Nutrient rich • Near shore • Abundant life • Open water • Photosynthesis • Benthic • No photosynthesis • Decomposers • Bottom-dwellers

9. Environmental Issue - Eutrophication • Eutrophication an increase in the amount of nutrients (nitrates) in an aquatic ecosystem • As the plants and algae grow, the number of bacteria feeding on the decaying organisms also grows • The bacteria use the oxygen dissolved in the lake’s waters • Eventually the reduced dissolved oxygen kills oxygen loving organisms

11. Freshwater Ecosystems: Wetlands • Areas of land flooded with water at least part of the year • Include freshwater marshes (non-woody plants), swamps (woody plants), bogs, and fens

13. Human Impact on Wetlands • Drained, filled and cleared for development Barbados The importance of wetlands is now recognized The law and the federal government protect many wetlands Most states prohibit the destruction of wetlands

14. Freshwater Ecosystems: Rivers and Streams Bodies of surface water that flow downhill, eventually reaching an ocean or inland sea Delaware Water Gap

15. Rivers in Danger • Industries use river water in manufacturing processes and as receptacles for wastes • People have used rivers to dispose of their sewage and garbage. • These practices have polluted rivers with toxins, which have killed river organisms and made river fish inedible. • Today, runoff from the land puts pesticides and other poisons into rivers and coats riverbeds with toxic sediments.

17. Marine Ecosystems • Marine ecosystems are located mainly in coastal areas and in the open ocean. • Organisms that live in coastal areas adapt to changes in water level and salinity. • Organisms that live in the open ocean adapt to changes in temperature and the amount of sunlight and nutrients available.

19. Coastal Wetlands • Coastal land areas that are covered by salt water for all or part of the time are known as coastal wetlands. • Coastal wetlands provide habitat and nesting areas for many fish and wildlife. • They also absorb excess rain, which protects them from flooding, they filter out pollutants and sediments, and they proved recreational areas for boating, fishing, and hunting.

20. Estuaries • Occur where a river flows into the ocean or an inland sea • Coastal estuaries are brackish ecosystems; organisms must tolerate wide salinity and temperature ranges. • Coastal estuaries are home to salt marshes and mangrove forests.

21. Estuaries • When fresh water meets salt water • currents form • nutrient-rich mud to falls to the bottom making in available to producers. • Estuaries are very productive • they constantly receive nutrients from the river and ocean • surrounding land protects the estuaries from the harsh force of ocean waves

24. Plants and Animals of Estuaries • Estuaries support many marine organisms • plenty of light for photosynthesis • plenty of nutrients for plants and animals • Light and nutrients support • large populations of rooted plants • plankton • plankton feed fish • fish eaten by larger animals such as dolphins. • Oysters and clams live anchored to rocks • feed by filtering plankton from the water

26. Plants and Animals of Estuaries • Organisms that live in estuaries can tolerate variations in salinity • Estuaries also provide • protected harbors • access to the ocean • connection to rivers • many of the largest ports have been built on estuaries • Six of the ten largest urban areas, including New York have been built on estuaries

27. Threats to Estuaries • Estuaries in populated areas often used as places to dump waste • Estuaries filled with waste could then be used as building sites • Pollutants that damage estuaries include sewage, pesticides, fertilizers & toxic chemicals • Most of these pollutants break down over time, but estuaries cannot cope with the amounts produced by dense human populations

29. Coral Reefs • Coral reefs - limestone ridges found in tropical climates and composed of coral fragments that are deposited around organic remains • Coral reefs among the most diverse ecosystems on Earth • thousands of species of plants and animals live in the cracks and crevices of coral reefs • Corals are predators that use stinging tentacles to capture small animals, such as zooplankton, that float or swim close to the reef

31. Coral Reefs • Corals live only in clear, warm salt water where there is enough light for photosynthesis.

32. Disappearing Coral Reefs • Coral reefs are very fragile • Coral may die if • the water is too hot or too cold • fresh water drains into the water surrounding the coral • the water is too muddy, polluted, or too high in nutrients • the algae that live within the corals will either die or grow out control • if the algae grows out of control, it may kill the corals

33. Oceans • Sunlight used by plants for photosynthesis penetrates only about 100 m into the ocean • Much of the ocean’s life is concentrated in the shallow coastal waters where sunlight penetrates to the bottom and rivers wash nutrients from the land • Seaweed and algae grow anchored to rocks, and phytoplankton drift on the surface. Invertebrates and fish then feed on these plants

34. Plants and Animals of Oceans • In the open ocean, phytoplankton grow only in areas where there is enough light & nutrients • one of the least productive of all ecosystems • The sea’s smallest herbivores are zooplankton • include jellyfish and tiny shrimp • live near the surface with the phytoplankton they eat • Fish and marine mammals (whales) feed on the plankton

35. Plants and Animals of Oceans • Deep ocean no sunlight • most food at the ocean floor consists of dead organisms that fall from the surface • Decomposers, filter feeders & the organisms that eat them live in the deep areas of the ocean • The types of organisms that may be found in the layers of the ocean at various depths is dependent on available sunlight

36. Plants and Animals of Oceans

37. Threats to the Oceans • The oceans are becoming more polluted • runoff from fertilized fields • industrial waste and sewage • Overfishing and certain fishing methods are also destroying some fish populations • Marine mammals can get caught and drown in the nets, too • Some ships illegally discard fishing lines into the ocean where they can strangle and kill fish ,turtles, dolphins and seals

39. Arctic and Antarctic Ecosystems • Arctic ecosystems are marine ecosystems • nearly all the food comes from the ocean • Arctic Ocean rich in nutrients from surrounding landmasses • supports large populations of plankton • plankton feed a diversity of fish in the open water and under the ice • These fish are food for ocean birds, whales and seals • Fish and seals then provide food for polar bears and people on land.

40. Arctic and Antarctic Ecosystems • Antarctic the only continent never colonized by humans • It is governed by an international commission and is used mainly for research • Even during the summer, only a few plants grow at the edges of the continent • Plankton form the basis of the Antarctic food web, nourishing large numbers of fish, whales, and birds such as penguins.

41. Chapter 7 Summary • Salinity, pH, sunlight, dissolved oxygen, temperature, and nutrients determine where an organism lives in an aquatic ecosystem • Littoral and benthic, photic and aphotic zones make up lakes or ponds • Wetlands store water, and trap pollutants and serve other environmental functions • Estuaries are productive ecosystems because they contain vast amounts of nutrients • Pollution threatens the health of river ecosystems, coral reefs and other ocean organisms