Chapter 19.2: Aquatic Ecossytems


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Grade 8 Integrated Science Chapter 19 Lesson 2 on different aquatic ecosystems. This lesson gives short defining characters of freshwater, ocean, wetland, and estuary ecosystems. Freshwater ecosystems include river, streams, lakes, and ponds. The ocean section describes the open ocean, coastal ocean, and coral reefs. There is also a short section about intertidal zones and layers of the open ocean. The objective of the lesson is that students should be able to identify defining characteristics of each ecosystem and be able to compare and contrast.

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Chapter 19.2: Aquatic Ecossytems

  1. 1. Chapter 19.2 AQUATIC ECOSYSTEMS
  2. 2. Vocabulary  Salinity – the amount of salt dissolved in water  Wetland – aquatic ecosystems that have a thin layer of water covering soil that is wet most of the time  Estuary – regions along coastlines where streams or rivers flow into a body of salt water  Intertidal Zone – the ocean shore between the lowest low tide and the highest high tide  Coral Reef– an underwater structure made from outside skeletons of tiny, soft-bodied animals called coral
  3. 3. Introduction to Aquatic Ecosystems  There are four major types of water, or aquatic, ecosystems  Freshwater  Rivers and Streams  Lakes and Ponds  Wetland  Estuary  Ocean  Open ocean  Coastal ocean  Coral Reefs
  4. 4. Introduction to Aquatic Ecosystems  Abiotic factors include  Temperature  Sunlight  Dissolved oxygen  Salinity  Each has a unique variety of organisms in and out of the water  Aquatic species have adaptations that enable them to use oxygen underwater  Fish use gills  Mangrove plants take in oxygen through small pores in their leaves and roots
  5. 5. Mangroves
  6. 6. Introduction to Aquatic Ecosystems  Salinity is another important abiotic factor  Salinity is the amount of salt dissolved in water  Water in saltwater ecosystems has high salinity compared to water in freshwater ecosystems, which contain little salt (…obviously)
  7. 7. Freshwater: Streams and Rivers  Streams are usually narrow, shallow, and fast- flowing  Rivers are larger, deeper, and flow more slowly
  8. 8. Streams...  form from underground sources of water, such as springs or from runoff from rain and melting snow  have water that is often clear.  Soil particles are quickly washed downstream  have high oxygen levels because air mixes into the water as it splashes over rocks
  9. 9. Rivers...  form when streams flow together  have muddy water from the soil that washes into it from streams or nearby land  Soil adds nutrients, such as nitrogen, into rivers  that are slow-moving have higher levels or nutrients and lower levels of dissolved oxygen compared to fast-moving water (obviously!)
  10. 10. Biodiversity  Willows and cottonwood trees are water-loving and grow along streams and on river banks  Trout, salmon, crayfish, and many insects are adapted to fast-moving water  Snails and catfish are adapted to slow-moving water.
  11. 11. Human Impact  Streams and rivers are over-used for drinking, laundry, bathing, crop irrigation, and industrial purposes  Hydroelectric plants use the energy of flowing water to create electricity.  Dams stop the water’s flow and impede anadromous and catadromous fish species  Runoff from cities, industries, and farms is a source of pollution
  12. 12. Freshwater: Ponds and Lakes  Ponds and lakes contain freshwater that is not flowing downhill  Ponds  Shallow and warm  Sunlight can reach the bottom  Lakes  Larger and deeper  Sunlight penetrates into the top few feet.  Deeper water is dark and cold
  13. 13. Biodiversity  Plants surround ponds and lake shores  Surface water contains plants, algae, and microscopic organisms that rely on photosynthesis  Cattails, reeds, insects, crayfish, frogs, fish and turtles live in shallow water near shorelines  Fewer organisms live in deeper, colder water of lakes where there is little sunlight  Lake fish include perch, trout, bass, and walleye
  14. 14. Human Impact  Humans fill in ponds and lakes with sediment to create land for houses and other structures  Runoff from farms, gardens, and roads washes pollutants into ponds and lakes, disrupting food webs
  15. 15. Wetlands  Wetlands are aquatic ecosystems that have a thin layer of water covering soil that is wet most of the time (not necessarily all the time)  Wetlands can be freshwater, saltwater, or both  They are among Earth’s most fertile ecosystems
  16. 16. Wetlands  Freshwater wetlands form at the edges of lakes and ponds and in low areas on land  Saltwater wetlands form along ocean coasts  High nutrient levels  High biodiversity  Wetlands trap sediment and purify water  Plants and microscope organisms filter out pollution and waste materials
  17. 17. Biodiversity  Water-tolerate plants include grasses and cattails  Few trees live in saltwater wetlands  Willows, cottonwoods, and swamp oaks are trees found in freshwater wetlands  Insects are abundant  Dragonflies, and butterflies  More than one-third of North American bird species, including ducks, geese, herons, loons, warblers, and egrets, use wetlands for nesting and feeding  Alligators, frogs, turtles, and beavers depends on wetlands for food and breaking grounds.
  18. 18. Cattails and Reeds
  19. 19. Human Impact  In the past, many people considered wetlands as unimportant environments. Water was drained away to build homes and roads and to raise crops.  Today, many wetlands are being preserved and drained wetlands are being restored
  20. 20. Estuaries  Estuaries are regions along coastlines where streams or rivers flow into a body of salt water  Most estuaries form along coastlines, where freshwater in rivers meets salt water in oceans.  They have varying degrees of salinity
  21. 21. Estuaries  Salinity depends on rainfall, the amount of freshwater flowing from land, and the amount of saltwater pushed in by tides  Estuaries help protect coastal land from flooding and erosion.  Like wetlands, estuaries purify water and filter out pollution  Nutrient levels and biodiversity are high
  22. 22. Biodiversity  Plants that grow in salt water include mangroves, pickleweeds, and seagrasses  Animals include worms and snails  They also have oysters, shrimp, crabs, and clams (yummmm)  Striped bass, salmon, flounder, and many other ocean fish lay their eggs in estuaries  Many species of birds depend on estuaries for breeding, nesting, and feeding
  23. 23. Human Impact  Large portions of estuaries have been filled with soil to make land for roads and buildings  Destruction of estuaries reduces habitat for estuary species and exposes the coastline to flooding and storm damage
  24. 24. Ocean: Open Oceans  Most of Earth’s surface is covered by ocean water with high salinity  Oceans have many different types of ecosystems  The open ocean extends from the steep edges of continental shelves to the deepest parts of the ocean  The amount of light depends on the depth
  25. 25. Ocean: Open Oceans  Photosynthesis can take place only in the uppermost, or sunlit, zone.  Very little sunlight reaches the twilight zone.  None reaches the deepest water, known as the dark zone. (no way!)  Decaying matter and nutrients float down from the sunlit zone, through the twilight and dark zones, to the seafloor
  26. 26. Biodiversity  The sunlit zone is home to microscopic algae and other producers. They form the base of the food chain  Jellies, tuna, mackerel, and dolphins also live here.  Many species of fish stay in the twilight zone during the day and swim to the sunlit zone at night to feed.
  27. 27. Biodiversity  Sea cucumbers, brittle stars, and other bottom- dwelling organisms feed on decaying matter that drifts down from above  Many organisms in the dark zone live near cracks in the seafloor where lava erupts and new seafloor forms
  28. 28. Human Impact  Over fishing  Trash discarded from ocean vessels or washed into oceans from land is a source of pollution.
  29. 29. Ocean: Coastal Oceans  Coastal oceans include several types of ecosystems, including continental shelves and intertidal zones  The intertidal zone is the ocean shore between the lowest low tide and the highest high tide  Sunlight reaches the bottom of shallow coastal oceans  Nutrients washed in from rivers and streams contribute to high biodiversity
  30. 30. Biodiversity  It is home to mussels, fish, crabs, sea stars, dolphins, and whales  Intertidal species have adaptations for surviving exposure to air during low tides and to heavy waves during high tides
  31. 31. Human Impact  Oil spills and other pollution harm coastal organisms
  32. 32. Ocean: Coral Reefs  A coral reef is an underwater structure made from outside skeletons of tiny, soft-bodied animals called coral  High biodiversity  Form in shallow tropical oceans  Protect coastlines from storm damage and erosion
  33. 33. Biodiversity  Coral reefs provide food and shelter for many animals, including parrotfish, groupers, angelfish, eels, shrimp, crabs, scallops, clams, worms, and snails
  34. 34. Human Impact  Pollution, overfishing, and harvesting of coral threaten coral reefs