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.

1. Chapter 19.2
AQUATIC ECOSYSTEMS

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. 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. 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. Mangroves

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. Freshwater: Streams and Rivers
 Streams are usually narrow, shallow, and fast-
flowing
 Rivers are larger, deeper, and flow more slowly

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. 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. 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. 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. 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. 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. 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. 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. 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

18. 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.

19. Cattails and Reeds

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

30. 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

31. 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.

32. 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

34. Human Impact
 Over fishing
 Trash discarded from ocean vessels or washed
into oceans from land is a source of pollution.

36. 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

37. 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

38. Human Impact
 Oil spills and other pollution harm coastal
organisms

39. 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

40. Biodiversity
 Coral reefs provide food and shelter for many
animals, including parrotfish, groupers, angelfish,
eels, shrimp, crabs, scallops, clams, worms, and
snails

41. Human Impact
 Pollution, overfishing, and harvesting of coral
threaten coral reefs