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.
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
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
17.
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.
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
28.
29.
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
33.
34. Human Impact
Over fishing
Trash discarded from ocean vessels or washed
into oceans from land is a source of pollution.
35.
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
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