Freshwater Biomes
Chapter 10
10.1 Aquatic Biomes
Objectives
 Describe
the factors that characterize the various
types of aquatic biomes.
Aquatic Biomes
 What
type of biomes have we learned about so far?
 Rainforest,
savannah, desert, decidious forest, etc.
 These are all terrestrial biomes meaning they are land
biomes.
 But, land only covers about 30% of the earth’s surface
 So
it’s not surprising that many of Earth’s organisms live in
aquatic habitats
 Aquatic habitat is one in which the organisms live in or on
water
If all the world's water were to form a single drop, this is how big it
would be: A sphere stretching from Salt Lake City, Utah to Topeka,
Kansas. Though this mega-droplet looks small compared to Earth's
bulk, the two dimensionality of this image is somewhat deceiving. In
fact, the water sphere would have a diameter of about 860 miles and a
volume of about 332,500,000 cubic miles.
http://ga.water.usgs.gov/edu/2010/gallery/global-water-volume.html
Aquatic Habitats

Aquatic habitats are not grouped the same way as
terrestrial biomes. What features are used to classify
terrestrial biomes?
Temperature and rainfall
 Temperature in large bodies of water is more stable than on land,
and rainfall does not affect aquatic creatures because they are
already underwater


Aquatic Biome Characteristics are determined by:
Salinity
 Depth
 Dissolved Oxygen
 Flow Rate

Let’s look at each of these factors!
Salinity
 Aquatic
biomes can be divided into two main
groups, based on the amount of dissolved minerals
in the water
 Saltwater
 Freshwater
 All
bodies of water contain some dissolved salts and
minerals, but ocean water has a lot more than lakes,
ponds or streams
 The amount of dissolved salts in a sample of water is
called salinity
Salinity
 Salinity
is measured in parts per thousand, the
number of units of salt in a thousand units of
water
ocean water: 30 ppt
 Fresh water: 0.5 ppt
 Brackish water: in between

 Brackish
water is more saline than fresh water, but less
saline than ocean water and is usally found where fresh
water meets the ocean
 Great
Salt Lake (hypersaline): 40 ppt
 Density demo
Depth
 The
ecosystem found in a body of water is greatly
influenced by the amount of sunlight that
penetrates to the bottom.
 Amount
of sunlight is key in determining the type and
amount of plants that can grow
 Since
plants provide the food for animals, depth
determines the amount and types of animals
 Video
Depth Zones

Photic Zone

The top layer of water that receives enough sunlight for
photosynthesis


Up to 200 m depending on how cloudy the water is
Aphotic Zone
Sunlight never reaches
 Very deep lakes and the oceans


Benthic Zone
The floor of a body of water
 May have plants and animals depending on depth

Fig. 52-16a
Littoral
zone
Limnetic
zone
Photic
zone
Benthic
zone
(a) Zonation in a lake
Pelagic
zone
Aphotic
zone
10.2 Standing-Water Ecosystems
Objectives
 Identify
the characteristics of different types of
standing-water ecosystems
 Explain the value of wetlands and the reason for
their decline
Standing-water ecosystems
 Freshwater
biomes can be divided into 2 main
types
 Flowing-water
ecosystems
 Standing-water ecosystems
 Lakes,
ponds also wetlands, bogs, swamps, marshes
 Net flow is little, but water circulates, distributing warmth,
oxygen and nutrients
Types of Standing-Water Ecosystems
Abiotic Factors
Biotic Factors
Lake
Deepest type of standing water; may
have an aphotic zone; may be fed by
underground aquifer
Main producers are floating algae in the
photic zone and benthic plants along
the shoreline, complex food webs
Pond
Light reaches the benthic zone; fed
mostly by rainfall; may be seasonal
Main producers are plants and algae
that grow on the bottom; food web
usually simpler than in lakes
Marsh
Very shallow water with land
occasionally exposed; soil is
saturated; water often lacks oxygen,
may be freshwater, saltwater or
brackish; often tidal, Florida
everglades largest in US
Plants have roots under water, but
leaves are above the water; mostly
grasses, cattails and rushes; ducks,
waterfowl and benthic animals are
common
Types of Standing-Water Ecosystems
Abiotic Factors
Biotic Factors
Swamp
Land is soaked with water
because of poor drainage;
usually along low streambeds
and flat land; mangrove
swamps are salty and found
along coastlines
Dominated by large trees and
shrubs, plants are adapted to
grow in muddy, oxygen-poor
soil; cypress trees common in
the south, willow and
dogwood common in N US
Bog
Inland wetland with little
inflow or outflow; soil is
acidic; decay is slow; carbon
is stored in dead plants
Sphagum moss is the
dominant organism; partly
decayed moss accumulates as
peat
Standing Water Organisms
 Standing-water
ecosystems have several
levels of habitat
 Organisms
that live in the upper levels are
different than those in the middle and bottom
layers
 Top
level supports the plankton community
 Plankton

are Microorganisms that drift in the water
About the size of dust
 Small
fish feed on plankton and insects
 Larger fish feed on the smaller fish so
are important to the food web
they
Standing Water Organisms
 Two
types of plankton
 Phytoplankton
 Carries
out photosynthesis
 The main producers in aquatic biomes
 Zooplankton
 Do
not carry out photosynthesis
 Consumers of phytoplankton
Question
Which is it?
A. Lake
B. Pond
C. Swamp
D. Bog
Lake
Question
Which is it?
A. Lake
B. Pond
C. Swamp
D. Bog
Pond
Wetlands
 Wetlands
are ecosystems in which the roots
of plants are submerged under water at least
part of the year
 Marshes
 Swamps
 Bogs
 Soil is soaked in water
 Very low in dissolved oxygen
 Wetlands
Wetlands
 Very
continued
important
 Act
as filters, detoxifying chemicals in the
water
 Can be used as part of treatment systems for
waste water
 Important for breeding, feeding & resting
grounds for migratory waterfowl
 Flood protection along banks of rivers
 Refilling of aquifers
Wetlands
 Are
being destroyed by human activity at an
alarming rate
 Not
as attractive as other natural habitats
 Breeding grounds for mosquitoes
 Unpleasant odor – swamp gas – methane
 The land is often near coastal areas so it’s very valuable
for other uses (resorts, motels, etc)
 Used as landfill sites
 Cities built on filled wetlands
 Bill Nye
Question
Which is it?
A. Swamp
B. Marsh
C. Mangrove
D. Bog
Marsh
Swamp
Question
Which is it?
A. Swamp
B. Marsh
C. Mangrove
D. Bog
Mangrove Swamp
Question
Which is it?
A. Swamp
B. Marsh
C. Mangrove
D. Bog
The Bog
Question
Which is it?
A. Swamp
B. Marsh
C. Mangrove
D. Bog
Florida Everglades
 Much
was drained to create farmland.
 The natural cycle was destroyed and
populations of many organisms was greatly
reduced
 Some land has been returned to wetlands
and the water flow has been adjusted
 Still an endangered habitat but now there is
hope
10.3 Flowing Water Ecosystems
Objective
 Describe
how abiotic factors of gravity, erosion,
and sedimentation affect stream ecosystems
Flowing-water ecosystems
 Flowing
water ecosystems have many different
names; rivers, streams, creeks, and brooks
 these
all refer to water that flows over land
 Most people associate these names with different sized
bodies of water, however, scientists call all above
ground bodies of flowing freshwater streams
 Recall
that fresh water can also flow underwater
through aquifers
 Even
though underground, they contain fish and other
animals
 Stream
organisms are adapted to the rate of the
waters movement
 Plants
have roots that keep them in place
 Some organisms burrow into sandy bottoms
 Some have hooks to grab hold of plants
 Some have suckers to anchor to rocks
 Some have ability to swim upstream
 Seek calm pools at sides of streams
The nymphs live under water up to two
years, move to land, and shed as adults.
The legs have a single claw and there
may be two to three tails.
Mayfly - As
adults, mayflies
live only a few
hours or days,
living only long
enough to mate
and lay eggs.
Stream Flow
 Often
begin from runoff from melting snow
 Flow downhill
 Flow towards the oceans
 At source flow is too fast for most organisms
 Water
near the source is called headwater
 Mountain headwaters are cold and contain large
amounts of dissolved oxygen that can support a variety
of organisms, but the water flows too rapidly
Stream Flow
 As
the slope of the land becomes more
gentle, streams slow
 As
stream slows, small particles settle to bottom
called sediments.
 Sediments provide a place for plants to grow
 Plant
growth slows water flow, allowing water to be
warmed by the sun
 Phytoplankton multiply in the warmer water providing
food to support consumers
The Course of a Stream
 Sedimentation
and erosion
cause the course to change
 Results in a winding or
meandering of the stream
As the stream curves, the water
flowing along side the streams
slows and the water outside speeds
up.
 Sediments accumulate on the inner
edge because of slowed flow
 Increased erosion occurs along the
banks of the stream cause it to
become more curved

Human Activity
 Streams
changed dramatically by human
activity
 Streams dammed to create reservoirs
 Stream beds become lake bottoms
 Levees for flood control
 Dredging for shipping
 Changing
the course of a stream damages or
destroys the delicate habitats of many organisms
 Stops natural flooding which is a natural and
beneficial part of the ecosystem.
The End