Chapter 10:
Freshwater Biomes
Freshwater is less than 3% of the Hydrosphere.
90% of the freshwater is locked beneath the Earth’s surface.
Water is cycled through evaporation and transpiration from the
atmosphere to the land and back again.
10.1 Aquatic Biomes
 Land biomes cover less
than 30% of the Earth’s
surface.
 Aquatic biomes contains
organisms that live in water.
 Two factors that are used to
classify aquatic biomes:
 1. The amount of salt in the
water - salinity
 2. The depth of the water
and the amount of sunlight
that reaches it
10.1 Aquatic Biomes
Salinity – the amount of
dissolved salts in a sample of
water
 Salinity is measured in parts
per thousand (ppt)
 Aquatic biomes are divided
into two groups: saltwater
and freshwater
 Saltwater biomes have 30
ppt – (oceans, seas)
 Freshwater biomes have 0.5
or less ppt (lakes, ponds,
rivers)
10.1 Aquatic Biomes
 Brackish water is more salty
that fresh but less than the
ocean – (anywhere freshwater
meets with sea water –
marshes, deltas, estuaries)
 Hypersaline – more salt than
the ocean - 40 ppt (the Great
Salt Lake –Utah and Mono
Lake – California)
10.1 Aquatic Biomes
 Depth
 Available sunlight is the
determining factor for
water depth.
 Sunlight amount
determines types of
plants that can grow
 Producers are the base
of all aquatic food webs
10.1 Aquatic Biomes
 Depth - Three layers:
 Photic zone – top layer
of water gets enough
sunlight for
photosynthesis to about
(100 m in open ocean)
 Aphotic zone – sunlight
never reaches this zone
(only deep lakes and
ocean)
 Benthic zone – the
floor of a body of water.
10.2 Freshwater Ecosystems
 Freshwater biomes
divided into TWO
classifications:
 Standing-water –
lakes, ponds, bogs
swamps, marshes.
Water does not move in
and out but does move
within the system.
 Flowing-water –
Rivers, streams. Water
moves in, out and
through the system
10.2 Standing-Water Biomes
 Upper level – warm, gets
most sunlight. Contains
plankton –
microorganisms that float
on the surface of the
water.
 Phytoplankton – perform
photosynthesis, make
their own food (producers)
 Zooplankton – cannot
perform photosynthesis,
eat phytoplankton
(consumers)
10.2 Standing-Water Biomes
 Benthic level – cool,
gets little or no sunlight.
Contains scavengers
that consume dead
organisms.
 Food Chain: Small fish
eat plankton and
insects, larger fish eat
small fish.
10.2 Standing-Water Biomes
 WETLANDS
 Found where water and land
meet.
 Roots of plants are under
water part or all of the year.
 Soils are soaked with water.
 Water can be fresh or
brackish
10.2 Standing-Water Biomes
 Wetlands act as water filters
- remove chemicals from
water as it passes through
them.
 Can be used as treatment for
waste water.
 Important breeding, feeding
and resting areas for
migrating birds.
 Wetlands protect areas from
flooding.
 Refill aquifers
10.2 Florida Everglades
 Once covered the entire
lower part of Florida from
Lake Okeechobee to the
Keys.
 Area reduced through human
activity (draining) from over
150 miles to just 1,508,537.9
acres
10.2 Everglades
 Home to many rare and
unusual organisms:
 Alligator
 Florida panther
 Florida soft-shelled turtle
 Key deer
 Great Blue Heron
 Ibis
 Florida Tree Snail
10.3 Flowing-Water Ecosystems
 Flowing-water
ecosystems all have
water that moves
over land.
 All water that moves
above ground are
streams
 All water that move
underground are
aquifers
10.3 Flowing-Water Ecosystems
STREAMS
 Begin at high altitude, as
runoff from melting snow on
mountain tops
 Gravity causes water to
move downhill
 Stream beginnings are
called the “origin” or “head”
 Water from the starting place
is called headwaters
 The water is cold and carries
much material with it – called
sediments
10.3 Flowing-Water Ecosystems
 Sediments are small
particles that settle to the
bottom of any body of water
 Provide nutrients and place
for plant roots to grow
 Increases in producers bring
increases of consumers
 Sedimentation (sediment
collecting) and soil erosion
cause streams/rivers to
change course - become
more and more winding