Transcript Chapter 22
Chapter 22
Ecosystems and the Biosphere
22-1
Energy Transfer
In an ecosystem, energy flows from the
sun to autotrophs and then to other
organisms
Autotrophs make their
own food (plants and
some bacteria and
protists)
Producers
Most producers are plants
Photosynthesis: plants use carbon
dioxide, water, and solar energy to make
glucose. (Oxygen is a byproduct)
6 CO2 + 6 H2O + solar energy C6H12O6 + 6 O2
Chemosynthesis
Some species of bacteria can produce
carbohydrates from inorganic molecules
Example: bacteria found along
hydrothermal vents in the ocean
Measuring Productivity
Gross primary productivity: the rate that
producers in an ecosystem capture
energy
Biomass: organic material
Only energy stored as biomass
is available to other organisms
Net Primary Productivity
The rate at which biomass accumulates
in an ecosystem
Can vary greatly in different ecosystems
Influenced by light,
temperature, and
precipitation
Consumers
Organisms that get their energy by eating
other organisms
Also called heterotrophs (“other feeders”)
Examples: animals
Herbivores
Consumers that eat only producers (plant
eaters)
Examples: rabbits, deer, cows, sheep,
grasshoppers
Carnivores
Consumers that eat only other
consumers (meat eaters)
Examples: coyote, bobcat, shark,
alligator, hawk, owl, snakes
Omnivores
Consumers that eat both plants and
animals
Examples: humans, bears, pigs, gorillas,
rats, raccoons, some insects
Detritivores
Consumers that feed on dead organisms,
animal waste, or fallen leaves and
branches
Examples: vultures, maggots, carrion
beetles, earthworms
Decomposers
Consumers that break down dead
organisms in an ecosystem (returns
nutrients to soil, water, and air)
Examples: fungi and bacteria
Energy Flow
Cellular respiration: breaking down food
to yield energy
C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy
Cells use glucose and oxygen to produce
carbon dioxide, water, and energy
Food Chain
A sequence in which energy is transferred
from one organism to the next as each
organism eats another organism
Represents one strand of a food web
Food Web
Shows many feeding relationships that
are possible in an ecosystem
DDT
Dichloro-Diphenyl-Trichloroethane
Pesticide once used to prevent
mosquitoes from transmitting malaria to
humans
Contaminated zooplankton small fish
large fish eagles and ospreys
Biomagnification
DDT became more concentrated as it moved up the
food chain
Caused eggshell thinning in eagles and ospreys
Banned in 1972, but is still present in some
ecosystems
Migratory birds are exposed to DDT in other countries
that still use it
Trophic Levels
Refers to each step in the transfer of
energy through a food chain or a food
web
Each time energy is transferred,
some energy is lost and less
energy is available to the next
trophic level
Energy Pyramid
Energy Loss
Since so much energy is lost at each
level, there are fewer organisms at the
higher trophic levels
Ecosystems rarely have more than 4-5
trophic levels
Quantity of Energy
Transfers
10% of the total
available energy at
one trophic level is
transferred to the
next level
Higher trophic levels
contain less energy
and can support
fewer organisms
22-2
Ecosystem Recycling
Biogeochemical cycles: The movement
of water, minerals, and elements through
the environment
Examples: the water, carbon, nitrogen,
and phosphorus cycles
The Water Cycle
Water is a renewable
resource because it is
circulated through the
water cycle
The water cycle is the
continuous movement of
water between Earth and
the atmosphere
Global Water Distribution
97% of Earth’s water is
saltwater
3% is freshwater, but
most of it is frozen as
icecaps or glaciers
Less than 1% is
available as liquid
freshwater
Watershed
An area of land
drained by a river
Pollution anywhere in
a watershed can
pollute a river
The Carbon Cycle
A process by which carbon is cycled
between the atmosphere, land, water,
and organisms
Carbon is present in all living things
Short-term cycle
Consumers eat producers and obtain
carbon from the carbohydrates
Some of the carbon is released back into
the atmosphere as a byproduct of cellular
respiration
Long-term cycle
Carbonates (found in bones, shells, &
coral) do not break down easily
Calcium carbonate deposits form
limestone
Limestone is one of the largest carbon
sinks on Earth
Fossil Fuel
When living organisms die, their remains
still contain carbon
Over time, the remains of ancient
organisms changed into coal, oil, and
natural gas
Humans and the Carbon Cycle
When we burn fossil fuels, we release
carbon dioxide into the atmosphere
Increased levels of carbon dioxide
contributes to global warming
The Carbon Cycle
The Nitrogen Cycle
The process by which nitrogen is cycled
between the atmosphere, bacteria, and
other organisms
The atmosphere is 78% nitrogen, yet
most organisms (including humans)
cannot use it until it has been “fixed”
Nitrogen-Fixing Bacteria
Legume plants, such as soybeans and
clover, have root nodules that contain
nitrogen-fixing bacteria
The bacteria “fixes” the nitrogen into a
usable form
All Life is Interconnected
All organisms need nitrogen to build
proteins
The bacteria alter the atmospheric
nitrogen for plants to use
Animals obtain the nitrogen they need
when they eat plants
Decomposers
Bacteria break down wastes and dead
organisms to return nitrogen to the soil
Some of the nitrogen is transformed into
a gas and is returned to the atmosphere
The Nitrogen Cycle
The Phosphorus Cycle
The movement of phosphorus from the
environment to organisms and then back to the
environment
This cycle is very slow
Phosphorus moves from phosphates in rock to
living organisms and eventually to the ocean
Phosphates
When rocks erode, they release
phosphates into the soil and water
Plants absorb phosphates through their
roots
Phosphates are also added to the soil
when organisms die and decompose
The Phosphorus Cycle
Fertilizers
Fertilizers contain both nitrogen and
phosphorus
Fertilizers can enter an aquatic ecosystem
through runoff
Excess nitrogen and phosphorus in an aquatic
ecosystem can result in an algal bloom
Artificial Eutrophication
Sewage and fertilizer
runoff enter lakes and
ponds and causes an
algal bloom
When the algae dies, the
decomposition from
bacteria uses most of
the oxygen and the fish
suffocate and die
22.3
Terrestrial Ecosystems
Biomes: very large terrestrial ecosystems
that contain specific kinds of plants and
animals
Biomes are influenced by climate and
altitude
Climate & Altitude
Climate: the temperature and
precipitation of an area over a long
period of time
Altitude: refers to the elevation above sea
level
Biomes
Each biome is made up of many different
types of ecosystems.
There are seven major biomes: tundra,
taiga, temperate deciduous forest,
temperate grassland, desert, savanna,
and tropical rainforest
Biomes of the World
Tundra
A cold biome located across northern
North America, Europe and Asia
The ground is permanently frozen at a
depth of 10-36 inches (trees can't grow)
Receives little precipitation and a very
short growing season (2 months)
Common Plants & Animals
of the Tundra
Plants: grasses,
sedges, mosses, and
lichens
Animals: caribou,
musk ox, lemmings,
snowshoe hares,
snowy owls, arctic
fox
Taiga
A forested biome dominated by conifers
(pine, fir, hemlock, and spruce)
Needles are specialized leaves that help
the trees survive the long, cold winters
Common Plants & Animals
of the Tiaga
Plants: evergreen
trees
Animals: lynx,
moose, bears,
wolves, great gray
owls
Temperate Deciduous Forest
Characterized by trees that lose their
leaves in the Fall
Variable temperatures and moderate
precipitation
Common Plants & Animals of the
Temperate Deciduous Forest
Plants: beech,
maple, oak, hickory,
sycamore, elm, birch
Animals: white-tailed
deer, raccoons,
foxes, squirrels,
great-horned owls
Temperate Grasslands
Regions that are dominated by grasses
and have variable temperatures
Found in the interior of continents
Also called prairies, steppes,
pampas, and veldt
Common Plants & Animals of
the Temperate Grassland
Plants: various
grasses (a lot has
been turned into
farmland!)
Animals: pronghorn,
prairie dogs,
meadowlark, bison
Deserts
Areas that receive less than 25 cm of
rainfall per year
Most deserts are hot, but there are also
cold deserts
Desert vegetation is sparse and has a
waxy coating that prevents water loss
Rain Shadow Effect
Common Plants & Animals of
the Desert
Plants: cacti and
succulents
Animals: lizards,
scorpions, jack
rabbits, roadrunners,
kit fox, snakes,
burrowing owls
Savannas
Tropical or Subtropical grasslands with
scattered trees and shrubs
Has alternating wet and dry seasons
Common Plants & Animals of
the Savanna
Plants: various
grasses, few trees,
shrubs
Animals: wildebeest,
zebras, gazelles,
giraffe, lions,
cheetahs, elephants
Tropical Rain Forests
Areas near the equator that have a
warm, wet climate and a year-round
growing season
Most biodiversity is found in tropical
rainforests
Common Plants & Animals
of the Tropical Rain Forest
Plants: trees,
epiphytes,
understory plants
Animals: parrots,
jaguar, monkeys,
insects, sloth,
snakes, lizards
(contains 1/5 of all
known species)
22-4 Aquatic Ecosystems
Water covers ¾ of Earth
97% of all water on our planet is
saltwater
3% is freshwater (less than 1% is liquid
freshwater!)
Ocean Zones
Photic Zone: the part
of the ocean that
receives light
Aphotic Zone: the
cold, dark depths
where sunlight
doesn’t reach
The Intertidal Zone
The area that includes the beaches, tidal
pools, and waves
Organisms are adapted to the rise and
fall of the tides
Tides
Tides are the cyclic rising and falling of
Earth's ocean surface caused by the tidal
forces of the moon and the sun acting on
the oceans
High and Low Tides
During the day, the Earth rotates 180
degrees in 12 hours. The moon,
meanwhile, rotates 6 degrees around
the earth in 12 hours. The moon's
rotation and its gravitational pull mean
that any given coastal city
experiences a high tide approximately
every 12 hours
Spring Tide
When the sun and moon
are aligned, there are
exceptionally strong
gravitational forces,
causing very high and
very low tides which are
called spring tides,
though they have
nothing to do with the
season.
Neap Tides
During the moon's
quarter phases the
sun and moon work
at right angles,
causing the bulges to
cancel each other.
The result is a
smaller difference
between high and
low tides.
The Neritic Zone
The most productive zone in the ocean
Upwelling refers to currents that carry
nutrients up from the bottom
Coral reefs, plankton, sea turtles, fish,
squid, etc. are found in this zone
Coral Reefs
Limestone ridges built by
coral polyps
Very diverse ecosystem
Corals are invertebrates
that only live in shallow
tropical seas
Threats to Coral Reefs
Coral reefs are fragile
Divers cut pieces of
coral to sell
Also threatened by oil
spills, pollution, sewage,
pesticides, and silt runoff
The Oceanic Zone
Nutrient levels are lower in this zone
Deep sea organisms have reduced
skeletons and slower metabolism
Threats to the Oceans
OVERFISHING!
Trawl nets entangle and
kill many animals
Industrial waste,
sewage, solid waste, oil
spills, toxic chemicals
Hydrothermal Vents
Areas that release water that is rich in
minerals and can exceed 750 °C
Chemosynthetic bacteria uses hydrogen
sulfide (H2S) to make their own food
Many organisms along a vent get their
food directly from the bacteria
Estuaries
Areas where freshwater rivers and streams
flow into the sea
Examples: bays, salt marshes, mud flats
Receive a lot of light and nutrients
Important breeding grounds for many species
Freshwater Zones
Freshwater contains less than .005 %
salt (NaCl)
Examples: lakes, ponds, streams, &
rivers
Lakes and Ponds
Eutrophic: rich in
organic matter and
vegetation
Oligotrophic:
contains little organic
matter
Rivers
Bodies of water that flow down a gradient
Headwaters: where a river begins
(usually as a mountain stream)
As a river flows down a mountain, it
becomes wider, warmer, slower, and has
less oxygen
Streams
Tributaries that flow
into larger bodies of
water
Faster flowing
streams are highly
oxygenated and
contain more benthic
macroinvertebrates