Transcript Section 5.3 - CPO Science

Organisms and the
Environment
Chapter Five: Ecosystems
• 5.1 Ecosystems, Energy, and Nutrients
• 5.2 Food Chains and Food Webs
• 5.3 Ecosystems- A Natural Balance
Investigation 5B
Testing Pollutants
• How will similar populations react to
different pollutants?
5.3 Types of Interactions
• Competition
happens when two or
more species depend
on the same food
source or any limited
resource.
On Sable Island near Nova Scotia, gray seals and
harbor seals both feed on sand lances.
5.3 Types of Interactions
• Animals that feed on
other animals are called
predators.
• Sharks in Sable Island’s
offshore waters are
known to eat seals.
• The sharks are called
predators and the seals
are prey.
5.3 Types of Interactions
• In symbiosis, at least
one member benefits
from the partnership.
• A remora is a small fish
that follows sharks
around and eats their
scraps.
5.3 Populations
• A population is a
group of individuals
of the same species
living in a given
area.
• Populations change
over time.
5.3 Populations
• The change in size of a population over
time is called its growth rate.
5.3 Invasive species
• Recently, European green
crabs have been found in
the United States.
• The arrival of the green
crab is cause for concern.
• Green crabs eat many
types of organisms
including clams, mussels,
How might European
and the young of other
green crabs be harmful
crab species.
to U.S. ecosystems?
5.3 Pollutants
• A pollutant is
something that
causes harm to a
living thing.
• Sulfur dioxide is a
chemical that is a
good example of
a pollutant.
5.3 Pollutants
• Sulfur dioxide can make
breathing difficult even
for healthy people.
• It reacts with water in
the atmosphere to
make acid rain.
• Acid rain kills trees and
harm life in lakes,
ponds, and streams.
5.3 Pollutants
•
Three things often determine how harmful
a pollutant is:
1. the pollutant’s ability to cause harm;
2. the amount of pollutant in air, water, or soil;
3. how long the pollutant stays in air, water, or
soil.
5.3 Toxins in the food chain
• Human activities
create toxic
pollutants (toxins).
• Food chains
concentrate some
toxins into the
tissues of animals.
5.3 Toxins in the food chain
• When carnivores eat many herbivores, they
accumulate toxins in their tissues.
5.3 Water quality
• We protect the
health of
freshwater
ecosystems by
testing the water.
• Common tests include:
– temperature, turbidity, dissolved oxygen, pH
5.3 Water quality
• To learn about the water
quality of a pond, first
make careful
observations.
– What does the pond water
look like or smell like?
– What animals and plants
are living in the pond?
– Where is the pond located?
– Are there houses or farms
nearby?
– Is the pond near a factory?
5.3 Water quality
• The turbidity test
measures the
cloudiness of water.
• If the water is too
cloudy, sunlight is
blocked, and pond
plants do not grow
well.
The secchi disk is lowered into the water until the
black and white panels are no longer visible.
5.3 Water quality
• The water temperature of a pond
is measured three or more inches
below the surface of the water.
• The higher the water temperature,
the less oxygen there may be in
the water for living things.
5.3 Water quality
• The pH scale ranges
from 0 to 14.
• Pure water is pH 7
(neutral).
• Most organisms in
ponds function best
when the water pH is
near 7.
5.3 Water quality
• Water quality is better
when dissolved
oxygen levels are
high.
• Oxygen is needed by
most organisms living
in the pond.
5.3 Water quality
• Nitrates and phosphates
are chemicals that can
enter ponds from farms,
fertilized lawns, or septic
tanks.
• Excess nitrates or
phosphates endangers
the health of the pond
ecosystem.
Biology Connection
Food Webs of the Deep
• In 1977, scientists
discovered a strange
community of living
things that forever
changed our
understanding of
Earth’s food webs.
Activity
Create a Species
• Create a species
that is perfectly
adapted to its
environment using
the information
provided.