Transcript Activity 84: Clam Catch

Activity 84:Clam Catch
Challenge How might an introduction of a
competing species, such as the invasive zebra
mussels, affect a population of native clams?
Key Vocabulary:
Competition
Native Species
Invasive Species
Define the following in your
notebooks:
• Competition  a contest for resources that can
occur between organisms of the same species as
well as between organisms of different species
• Native Species  a species found within a
particular habitat
• Invasive species  an organism that is not
native and has negative effects on our economy,
our environment or our health
What do organisms need to
live?
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Space
Food
Sunlight (if you are a plant)
Water
• Remember that living and nonliving factors can affect
population size.
If there are no changes in an
ecosystem from year to year,
would you expect populations to
also stay the same?
• Remember from Activity 77 “Ups and Downs” that
populations can fluctuate.
In our activity tomorrow, you are going
to model a clam population over ten
years.
• Do you expect the clam population to stay exactly the same?
• Do you expect a population of real clams to stay the same?
In round 1:
Clams wear a wrist band
Only one clam per circle
Clams can only catch plankton with
one hand and both feet must remain
in their circle.
Plankton begin in the safety zone.
May not go around the ends of the
clam beds.
The goal is for plankton to get
through the clam bed without being
“eaten” (tagged)
Tagged plankton, stay with your clam
until told. Tagged plankton become
clams.
Clams that do not tag any plankton is
considered dead and also becomes
plankton.
Clam and Zebra
Mussels
Round 2:
Two mussels can occupy one circle, or one
mussel and one clam. Two clams CAN NOT
share a circle.
Zebra mussels are better filter feeders so
they can use two hands to tag plankton
Zebra mussels will not wear wrist bands.
Plankton tagged by zebra mussels, become
zebra mussels and receive an arm band
Plankton tagged by clams become clams and
do not collect arm bands.
Any clam or zebra mussel that does not tag
a plankton dies and becomes a plankton
Reminders for the game
Round 1
Clams
• 8 in the middle circles
• Can “tag” only using
one hand
• If you tag the plankton,
they become clams.
• If you don’t tag
anything, you “die” and
become plankton.
Plankton
• Start in the Safety Zone
• Run across the lake to
the other safety zone
trying to avoid being
tagged by a clam in 10
seconds.
• If you are tagged, you
become a clam and stay
in the middle circle.
Reminders for the game
Round 2
Zebra Mussels
• Start with 3
• Can use BOTH
Hands.
• Wear a Red Band.
• 2 per circle or 1 with
a Clam
Clams
• Start with 8
• Can only Use ONE
Hand.
• Only 1 per circle
Record your data into your
notebooks on SS 84.1
Once you have
recorded your class
data, Answer Analysis
Questions 1, 2, 5 and
6 in your notebooks
with your group!
Analysis Question #3 is for
homework and will be graded
using the OD Assessment and
the AD Assessment.
Analysis #1
b. In general, the
population fluctuated.
But it did remain fairly
steady between 6 and 14
clams. Over the first 2
years the population
increased from 6 to 14.
It then decreased to 8
clams by year 4. These
types of variations
continued to be
observed for the
remaining 6 years.
Number of Clams
a. Should have made a line
graph
Analysis #2
• The availability of plankton, or food, was the limiting factor
that affected the size of the clam population.
• When more food was available, it was easier for clams to
catch it and the clam population grew.
• When food was scarce, the clam population decreased,
reducing competition for food allowing the plankton
population to increase.
Analysis #5
A. In a real lake, non living factors such as:
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water temperature,
amount of sunlight,
pollution levels
, availability of oxygen,
and amount of suitable space are all factors that would affect the
size of clam and zebra mussel populations
B. Predators, competition between species, and food
availability are living factors that might affect population
size.
Analysis #6
• See SS 77.2 After column #6-8