2. Recycling within the AquaWorld.
Decomposers exist in the AquaWorld (and our World) to break down dead
plant and animal material, called detritus, making the material
available again for plants to use. If decomposers weren't there then the
minerals (nitrogen, phosphorous etc.) would become "locked-up"
in the dead bodies causing other plants and animals to die. Decomposers
in our environment include scavengers (e.g.insects, birds, etc.), worms,
bacteria, and fungi. The decomposers are the recyclers of the AquaWorld.
Have students talk about decomposers in the AquaWorld
and in our world. Talk about how large decomposers, such as
the snails, break up material so that smaller decomposers, like bacteria,
can consume it.
Ask the students to create a small compost pile
at home (with their parents permission) and watch what happens over time.
Have the students to point out which things break down most quickly. Are
there some materials that don t break down at all?
Talk with the students about recycling and why its important in our
biosphere: The Earth. Ask them to bring one thing to recycle (e.g. can,
bottle, paper) each day for a week and observe how quickly the pile
grows. If you haven t already, start a school-wide paper recycling
program. Take a field trip to a recycling plant and contribute the class
s recyclables.
3. Carbon and Oxygen
Cycles.
Atmospheric processes, like carbon and oxygen cycles inside the AquaWorld, can provide several interesting exercises. Plants are most
known for creating oxygen and consuming CO2. However, a less known fact
is that plants, like animals, also burn O2 and produce CO2. Thus,
animals would not survive without plants, but plants could survive
without animals (although the plants might be smaller if no were animals
present). The reason our atmosphere works (i.e. animals survive), is
that actively growing plants consume more CO2 than they produce and
produce more O2 than they consume. Almost all of the O2 in the
atmosphere comes from plants and algae, and some of this oxygen gets
converted to ozone which protects us from the Sun s harmful radiation.
There is much more O2 in the atmosphere than CO2 so any talk about
running out of O2 due to deforestation is not credible. However, since
the amount of CO2 in the atmosphere is much smaller, human activities
can have a more marked impact which could potentially lead to greenhouse
warming of the atmosphere (a controversial subject. some scientists
believe greenhouse warming is already occurring while others claim it is
not).
Talk with the students about the difference between CO2 and O2 and how
photosynthesis works. Make diagrams showing the oxygen and carbon cycles
within the AquaWorld. What basic elements make up CO2 and O2? Where
does the Carbon come from? What is the plant made of and why are most
plants green? Why does the plant not outgrow the AquaWorld?
Look at a map or globe of the Earth. Where is
most of the World s O2 consumed/produced (e.g. point out heavily
populated areas vs. wilderness or forested areas)? Where is most of the
world s CO2 produced/consumed? Talk about the productivity of different
parts of the planet (or different biomes). Talk with the students about
the role of our forests in maintaining atmospheric balance?
Talk with the students about the Earth s
atmosphere and how it works. Talk with the students about what gases are
in the Earth s atmosphere. What role do each of the gases play? Look at
a picture of Earth from space to observe how thin the Atmosphere is. Why
do astronauts need space suits? Why do divers use SCUBA gear? Talk about
the different layers of the atmosphere and why the air is thinner in the
mountains. Where do we get oxygen when we re in an airplane?
Show the students a picture of a greenhouse.
How does a greenhouse work? How is the AquaWorld similar to a
greenhouse? How is our Earth similar to a greenhouse? What role does
ozone play in regulating our atmosphere?
4. Energy Exchange.
Energy
exchange from the Sun and within the AquaWorld can provide interesting
curricular activities. With few exceptions, all the sugars that we and
other animals (consumers) use come from plants and algae. The plants and
algae derive their energy to make these sugars from sunlight. Thus the
amount of plants and animals in the AquaWorld is directly related to
the amount of sunlight or lamplight the AquaWorld receives. We breathe
out CO2 because we are burning these sugars: a process called
respiration. We breath in O2 to help us burn the sugars. For this reason,
sugars and other carbon compounds are called the "biological
currency" for energy. Only about 10% of the energy that is made
into sugars by plants is ever used to build muscle and other body
tissues in herbivores. This is because:
(a)
Plants burn much of the energy they produce (e.g. they respire);
(b)
Not all parts of plants are eaten;
(c)
Not all parts of plants are digestible;
(d)
Animals respire too. For similar reasons only 10% of the algae eaten by
the snail inside the AquaWorld is converted into snail body mass.
Make a
diagram of the energy flows within the AquaWorld. Talk with the
students about what the animals in the AquaWorld eat. Show the students
pictures of plants and animals and explain what parts we eat and why.
Talk about the four food groups and categorize different foods in them.
Talk with the students about what foods have sugar in them. Identify
where the sugar comes from. Bring in a piece of sugar cane or fruit for
the students to taste. What happens if we eat too much of any one food
group and why? How do the animals in the AquaWorld maintain a balanced
diet?
Talk with the students about how respiration
works. Have them breathe heavily and listen to their heart rate (point
out that they are consuming more O2 and generating more CO2). Why do we
breathe hard when we exercise or perform strenuous work? How do
respirators in hospitals work?
5. The Nitrogen Cycle.
The AquaWorld
s Nitrogen Cycle is an interesting process. Approximately 78%
of both the Earth's and the AquaWorld's atmosphere is N2 gas. This form
of nitrogen is not usable by plants. However, there are bacteria inside
the AquaWorld that fix nitrogen. This means that they take an
unavailable source of nitrogen from the ecosystem (e.g. N2 gas) and turn
it into a source (e.g. ammonia, nitrates) that can be absorbed by the
plants. Also inside the AquaWorld are microbes called nitrifying
bacteria that take the ammonia from animal waste and fixation (which can
be very poisonous to animals) and turn it into nitrite and nitrate (less
poisonous). This can also be absorbed and utilized by the plants and
algae. Nitrogen compounds can also be made back into nitrogen gas by
denitrifying bacteria, making it unavailable again to plants. This last
cycle does not often occur in the AquaWorld as an anaerobic (absent of
oxygen) environment is required. When the detritus at the bottom of the AquaWorld
becomes thick and the AquaWorld is not moved for a long
period of time then an anaerobic condition may be created at the bottom
of this layer and denitrification may occur. On Earth, some of these
bacteria live on legumes (e.g. green bean plants, peanuts, etc.) and
others are free-living in the soil and water. Other sources of usable
nitrogen include lightning, car exhaust, and commercial fertilizer.
Draw the nitrogen cycle of the AquaWorld, including the animals and
plants. How does it differ from Earth's?
Have the students grow beans (inoculated)
and look for root nodules. What is the purpose of the root nodules? Add
different amounts of nitrogen fertilizer over time and observe how the
plants behave.
Have the students grow bacteria (there are kits
that include culture plates and swabs). Talk about the purpose of
bacteria in the AquaWorld and in our world.
6. Build your own AquaWorld.
The AquaWorld
is a self-contained system that behaves differently depending
on its environment. Many interesting lessons could be centered around
having students create and observe their own AquaWorld
Guide the students in building their own
biospheres using empty mayonnaise jars (sterilized with 5% bleach
solution, for example). Have them try to recreate the AquaWorld and or
try modifications like adding or removing snails, adding or removing
plants, etc. Be aware that the results of changes may take days or even
weeks to observe. What does this tell us about time scales on Earth?
Have the students make hay infusions by
putting hay into a jar full of water. This can be very interesting
because all sorts of small creatures and other organic matter are
present on hay which may become active when put into the water (you may
need a microscope to see them).
