Transcript Aquariums * Miniature Oceans

Aquariums – Miniature Oceans (part 1)
The main goal
• To highlight a few of the versatile ways
aquariums can be used in the classroom to
demonstrate fundamental concepts in biology,
chemistry, and earth science
• To show the utility of having an aquarium in
the classroom is that there is a “one-time”
cost in which you can refer to over the course
of the year to help leverage lesson plans
What are the main components of an
aquarium? How to replicate the oceans?
• Light
• Water movement
• Filter (what makes a
good filter and why)
– Chemical
– Physical
– Biological
• Salt (depends on the
system)
• Research, Research,
Research
In other words: habitat
recreation
Salinity
DIY hydrometers and Salt Mixing
Goals
• To introduce students to a major
property of seawater
• Encourage students to relate chemical
properties (i.e. ion concentration) to
physical properties (i.e. density)
• Illustrate a simple method to harness
physical properties of seawater to
estimate a chemical parameter, salinity
Salinity
How much salt is there in 1 kg (1L) of seawater? What are the chemical
components of salinity? 3.5% or 35 ppt (‰)
Na+, Cl-,
Mg2+, Ca2+, K+, Sr2+, Br-, F-, I-,
SO42-, HCO3-, BO33-, SiO32How do these ions get
concentrated in the oceans?
Weathering of rock by rain
removes ions from the land, rivers
bring them to the oceans,
evaporation removes fresh water
leaving the ions (salt) behind in
the ocean basins
How do you think warming will
affect salinity based on this
simple diagram? 
Salinity – Why is it important?
• Key driver of ocean density
– What are the implications? Stratification, defining
oceanographic regions
– Impacts microbial communities
Impact Biogeochemical
– How can this be influential in the cycles, alter food web
oceans?
dynamics
• Sensitive to Climate Change
– How could global warming
influence surface salinity?
Increased evaporation could
increase salinity at the equator
or at polar regions increasing
freshwater from melting ice
could decrease salinity
Activity 1 – Make and calibrate
hydrometer
• Fill Clear bottle with enough sand to
keep it floating vertical (~1/4 full)
• Place bottle in saltwater of known
salinity
• Take bottle out of water and use
marker to mark the water line* and
write the known salinity
* You may need to adjust the amount
of sand to achieve a workable
waterline
Activity 2 – Mixing Saltwater
• Collect 8L of water
• Add 240g or ~ 1 cup of salt
• Mix
• Check Salinity with your homemade
hydrometer
• Is it higher or lower than your
calibration mark?
8L water
+
~ 1 cup
salt
Salinity – Follow up
• What physical property are we using as a
proxy to check a chemical parameter of
seawater? Density
• How will you be able to tell if you need to add
more salt or more water to your freshly mixed
salt based on your hydrometer reading?
– If the mark is below the water line? Salt, why?
– If the mark is above the water line? Water, why?
Nutrient Testing
Testing nutrients between heavy bio-load and light bio-load systems
Goals
– Challenge students to draw connections between
water chemistry and biological activity
– Introduce students to simple tests for measuring
nutrients and water column diagnostics
– Familiarize students with the major nutrients in
ocean ecosystems
Microbes and Chemical Cycles
• Microbes are everywhere
• They are not all bad, in fact
many of them carry out
critical ecological functions
that keep environments
healthy
• 1mL of seawater can harbor
100 of thousands to millions
of microbes
• Crucial link between chemical
energy and higher trophic
levels in food webs
Microbial Filter – Moving Nitrogen
Fish + food
O2
NH3 + NH4+
(Fish waste)
Ammonia Oxidizers
O2
NO2(Bacterial waste)
Nitrite Oxidizers
NO3(Fertilizer for
primary productivity)
How does this process differ in oceans?
It only differs in that it is half of the cycle. The
other half if carried out in sediments or low
oxygen water columns.
Why is it important to remove these nutrients
from the aquarium?
Ammonium disrupts neuron charge balance
What compounds are
toxic to fish and inverts?
Ammonia/Ammonium
(NH3/NH4+)
&
Nitrite (NO2-)
Why are these
compounds toxic?
NH4+
NH4+
NH4+
NH4
+
NH4+
Nitrite irreversibly binds to the iron
hemoglobin, preventing oxygen utilization
Activity 1 – Nutrient Testing
• Collect 15mL of water from
each aquarium
• Following the instructions on
the kit
• Dip the test strip into the
water sample
• Check the strips against
color key on kit
• Record values from each test
• Plot the values on the graph
proved
By looking at the systems, which
one do you think will have
higher nutrient concentrations?
Activity 1 Questions
Values in ppm
• Are these healthy levels
compared to pristine
reefs?
• What factors may
influence these
differences? What are
consequences
• Predict how the nutrient
concentrations will
change over time? What
could be mediating
these changes?
Natur
al reef
Ammonia (NH3/NH4+)
0.2
Nitrite (NO2-)
0.5
Nitrate (NO3-)
1.2
Ammonia
(NH3)
8
Concentration (ppm)
• Why do the tanks differ?
Chemical
6
Heavy
bioload
Nitrite
_
(NO2 )
Nitrate
_
(NO3 )
10
100
8
80
6
60
4
40
2
20
0
0
4
2
0
Light
bioload
Activity 2 – Gram stain bacteria
Goals
– Challenge to students to think about
microorganisms in seawater
– To understand linkages between nutrients and
microorganisms
– Introduce simple methods for visualizing bacteria
– Introduce students to microscopes
Activity 2 – Gram stain bacteria
Based on activity 1, which system should have a more dense bacteria population?
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Take 0.5 mL of water from each tank with disposable pipette
Place a thin, dime size amount water on slide.
Allow to air-dry
Pass the smear through a flame 2-3 times to heat-fix.
Gently flood the smear with crystal violet and let sit for 1 minute.
Gently rinse with water.
Gently flood the smear with Gram’s iodine and let sit for 1 minute.
Gently rinse with water.
Tilt the slide and drop Gram’s decolorizer on the smear drop by drop until it runs almost clear.
Gently rinse with water
Gently flood the smear with Safranin and stain for 45 seconds.
Gently rinse with water
Blot dry
View under microscope using the 40X objective.
To view samples at 100X, first focus in using the 40X objective; then rotate the objectives so that
the 40x objective is out of the way, but not all the way onto the 100x objective.
Add a drop of immersion oil over the center of the hole where the light is coming through the slide,
and then rotate the 100x objective into place.
Use the fine focusing knobs to focus in, but be very subtle, because even the slightest slip can cause
you to overshoot the depth of focus for the specimen
Activity 2 – Gram stain bacteria
• How do microbes in the environment
differ from those in culture?
Less dense, smaller, slow growing…
• Do you expect there to differences in
lifestyle strategies between different
niche spaces?
Much like macrofauna, microbes
exhibit different strategies to live in
very diverse environments: free
living, aggregate forming or particle
associating, biofilms, migrating,
symbionts