Classroom
Activities - Grades 9 to 12
Designing
A Submersible
What
is Neutral Buoyancy?
Purifying
the Air for DeepWorker
Pilots
"In the
Zone" Laboratory Activity
SSEbackground.pdf
These activites have been
created by Mike Guardino, Monterey Bay's Teacher in
the Sea. We welcome educators to use these
activities in their classrooms. Please submit any
comments or improvements to Laura.Francis@noaa.gov
Designing A
Submersible
Guiding
Question
How does a submersible's
design address the limitations inherent to
exploring the sea?
Discussion
The Sustainable Seas
Expeditions will use a small submersible,
Deepworker, to explore, conduct research in and
promote conservation of the nation's 12 marine
sanctuaries. This one-person vehicle must be simple
enough to operate so pilots may complete their
mission, yet sophisticated enough to safely reach
depths of up to 600 meters (2,000 feet). By
researching, constructing and testing a scale model
prototype of a submersible, students will discover
some of the design characteristics that make this
vehicle so important to ocean
exploration.
Materials
A small aquarium (25 cm
deep
25 cm wide, 50 cm long)
child's pool or other container filled with
clear, fresh water at ambient room temperature for
testing and demonstrating submersibles
copies of the Submersible Specifications
sheet
copies of the DeepWorker and Other
Technologies Background Information sheet
materials for submersibles such as PVC pipe,
batteries and propellers to be determined by
student teams
Procedure
1. Tell students that their
goal is to work with a classmate to design, build
and test a submersible prototype that is neutrally
buoyant and can travel through water. A small
aquarium or other container, filled with clear,
fresh water at ambient room temperature, will be
available to test and demonstrate their
submersibles.
2. Explain to students that
their submersibles must meet certain
specifications. Give them the Submersible
Specifications and DeepWorker and Other
Technologies handouts.
3. Set a date for students to
demonstrate and explain their submersibles with
each other, including what worked, what didn't work
and how they redesigned their vehicle accordingly.
(top)
What is
Neutral Buoyancy?
Guiding
Question
What is neutral buoyancy and
how does it affect a submersible's
design?
Discussion
Density is a basic property
of matter that measures the amount of mass of an
object per unit volume (D=M/V). The density of
freshwater is 1g/cm3; the density of seawater is
greater and varies considerably depending upon
salinity and temperature. (For seawater with a
salinity of 34.5 parts per thousand and a
temperature of 15C, the density is 1.025 g/cm3). In
the ocean, solids are generally more dense than
seawater. They tend to sink while gases are less
dense and tend to rise. Water has an unusual
property: its solid phase (ice) is less dense than
most other solids, enabling it to float in liquid
water. Buoyancy is the tendency of a fluid (gas or
liquid) to exert an upward force on an object that
is submerged in it. An object that is positively
buoyant will float, one that is negatively buoyant
will sink, while a substance that is neutrally
buoyant displaces a quantity of matter of equal
density. An object placed in seawater is more
buoyant than the same object placed in freshwater.
This is because the dissolved salts in seawater
cause the water to be more dense.
The volume of freshwater
displaced by an object can be used to determine the
mass required to make it neutrally buoyant.
Important regularities concerning freshwater
include:
1 mL H2O @ 4oC=1cm3=1
gram.
Materials
Lead shot
13 x 100 mm test tube
#00 rubber stopper
Milligram balance
100 milliliter (mL) graduated cylinder
Water
Indelible marker
Procedure
This activity may be used as
a lab that students perform or as a
demonstration.
1. Carefully measure
freshwater into a 100 mL graduated cylinder so the
bottom of the meniscus is precisely on the 80.0 mL
line when viewed at eye level.
2. Mass a clean, dry 13 X 100
mL test tube and #00 rubber stopper on a milligram
balance.
3. Add enough lead shot to
the test tube (about half full) to make it
negatively buoyant. Seal it with a tightly-fitting
rubber stopper. Make a mark on the outside of the
glass to record how far the stopper is inserted
into the test tube.
4. Gently slide the test
tube, stopper end down, into the graduated cylinder
by tilting the glassware to one
side.
5. Read the new volume in the
graduated cylinder and determine the amount of
water that has been displaced by the sealed test
tube. Be sure no air bubbles have been trapped
before taking this measurement. (Ask students why
this is important: the trapped air displaces water,
giving an inaccurate measurement.) Subtract the
initial water volume (80.0 mL) from the (greater)
final volume and convert to mass in
grams.
6. Pour out the water and
remove the weighted test tube from the graduated
cylinder. Empty the test tube and replace the
rubber stopper to the same mark on the glass.
Refill the graduated cylinder to the 80.0 mL line
and drop the empty tube in with the stopper end
down. What volume does this positively buoyant
object displace?
7. Remove the test tube again
and add just enough lead shot to equal the mass of
the displaced water. Refill the graduated cylinder
with water to the 80.0 mL line and slide the
neutrally buoyant test tube back in. Does the tube
now rest in the water column rather than sink or
float? Make any adjustments necessary to achieve
neutral buoyancy.
Data and
Calculations:
Mass of test tube and stopper
= _____g
Final volume (_____mL) -
initial volume (80.0 mL) = H2O volume displaced
(_____mL)
Mass of displaced water (1 mL
= 1g) = _____g
Conclusion
Compare to what would happen
if the same activity was done using seawater. How
would the shot weight need to be adjusted in
seawater? Guide the discussion to consider how
neutral buoyancy relates to submersibles, how
students might address this in their designs and
how this feature benefits research.
(top)
Purifying
the Air for DeepWorker Pilots
Guiding
Question
How is the air in DeepWorker
continually purified for pilots?
Discussion
The DeepWorker 2000
submersible uses "rebreather" technology to
chemically remove carbon dioxide from a pilots'
expired breath and a pair of high pressure
cylinders to replenish the oxygen gas metabolized
by aerobic respiration. This lab allows students to
calculate the volume of carbon dioxide gas that can
be removed from DeepWorker's cabin by the absorbent
chemical "Soda-Lime." Soda-Lime, which is a mixture
of caustic soda and lime [NaOH and
Ca(OH)2], is a chemical scrubber used to remove
carbon dioxide from the air that has been expired
by the pilot. SodaSorb ® (the brand of
soda-lime used by DeepWorker) is manufactured by
the W.R. Grace Company in the United States.
SodaSorb ® consists of 70-80 percent Ca(OH)2,
16-20 percent H2O, 1-2 percent NaOH and 0-1 percent
KOH.
The mechanism for this
exothermic reaction is:
H2O(l) = CO2(g) -------
Na2CO3(s) = 2H2O(l)
2NaOH(s) = H2CO3(aq) -------
Na2CO3(s) = 2H2O(l)
Ca(OH)2(s) = H2CO3(aq)
------- CaCO3(s) = 2H2O(l)
There is a net production of
three H2O molecules for every molecule of CO2
absorbed. Some chemical absorbents employ an
indicator that changes color when the reactant is
exhausted. The ethyl violet indicator in SodaSorb
® changes from white to purple when the
chemical can absorb no additional CO2.
When a person breathes, 0.82L
of CO2 is exhaled for every liter of O2 inhaled. An
O2 generation system should either produce a larger
volume of O2 than the volume of CO2 consumed or
make-up for the difference with a supplemental O2
supply. A gas "regulator" is used to deliver gas to
the DeepWorker's cabin at the proper rate. Pressure
gauges monitor the supply of O2(g) in DeepWorker's
twin cylinders.
The temperature of the
absorbent influences the effectiveness of the
reaction. SodaSorb ® works much better in the
relatively warm cabin of DeepWorker.
Materials
Safety equipment
(rubber gloves and eye protection)
SodaSorb ®
Timer
Milligram
balance
Spirometer
Gas collecting
device
Calculator
Procedure
This activity may be used as
a lab that students perform or as a
demonstration.
1. Mass out 1.000 grams of
SodaSorb ® on a milligram balance and place it
in a gas collecting device. Be careful to avoid
packing the solid too tightly and be certain not to
breathe the dust.
"Scrubbed" air exits through
small holes in cap
1.000 grams SodaSorb
®
Exhale into large hole at
end))
2. Determine the tidal volume
of gas that you produce in one minute by exhaling
into a spirometer. An adequate homemade spirometer
can be constructed with an overturned bottle of
water, a dish pan and a length of rubber
hose.
3. Begin exhaling at a normal
rate into the gas collecting device and use a timer
to determine how long you can continue before the
ethyl violet indicator in the SodaSorb ® turns
purple. Assume that the chemical is exhausted at
the first sign of a color change.
4. Determine the volume of
gas that you exhaled by multiplying the time in
minutes by the volume produced per
minute.
5. Given that the average
person at rest has 3.6 percent CO2 (g) by volume in
their expired breath, calculate the volume of CO2
(g) that was absorbed by the SodaSorb ®.
Data and
Calculations
Volume of expired breath per
minute: _______ liters
Time elapsed before indicator
changes: _________ minutes
Volume of CO2 absorbed per
gram of SodaSorb ®: ____________
(top)
Sustainable
Seas Expeditions "In the Zone" Laboratory
Activity
Guiding
Questions
How are No-Take Zones
monitored within our national marine sanctuaries?
How is undersea research conducted? What role does
technology have in the preservation of the marine
environment? How can a concerned citizen take
action that will make a positive impact upon the
future of America's National Marine
Sanctuaries?
Discussion
A number of "marine
ecological reserves" have been designated along the
California coast, including the Big Creek
Ecological Reserve (BCER) located in the Monterey
Bay National Marine Sanctuary. In January 1994,
this 8 km2 area was designated a "No-Take Zone",
where commercial and recreational harvesting of
natural resources is not permitted. No-Take Zones
serve as excellent locations to study the
effectiveness of a "sanctuary within a sanctuary".
By affording a higher degree of protection to these
marine ecological reserves within our national
marine sanctuaries, we can better understand the
dynamics of natural systems that are free from
consumptive exploitation. "Zones" can be used as
natural laboratories to further the research,
conservation, exploration, and educational goals of
the national marine sanctuary in which they lie.
For example, the base-line data collected in a
No-Take Zone can be used to help monitor the health
of the national marine sanctuary with which it is
associated, and be the basis for informed
management decisions. In addition, the abundant,
mature, reproductive stock in a No-Take Zone can
help nearby populations of organisms recover from
the pressures of overfishing by the recruitment of
juveniles to denuded areas. A clearer picture of
how to manage fisheries and establish (accurate)
maximum sustainable yields of marine resources can
also result. Therefore, an entire national marine
sanctuary surrounding a No-Take Zone can benefit
from the protected areas within it.
Some No-Take Zones are chosen
because they already feature an undisturbed
environment that is worth preserving, while others
may be selected to prevent further damage to, and
allow for the recovery of, a unique marine
community. Such was the case when 750 submerged
acres were added to the Pt. Lobos Reserve in 1960.
After recovering from many years of heavy fishing
pressure, including the commercial harvest of
abalone, the reserve now features the species
abundance and diversity that is characteristic of a
pristine kelp forest community. It may take time to
realize the benefits of No-Take Zones within our
national marine sanctuaries, but it will certainly
be worth the wait as we witness their establishment
and recovery.
Much like our national park
system that encourages multiple non-consumptive
uses, No-Take Zones can also be enjoyed by
photographers, boaters, surfers, swimmers, divers,
and those who appreciate the value of protecting a
natural system.
The Sustainable Seas
Expeditions will assist in conducting research
projects at Pt. Lobos and BCER. The DeepWorker 2000
submersible will be deployed from the NOAA Ship
McArthur where Dr. Mary Yoklavich of the National
Marine Fisheries Service will have the opportunity
to verify the benthic features that were remotely
identified in previous investigations. She will
also be able to monitor the variety of benthic
rockfish species and their habitat preferences as
she completes a strip transect and records her
observations on video.
Materials
(2) laser pointers
rockfish (Sebastes sp.) identification
books
GIS (Geographic Information Systems) Data off
the Monterey Bay (MBARI) computer (www.mbari.org)
Monterey Bay National Marine Sanctuary
Bathymetric Map (offered on this site in the
future)
Indices of refraction (air, seawater, and
acrylic)
Calculator
Glossary
References
Procedure
1
How can No-Take Zones such
as Big Creek Ecological Reserve (BCER) and Pt.
Lobos be accurately located on existing nautical
charts? How can technology be used to produce
reliable maps of these protected
areas?
1. In order to establish,
monitor, and effectively manage a marine reserve, a
variety of data must be collected to accurately
characterize the physical and biological features
of the No-Take Zone. A fundamental challenge lies
in producing a precise map of the benthic habitat
with sufficient enough detail to determine the
correlation between various species of
invertebrates and fishes and their preferred
habitat. Locate the Big Creek Reserve on the
Monterey Bay National Marine Sanctuary Bathymetric
Map (scale 1:30,000).
BCER is a small (8 km2)
No-Take Zone located approximately 90 km south of
Monterey between Partington Point and Lopez Point.
BCER ranges from 36o05'50" (north latitude) at its
northern border to 36o03'38" at its southern edge
and it extends ~3 km offshore to the 50 fathom
contour (91 meters). This represents 4.5 km of
coastline between Rate Creek and a point ~ 1 km
south of the Big Creek Bridge. The northern and
southern boundaries are marked by 2 meter diameter,
orange-red triangles 30 meters above the
ocean.
What are the bathymetric
contour intervals on the map?
Why do you think the contour
intervals change at 150 meters?
What is the depth range
within the BCER?
How would you interpret the
bottom topography of BCER based upon the number and
spacing of contour lines?
Procedure
2
The Monterey Bay Aquarium
Research Institute (MBARI) produced a Geographic
Information System (GIS) Data CD-ROM of Monterey
Bay in September, 1998 that is readily available
(http://www.mbari.org). The program can be used to
produce maps of coastlines, bathymetry, and
geologic features within Monterey and Carmel Bays.
Use the GIS to generate maps of Carmel Canyon in
and around Pt. Lobos Reserve.
What problems exist with
making observations from inside of the acrylic dome
of the DeepWorker submersible and how can the
length of a transect and the size of organisms be
accurately measured?
1. Due to the double
refraction of light that passes from sea water,
through the DeepWorker's acrylic dome, and into the
air of the cabin, it is extremely difficult for a
pilot/scientist to accurately judge size and
distance. The pilot must use an alternative method
of making precise quantitative measurements while
conducting strip transects.
2. To illustrate the problem
of visual distortion experienced by a pilot, the
following calculations illustrate why the observer
must not trust the "fish bowl" view of her study
site.
3. The speed of light (c=3.00
X 108m/s in a vacuum) is much slower when it passes
through other transparent media. Typical values for
light passing through seawater, acrylic, and air
are .704 c, .625 c, and 1.00 c respectively. Due to
the velocity change when light passes from one
medium into another, it bends at their interface.
Approximate indices of refraction for this bending
include: n (seawater)=1.42, n (acrylic)=1.60, n
(air)= 1.00. Snell's Law (n1 sin i = n2 sin r,
where i is the incident angle and r is the
refracted angle) can be used to determine the
changing path of light (an image) from its source
to the eye of the pilot.
Example: Calculate the path
of light coming from seawater and passing through
an acrylic window at a 30.0o angle before being
received by a pilot inside the DeepWorker (Figure
#1).
If 1.42 sin 30.0o = 1.60 sin
r, then 1.42/1.60 sin 30.0o=sin
r=.444=26.3o
If 1.60 sin 26.3o = 1.00 sin
r, then 1.60/1.00 sin 26.3o=sin
r=.709=45.1o
Figure #1: Refraction of
light being received by DeepWorker
pilot.
4. Compounding the problem of
distortion is the curvature of the acrylic dome
though which a pilot views her study
site.
Procedure
3
How can the velocity of a
submersible and the length of a transect it follows
be accurately measured? How can the size of
organisms and geologic features they are associated
with be accurately measured?
1. Mount a pair of laser
pointers on a video camera at a measured distance
apart. Arrange the lasers so that the beams are
exactly parallel to each other and separated by at
least .2500 meters. Slowly walk along a straight
line course at a constant velocity while filming
the ground and the pair of red spots produced by
the lasers. Try to maintain a constant camera angle
while filming your simulated transect for 1.00
minutes.
2. Watch the video you have
produced and use a stop watch to determine how long
it takes for the image of both laser spots to
travel past one position on the ground and repeat
this procedure several times in order to increase
the sample size. Calculate the mean velocity
maintained during your simulated transect in m/s
(velocity = distance ÷
time).
3. Calculate the length of
your transect by solving the uniform velocity
equation for distance (distance = velocity X time).
4. Estimate the size of
"organisms" and "benthic features" by comparing
their video images to the known distance between
laser spots in the image
Procedure
4
What do we now know about
BCER and what do we still need to study?
A brief summary of the
biological, geological, and oceanographic data that
has been collected in and around BCER is provided
below. It is your job to analyze the data and make
recommendations concerning the value of designating
No-Take Zones within our national Marine
Sanctuaries. You can also suggest additional
investigations and/or data that should be collected
in order to produce an accurate characterization of
the BCER. While reading through the information,
consider whether establishing BCER is an effective
way of protecting, monitoring, managing, and
enhancing a fishery within the Monterey Bay
National Marine Sanctuary.
There are ~57 species of
rockfish (Sebastes sp.) along the California coast
and several of them have experienced considerable
fishing pressure. Many species of benthic
rockfishes are sedentary in their behavior and are
extremely long lived.
Just what is a "rockfish" and
what is the value of their commercial and
recreational fisheries?
The BCER is located in a
geologically diverse area near the Pacific and
North American Plate boundaries. The area features
a narrow continental shelf with exposed bedrock.
Roughly eight percent of the area inside and
adjacent to the reserve is composed of rocky
substrate with high relief that serves as habitat
for a variety of benthic rockfish species (Sebastes
sp.). Researches have identified eight types of
benthic fish habitat in their efforts to render an
accurate characterization of 24.6 km2 of BCER and
adjacent areas in 30-200 meters of
seawater.
fine sediment (particle
diameter <.06 mm)
sediment ripples
sand (.06-2 mm diameter)
individual boulders (>.25 m diameter)
boulder fields
rock outcrop
matrix of various substratum textures
including rock outcrop, boulder, cobble (64-256 mm
diameter), pebbles (2-64 mm diameter), and fine
sediment.
isolated pinnacles
Why is it important to
consider the geologic history and types of
substrate associated with BCER?
In order to assess the
distribution of larval fishes from BCER and their
recruitment to adjacent fisheries, the currents
that flow along the coast were carefully monitored
from the surface to depths of 200 meters.
Persistent winds (blowing
toward the equator) in the spring and summer along
the California coast cause the Ekman spiral, the
transport of a warm surface layer offshore, and its
replacement with cooler water that upwells from
below. The onset of upwelling season in the Spring
is variable and the cool temperatures and general
southward current flow associated with it can be
interrupted with periodic changes in wind speed and
direction. Strong upwelling can be detected by SST
imagery as cold coastal water. When wind strength
weakens there is a relaxation in upwelling and the
warm waters of the California Current move closer
to shore.
Currents along the Big Sur
coast exhibit a persistent northward flow that has
been documented at various times in the past. This
north flowing current can be quite strong and it
extends from the surface to the depths of BCER.
There are also a number of cyclonic cells in the
area that can move water offshore and return it to
the coast. Many species of rockfish may have
planktonic larval and juvenile stages that last for
months.
How do prevailing currents
affect the transport of larva and the recruitment
of juvenile fish in areas within and adjacent to
BCER?
How does water movement
influence the site selection for a No-Take
Zone?
When would be the optimum
time to conduct additional groundtruthing in
BCER?
What advantages and
disadvantages are associated with groundtruthing
conducted in both manned submersibles and
ROVs?
Glossary
The equipment employed to
render an accurate characterization of the BCER
includes some traditional as well as other, more
innovative, technology and research methods. The
project is a coordinated effort of several
biologists, geologists, and physical
oceanographers. The following glossary is provided
to help the student better understand the roles of
government agencies, participating scientists, and
the research efforts involved in mapping benthic
habitats and ocean currents in and around BCER in
an effort to protect and enhance a coastal
fishery.
Acoustic Doppler Current
Profiler (ADCP) = Instrument mounted to the
hull of a ship that monitors water current velocity
(speed and direction) at various
depths.
Advanced Very High
Resolution Radiometer (AVHRR) = Satellite
images of sea surface
temperatures.
bathymetry =
Bathymetric maps use isobaths (contour lines) to
indicate the profile of the seafloor.
Big Creek Ecological
Reserve = No-Take Zone within the Monterey Bay
National Marine Sanctuary about 90 km south of
Monterey.
chart = A nautical map
that usually includes longitude, latitude,
bathymetry, and depth soundings.
conductivity, temperature,
depth (CTD) = An instrument that takes seawater
samples.
differential Global
Positioning System (dGPS) = The latitude and
longitude of a study site can be accurately (within
1-2 m) determined with the aid of satellites and
land based corrections. This information is
integrated with sonographs (from side scan sonar)
to form a mosaic of the seafloor that is
interpreted to predict bottom types.
fathom = A fathom is a
unit of length equal to six feet that is used on
nautical charts to measure depth.
geographic information
system (GIS) = Data base that incorporates
bathymetry, bottom types, sonographs, dGPS, and
groundtruthing from manned submersibles to produce
maps of the seafloor.
groundtruthing = The
use of a manned submersible or ROV to verify the
interpretation of sonographs and to more accurately
describe benthic fish habitat.
LORAN-C = Land based
positioning system that is accurate near the
coast.
manned submersible =
Small submarines such as the two person Delta and
single pilot DeepWorker are used to verify
(groundtruth) the features identified in side scan
images. Continuous video footage is taken to
document the benthic habitat and associated
organisms.
Monterey Bay Aquarium
Research Institute (MBARI) = A unique private
oceanographic center, the non-profit Monterey Bay
Aquarium Research Institute (MBARI), was
established in 1987 by David Packard (1912-1996)
with the goal of developing state-of-the-art
equipment, instrumentation, systems, and methods of
scientific research in the deep waters of the
ocean.
Monterey Bay National
Marine Sanctuary (MBNMS) = The MBNMS,
established in 1992, is one of twelve Marine
Sanctuaries managed by the Sanctuaries and Reserves
Division of NOAA. The MBNMS protects many habitats
in 5,300 square miles of ocean along the central
California coast.
National Data Buoy Center
(NDBC) = Source of meteorological data from
fixed locations at sea. Sea surface and air
temperature along with wind speed and direction
information is collected.
National Marine Fisheries
Service (NMFS) = A branch of NOAA that is
responsible for fisheries policy.
NOAA (National Oceanic and
Atmospheric Administration) = United States
government agency which establishes national
policies and manages and conserves our oceanic,
coastal, and atmospheric
resources.
NOAA Ship McArthur =
175 foot research vessel used to conduct
hydrographic surveys, environmental assessment,
fishery and oceanographic
research.
remotely operated vehicles
(ROV) = Unmanned submersibles that may be
tethered or controlled via transducers for
communication with the operator.
satellite sea surface
temperature (SST) imagery =
seawater spiciness = A
variable that increases with the salinity and/or
temperature of seawater where high values indicate
warm and/or salty waters that originate in southern
regions.
sonar (sound navigation
and ranging) = Sonar measures bottom topography
and depth of the ocean by producing and later
receiving a sound that is reflected from the
substrate. A fathometer or echosounder uses the
speed of sound in seawater to measure depth as: (m)
= travel time (s) X 1460 m/s ÷
2
side scan sonar = Side
scan sonar is used to distinguish areas with hard
substrate from others with softer sediments. Marine
geologists interpret the sonographs that are
produced to determine the orientation of vertical
relief on the seafloor.
Sustainable Seas
Expeditions = A five year deep-water
investigation of our twelve National Marine
Sanctuaries under the direction of
Explorer-in-Residence Dr. Sylvia Earle.
thermosalinometer (TS)
= Instrument that measures seawater temperature
and salinity.
Going
Further
What interactions occur
between various rockfish species?
What small-scale movements of
rockfish occur within complex benthic rock
formations?
What seasonal differences in
habitat use occur in various rockfish
species?
What differences exist
between the day and night activities of
rockfishes?
Are deep water rockfishes
experiencing more fishing pressure now than in past
years?
(top)
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