Visit an estuary. Record
as many different microhabitats as you can. Identify and record
the plants and animals found in these habitats. Draw an outline
of the estuary and trace the water flow at high tide and at low
tide. How does the water flow determine the distribution of plants
and animals? Spend some time in teams of three being absolutely
quiet, observing the habitats to see what sorts of creatures emerge
when you don't disturb them. Remember many creatures, like crabs,
feel the vibrations caused by just moving your feet and stay hidden.
So you have to remain motionless and quiet to see what really
lives there.
Estuaries are a good
place to study birds. How
do birds fit into the flow of nutrients in the estuary? How do
different birds segregate themselves into different roles and
habitats?
Form a hypothesis on
how the body parts of the creatures help them adapt to their specialised
habitats. Design a fair test to discover if your hypothesis is
correct.
Working together with
other students, make a list or poster showing the many different
ways we can think of mangrove trees or other estuary creatures.
How many different roles do these creatures play in their habitats?
What animals spend
only part of their life-cycles in Estuaries? How do their shapes
and abilities fit them into their specialised roles within the
estuary habitats?
Examine the microflora
and fauna of the surface of the mud flats and of the foam that
forms on the incoming tide. These creatures are very important
as highly productive members of the food web. Develop a project
to map patterns of distribution of the microflora in relationship
to the tides, fresh water, or silt.
Discuss what happens
to the specialised estuary creatures when the estuary is filled
in or polluted.
Build a model water
catchment system in a sand box. Sculpt the sand into a model of
the water catchment system where you live. Use a sheet of plastic
to cover the sand and shape the rivers and creeks with your fingers.
Have an estuary at the lower side of the box where the water will
enter the sea.
Pour water onto the
model with a watering bucket (rain) and see how the water collects
in the rivers and runs to the sea.
Add "plants"
to the system. The plants can be cut up pieces of a towel. Add
some mud to the water and pour it over the catchment. Observe
how the cloth captures the mud from the water and slows down the
water flow.
Identify estuaries
in your area from maps. How many of these estuaries have been
changed by human development? What changes can you identify in
the estuary nearest to your school?
Help with a major scientific
effort to measure changes in New Zealand estuaries. To do this,
you must determine the extent of estuary plants that exist in
an estuary now and see if you can find out how much of the estuary
has been filled or otherwise changed in the past 10 years, 20
years or longer.
The first step is to
obtain an aerial photograph and topographic map of the estuary.
Contact the local office of the Dept. of Survey and Land Information
to order Aerial Photographs of almost anywhere in New Zealand.
These cost $10.70 for an 8X10 black and white print, plus $12
handling per order. Enlargements cost from $30. They are available
from 1935 on, so you can get a series showing change over time
of the estuary you wish to report on. They also have topographic
maps that will often show estuary plants and will help orient
your aerial photographs.
Before you buy aerial
photos, however, check with your Regional Council. Many Regional
Councils have aerial photographs of estuarine and coastal areas.
These may be available at no cost. Some local libraries have collections
of old photographs of great value to seeing long term changes
in your area. Be sure to get the date the photo was taken and
the scale of the image. Low altitude photos (5,000 feet or less)
are best as they show the most detail.
The easiest way to
determine the total extent of estuarine plants from the aerial
photograph is to very carefully trace the features of the image
onto clear overhead projector plastic sheets. Be sure to include
at least four distinctive landmarks in your tracing that you can
identify in the photograph AND in the real world. You will use
these known landmarks to check the scale of your tracing and your
measurements, so pick landmarks that you can go to and accurately
measure the distance between them (you might ask a surveyor to
help with these measurements if you are not sure how to do them).
In your tracing, use
a heavy solid line for the shoreline, a dotted line for estuary
trees, a dashed line for sea grass beds, and a thin line for the
edge of the water channels in the mud flats (if visible in the
photo). Include roads and "developed" areas on the shores
of the estuary (houses, factories, and farmland) within two centimetres
of the estuary shore. Also mark any structures that have been
built in the water (wharves, aquaculture farms). Have more than
one student team try this and compare the tracings. If there are
differences, which one is correct? Make any needed changes and
use the best tracing for the next step.
Use an enlarging photocopier
to make a blow-up of the tracing, as large as the photocopier
can make it. Use graph paper with the smallest sized squares you
can find as photocopier paper so your tracing is now shown on
graph paper. Make a label in one corner with the name of the people
who did the tracing and the date it was done. Include the identification
number of the aerial photograph amount of enlargement from the
original photograph and the scale of the original photograph (This
will be available from the people you got the image from).
Label the landmarks,
names of streets or rivers, and other features on the enlarged
tracing.
Count the total number
of squares within the boundaries of the estuary (This is easier
if the graph paper has thicker lines every ten little squares)
estimate how much of a square is within the estuary if the line
cuts a small square into sections. Count the numbers of squares
inside the grass, tree, and water channel lines. Count the numbers
of squares inside developed areas along the coast.
You can now calculate
the percentage of the estuary covered by each feature. Determine
the exact distance (in the real world) between the known landmarksyou included on the tracing. Measure the distance between landmarks
on the tracing and you can calculate the scale of the tracing
(eg. 1-mm = 10 metres). How does this compare with the known scale
from the photograph plus the known enlargement factor? Now you
can calculate the exact area covered by each square of graph paper
and the exact areas covered by trees, sea grass, the water channels
and the whole estuary.
Repeat this process
in aerial photos of the same area taken in later (or earlier)
years and compare the changes you observe. Quantify the changes
and write a report on how the estuary has changed.
Record your research
in your Sea Keeper Estuary Log Book and keep the tracing in the
log book.
