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Where and the means in which plants and animals can
live are governed by abiotic (non-living) and biotic (living) factors.
Examples of abiotic factors for marine habitats may include nutrients,
pressure, temperature, pH, salinity, substrate type, circulation patterns,
and dissolved oxygen. Biotic factors may encompass predation, availability
of food, and genetics.
Marine organisms born and reared in estuaries must survive daily changes in
salinity, temperature, and often, dissolved oxygen. Since humans often live close to estuaries, many pollutants may be flushed into the water. Estuaries are highly productive environments and important habitats for a diversity of organisms because of the presence of abundant food, vegetation, and shelter.
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Students will be able to do the following:
- Explain the importance of preserving estuaries.
- Discuss limiting factors.
- Develop experiments to test the effects of salinity and temperature on
brine shrimp eggs.
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- Nine baby food jars per cooperative learning group
- Celsius thermometer
- Hand lens
- Marking pens
- Eye dropper
- Brine shrimp eggs
- Three liters of 3% salt water
- Two liters of 10% salt water
- Two liters of fresh water
- Air pump
- Salt
- Bleach
- Oil
- Detergent
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Activity
Place students into cooperative learning groups of
four students each. Each group should research the role of estuaries within
the environment. Each research group will then perform the following
experiment.
- Label nine baby food jars with numbers 1 to 9, using marking pens.
- Fill each jar 3/4 full with the following solutions: jar #1-freshwater,
jar #2-10% saltwater, jars #3-9-3% salt water.
- Place equal amounts (20-40) of brine shrimp eggs in each jar with an eye
dropper. Retain 20-40 brine shrimp eggs in the original jar as a control.
This jar should be stored at room temperature.
- Store jars #1-3 at room temperature (an air pump will oxygenate the
water and should provide improved results).
- Store jars #4-6 at the following temperatures: jar #4-at room
temperature, jar #5- in a refrigerator at approximately 4 °C and jar #6-in
an incubator/light box at approximately 35 °C.
- Add a few drops of the following pollutants to each jar and store at
room temperature: jar #7-bleach, jar #8-detergent, and jar #9-oil.
- Record the following data for each jar: exact temperature, salinity, and
type of pollutant.
- Observe each jar daily with a hand lens. Estimate the percentage of eggs
that hatch after three days. Sketch eggs and hatched larva.
- Record the results of these experiments in a laboratory journal and
identify the limiting factors observed for each jar. Each student group should develop conclusions based on its results. Each group should present its results and conclusions of the experiment to the class. After each group has presented
its research results, the class should compare and contrast these results
and conclusions. A new list of limiting factors should then be identified.
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- Repeat the experiment using eggs of other estuarine species.
- Visit an estuary.
- Research a particular estuary and list endangered species
that may reside in the estuary.
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Have the student groups write a report on the
importance of estuaries and marshes. Evaluate the laboratory journal
on the basis of results of the experiments and conclusions drawn
from the results. Evaluate student reports and involvement in class discussions.
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Marine & Aquatic Resources Activities - The Effects of Salinity, Temperature, and Pollutants on Brine Shrimp Eggs