Final aim and hypothesis

My previous aim and hypothesis are as follows:

Aim: To find out if different levels of low-frequency sound waves (ocean noise pollution) emitted by the human's marine activities affect the hatching rate of brine shrimp

Hypothesis: Different levels of low-frequency sound waves (ocean noise pollution) emitted by the human's marine activities affect the hatching rate of brine shrimp

However, I have decided to refine it to make it less of a "yes, no" question but more of one that would allow for greater research. In other words, I would like to change it to a "How" question. Another point is the words "hatching rate". Rate is a rather vague term and does not accurately define what I would like to measure. The dictionary's definition of rate is " A quantity measured with respect to another measured quantity" which is not how I am going about with my experiment. Therefore, I am changing it to "speed".

Therefore, my new aim and hypothesis are as follows:

Aim: To find out how different levels of low-frequency sound waves (ocean noise pollution emitted by human's marine activities) affect the hatching speed of brine shrimp.

Hypothesis: The lower the level of low-frequency sound waves (ocean noise pollution emitted by the human's marine activities), the slower the hatching speed of brine shrimp eggs

Revised experimental procedure

Since I have to set up two set-ups testing the same frequency at one go, I have revised my experimental procedure.

Materials and apparatus

1. Artemia (Brine Shrimp) eggs
2. Macbook with the app, Tone Generator X
3. Hands lens
4. Counter
5. 2 transparent beaker
6. 160g of sea salt
7. Boiled water
8. Science journal

Procedure

1. Place 2 beakers in a semi-lit room
2. Pour 1000 ml of boiled water into each beaker
3. Add in 20g of sea salt into each beaker
4. Place the speaker of the Macbook directly above the mouth of both beakers
5. Switch the software, Tone Generator X, on to 186 Hz at the volume level of 80%
6. Add in half a teaspoon of Artemia (brine shrimp) eggs
7. Check the set-up with a hands lens at every 12-hour interval and use the counter to count the number of eggs that have hatched
8. Record down in my journal the number of eggs that hatched
9. Repeat steps with 171 Hz, 259 Hz and 223 Hz

[Video] Successful trial experiment

I am elated! After several failed attempts, the brine shrimp have finally hatched! This is a video of the successful hatching of my brine shrimps.

http://www.youtube.com/watch?v=daPWk3hEzLA&feature=channel_video_title

New experimental aim and hypothesis

Aim: To find out if different levels of low-frequency sound waves (ocean noise pollution) emitted by the human's marine activities affect the hatching rate of brine shrimp

Hypothesis: Different levels of low-frequency sound waves (ocean noise pollution) emitted by the human's marine activities affect the hatching rate of brine shrimp

Research

This is the raw research I've found. I will be summarizing it and using it in my report.

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Artemia (Brine shrimp) are a food source for crustaceans and fish. Cultured brine shrimp feed on yeast, wheat flour, soybean powder or egg yolk. Sea, aquarium or kosher salt and pH of 8-9 is required for the eggs to hatch. Their young hatch out of cysts, which are metabolically-inactive, at the optimal temperature of 25 to 27 degrees Celsius (room temperature). Artemia eggs take about 24 to 48 hours to hatch. Crustaceans, like Artemia, do not have ears. They have tiny hairs, called mecanoreceptors, on their shell that respond to physical stimuli such as water movement, vibration or touch by sending a message to the nervous system. A type of mechanoreceptors that respond particularly to vibration or changes in water pressure are called "hearing hairs". Some crustaceans use noise for orientation.

Sound waves propagating underwater are alternating compressions and rarefactions (decrease in density and pressure of sound wave) of the water. They travel through the air and get refracted when they pass through a medium with gradually varying properties (e.g. water). Sound waves are transmitted through water as a pressure waves. High intensity sound is transmitted by high intensity pressure waves. These pressure waves cause vibrations in the water and hence, affect the hatching process of brine shrimp eggs.

Frequency is the number of cycles/waves a sound makes per second. It is a periodic vibration and a property (subset) of sound that determines pitch. It is measured in Hertz (Hz). Low-frequency noise refer to sounds below 200Hz. Broadband source levels are the sum of the acoustic energy over all of the frequencies generated by the source. Lower frequencies result in higher intensity sound waves that cause greater vibrations of the water.

The world's oceans are mostly polluted with low-frequency sounds due to boats, ships, underwater industrial activities, or seismic military and scientific explorations. I intend to test broadband source levels of:

• Ships- 186 Hz (noise generated by a large tanker ship)
• Ships- 171 Hz (noise generated by a tug and barge aka tugboat)
• Seismic survey- 259 Hz (noise generated by airgun array)
• Military sonar- 223 Hz (noise generated by U. S. Navy tactical mid-frequency sonar, center frequencies 6.8 to 8.2 kHz)

Prawns [shrimps] are very sensitive to sound, just like many fish, and hence, ocean noise have potential impacts on them in the marine ecosystem. (Lovell et al. 2005). Such low-frequency sounds have shown to have detrimental, lethal effects on marine life, damaging their hearing and interfering with their feeding habits and other life cycles such as reproduction.

Hard materials, such as plastic, are dissimilar to the air that sound waves move through and hence, the walls reflect most of the sound waves and little is absorbed. This would cause a reverberation, prolonging the music and diffusing it to all parts of the tank. Therefore, plastic is an ideal material for the tank.

Consultation with Ms Tan

Yesterday, I consulted Ms Tan regarding by SIP project. The following was what we discussed:

• Instead of testing the effects of music on brine shrimp (heavy metal, pop, country and classical), I should test on the effects of different audio frequencies on the hatching rate of brine shrimp. Such a research would have great environmental advantages in marine conservation.
• Upload photographs/drawing of set-ups
• I do not have to photograph the brine shrimps of each set-up at every 12-hour interval unless there is a significant change in number. I just have to photograph the set-up at the start of the experiment.
• I have to get a counter from the Bio lab to help me count the brine shrimp more quickly and accurately. With each brine shrimp that I see, I will just have to click the counter. After counting all the brine shrimp, I can check the counter for the number of clicks that I have logged.
• I could go to the Bio lab to photograph the brine shrimp with a microscope-cum-camera so that I could track its hatching progress at every 12-hour interval more clearly as the pictures would be enlarged.
• I should carry out each set-up twice to ensure greater accuracy of results and consistency of data collected. For example, I should set up two set-ups testing 171 Hz at the same time.

Brine shrimp hatching: Success!

The brine shrimps have finally hatched! It turned out that there was a problem with the eggs and not the hatching conditions. The eggs that I got had probably rotted and lost their viability. Hence, I went to an aquarium shop to buy new brine shrimp eggs, imported from Germany. They hatched in less than 24 hours! I can properly start on my experiment now.