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coral bleaching

Postby sjenguidanos » Sun Nov 18, 2018 9:02 pm


I am introducing different levels of CO2 to coral in enclosed aquariums to learn about coral bleaching and then will try to find ways to reduce coral bleaching. How can I measure the coral bleaching, ex, if I measure color change, how do I do it scientifically? I don't have the money to buy a spectrometer (spelling???)

Thank you,

7th grade student

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Re: coral bleaching

Postby Ultra » Tue Nov 20, 2018 3:13 pm


Thank you for using the Science Buddies fora. I would suggest taking pictures of the coral against a common, "constant" background and using software to analyze the pixel values. On a computer, each pixel has a red component, a green component, and a blue component. The brightness of each colored component yields the color you see on your computer screen.

By a "common background," I mean something that is very easy to keep constant between pictures such as a large square of black felt or a matte black surface. The idea here is that you can take each picture in front of the same background without having to worry too much about exactly where the backdrop is in the picture. The backdrop should be larger than the camera can see so that you have wiggle room with the edges (i.e., the entire background in the picture is only a portion of a uniform backdrop).

Just take these pictures (probably several pictures of each coral) periodically throughout the experiment.

Once you have your pictures, use software like to extract average color values for each coral measurement. This will give you the numbers you are looking for. You'll get a measure of approximately how much red, blue, and green are in the picture (and how bright the picture is, which is what you seem to need).

I hope that my answer is helpful. If you have any further questions, please feel free to post them on this thread.
For science!
- Ultra

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