Finding Nemo Becoming Easier

Here is my favourite scene from Pixar’s Finding Nemo.

It is one of my favourite movies. The story of a young clownfish scooped up from the Great Barrier Reef after venturing too close to a butt and his father sets out on a rescue mission braving sharks and jellyfish while surfing with a crew of green sea turtles and hitching a ride in the mouth of a humpback whale.

Scientists studying the effect of ocean acidification on coral reef systems have found that juvenile clownfish, (Amphiprion percula),
lose their capacity to detect danger in slightly more acidic seawater. The failure of a fish to move away from danger in the ocean could very well mean being the next meal for something larger. At levels of acidity predicted to become more common by the end of the century, the fish did not respond to recorded daytime reef sounds.

A team of researchers raised baby clownfish in tanks containing different levels of acidity. One tank resembled ocean water today with about 390ppm of carbon dioxide while other tanks contained higher levels of carbon dioxide at 600ppm, 700ppm and 900ppm. The clownfish were then allowed to decide whether they wanted to be near an underwater speaker playing sounds of predators found on a coral reef that would eat a clownfish. The clownfish in the tank corresponding to the acidity levels of today spent 75% of the time away from the loudspeaker but at higher concentrations there was no difference between the time spent at the loudspeaker or away from it. It appeared that the fish had gone deaf at higher acidity levels.

When the ears of the juvenile clownfish were examined, there was no sign of physical damage and the team suggests that the acidity levels could be affecting the nerves of the fish or perhaps the higher acidity levels were stressing the fish resulting in a different set of behaviours. There does need to be more experimentation to determine what is occurring to the juvenile clownfish at lower pH ranges. And are there any other fish species that are affected like this?

Related articles

• Ocean acidification leaves clownfish deaf to predators (physorg.com)
• Fish ignore alarming noises in acidifying seawater (sciencenews.org)

Making Rubber Eggs in the Kitchen

I like this experiment because of its unexpected result and because it’s so easy to do at home. You need one egg, a glass jar large enough to hold an egg, vinegar, and time.

All you need to do is place the egg in the jar and fill the jar so that the vinegar covers the egg and leave it for 24 hours. After 24 hours, carefully pour out the vinegar down the sink and then cover the egg with vinegar. This time, leave it for a week, (I did tell you that you needed time for this one.).

After a week has passed, pour off the vinegar and gently rinse the egg with water. The shell made of calcium carbonate should have been dissolved by the acetic acid in vinegar leaving the membrane of the egg behind. You should be able to press and squeeze it gently and if you hold it up to the light and shake it, you will see the yolk inside moving around. Though do this gently because the membrane can burst and you really don’t want to end up with egg on your face. It’s messy.

You can also drop this egg onto a surface and it will bounce. Just don’t drop it from a great height though because it will burst.

pH

pH scale, Source: Wikimedia Commons

The pH scale measures the acidity or basicity of a solution. It ranges from 0 to 14. At a pH of 7, a substance is neither acidic or basic and is considered neutral. Pure water is has a pH of 7.

Acidic and basic are two extremes that describe a chemical property of chemicals, especially in the case of solutions.

The term pH was first was introduced in 1909 by the Danish chemist Søren Sørensen (1868–1939) as a convenient way of expressing acidity of a solution. He derived a mathematical formula to do this.

pH = -log₁₀[H+]

Although the original symbol used by Sørensen was p_H⁺. The mathematical formula makes the pH scale logarithmic. This means that a pH of 5 is ten times more acidic than pH 6 and 100 times more acidic than pH 7. On the basic side, (alkaline side) of the pH scale, it is a similar case. A pH of 10 is ten times more alkaline than a pH of 9.

The measurements of pH are important in fields beyond chemistry like biology, medicine, environmental science, engineering, nanotechnology and many more. Many processes only occur at a specific pH.

The “p” in pH does not mean “power” of hydrogen as many sources will state. It was one of two letters that Sørensen used to identify different variables in his work to find a simple way of characterising the acidity or alkalinity of solutions. The other letter he used was “q”.