Tuesday, June 17, 2008

Well, it's that time of year when our 5th and 8th graders will be coming home begging you to help them with their science fair projects; that were handed out to them over a month ago! Isn't that ironic?! It seems that it wasn't that long ago when I had my 5th grade science fair, then my sons just a few years ago when he was just 10 or 11 years old and boy! how times have changed. I did my science fair project on the study of (Crushed Egg Shells & The Benefits of using them in your Garden) My son did his science fair project on (Dissolved Oxygen & The Oxygen Levels in Your Fish Tank), (How to Determine if Low DO is the Cause of a Fish Kill) My project was a bit on the boring side. There were many other projects around mine that involved imagination, creation and the determined assistance of a parent. My Dad worked nights and slept during the day. That is what he had to do to support his family back then. My son was lucky enough to have a mom who worked at a Laboratory Supply Company and could provide him with a lot of assistance. We worked on it together. We purchased 2 goldfish bowls, 2 goldfish, 1 air pump, some tubing, filters, rocks, and fish food. I provided my son with a Dissolved Oxygen meter and a Dissolved Oxygen electrode as well as a temperature meter and general purpose temperature electrode. Dissolved Oxygen (DO) refers to oxygen gas that is dissolved in water. Fish breathe oxygen just like land animals do. Although, fish are able to absorb oxygen directly from water into their blood stream using gills, whereas land animals use their lungs to absorb oxygen from the atmosphere. My son wanted to show how the life of the quality of fish life would differ, one with oxygen added to the water, and the other with no oxygen added. He took 3 (DO) readings a day from each tank, as well as the temperature of each tank. He wrote down his readings for a month, recording the health of the fish along with each (DO) and temperature reading. There are 3 main sources of oxygen in the aquatic environment. 1) direct diffusion from the atmosphere; 2) wind and wave action; and 3) photosynthesis. Oxygen derrived from photosynthesis , is produced during the day when the sun shines on the plants in the water. Oxygen levels drop at night because of plants and animals, including fish. Oxygen depletion refers to low levels of (DO) and may result in fish mortality. The cause of oxygen depleation occurs when oxygen consumption exceeds oxygen production. This can be caused by an overabundance of plant life or alge in the water. All fish die at approximately the same time often during the night or in the early morning hours. Large fish may be more effected more than small fish. When a fish is depleated of oxygen, you may often see him at the surface "gasping" for oxygen. Some fish may die with their backs arched, gills spread and mouth open. The weather immediately following the fish kill may have been very hot, still and overcast. There may have even been a storm prior to the kill. An oxygen depleating event sever enough to result in signifigant fish mortality is often observed in water with heavy populations of algae of aquatic plants. The moral of this story is: to remember that we are in the time where technology is everywhere. Spend time with your children helping them with their school work and enjoy them while they are young. My son is almost 18 years old. Time sure does fly when your having fun!!! Footnotes: The technical information regarding Dissolved Oxygen for fish production is a Fact sheet FA27 one of a series of the Department of Fisheries and Aquaculture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published September 1992. Reviewed: May 1997, Feb 2003. Please visit the EDIS website at http://edis.ifas.ufl.edu