Science Buddies: "Ask an Expert"

Hi,

I live in Miami and we have king tides. For my science fair project, I want to measure the salinity levels of estuaries before and after a high (king) tide. I think that the salinity levels will be higher after the tide. I have already collected water samples at different places near my home before and after the high tide that came a couple of weeks ago. I think my independent variable is the date of water collection (before or after the tide). I think my dependent variable is the salinity level. I think my controlled variables are the time of day the water was collected, the type of body of water (estuary), and the water temperature at testing. I plan to use a refractometer to measure. I have some questions: 1) I collected water samples at 3 different locations - they are places where the freshwater connect to the ocean but they aren't labeled as estuaries. Is that okay? 2) are my variables correct? 3) should I take a water sample from the ocean to compare? 4) should I just test one location before and after or is it okay to test the three locations before and after since all three are types of estuaries? 5) Do you have any other suggestions?

Thank you

Leo

Hi Leo!

Your science project sounds really interesting! 1) The locations you gathered the water from works perfectly. Even though the locations aren't labeled as estuaries they still fit the definition of an estuary. 2) Your variables are correct! The salinity level does depend on what time of day the water was collected. Controlled variables are unchanging throughout the experiment. Some examples of controlled variables would be temperature, amount of water given, type of water, etc. 3) You don't have to take a sample from the ocean, but it would be really cool to compare the salinity levels to it! 4) Measuring water before and after tides of each location would be neat because the audience can see what change is really there!

I find your project really interesting, and am already curious to know what the results will be! I hope this helped Leo! If you have anymore questions or questions please let us know!

Good luck on your project!

Raegan

Reagan,

Thank you very much! This helps a lot. I am excited about using the refractometer. That is my favorite part.

Leo