Club meeting Nov 17

Today, Samantha, Emma, Paige, Isabella, Eden, Naomi, Nathan, Nathan, Jonah and Brennan attended our Science Club meeting.

First, we did the Horseshoe Crab Tank Chemistries. Last meeting, we were concerned about the higher levels of ammonia in the tank which could make the horseshoe crabs sick. Happily, we found that the ammonia, nitrate and nitrite levels were all 0 ppm so reducing the feed, changing the water and adding some good bacterial all helped.

We also looked at the Salinity experiment that we did last month. Miss Linda was surprised at how low the salinity was when we got data from the NOAA buoy in Annapolis. When she looked before, the salinity converted to ppt was about 22. But, when we looked on Oct 20 we got a reading of about 9.3. When Miss Linda looked at all the readings from that day, she found this.

At the very time we looked at the data, salinity levels dropped! We took a look at the type of equipment on the buoy to see if we could figure out why the salinity was so low just for that one reading. Here is what the equipment is like on the buoy.

This is from the website buoybay.noaa.gov

Mr Paul then showed us how the buoy measures salinity using conductivity. Saltier water is more conductive (more electricity passes through it) than less salty water. We experimented with this using the following set up.

Using a measuring cup with aluminum foil electrodes, we measured the conductivity of deionized water (12.5 microamps) and tank water (27 microamps). The salty tank water conducted significantly more electricity than pure (deionized) water.

We then listed all the things we could think of that might have caused the drop in salinity over such a short amount of time.


Here are our hypotheses:

1. Equipment malfunction
2. It was raining causing a decrease in salinity
3. Tides pushing against water coming down from the Susquehanna River.
4. A sea creature got stuck in the probe.
5. Trash got stuck in the probe
6. A ship going by raised the probe out of the water.
7. Something hit the anchor causing the probe to come out of the water

We decided to send an email to the Eyes on the Bay "Ask an Expert" to see if they could help us narrow down our hypotheses. Our next club meeting is Dec 15. See you there!