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!

Club Meeting Summary Oct 20

On October 20, Paige, Isabella, Ashley, Amber and Cross performed chemistries on the Horseshoe Crab tank. We found that both Ammonia and Nitrite levels were too high! We looked at the nitrogen cycle chart.

We had two hypotheses:

1. we were feeding the crabs too much and the food was rotting before it could be eaten.
2. There was not enough good bacteria.

The team decided that we should not feed the crabs unless all the food was gone. We will ask the librarians to keep an eye on the amount of food in the tank. Paige suggested that we look under a microscope to see if there were enough bacteria. We talked about the problem of telling the difference between good and bad bacteria. (Miss Linda has been thinking about this. We will bring a microscope to the next meeting to see if we can tell the difference.) Miss Linda said that we have some good bacteria that we can add to the tank. We also changed some of the water in the tank to reduce the ammonia levels.

Salinity The Club then analyzed the salinitiy (saltiness) of the tank. We then compared it with the salt level of tap water and the salt level of water from the Lighthouse beach in Havre de Grace (Lat 39 degrees 32.389 minutes N Long 76 degrees 5.087 minutes W)
Here are our results

1. Tank water 22 ppt
2. Tap water 3 ppt
3. Bay water 6 ppt

Since we know that horseshoe crabs do best in water with salinity between 20-30 ppt, Havre de Grace would probably not be a good place to release them. The Club hypothesizes that the water from the Susquehanna river makes the water less salty up near Havre de Grace. The Club then went to the Eyes on the Bay website.http://mddnr.chesapeakebay.net/eyesonthebay/index.cfm

We looked at the buoys that were monitoring salinity and used a conversion chart to change salinity using PSU (practical salinity units) to ppt. We discovered that as we moved down the bay, salinity increased. The buoy at Annapolis registered 7.31 PSUs which converts to about 9.35 ppt. Miss Linda was surprised that this was so low. When she looked at this buoy some time ago, it was registering about 22 ppt. We will need to check this again as the seasons change.

The next Let's Do Science Club meeting will be Nov 17 at 2 pm. We will be checking the ammonia levels in the tank to see if we have corrected the problem and we will be looking a little more at salinity.

Programs at Whiteford Library this week

We have two science happenings this week at Whiteford Library. On Thursday, Oct 18 at 6:30, Mr. Paul Gilka will get us Charged up about Electricity with his hand-on Electricity lab.

The next meeting of the Let's Do Science Club is this Saturday, Oct 20 at 2 pm. We will be working on analyzing salinity. See you there!

New Horseshoe Crab Ancestor

Take a look at this cool horseshoe crab ancester that was found in Herefordshire, England. It was found in a layer of rock from 450 million years ago. Here is a link to the article. Click here

Welcome Horseshoe Crab program

Last night, we had a nice group in attendance for our Welcome Horseshoe Crab program. We learned that the horseshoe crab species is older than the dinosaurs, that horseshoe crabs can see all the way around their body (360 degrees)and that they have blue blood with copper in it. (It is the copper that makes the blood blue.) Here is a link to Miss Linda's slides from the program. Afterwards, Let's Do Science Club members introduced some of our new friends to the horseshoe crabs. We also fed them their dinner.

During the program, we came up with two questions that the Let's Do Science Club will try to answer. 1. Do horseshoe crabs see in color? 2. How long does it take them to molt their shells when they grow? We'll be working on these research topics at our next meeting on October 20.

Robbie's Guest book comment

Robbie saw a red ball in the tank that looked like blood. It didn't seem likely that it came from the crab since club members noted that horseshoe crab blood is blue. At the Science Club, we looked at it under the microscope. Some people thought it looked like a piece of shrimp. Some people though that it looked like a dead crab egg. So, at the end of the meeting, we weren't sure.

However, on Monday, when Sam and Sadie were feeding the crabs, their mom noticed that one of the shrimp seemed to have a red ball in its middle. Do you think this might be the answer?

Apparently, that is the egg sac.

We will try to get a photograph of the red ball.

The first meeting of the Let's Do Science Club is on September 15 at 2 pm

Agenda

1. Introductions
2. Club Goals
3. Let's Do Science Club blog (Our website)
4. Upcoming programs
• Sept 27 at 6:30  Welcome Horseshoe Crabs--Everything you wanted to know.
5. What Science do you like?
6. Horseshoe Crab Tank Chemistry: What we measure and why
7. How to measure
8. Recording results
9. Let's Do it!

Next Club meeting: October 20 at 2 pm