Behavior of Brine Shrimp in Habitat Selection Introduction

This experiment was developed primarily to find the optimal or preferred living conditions of adult brine shrimp. In this lab 3 variables were tested in different degrees to determine which the shrimp prefer. The different variables were light, ph, and temperature. From outside resources I have found that brine shrimp can survive in temperatures ranging from 4° Celsius to 40° Celsius with an optimal temperature of 20°-25°. So I hope to reinforce this research by testing its validity in the lab. From another outside source brine shrimp display positive photo taxis, which means that they are attracted to light. And finally from my last outside source I have found information that suggests brine shrimp prefer a ph of 7-9 and will die if placed in a solution of salinity higher than 10 and less that 5 for longer periods of time.

This lab is important because it is a fairly easy experiment to test and find behavioral traits of a simple organism. Even though from research I was able to find the data that is to be tested in this lab it is important to actually prove the results as they may be incorrect for this population of brine shrimp. So for this lab I am trying to find out what environment brine shrimp prefer to live in and what they don’t prefer to live in, and possible what they are unable to live in. I expect that the results of this lab will be fairly similar to the information stated above, but not totally the same. I believe that like most organisms these brine shrimp will prefer to live in the middle of environmental extremes.

Abstract: Materials and Methods: Materials: -Adult Brine shrimp -4 Plastic Hose Clamps -50 ml graduated cylinder -1 meter of tygon tubing -1 Syringe -2 hose plugs -Paper towel -7 sheets of mesh screen -2 plastic zip-lock bags -Ice -Hot plate -500ml beaker of water -Thermometer -4 25ml test tubes -.1m HCL -.1m NaOH -Ph paper Control: For the control of the experiment we took our tygon tubing and spread it out on the table and taped both ends down and corked one end.

Because our tubing was longer than 1 meter we evenly divided the tubing into 4 26cm sections with the hose clamps. We then scooped up approximately 50ml of brine shrimp from the holding tank into a graduated cylinder. We then proceeded to suck up all of the water from the cylinder with a syringe and put them into the tubing, when the tubing was full we corked the open end so that there was no air bubbles and the system would be sealed. Then we placed paper towel over the entire tube so that every section was given equal light and there would be no variance between the different sections and waited for 20 minutes for the shrimp to disperse themselves. We only waited 20 minutes instead of 30 because time was not permitting us to wait the extra 10 minutes. After the 20 minutes were up we closed the clamps and proceeded to count the brine shrimp in the each section and we then recorded our results.

Light Gradient: We proceeded to fill and measure the tubing as we did in the previous step. After we had our equipment set up and the tygon tubing filled with water and adult brine shrimp we took the mesh screen and in section 1 placed 4 folded sheets over the tube to create a layer of mesh screen 8 sheets thick and taped it down. In section 2 we placed 2 folded sheets over the tube to create a layer of mesh screen 4 sheets thick and taped that into place. For section 3 we placed 1 folded sheet of mesh screen over the tube to create a layer of mesh screen that was 2 sheets thick. And in section 4 we placed no mesh screen to give the shrimp clear unfiltered light. We waited for 20 minutes for the shrimp to move to their preferred light gradient and then we closed the clamps. Again we only waited for 20 minutes because time did not permit us do the full 30 minutes. We counted the number of brine shrimp in each section and recorded our results on a separate data table.

Temperature Gradient: We proceeded to fill and measure the tubing as we did in the previous step. After we had our equipment set up and the tygon tubing filled with water and adult brine shrimp we placed at one end of the tube a bag filled with ice and water, on the opposite end we placed a bag filled with hot water which we had heated up from the hot plate using the 500ml beaker. The water in the hot bag was approximately 65° Celsius. We allowed the shrimp to move about for 30 minutes because we had the time. Every 10 minutes we replaced the hot water in the bag with fresh hot water because it was slowly cooling down. After the 30 minutes were up we closed the clamps and removed the hot and cold bags from the tubing and counted the number of shrimp in each section and recorded our results. We did not count any dead shrimp because that condition would obviously not be a condition they could survive in. In this part of the lab we measured the temperature of water from each section and recorded that number also. We did this by simply pouring the water from each section into 4 different test tubes and placing a thermometer in each.

Ph Gradient: We proceeded to fill and measure the tubing as we did in the previous step. After we had our equipment set up and the tygon tubing filled with water and adult brine shrimp we removed 1ml of water from each end of the tygon tubing and replaced it in one end with 1ml or 20 drops of .1m HCL (acid) and in the other 1ml or 20 drops of .1 NaOH (base). We then allowed them to move about for 30 minutes and then closed the clamps. We then counted the number of shrimp in each section and recorded our results on a separate sheet of paper, again we did not record and shrimp that were dead because this would not be a suitable environment for them. In this lab we measured the ph of each section using ph paper and recorded our results. To do this we emptied the water from each section into a separate test tube and measured the ph. In this part of the experiment we measured the amount of water for one sections be the data is needed to find how many shrimp per ml there were in each sections. We only did this on the last sections because we used the exact same tygon tubing for the entire lab.

Results: Control Section Number and Environment Specifications Number of Brine Shrimp 1-None 7 2-None 8 3-None 3 4-None 8 In the Control apparatus because all of the sections had equal conditions every section should have contained theoretically 6 shrimp and the results were close to this except for section 3.

Light Gradient Section Number and Environment Specifications Number of Brine Shrimp 1-8 layers of screen 8 2-4 layers of screen 4 3-2 layers of screen 2 4-0 layers of screen 10 In the light gradient the shrimp seemed to prefer more light, but there were still a good number who remained in the dark section as well.

Temperature Gradient Section Number and Environment Specifications Number of Brine Shrimp 1-22° Celsius 5 2-24° Celsius 5 3-26° Celsius 1 4-36° Celsius 0 (1 dead so not counted) In the Temperature Gradient there was an obvious preference to the colder water, and the warmer water actually killed one of the shrimp.

Ph Gradient Section Number and Environment Specifications Number of Brine Shrimp 1-Ph of 1.2 0 (3 dead so not counted) 2-Ph of 4.4 3 3-Ph of 5.9 4 4-Ph of 9.1 6 In the Ph Gradient there was another obvious preference for the higher ph so they liked more basic solutions, 3 were killed in the most acidic sections showing that they cannot survive in that type of environment.

Analysis: From the data obtained in this experiment I am rather confident when I say that it answers the questions posed in the introduction. The control did not really prove anything it was meant to show that if given conditions that are all equal the shrimp would spread out evenly within the entire tygon tube. Our data did show this accurately as the readings were not significant so you accept the null hypothesis, which is there, was no abnormal affect on the shrimp. In the light gradient it showed that a large number were attracted the sections that had completely unfiltered light. A large majority of the shrimp remained in the dark area, I believe this was because they could not see the light because they were so far away and just wandered around aimlessly in the dark, and some found got closer and found the light while others swam around in circles.

The chi square test shows that you would reject the null hypothesis which was there was no affect of the light on the shrimp, so the opposite of that would be the light did have a significant affect on the shrimps behavior. Again I believe that they are attracted to light, and the ones who were in the dark could not find their way to the light. In the temperature gradient there was definitely a trend, they seemed to prefer the cooler temperatures to the hot. In the hottest section only one shrimp was found and he or she was dead meaning that area was not a habitable environment for the shrimp. Once again the chi square test showed that the null hypothesis was rejected so the temperature did have a significant affect on the activities of the shrimp. I would have to say that the brine shrimp prefer temperatures from 21 to around 25 degrees Celsius, which is rather close to my hypothesis and outside information.

For the ph gradient that was a slight trend, as more seemed to go towards the higher base levels. In the ph that was quite low of 1.2 all 3 shrimp that were found in the section were all dead which definitely shows that they cannot survive in conditions that are this harsh. Once again there was great significance in the chi square test and I rejected the null hypothesis and stated that ph does have a noticeable affect on the brine shrimp. The shrimp were found to like the mid to higher ranges of ph, more neutral to slightly basic. Some were found in the acidic range, but very few it was found to be deadly in the extremely acidic section of the tube. This proved to be right on with my hypothesis and outside information. Maybe to test my idea on why a large portion of the shrimp remained in the light, the full light could be placed directly next to the completely covered light, that way the shrimp would not need to travel nearly as far to find the light. Also to find more accurate results it would be much better to use a larger population of adult brine shrimp simply because it would provide more accurate results.

It would also be interesting to have a large range of ph, such as have it increasing by 1 in every section and allow the shrimp to freely move in the tubing for a few hours to actually see which one they prefer the most. In our lab we had a few sources of error that could have altered the overall outcome. First in 2 of the 4 tests we only allowed the shrimp to remain in the tubing for 20 minutes as opposed to 30. Because they were not allowed to move around for that extra 10 minutes they may not have found the place that they most preferred, an example of this would be in the light gradient test quite a few still remained in the dark area. Another form of error was measuring the temperature of the water in each section, by the time we measured the water temp it had already started to move back to room temperature.

This made some of our data a little bit inaccurate because we were not able to find the actual temperature that the shrimp prefer. From this I can conclude that the shrimp seem to be attracted to light, prefer water that is luke warm, not to hot and or not to cold, and actually like water that is neutral or mildly basic, which my data and previous explanations clearly show. I can also conclude that the shrimp cannot stand hot temperature of 36 degrees Celsius or extremely acidic solutions, as it will kill them.

References:

http://www.hmsc.orst.edu/odfw/devfish/sp/brine.html http://www.terc.edu/handsonIssues/f94/shrimp.html
http://www.ee.pdx.edu/~davidr/discus/articles/artemia.html