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Date Created: 12/05/15
1 INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP Investigating the Salt Tolerance of Brine Shrimp Abigail Grant BIOL 1108L The University of Georgia December 2, 2015 Graded By: Andrew Wheeler 2 INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP Abstract Brine shrimp are microcrustaceans who have adapted very well to salt water conditions. There are very few planktonic organisms capable of adapting to such conditions. Brine shrimp (Artemia franciscana) are an important aspect of ecosystems and aquaculture. They produce embryos in the form of cysts, which are dried and made commercially available (Gajardo 2012). These cysts can be stored for years and are capable of producing larvae after a 24hour saltwater incubation period (Gajardo 2012). Brine shrimp are also used in aquaculture. It has been discovered that Artemia serve as a sole food source for many other organisms such as whitefish and lobster larvae (Gajardo 2012). In this experiment, brine shrimp were introduced to environments with various salt concentrations. The purpose of this experiment was to determine how extreme low and high salinities effect brine shrimp and which environments they thrive in. Other studies have shown that brine shrimp are more suited to higher salt concentrations rather than low concentrations (wildlife.utah.gov 2015). The ideal living conditions for this species were determined by testing their suitability in different environments. This knowledge of brine shrimp can be applied to further studies as well as the aquaculture industry. Introduction Because of the different evolutionary strategies and adaptations of brine shrimp, they serve as a model for survival to other marine organisms. They are able to tolerate the many different variations that exist in saltwater lakes, allowing them to attain very large 3 populations (Gajardo 2012). Unlike almost all other microcrustaceans, brine shrimp are capable of withstanding ten times the average salt concentration of typical seawater, INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP which is about 3% salinity (wildlife.utah.gov 2015). Laboratory studies have previously shown that the optimum condition for brine shrimp is 60 grams of NaCl per liter of water (Dockery 2000). However, the shrimp are capable of surviving in a maximum of 340 g NaCl per liter of water, which is a similar level to a saturated pond or lake (Dockery 2000). These shrimp have adapted the ability to control the amount of salt that enters their bodies through tissues (Emslie 2003). Their stomach and gills have waterresistant lining, giving the shrimp a barrier against high salt concentrations (Dockery 2000). Whereas most organisms digest salt, brine shrimp are able to pump it out through their gills (Dockery 2000). Female brine shrimp have adapted the ability to perceive upcoming conditions and switch their reproductive modes (wildlife.utah.gov 2015). In good conditions, female shrimp release developing embryos into the water. However, if conditions have a low salt concentration, the females release dormant cysts. These embryos remain in their current state and will resume development when the conditions improve (wildlife.utah.gov 2015). It has been said that cysts are “the most resistant of all animal life history stages to environmental stress” (Gajardo 2012). These cysts contain 324 proteincoding genes that protect them from outside oxygen. The proteins are stored during dormant stages and then used again after the embryos become active again (Gajardo 2012). They protect from dehydration and aid newly hatched shrimp to obtain nutrients (Gajardo 2012). Low salinity levels also have an effect on mature brine shrimp. Because Artemia are able to survive in conditions that many other organisms cannot, the 4 number of predators is greatly reduced. In environments with low salt concentrations, predators such as fish larvae and crustaceans are able to thrive and feed on cysts and INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP mature shrimp (Gajardo 2012). Competition for food and space can become an issue and possibly cause brine shrimp populations to decrease in size. These factors are important when observing brine shrimp. This experiment will test how four different environments affect behavior of Artemia. The mobility and feeding tendencies will be recorded in environments of different salt concentrations. I hypothesize that brine shrimp placed in high salt concentrations will be more active while brine shrimp placed in low and no salt concentrations will be less active. Methods Four separate environments were created for the shrimp. Each environment was constant in beaker size, volume of water, temperature of water, and amount of food administered to the environment. Each environment was a 250 mL beaker with 100 mL of water all at room temperature (2025 degrees Celcius). However, the salt concentration was different for each environment, making it the variable. The first beaker contained no salt, which served as the most extreme condition. The second beaker contained approximately 5% salt concentration. We mixed 0.5 grams of NaCl into the water with a stir plate. The third beaker contained approximately 15% salt concentration. We mixed 1.5 grams of NaCl into the water with a stir plate. A premium environment for brine 5 shrimp contains 14%17% salinity, making beaker 3 our control. The fourth beaker contained approximately 30% salt concentration, serving as an extreme condition of high salinity. We mixed 3.0 grams of NaCl into the water with a stir plate. After creating these environments, we introduced ten brine shrimp into each beaker and observed their behavior for 30 minutes. We recorded our observations every 5 minutes in order to see INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP how their behavior changed over time. We introduced a moderate amount of algae as a food source after 10 minutes. We also introduced yeast as a second food source after 20 minutes. We recorded any observations of the organisms’ feeding habits, movements, and activeness during the duration of the 30 minutes in each beaker. Each group member was responsible for taking notes on each of the four environments to ensure all observations were recorded. Notes and results of each member were compared at the end of the experiment. Results The data collected shows how brine shrimps react to different levels of salinity in an environment. Our results proved that the shrimp were most active in beakers 3 and 4, which were the environments with more salt. They became lethargic and less active in beakers 1 and 2, environments with less salt. The shrimp immediately moved slower in the freshwater environment. They appeared to be using a large amount of energy but were not capable of quick movement. They did not eat when food was introduced at 10 minutes. However, two of the shrimp fed on yeast that was introduced at 20 minutes. Towards the end of the experiment, all of the shrimp were towards the bottom of the 6 beaker struggling to move. The beaker with 5% salt concentration had similar results. The shrimp did not eat at either feeding time and had very slow movement. They traveled toward the bottom of the beaker for the majority of the time. One shrimp was almost fully incapable of movement after 10 minutes in the environment. In beaker 3, the shrimp moved quickly and swiftly. They immediately swam throughout the entire beaker when introduced to the environment. Nearly half of the shrimp ate both algae and yeast. INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP None of the shrimp appeared to be immobile or slowed down. Because this was our control environment, it was expected to have positive results. The shrimp also thrived in beaker 4, which contained 30% salt. They were extremely active. However, the shrimp did not eat at either feeding time in this environment. This was the only noticeable difference between beakers 3 and 4. Discussion Our experiment supported the hypothesis that brine shrimp would thrive in environments with higher salt concentrations. Initially, we intended for the freshwater beaker to be our control but changed our control to beaker 3. This change was necessary because beaker 3 contained an optimal level of about 15% salinity, making it the most favorable environment for the shrimp. In low salinity levels, the shrimp were immediately less active and the majority did not eat the food that was introduced. It is possible that they immediately realized the conditions were unfavorable but had no way of removing themselves. The shrimp were taken directly out of their initial environment and placed in the testing conditions. This was an abrupt change that did not allow them time to adapt in any way. The shrimp were extremely active in both the control and high 7 salinity environment. This was slightly different that what was expected because beaker 4 contained more salt than what brine shrimp typically thrive in. It is possible that the shrimp would initially thrive in an extremely saline environment and gradually become more uncomfortable. Because the environment of brine shrimp is constantly changing, it is necessary and biologically relevant to test these conditions. This experiment could be improved by testing a multitude of salinity levels with a larger number of shrimp. INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP Also, larger environments with plants or substrate that the shrimp are accustomed to would be more beneficial. They could be tested over a longer period of time so that reproductive cycles could be monitored and therefore the entire life cycle would be observed. This would make it possible to see adaptations through generations and further research on the abilities of these organisms. 8 INVESTIGATING THE SALT TOLERANCE OF BRINE SHRIMP References “Brine Shrimp: What are the Effects of Salinity?” Great Salt Lake Ecosystem Program. State of Utah. Web. 22 September 2015. http://wildlife.utah.gov/gsl/brineshrimp.salinity.php Baxevanis, A. D., N. ElBermawi, T. J. Abatzopoulos & P. Sorgeloos, 2004. Salinity Effects on Maturation, Reproductive and Life Span Characteristics of Four Egyptian Artemia Populations (International Study on Artemia LXVIII). Hydrobiologia 513: 87–100 Browne, R. A. & G. Wanigasekera, 2000. Combined Effects of Salinity and Temperature on Survival and Reproduction of Five Species of Artemia. Journal of Experimental Marine Biology and Ecology 244: 29– 44. 9 Dana, G. L & P. H. Lenz, 1986. Effects of Increasing Salinity on an Artemia Population from Mono Lake, California. Oecologia 68: 428–436. Dockery, BrineShrimpResearchM. (2000). Investigating the feeding behavior of brine shrimps. Journal Of Biological Education (Society Of Biology), 34(4), 211. Emslie, S. 2003. "Artemia salina" (Online), Animal Diversity Web. Accessed September 23, 2015. http://animaldiversity.org/accounts/Artemia_salina/ Gajardo, G. M., & Beardmore, J. A. (2012). The Brine Shrimp Artemia: Adapted to Critical Life Conditions. Frontiers in Physiology, 3, 185. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3381296/
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