Changes in water chemistry associated with beaver-impounded coastal marshes of eastern Georgian Bay
Fracz, Amanda.; Chow-Fraser, Patricia. Changes in water chemistry associated with beaver-impounded coastal marshes of eastern Georgian Bay. Can. J. Fish Aquat. Sci. (online) 2013, 70: 834-840. https://eds-a-ebscohost-com.libproxy.chapman.edu/ehost/pdfviewer/pdfviewer?sid=99eb69ff-1148-4ddf-9fc5-e14d12e7062e%40sessionmgr4002&vid=2&hid=4203 (accessed Sept. 31st, 2014)
In the area of the Great Lakes, eastern Georgian Bay houses thousands of miles of marshlands and wetlands. These areas are some of the most threatened habitats in the world because they form where human development is highly concentrated, near the coast. Yet, the uninhabited wetlands are sometimes taken over by beaver dams. The water chemistry of these marshes depends on their location and connection with other bodies of water. Scientists Amanda Fracz and Patricia Chow-Fraser hypothesized that open wetlands
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connected to large bodies of water have a different chemical composition to that of a protected body of water. Many of the marshes of eastern Georgian Bay form along the shoreline. Depending on the water levels, some can become hydrologically disconnected from the bay from naturally occurring instances or from beaver dams built across the outlet. In the wetlands of Georgian Bay, beavers look for areas with no hydrological connection to a large body of water and only marshland that receives an intermediate amount of watershed. Fracz and Chow-Fraser looked specifically at the water chemistry between the beaver-concentrated marshlands and other coastal marshes in eastern Georgian Bay. The scientists collected data from 18 coastal marshland areas in the Georgian Bay. All of the marshlands were more than 2 ha (10,000 sq. meters) in size in order to meet the criterion set by the Ontario Wetland Evaluation System. They also collected data from 17 beaver-impounded wetlands. Both scientists believed that the wetlands were at one point connected to the Georgian Bay but had become beaver-impounded by 2010. The coastal marshes were sampled between May and September of 2010 while the 17 beaver wetlands were sampled between May and mid-July of 2011. They collected the samples during the day between 9am and 4:30pm and made sure to avoid collecting after any rainfall. The samples that were collected consisted of total nitrate nitrogen, total ammonia nitrogen, total suspended solids, total phosphorus, and soluble reactive phosphorus. They also recorded measurements from specific conductivity and the pH of the water. Fracz and Chow-Fraser used various protocols for accurately measuring the samples such as Hach reagents and a Hach DR/890 colorimeter for measuring nitrate nitrogen and ammonia nitrogen. Values that measured below the detection limit were assigned half the detection limit value. In order to compare results amongst the coastal marshlands and the beaver-impounded wetlands, they used a Kruskal-Wallis test to determine the water chemistry variables. They also proceeded to use a nonparametric Wilcoxon test to further their accuracy. The results they obtained showed that water chemistry samples varied significantly between the coastal marshlands and the beaver-impounded wetlands. They obtained the mean value amongst all samples to determine what the value was. “n” was the symbol for the average of these samples. The only variable that did not significantly differ between coastal marshlands and beaver-impounded wetlands was the total ammonia nitrogen with a p value from the Wilcoxon test of 0.1888p. The rest of the variables all had much lower p value, which meant that they differed significantly. In the coastal marshlands, specific conductivity and pH values were much higher in the beaver-impounded wetlands while the rest of the values were significantly lower. Fracz and Chow-Fraser also analyzed the samples further by using Principal component analysis (PCA) impoundments to differentiate between not only the samples of the coastal marshlands and beaver wetlands, but also the samples of the open water.
Sites with positive PC1 scores (on the x-axis) corresponded with the beaver-impoundments that contained suspended sediments, aglae in the water and high concentrations of phosphorus. The negative PC1 scores were the open-water sites with high concentrations of nitrate nitrogen, conductivity and pH. The coastal marshland sites ended up in the middle of the graph between the other sites.
The scientists had originally hypothesized that coastal marshlands had similar water chemistry to that of open water areas whereas beaver-impounded wetlands did not because of the lack of free-flowing water. However, after the Kruskal-Wallis test, they concluded that all water chemistry of open-water, beaver-impounded wetlands and coastal marshes differed quite
significantly. I found this article to be very insightful for learning about the water chemistry in different wetland areas. The authors focused on providing accurate data that was compared and analyzed to conclude their points. When I read the title of this article, it interested me to find out if there was actually a difference in the water chemistry of various wetlands. I figured that there couldn’t really be much of a change because all water comes from the same source, technically speaking. However, I was wrong and in fact, the changes between coastal marshland and beaver-impounded marshland are significant. The data that was provided gave a detailed analysis of the chemistry of the various locations. It was helpful that they included not only the water chemistry in the coastal marshland and beaver-impounded areas, but also samples from the open water of the Georgian Bay. This way, they proved that beavers could actually affect the chemistry of water just by hydrologically disconnecting the wetlands from the bay. One thing that I am skeptical of is why they didn’t take the samples of the water within the same year? Why couldn’t they have done it all within the same time period to ensure their results were accurate? This is the one thing I was questioning when reading the article because it seemed like the locations were not far off from each other which meant that access from one location to the other was not far. A future study could maybe test for the same samples within a year of each other and compare it to the samples recorded by Fracz and Chow-Fraser. However, I enjoyed reading the article because I learned about water chemistry, (something I had never heard of before), and its affects on the composition of various wetlands near the Great Lakes.
Perhaps the most devastating disregard of the Fraser Valley’s biodiversity was the draining of Sumas Lake to create farmland, resulting in the loss of habitat and the extirpation of endemic species. As it was originally intended to be, the Fraser Valley was a “perhaps unparalleled ecosystem” (Rosenau, p. 55), with bountiful wetlands and remarkable biodiversity. The European settlers 150 years ago considered it to be “wasteland” (Thom, p. 172), certainly uninhabitable and a breeding ground for mosquitoes, so the most logical thing to do would be to drain the body of water once known as Sumas Lake...
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Methodology: The experimenter used two ten gallon tanks. One tank will be used for the controlled group and the other tank will be used for the experimental group. Each tank will have two pounds of sand spread among the bottom of the tank along with rocks and artificial habitats to add nitrogen to the tanks. To add optimal living conditions for the oceanic life water filtration systems, temperature regulator, circulation systems, and a light to mimic the sun’s rays were added to each tank. At all times both tanks had a temperature of 75 degrees F. This experiment was done over a three month period. The first month was to allow the nitrogen cycle to occur. This allows the fish to be exposed to the water without having stress reactions due to unhealthy living conditions due to the nitrogen. Once the first month was complete six fish was added to both tanks. Two tangs, two damsels, and two clownfish. At first both tanks had a pH level of 8.2, ideal living conditions. After one week the experimental group was exposed to a pH level of 8.6. After two weeks it was raised to 9. Two weeks later it was raised to 9.3. The final raise was done two weeks after making the pH level 9.5. The final week of the experiment the pH lev...
...sica Leahy, and Kathleen Bell. "Interactions between Human Communities and Estuaries in the Pacific Northwest: Trends and Implications for Management." Estuaries. 26.4 (Aug., 2003): 994-1009 . Print.
First test you will see if the phosphates test. All together, the average of the test was 0.3 ppm. Which in that case is good showing that there is not much eutrophication in the creek. My group personally did a nitrates test. Our group got about 0.4 ppm. On average the tests were around 0.8 ppm. Like the phosphates that means that there isn’t much eutrophication in the creek. Another test we did was a dissolved
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Smith, Zachary A., and Grenetta Thomassey. Freshwater Issues: A Reference Handbook. Santa Barbara, CA: ABC-CLIO, 2002. Print
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