Macroinvertebrates+Study

media type="file" key="01 Careless Whisper.mp3" media type="file" key="Don't Stop Believing.mp3" UEI- Foundations @ Boston College  Melissa, Angela, and Sasha Chandler's Pond Boston, MA [|Click to find info on nitrates in ponds] [|Biotic Index Resource] 


 * Correlations of Nitrate Levels and Biotic Index At Chandlers Pond**

**Research question:** What is the correlation between nitrate levels and the biotic index of macroinvertebrates found at three (3) sites?


 * Hypothesis:** The higher levels of nitrates in the H2O, the fewer level 1 macroinvertebrates will be found at the sites; the lower the nitrate levels the greater the number of level 1 macroinvertebrates will be found .

** Background ** : The Biotic index score at a site is a direct indicator of water quality. The biotic index is calculated based on the macroinvertebrates present at the site. When calculating the biotic index, “the number of animals found is not important; rather, the number of types of macroinvertebrates and their tolerance to pollution tells us the biotic index score. “ Macroinvertebrates can be separated into four levels based on their tolerance of pollutants in the water. Level one being the most intolerant, while level four is the most tolerant to pollutants. Water quality can be affected by a multitude of factors including nitrate levels, phosphate levels, dissolved oxygen levels, and pH. In designing our experiment we chose to measure nitrate levels at three different sites and to look at how those levels correlate with the biotic index at each. We chose to measure nitrates due to the fact that at high levels nitrates can cause a process called eutrophication to occur in a body of water. Eutrophication is the process in which excessive nutrients in the water stimulate excessive plant growth. This growth is followed by plant death, resulting in a decrease in dissolved oxygen in the water and consequently fewer organisms. Nitrates come from sources such as fertilizers, which we thought might play a significant role in the Chandler Pond ecosystem. We chose our sites based on their proximity to Boston Sewer inflow (water entering) and outflow (water leaving) pipes around the pond. **Site 1** is located on the Southwest corner of the pond and is an inflow pipe. It is located on the edge of a grassy slope across the street from several single family homes. **Site 2** is on the Northeast corner of the pond and is an inflow pipe. The site is located on a side of the pond that is bordered by homes and a flat, grassy field. **Site 3** is located on the Northwest corner of the pond and is an outflow pipe. This site is located on a section of the pond that has a gentle, grassy slope leading down to the water and a large condominium unit located behind it.

Pond Nitrate testing kit Net Tray Magnifier Pail Macroinvertebrate guides Boots Camera Pen Paper Computer with internet access  We obtained our water samples by dunking the pail into the water. We then followed the Lamont Nitrate/Nitrogen test kit procedure at each site to determine the nitrate levels. To gather our information on macroinvertebrates we ran the net along the bottom of the pond in the same location where we took the water samples from. The contents of the net were then emptied into a tray. We observed the macroinvertebrates present in the sample and identified them using the guide. We used this information to calculate the biotic index of the site using the calculations found in the results section.
 * Methods and Materials:**

Table 1: results of nitrates test and biotic index calculations
 * Results:**
 * Site || Nitrates (ppm) || Biotic Index ||
 * 1 || 1.5 || 1.9 ||
 * 2 || 2.0 || 1.7 ||
 * 3 || 1.0 || 2.0 ||

In order to calculate the biotic index the following equations are used. 1. Number of animals circled from group 1 :_ x4 = 2. Number of animals circled from group 2 :_ x3 = 3. Number of animals circled from group 3 :_ x2 = 4. Number of animals circled from group 4 :_ x1 = Total: (a) _ (b)

Divide totaled value (b) by total number of animals (a) for index score: Table 2: Biotic Index values chart
 * Biotic Index Chart ||
 * Excellent…………………………..….…3.6+ ||
 * Good……………………………….…….2.6-3.5 ||
 * Fair……………………………...…...….2.1-2.5 ||
 * Poor…………………………….………..1.0-2.0 ||

Figure 1: Graph of nitrate levels (ppm) and biotic index scores by site.

**Conclusion:** In conclusion, we did see a very slight correlation between the nitrate levels and the biotic index at our three sites. Each site received a biotic index of “poor”, however, there was a small variation within that level. Site 2 had the lowest biotic index and Site 3 the highest biotic index; the Nitrate levels correlated with this, Site 2 had the highest nitrate levels and Site 3 had the lowest nitrate levels.


 * Changes for the future:** If we had had more time, we could have monitored nitrate and biotic index levels over a much longer period of time. This would have eliminated any irregularities and allowed us to gather more data and make a more accurate conclusion. Another change that we would have made was to monitor all factors of water quality (temperature, nitrate, phosphate, pH and dissolved oxygen) and compare that with the biotic index level at our three sites.

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