You are investigating the potential impacts of urbanization on water quality and macroinvertebrate diversity in rivers...

  

  

  

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You are investigating the potential impacts of urbanization on water quality and macroinvertebrate diversity in rivers and streams in Gwinnett County. You have randomly selected 10 streams that have over 50% Developed-Urban land-use-land cover in their respective subwatersheds, and 10 additional streams that have less than 10% Developed-Urban land cover. All sites were located in Gwinnett County, in the Piedmont ecoregion of Georgia. At each stream location, you randomly select 5 riffle habitats, 5 run habitats, and 5 pool habitats. In each habitat, you prepare and set 5 leaf packs, each with 30 grams of maple leaves per pack (15 total mesohabitats * 5 leaf packs = 75 leaf packs prepared and set per stream location). You set all leaf packs in mid Spring, and allow them to soak for 30 days. You also recorded the water depth (cm), and documented the subtrate type (i.e., sand/silt, gravel, cobble, and boulder) for each leaf pack (i.e., the substrate type where each leaf pack was set). You also note the presence OR lack of submerged woody debris at each leaf pack location. After 30 days, all partially decomposed leaf packs were collected, placed in individual ziplock bags, labeled appropriately, and transported to the lab for processing. Each leaf pack was opened, and you and your lab associates very carefully sort through the remaining leaves and leaf fragments of each pack. All macroinvertebrates that colonized each leaf pack were transferred to water-filled petri dishes for identification and enumeration. After sorting through an entire leaf pack, you identify each macroinvertebrate to the Order level, record the number of individuals counted in each Order, and then place all macroinvertebrates from that sample in a small jar with ethanol for future research and additional analyses (properly labeled). Spreadsheet. For each stream location (10 urban and an , recall above), you calculate the tota You enter all of your into an number of macroinvertebrates representing the Ephemeroptera (mayfly nymphs), Plecoptera (stonefly nymphs), and Trichoptera (caddisfly larvae) Orders. You then compute an EPT index (%) for each stream location, by taking the total number of Ephemeropterans, Plecopterans, and Trichopterans (E + P + T), and dividing it by the total number of macroinvertebrates collected at that location [EPT % index = (E + P + T)/ Total macroinvertebrates in sample x 100]. The EPT index measures the proportion of the macroinvertebrate community that consists of taxa that are most sensitive to poor water quality, pollution, and degraded habitat (E + P + T), with the stonefly nymphs being most sensitive, mayfly nymphs showing variable sensitivities, and caddisfly larvae being the least sensitive of the three indicator (intolerant) groups. The higher the EPT index, the better the water quality and overall habitat conditions. HIGHER = BETTER Here are the computed EPT indices for the urban and non-urban stream locations: Urban Sites Site # 1 2 345 6 7 8 9 10 EPT (%) 15 12 8 6 35 11 18 32 16 3 Non-Urban Sites Site # 1 2 3 4 5 67 8 9 10 EPT (%) 32 28 9 23 22 31 26 12 36 27 1) This study is more than just an observational study, and it can be argued that this is an example of a field-based experiment. Based on the information given, explain why this is the case. 2) State your null hypothesis (H.) and your alternative hypothesis (HA), given the described scenario. Please state your hypotheses as if they were a priori, BEFORE any data were collected. 3) Using the data analysis function in Excel (see video tutorial), compute descriptive statistics for the urban and non-urban groups. Provide your output to the left, in this spreadsheet. 4) Conduct an F-Test Two-Sample For Variances first, to determine if variances in EPT differ between the urban and non-urban groups. Based on these results, perform the correct t-test to determine if the mean EPT is significantly different between the urban and non-urban groups. Provide all of your output to the left, in this spreadsheet. 5) Based on the results above (#4), do you reject or accept the null hypothesis? Explain. What is your overall conclusion? 6) You notice that two stream locations in urban areas had higher EPT values (35 and 32%), while two stream locations in non-urban areas had relatively lower EPT values (9 and 12%). How do you explain this? What could also be influencing EPT levels at these locations?????? 7) Construct a professional-looking bar chart, displaying the mean EPT (± S.E., Standard Error bars) for the two groups (urban vs. non-urban). Be sure to include x-axis and y-axis labels. You are investigating the potential impacts of urbanization on water quality and macroinvertebrate diversity in rivers and streams in Gwinnett County. You have randomly selected 10 streams that have over 50% Developed-Urban land-use-land cover in their respective subwatersheds, and 10 additional streams that have less than 10% Developed-Urban land cover. All sites were located in Gwinnett County, in the Piedmont ecoregion of Georgia. At each stream location, you randomly select 5 riffle habitats, 5 run habitats, and 5 pool habitats. In each habitat, you prepare and set 5 leaf packs, each with 30 grams of maple leaves per pack (15 total mesohabitats * 5 leaf packs = 75 leaf packs prepared and set per stream location). You set all leaf packs in mid Spring, and allow them to soak for 30 days. You also recorded the water depth (cm), and documented the subtrate type (i.e., sand/silt, gravel, cobble, and boulder) for each leaf pack (i.e., the substrate type where each leaf pack was set). You also note the presence OR lack of submerged woody debris at each leaf pack location. After 30 days, all partially decomposed leaf packs were collected, placed in individual ziplock bags, labeled appropriately, and transported to the lab for processing. Each leaf pack was opened, and you and your lab associates very carefully sort through the remaining leaves and leaf fragments of each pack. All macroinvertebrates that colonized each leaf pack were transferred to water-filled petri dishes for identification and enumeration. After sorting through an entire leaf pack, you identify each macroinvertebrate to the Order level, record the number of individuals counted in each Order, and then place all macroinvertebrates from that sample in a small jar with ethanol for future research and additional analyses (properly labeled). Spreadsheet. For each stream location (10 urban and an , recall above), you calculate the tota You enter all of your into an number of macroinvertebrates representing the Ephemeroptera (mayfly nymphs), Plecoptera (stonefly nymphs), and Trichoptera (caddisfly larvae) Orders. You then compute an EPT index (%) for each stream location, by taking the total number of Ephemeropterans, Plecopterans, and Trichopterans (E + P + T), and dividing it by the total number of macroinvertebrates collected at that location [EPT % index = (E + P + T)/ Total macroinvertebrates in sample x 100]. The EPT index measures the proportion of the macroinvertebrate community that consists of taxa that are most sensitive to poor water quality, pollution, and degraded habitat (E + P + T), with the stonefly nymphs being most sensitive, mayfly nymphs showing variable sensitivities, and caddisfly larvae being the least sensitive of the three indicator (intolerant) groups. The higher the EPT index, the better the water quality and overall habitat conditions. HIGHER = BETTER Here are the computed EPT indices for the urban and non-urban stream locations: Urban Sites Site # 1 2 345 6 7 8 9 10 EPT (%) 15 12 8 6 35 11 18 32 16 3 Non-Urban Sites Site # 1 2 3 4 5 67 8 9 10 EPT (%) 32 28 9 23 22 31 26 12 36 27 1) This study is more than just an observational study, and it can be argued that this is an example of a field-based experiment. Based on the information given, explain why this is the case. 2) State your null hypothesis (H.) and your alternative hypothesis (HA), given the described scenario. Please state your hypotheses as if they were a priori, BEFORE any data were collected. 3) Using the data analysis function in Excel (see video tutorial), compute descriptive statistics for the urban and non-urban groups. Provide your output to the left, in this spreadsheet. 4) Conduct an F-Test Two-Sample For Variances first, to determine if variances in EPT differ between the urban and non-urban groups. Based on these results, perform the correct t-test to determine if the mean EPT is significantly different between the urban and non-urban groups. Provide all of your output to the left, in this spreadsheet. 5) Based on the results above (#4), do you reject or accept the null hypothesis? Explain. What is your overall conclusion? 6) You notice that two stream locations in urban areas had higher EPT values (35 and 32%), while two stream locations in non-urban areas had relatively lower EPT values (9 and 12%). How do you explain this? What could also be influencing EPT levels at these locations?????? 7) Construct a professional-looking bar chart, displaying the mean EPT (± S.E., Standard Error bars) for the two groups (urban vs. non-urban). Be sure to include x-axis and y-axis labels.

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