Eyes on the Estuaries
ELMR Data Base Student Worksheet
The ELMR Data Base includes data on selected fish and invertebrate species in 122 estuaries along the coastlines of the United States. Each estuary is divided into one to five salinity zones. In each zone, data are provided for the relative abundance of five life stages for each of the selected species that are present. These life stages are adults, eggs, juveniles, larvae, and spawning adults. Data for each life stage for each species are provided for each of twelve months. Relative abundance is represented by a scale from 0 to 5:
0 = not present
2 = rare
3 = common
4 = abundant
5 = highly abundant
An entry of “.” means that no data are available.
Your assignment is to compare data for certain species in two or more estuaries assigned by your teacher. For each assigned species, you should find out:
- In what months is each of the five life stages present, and in what months is each stage most abundant?
- In what salinity range is each of the five life stages found during the months that it is most abundant?
- Open the ELMR Data Base at: http://www8.nos.noaa.gov/biogeo_public/elmr.aspx/.
- Select the “Region” that includes the estuary you are interested in (SOUTHEAST), then the appropriate estuary name in the “Estuary” window (WINYAH BAY). You can confine your search to specific Species, Life Stages, and Salinity Zones, or just leave “All” selected in these windows. For now, leave “All” selected. Click the “Save As Text” button. The file will be saved onto your hard drive as a “zip” archive.
- Unzip the downloaded data file, and open the ELMR download text file in Microsoft Excel®. You will get the Text Import Wizard
Step 1. Select “Delimited,” “Start Import at Row: 1,” and the operating system you are using next to “File Origin.” Click “Next.”
Step 2. Select “Delimiters: Tab” and “Text Qualifier: “ Click “Next.”
Step 3. Click the “General” button under “Column Data Format.” Click “Finish.”
- You now have a spreadsheet with all of the data for Winyah Bay. Now, you need to make a few adjustments to this spreadsheet to make it easier to analyze:
- Highlight columns B and C. Under the “Format” menu, select “Column” and then “Width.” Change the width of columns B and C to 2 inches.
- Highlight columns E through P. Under the “Format” menu, select “Column” and then “Width.” Change the width of columns E through P to 0.5 inch.
- Highlight all cells by clicking on the empty cell in the upper left corner. Under the “Data” menu click “Sort.” Check the box next to “Header Row” under “My list has.” Under “Sort By” select “Common Name.” Under “Then by” select “LifeStage.” Click “OK.
- Prepare data summary graphs for each of your assigned species as follows:
- Highlight all cells in columns C through P for all Life Stages of the species you are analyzing. For this example, suppose “Alewife” is one of your assigned species; so you would highlight cells C2 through P16
- Click on the Chart Wizard icon. Select “Column” under “Chart type” and the upper left icon under “Chart subtype.” Click “Next.”
- Click the button next to “Rows” under “Series in.” Click the “Series” tab, and remove all life stages except “Adults” and “Spawning.” Click “Next.”
- Click the “Titles” tab. Enter a title for your chart (such as “Alewife Adults and Spawning”). Enter “Month” in the “Category (X) axis:” box and “Abundance” in the “Value (Y) axis:” box. Click “Next.”
- Click the button next to “As new sheet” and enter the name that you want to appear on the tab for your chart in the spreadsheet workspace. Click “Finish.” You now have a column chart that shows the relative abundance of alewife adults, and spawning adults in each salinity zone for each month.
- If you want to print your chart and do not have a color printer, you may want to change the column fills to black and white patterns. To do this, double click on one of the columns on your chart. The “Format Data Series” dialogue box will open. Click on the “Colors an Lines” tab, then select “Fill Effects . . . “ from the Color drop down menu, then click the “Pattern” tab. Select black in the window under “Foreground:” and white in the window under “Background:” Select the pattern you want, then click “OK.” Click “OK” in the “Format Data Series” dialogue box.
- The column on your chart should now contain a black-and-white fill pattern. Repeat these steps for the other columns.
- Repeat steps a. and b. Click the button next to “Rows” under “Series in.” Click the “Series” tab, and remove “Adults” and “Spawning” life stages. Click “Next,” and repeat steps d. and e. You now have a second column chart that shows the relative abundance of alewife eggs, larvae, and juveniles in each salinity zone for each month. Adjust the column fills if necessary.
- Use your chart to find out:
- When are spawning adults most abundant?
- When are eggs most abundant?
- When are larvae most abundant?
- When are juveniles most abundant?
- When are adults most abundant?
- Are any of these life stages more abundant in certain salinity zones?
For the Winyah Bay alewife example, adults and spawning adults are most abundant in March, April and May; eggs are most abundant in March, April and May; larvae are most abundant in March, April, May and June; juveniles are abundant from April through November. Notice that all life stages of alewife are absent from December through February. Different life stages of alewife appear to have different salinity preferences. Alewife eggs and larvae are found only in salinities of 0 - 0.5 ppt. Juveniles are also confined to this salinity zone during April, May, June, and July; but are found in the 0.5 - 25 ppt salinity zone between August and November, and in the >25 ppt zone between September and November. Alewife adults are found in all three salinity zones, but spawning adults are only found in the 0 - 0.5 ppt zone.
- Discuss possible reasons for seasonal variations in the abundance of different life stages. What effect could severe storms or prolonged drought have on your assigned species?