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:

  1. Open the ELMR Data Base at: http://www8.nos.noaa.gov/biogeo_public/elmr.aspx/.

  2. 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.

  3. 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.”

  4. 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:
  1. Prepare data summary graphs for each of your assigned species as follows:
  1. Use your chart to find out:

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.

  1. 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?

 

 

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