Alan Davis Field Trip Activities Establish your sampling group. Groups should be no larger than four students. Obtain an assigned sampling region and a bucket with a variety of tools for sampling. Other sampling tools will need to be shared among the different groups. These can be temporarily obtained from the instructor or used at the field station set up by the instructor. The field sampling tasks described below should be completed in the order listed. Establish Sampling Site Locate the general area assigned as your sampling region. Objectively select a sampling site by closing your eyes and tossing the PVC pipe square (area=0.25 meters) a short distance into an area no one has walked or disturbed. You will use the bounds of the PVC pipe square as the perimeter of your sampling site. Water Depth Measure the depth of the water at your sampling site. Water Temperature Use a thermometer and meter stick to measure the temperature at various levels in the water column. Start with a temperature measure just below the surface. Then take 4 more readings equally spaced through the water column in your sampling area including one within the substrate (be careful not to break the thermometer). You should have five readings in all. Water Sampling Take water samples in your sampling area using the covered containers. Take four samples in all starting just below the surface with the remaining samples equally spaced through the water column. The fourth sample should be taken just above the substrate. The proper sampling technique should be lowering a covered sampling container to the level the sample is to be taken. Partially lift the container lid to release the air inside while filling with water. Once all of the air has escaped, replace the cover and bring the container back to the surface. No air should be in the container. When all four samples have been collected, perform the various measures below ASAP. These testing devices will be located at the instructor s field station. Dissolved oxygen Salinity ph Water Transparency Measure the clarity of the water using the transparency tube with the black and white pattern on the bottom. Close the drain tube by squeezing the crimp. Place your hand over the end of the tube and submerge it halfway between the surface and the substrate. Allow water to flow into the tube till all air is exhausted. Recover the tube opening with your hand and bring the tube to the surface in an Page 1 of 5
upright position. While looking down through the opening of the tube, partially open the drain crimp to slowly draw off sample. When the black and white pattern faintly begins to appear, immediately tighten the crimp and record the level of the water remaining in the tube (in cm). Plankton Sampling Obtain a plankton net (fine mesh). Stand in one place beside your sampling site and drag the net across you site just below the surface of the water. Examine the inside of the net for minute organisms. If you find something, drain the sample through the tube at the bottom of the container into a beaker of saltwater for later examination under the field dissecting scope. The field dissecting scope will be at the instructor field station. Do another plankton sampling, this time just above the surface of the substrate. Substrate Core Push an open ended (both) core tube into the substrate within your sampling area. Push it as far in as possible or until two centimeters of the tube remains exposed. Withdraw the core tube and gently bring it to the surface. Review the core sample for color, odor, texture and grain size of sediment. Substrate Particle Size Place about 250 ml of sediment in a 1,000 ml graduated cylinder or some other transparent container that can be measured. Measure the volume or height of the sediment in the container. Fill the cylinder with water and vigorously agitate the sediment-water mixture. Allow the sediment to settle for at least 10 minutes. Use the graduated scale of the cylinder to compute the approximate percentage of each of the following sediment grain types: 1. Sand ( material that settles in less than one minute) 2. Silt (material that settles in one to 10 minutes) 3. Clay (material that does not settle in ten minutes) Census of Substrate Organisms Using a scoop provided, remove a 10 cm layer of substrate from the whole of your sampling area (everything within the PVC pipe boundary. Place each scoop of substrate in a screened sieve to separate organisms found within the substrate. You may find that spilling water into the sieve with help the separation. Retrieve all organisms found. When finished, count the number of each type and return all but one of each to their environment. Use the example of each organism saved to identify the organisms found within your sampling site. A variety of reference books will be available. Page 2 of 5
Names of Group Members: Site Location: Alan Davis Field Trip Sampling Sheets Description of Site Location (e.g. wave action, water movement, nearby shoreline, etc.): Water Depth (meters): Water Temperature: Temperature 1 Temperature 2 Temperature 3 Temperature 4 Temperature 5 Depth from Surface (meters) Surface Substrate Temperature ( C) Water Sampling Tests: Sample 1 Sample 2 Sample 3 Sample 4 Depth from Surface (meters) DO Salinity ph Water Transparency (in cm): Page 3 of 5
Plankton Sampling: Draw some of the different types of plankton that you observed in the two samples taken. Substrate Core: Show and describe (color, grain size, etc.) the different layers of the substrate at your sampling site. Top Substrate Particle Size: Initial volume of sediment Volume settled after one minute Volume settled after tem minutes Calculated % Sand Calculated % Silt Calculated % Clay Census of Substrate Organisms: General Classification Species (if known) Count Page 4 of 5
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