The Thacher School and The Turtle Conservancy
The
Southwestern
Pond
Turtle
(Actinemys pallida)
Identifiers
Color: olive green/brown
Size: 4.5-8.5 inches
Body: grey with scales (yellow under head and tail)
Habitat: Quiet marshes, pools, rivers, ponds
Location
The Southwestern Pond Turtle resides on the West Coast of the United States and Mexico. They are prevalent in mid-Southern California and Baja California. They have been spotted in the Sespe Wilderness, right in the backyard of Thacher's campus.
BEHAVIOR
Enjoy basking on rocks, logs, and beaches.
Shy- jump into water or hide for shelter.
Eat plant rots, algae, tadpoles, frogs, crayfish, insects, and macroinvertebrates
Can live up to 40-50 years.
METHODOLOGY
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Navigate using GPS coordinates to the beginning of the transect
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Be careful to not disturb the water upstream from the start of the transect in order to avoid kicking up macroinvertebrates
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Upon arrival to a site:
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Mark the time of day
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Note if there has been rainfall in the past 7 days
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Test using probeware
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pH
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Dissolved Oxygen
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Total Dissolved Solids
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Temperature of Water
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Temperature of Air
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In order to determine the flow rate
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Measure the average depth of the stream using 5 depths across the width of the stream at the beginning/end of the transect. Use ruler to measure
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Measure the stream width using a tape measure
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Then use the bobbing orange method to measure time
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Measure 15 meters using the tape measure and place an orange in the water and time how long it takes to travel the 15 meters. Repeat twice or three times depending on the time of the first trial.
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Once calculated, multiply the stream depth by the stream width, then multiply by 15 (15 m distance from orange flow) then divide by the time taken to get the volume of water flowing at the given site.
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The Survey:
Stream Health Assessments are ompleted at the beginning and end of each transect, the beginning being downstream from the end. They work to determine the physical, chemical, and biological characteristics of a stream.
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Physical Assessments:
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Done visually by looking 20 meters upwards and downwards of the stream
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Assesses vegetation, rocks, macroinvertebrate habitat, fish/turtle shelter, bank stability, velocity and depth, and basking sites
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Complete each section and analyze the stream ecology by adding the numerical values
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Chemical Assessments:
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Done with calibrated probes to calculate dissolved oxygen, pH, turbidity, and dissolved solids in a stream.
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Probes are dipped in moving, undisturbed water
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Analyzed by adding the individual scores of each section
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Biological Assessments:
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Dip a net into moving water and disturb the sediment upstream for 30 seconds. Dump the contents into a pan to observe the macroinvertebrate catch.
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Macroinvertebrates can be identified using an identification sheet at the end of the survey
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Each macroinvertebrate type is categorized into ‘sensitive’, ‘less sensitive’, ‘somewhat tolerant’, and ‘tolerant’.
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If a type is found, check the box next to its name and analyze as directed
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The scores are analyzed based on sensitivity and variety of macroinvertebrate types.
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COMparing the 3 transects:
The three graphs on the right compare the cross-section area, dissolved oxygen, and water temperature of each stream transect. In all of the streams, each result was different, which makes sense because the start and end marks are 250 meters apart.
