Thermometer Exploration

The temperature of the soil or water has a great influence on the behavior of the indwelling plants and animals. Florida is a great place to follow the behavior of the plants and animals that dwell in or on these substrates. As an example, the temperature of the soil determines the percentage of male/female hatchlings from eggs buried by turtles in the costal regions.

This is called temperature-dependent sex determination TSD. Researchers found that if a turtle’s eggs are incubated below 27.7° C (81.86° F), the turtle hatchling populations will be predominantly male. If the eggs incubate above 31° C (88.8° F), the hatchlings will be predominantly female.

This instrument, added to our tool kit, may disclose new findings. Questions regarding change in temperature might include: the temperature differential at various depths, how does the temperature change over time, exposure to direct sun, proximity to bodies of water, consistencies and composition of the soil. The secondary effects might show other effects on the plants and animals life, presence of species at depth, rates of growth, other gender or morphology changes. The interactions and permutations of this would be extensive.

I have devised a method of measuring temperature at depth of up to 50 mm. This could be extended to greater profundity if the results show promise. The instrument consists of three parts; an aluminum arrow shaft (8.6 mm dia.) with an aluminum field point at the down end and a wooden ball at the up end; a length thermocouple sensor wire that can be threaded through the ball end to the length of the probe and temperature can be measured with a Fluke 52 electronic thermometer with a scale -328F (-200C) to +1400F (+760C) accurate to 1/2 degrees. (John Fluke Mfg. Co. Inc. Everett, WA),

The instrument was calibrated at zero degrees C in ice water. It is pictured below. The depth of penetration was dependent upon the hard pack of the soil. Where necessary, a steel shaft of similar diameter could be driven to depth which a mallet prior to insertion of the thermometer.

The assembled thermometer showing yellow bands at 10 cm intervals.
Thermometer probe at 20 cm at 12:00 PM
Thermometer reading at 12:00 PM
Thermometer ambient air temperature at 12:00 PM

Early readings of beach sand between 10:00 AM and 12:00 PM.

  • At water line 10 cm, 26.4 C
  • Mid beach 10 cm, 27.9 C
  • Berm 10 cm, 27.8 C
  • Veg line 20 cm, 27.3 C
  • Remed. sand 50 cm, 28.2 C

Conclusions would require much more investigation to confirm my suspicions. I found that, except for the water line reading these recordings show a remarkable similarity. The average of the last four is 27.8 (+/- 0.4 C/0.5C). It is especially notable to see that the remediation sand which is stacked to 10 ft high was easily penetrated to 50 cm depth at the 4 ft level and was only +0.4 degrees from the average temperature. All of the sand temperature readings were significantly lower than the ambient air temperature.

The implication of these finding suggests that turtle egg hatched in these samples of sand would result in a population predominantly of males. Additionally, the remediation sand behaves similar to the un-remediated beach sand in its ability to moderate the results of direct sun or ambient air temperature fluctuations. This does not consider very important variables such as time, duration, season, weather, moisture, distance away from water line and other factors.

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#thermometer #sand #beach #temperature dependent #probe

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