Transcript Characteristics of rainfall and its effects on earthworms

Characteristics of rainfall and its
effects on earthworms
Natalie Rideout, Aaryn Tays, Kaitlyn VanKoppen
Introduction
● Worm’s habitat is a burrow in moist, compacted soil
● Worms that come to the surface after a rainfall are
vulnerable to predation
● Debate over the reason why earthworms come to
the surface
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Flooding of the burrows
Oxygen intake
Migration
Seismic vibrations simulating voles digging
Purpose
● To determine what aspects of rainfall makes
earthworms come to the surface
● Tested using
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Control, moisture, vibrations, sound and a
combination tank with all three stimuli
Hypothesis
We hypothesized that a combination of all the
stimuli (vibrations, sound, and moisture) will
result in the greatest number of worms coming
to the surface.
Methods
● 10 worms in 5 tanks
● Stimuli applied under red light for 2 minutes
for each tank
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Control, moisture, vibrations, sound and a
combination of all three stimuli
● Number of worms at surface counted
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Before stimulus, during stimulus and in 2 minute
intervals for 30 minutes
Preparing to apply stimulus
Results
● Control
o No worms surfaced
● Sound
o No worms surfaced
● Vibrations
o 2 worms surfaced
● Moisture
o Mean of 2 worms surfaced during N=3 trials
o Range from 0 to 5
● Combination
o Mean of 1.5 worms surfaced during N=3 trials
o Range from 0 to 5
Figure 1. Average results for five trials. Stimuli included sound, vibration, moisture, and combination
(n=10). A control tank was also tested where no stimuli was present. Number of earthworms observed
in the moisture stimulus was 33% more than the combination stimulus.
Discussion
● The results showed that moisture had the greatest
effect on the worms
o This disagreed with our hypothesis
● No results were obtained from the sound or the
control condition
● Possible Confounding Variables:
○ High temperature of lamps
○ Variable species of earthworms
○ Grunting technique
Real World Applications
● Increase in danger for earthworms to surface
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Higher vulnerability to predators
● Could help researchers develop ecological
plans
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More stable population size
Helpful when working in areas of high flood
● Harvesting of earthworms by fishermen
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Better understanding of why and when earthworms
surface
Future Research
● Focus on the reason why moisture encourages
worms to leave their burrows
● Possible explanations include:
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Facilitate rapid migration
Avoidance of drowning in burrows
Facilitation of gas exchange
Conclusion
Earthworms preferred to surface at a point with high
moisture levels. It is possible this is due to flooded burrows
or the need to migrate.
Earthworms showed no preference for sound or
vibration.
Questions and Comments