Effects of Synthetic Estrogen (17α-Ethinyl Estradiol) on Male Fiddler Crab Aggression
Location
Presentation- College of Science and Mathematics
Document Type and Release Option
Thesis Presentation (Archived)
Faculty Mentor
Dr. Risa Cohen
Faculty Mentor Email
rcohen@georgiasouthern.edu
Presentation Year
2021
Start Date
26-4-2021 12:00 AM
End Date
30-4-2021 12:00 AM
Keywords
Georgia Southern University, Honors Symposium, Presentation
Description
Pharmaceuticals, including hormones and antibiotics, are considered contaminants due to their widespread use and release into the environment. Synthetic estrogen used in oral contraceptives (17α-ethinylestradiol), is present in freshwater and marine systems, but with relatively unknown effects on the organisms that live there. Ethinylestradiol (EE2) accumulates in waterlogged soil (sediment) with potential to harm sediment-dwelling animals. For example, fiddler crabs (Uca pugilator) are vital members of salt marsh communities. Their burrowing adds oxygen to sediments and cycles nutrients, and they are an important food resource. Male fiddler crabs are territorial, aggressively defending their burrows from intruders. Given that synthetic estrogen reduces aggression in other aquatic organisms, I hypothesized that EE2 affects male fiddler crab aggression. Male crabs exposed to EE2 were expected to retreat from threats instead of attacking more often than control animals. Male aggression was measured as responses to threats (fleeing, attacking, no response) after exposure to sediment without (control) or with added EE2 (0.5 mg L -1 ). There was a trend toward EE2 treated crabs fleeing from a fight more often than control crabs, but none of the other responses differed between treatments. The lack of significant response was likely due to the measured concentration of EE2 in the treated sediment being two orders of magnitude less than the calculated concentration. Therefore, while these findings indicate the possibility that EE2-exposed males may have difficulty protecting themselves, their burrows, or their mate from predators, higher EE2 concentrations with larger sample sizes need to be tested for verification.
Academic Unit
College of Science and Mathematics
Effects of Synthetic Estrogen (17α-Ethinyl Estradiol) on Male Fiddler Crab Aggression
Presentation- College of Science and Mathematics
Pharmaceuticals, including hormones and antibiotics, are considered contaminants due to their widespread use and release into the environment. Synthetic estrogen used in oral contraceptives (17α-ethinylestradiol), is present in freshwater and marine systems, but with relatively unknown effects on the organisms that live there. Ethinylestradiol (EE2) accumulates in waterlogged soil (sediment) with potential to harm sediment-dwelling animals. For example, fiddler crabs (Uca pugilator) are vital members of salt marsh communities. Their burrowing adds oxygen to sediments and cycles nutrients, and they are an important food resource. Male fiddler crabs are territorial, aggressively defending their burrows from intruders. Given that synthetic estrogen reduces aggression in other aquatic organisms, I hypothesized that EE2 affects male fiddler crab aggression. Male crabs exposed to EE2 were expected to retreat from threats instead of attacking more often than control animals. Male aggression was measured as responses to threats (fleeing, attacking, no response) after exposure to sediment without (control) or with added EE2 (0.5 mg L -1 ). There was a trend toward EE2 treated crabs fleeing from a fight more often than control crabs, but none of the other responses differed between treatments. The lack of significant response was likely due to the measured concentration of EE2 in the treated sediment being two orders of magnitude less than the calculated concentration. Therefore, while these findings indicate the possibility that EE2-exposed males may have difficulty protecting themselves, their burrows, or their mate from predators, higher EE2 concentrations with larger sample sizes need to be tested for verification.
Comments
This work is archived and distributed under the repository's standard copyright and reuse license, available here. Under this license, end-users may copy, store, and distribute this work without restriction. For questions related to additional reuse of this work, please contact the copyright owner.