Environmental chemicals can affect the sex of anemonefish. Credit: Ed Clint.
Concerns over the effect of chemicals on the water have been raised due to ocean pollution. Researchers have discovered how these chemicals can affect the reproduction of a common anemonefish.
Normal reproduction in animals can be disrupted by chemicals that interfere with hormones. Two common chemicals are bisphenol A and 17a-Ethinylestradiol. Water bottles and birth control pills are both found in the ocean with the exception of birth control pills.
Jose Gonzalez, a former undergraduate researcher in the Rhodes group, said that in Indonesia, there are beautiful coral reefs found below a lot of garbage.
According to a professor of psychology, there have been studies that show that pollutants tend to affect animals. No one has studied their effects on fish whose sex is determined by the environment.
A. ocellaris live in small groups with one alpha female, one alpha male, and lower ranking non-reproductive males. The sex of males and females is dependent on the environment and can be changed if a female is removed from the group.
Sarah Craig, an undergraduate research assistant in the Rhodes group, said that they looked at fish specifically because they can transition from male to female.
The researchers fed sexually immature male fish with normal food twice a day. Nine pairs of fish were monitored for six months. The amount of EE2 was determined by the concentrations of the chemicals in the environment.
"We looked at different indicators such as behavior, gene expression in the brain, and hormone levels, since these fish are able to change their sex," said Histed, an undergraduate research assistant in the Rhodes group. The effect was found in all the other categories.
The researchers found that the fish that were fed the chemical had no testicular tissue, lower androgen levels, and increased expression of genes in the brain that are responsible for female fish. Although females are more aggressive, the aggression in these fish decreased. The effects of EE2 were less pronounced.
The females are very aggressive and do not tolerate other females. The fish are not aggressive and can live with each other. The results suggest that the brain has a different structure than gonadal hormones.
It's not clear how BPA is affecting it. In other studies, it was thought that BPA was bound to the estrogen receptors. Since EE2 is an estrogen mimic, the researchers believe that there are other effects on the body. BPA could be interfering with androgen signaling. It could be a mix of different effects.
The implications of the findings are clear. The fish can only change their sex from male to female. If they are turned female in the wild, they can't go back to being a male and that can affect their population numbers.
The researchers want to investigate the effects of EE2 further. They would like to use higher concentrations of EE2 because they are concerned that the levels were not high enough. They would like to follow the fate of these fish for a longer period of time.
It would be better to compare the degrees of feminization with the degrees of BPA. "Maybe they do eventually fight and kill each other and it's something we missed with a shorter time frame," Rhodes said.
The study looked at the impact of synthetic estradiol on brain, behavior, gonads and sex hormones in a sexually labile coral reef fish.
The impact of synthetic estradiol on brain, behavior, gonads, and sex hormones in a sexually labile coral reef fish, Hormones and Behavior, was studied by Jose A. Gonzalez. The article is titled "Yhbeh.2021.105043."
Journal information about hormones and behavior.
The study found that chemical pollutants disrupt reproduction in anemonefish.
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