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Chemical pollutants interfere with clownfish breeding, studies find

The sex of clownfish depends on environmental clues, allowing researchers to study how environmental chemicals affect their reproduction. Credit: Ed Clint

Unfortunately, marine pollution is becoming more common and there is growing concern about the effects of chemicals that seep into water.In a new study, researchers have discovered how these chemicals affect common clark’s anemone breeding. Clownfish.


Endocrine disrupting chemicals interfere with the body’s hormones and can interfere with the normal reproduction of animals. Bisphenol A and 17a-ethinyl estradiol (EE2) are two common chemicals of this nature. BPA is an endocrine disruptor and is found in various plastics such as water bottles and EE2. Oral contraceptivesEnter the sea from Manure Wastewater from manufacturing plants and hospitals.

“For example, in Indonesia, there are beautiful coral reefs under a lot of garbage, so everything that goes into the water. fish“. Jose Gonzalez, a former undergraduate researcher at the Rhodes Group, said.

“There are previous studies that have demonstrated that these pollutants tend to feminize animals, such as: Freshwater fishJustin Rhodes (GNDP), a professor of psychology, said, “Rats, mice, and even humans,” said “but anyone who studied the effects on fish whose gender is completely determined by the environment. There is no one. “

A. Clownfish Live in Small group With one alpha female, one beta male, and a lower-ranked non-reproductive male. Their gender is not genetically programmed and instead relies on environmental clues. If the female is removed from the group or the male is paired, the male will change to female.

“These fish can transition from male to female, which helps us understand how BPA and EE2 affect reproduction,” said Sarah Craig, an undergraduate research assistant at the Rhodes Group. ..

Researchers paired sexually immature male fish and fed them a regular diet, a diet containing BPA, or EE2 twice daily. There were 9 pairs of fish in each group and they were monitored for 6 months. The amounts of BPA and EE2 were determined based on the environmental concentrations of these chemicals.

“Because these fish can change gender, behavior, gene expression in the brain, Hormone level“Interestingly, apart from behavior, we have seen feminization in all other categories,” said Abigail Histed, an undergraduate research assistant at the Rhodes Group.

Researchers found that BPA-fed fish, like female fish, lack testicular tissue, have low androgen levels, and have increased expression of genes in the brain that cause feminization. discovered. Surprisingly, females tend to be more aggressive, but BPA has reduced the aggression of these fish. In contrast, the effects of EE2 were similar, but less pronounced.

“In essence, women are very aggressive and do not tolerate the existence of other women,” Rhodes said. “We found that BPA feminizes gonads, but fish are less aggressive and can live with each other. These results suggest that feminization of the brain occurs independently of gonad hormones. There. “

It is still unclear how BPA works. In other studies, BPA was thought to bind to the estrogen receptor. However, because EE2 is an estrogen mimic and has subtle effects, researchers believe that BPA has other additional effects. “BPA may be affecting other hormone receptors or interfering with androgen signaling. It can be a combination of different effects, not yet known,” Rhodes said. Stated.

However, the meaning of the survey results is clear. “These fish can only change sex from male to female. If BPA is wild and changing to female, they cannot return to male, which can affect populations,” Gonzales said. He said.

Researchers are interested in further investigating the effects of EE2. Specifically, I’m concerned that the dose isn’t high enough, so I’d like to use a higher concentration of EE2. We also want to track the fate of these fish longer, as it usually takes more than 6 months for the fish to fully mature.

“It would be better to have a longer time frame to compare the degree of feminization with BPA compared to natural feminization. Maybe they will eventually fight and kill each other, that’s what we do. I missed it in a shorter time frame, “Rhodes said.

A study “Effects of bisphenol A and synthetic estradiol on the brain, behavior, gonads, and sex hormones of sexually unstable coral fish” Hormones and behavior..


In the case of clownfish, male-to-female sex change first occurs in the brain


For more information:
Jose A. Gonzalez et al, Effects of bisphenol A and synthetic estradiol on the brain, behavior, gonads and sex hormones of sexually unstable coral reef fish, Hormones and behavior (2021). DOI: 10.1016 / j.yhbeh.2021.105043

Quote: Chemical pollutants interfere with the breeding of anemone fish. The findings (December 4, 2021) were taken from https://phys.org/news/2021-12-chemical-pollutants-disrupt-reproduction-anemonefish.html on December 4, 2021.

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Chemical pollutants interfere with clownfish breeding, studies find

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