There’s something funny in the water, and it’s making fish act weird

Have you ever seen a fish hanging out with their mates at the pub? Me neither. But research suggests that chemicals leached from plastics are making fish less social. News broke a decade ago that these chemicals, like BPA, were compromising our health. As a result, the ‘BPA-free’ logo is a non-negotiable for us, but now it’s accumulating in the environment and fish are under threat. How will they cope?

Bisphenol A (aka BPA) is one of the world’s most highly produced chemicals by volume and can be found in plastic items such as water bottles, storage containers and cans. BPA is an endocrine disruptor, meaning that it can disturb the body’s normal hormone functioning. This has been associated with diabetes, allergies, liver disease, fertility problems and abnormalities in human embryo development. Big yikes.

Now, we’re seeing BPA rear its ugly head in freshwater ecosystems. Wastewater treatment sites and landfill are the main culprits of environmental discharge. The big question now is, how are the fish coping?

Researchers, such as Ju Wang from Hefei University of Technology, investigated this by treating zebrafish with BPA over 6 months. Their work revealed that low doses of BPA can decrease social behaviour and adaptability to environmental changes. It’s almost like BPA brainwashed fish to Netflix and chill instead of clubbing on a Friday night.

More specifically, aggressive behaviour was significantly reduced with BPA exposure. For many species aggression is important for establishing hierarchies, so this decline makes fish more vulnerable to threats. Results also showed that BPA can influence how fish behave in new and novel environments. BPA-exposed fish were less exploratory and unable to adapt to environmental changes. Again, this makes them more vulnerable to predation. Not good for Mr. Zebrafish!

What’s worse is that, like an ugly family heirloom, the effects of BPA can transfer from generation to generation. Research by Ramji Bhandari from the University of Missouri suggests that BPA reduces reproduction and survival rates of embryos up to two or three generations down the line. As a result, we may see compounding issues resulting from poor BPA management in the future.

All of this may sound bad, and it is. But what this research encourages, is to be mindful with the products we use and how we choose to dispose of them. Ideally, all plastic items should be replaced with stainless still or wooden alternatives. BPA contamination is still a poorly understood concept and demands thorough wastewater treatment and disposal. If we don’t, who knows? You may end up seeing a loner fish order a schooner at your local.

Referenced studies:

Bhandari, R. K., vom Saal, F. S., & Tillitt, D. E. (2015). Transgenerational effects from early developmental exposures to bisphenol A or 17α-ethinylestradiol in medaka, Oryzias latipes. 5(1), 9303.

Wang, J., Wang, X., Xiong, C., Liu, J., Hu, B., & Zheng, L. (2015). Chronic bisphenol A exposure alters behaviors of zebrafish (Danio rerio). 206, 275-281.