Marine fish grow slowly because of plastic pollution and global warming

Scientists at the University of Sydney found that fish exposed to the industrial chemical BPA in warm waters often need more food to grow and reach a certain size.

New research also shows that when fish are exposed to higher temperatures and a common chemical in plastic, their growth slows down. It also shows that the combination of plastic pollution and global warming creates huge adverse effects on marine populations. In an environment containing the industrial chemical bisphenol A - commonly known as BPA - fish will need more energy to thrive in hot water.

The chemical BPA is directly related to reproductive and developmental functions.

BPA is a common chemical used in plastic manufacturing and has been shown to disrupt hormone signaling, metabolism, and growth in marine animals. In humans, BPA is directly related to reproductive and developmental functions, sadly millions of tons of this compound are still produced globally each year.

Scientists performed an experiment that exposed zebrafish to levels of BPA commonly found in waterways. They found that the chemical reduces the energy needed to grow fish at 24 degrees Celsius, but when the water temperature is at 30 degrees Celsius, it greatly hinders their growth. A level of 30 degrees Celsius is the temperature that animals can regularly encounter in their natural habitat, due to the effects of global warming.

The results also point to the need for interventions to reduce climate change and plastic waste globally, said Frank Seebacher, a professor of biology at the University of Sydney and study author. He also added: "The combination of high temperatures and BPA increases the energy costs of growth, which means that animals need to eat more to reproduce and grow, which has the most impact. to large fish and carnivores".

"In the marine environment, there is another layer of nutrients from small animals, but their numbers will be less and less due to plastic pollution and global warming. That is a potential problem for us. sustainability in catch rates, as marine fish stocks decline." The chemical BPA is released into the marine environment from manufacturing wastewater, much like the breakdown of plastics. "Wherever there's a lot of manufacturing, a lot of plastic pollution, you're going to see higher levels of BPA."

The researchers also attempted to model the risk of warming and plastic pollution in coastal areas in conjunction with current fishing intensities. This analysis predicts that Southeast Asia has the highest risk of fish biomass reduction directly attributable to warming and pollution. In addition South North America and North South America will also be really affected.

One limitation of this finding is that the sample the scientists used was zebrafish because they are small fish that live in freshwater environments. However Seebacher hopes these findings will also hold true for other fish species, although more research will be needed to be sure.

"All endocrine systems are highly conserved among vertebrates, and there is still variation among vertebrates in how they respond to plastic pollution, but the potential for this is still possible," he said. The ability to survive and thrive in all species must be shown to be affected".