Scientists make stunning discovery while researching the health of critical waterways: 'Strong evidence'

We've known for years that rampant pollution was one of the leading causes of the decrease in the quality of some of our greatest freshwater resources. Thankfully, proactive and eco-friendly legislation across the globe has started to turn the tide.

A recent study published by the American Chemical Society has claimed to reveal the most impactful pollutants that contributed to the lowered levels of biodiversity in freshwater.

A team of researchers from the UK Centre for Ecology and Hydrology report that zinc and copper greatly impacted freshwater invertebrate diversity for years. The team scoured data over a stretch from 1989 to 2018 from 1,457 macroinvertebrate monitoring sites in England. They then used what they call "41 chemical, physical, habitat, and geographic variables" to run their analysis.

The study concluded that it found no other variables that were "more consistently and strongly associated" with the number of taxa — or a classification unit of organisms — than zinc and copper. As amounts of zinc and copper in freshwater locations decreased, biodiversity levels increased.

Andrew Johnson, an environmental research scientist at UKCEH and study co-author, believes public outcry heavily contributed to the reduction of zinc and copper. However, there is one slight difficulty in establishing new policies.

Johnson spoke to Phys.org regarding the data from the study: "There is a widespread desire by the public to improve water quality and biodiversity in our rivers, but the problem for policymakers is what steps would be most likely to achieve results.

Watch now: Giant snails invading New York City?

"Our study provides strong evidence that concentrations of zinc and copper have the biggest influence on invertebrate species richness, so future attempts to increase freshwater biodiversity are unlikely to bear fruit without further reductions in these metals."

According to the study, the European Union's Urban Wastewater Treatment Directive likely played a pivotal role in reducing pollution in freshwater sources. However, the researchers say that "reductions in atmospheric pollution associated with the end of coal-burning" may also have been a major factor.

Freshwater biodiversity is vital to the sustainability of our food chain. Many freshwater ecosystems impact us by cleaning water and filtering excessive nutrients, pathogens, and pollutants.

Johnson pointed to data from long-range studies that enable "the wildlife themselves to speak to us directly."