A recent study has demonstrated that reducing metal pollutants, such as zinc and copper, in English rivers leads to a significant increase in aquatic biodiversity, particularly among macroinvertebrates. The research found that lowering zinc levels below 14 micrograms per liter and copper levels below 3.3 micrograms per liter resulted in the most substantial improvements in species richness. While reductions in other pollutants, like sewage, also positively impacted invertebrate diversity, the decrease in metal contaminants had the most pronounced effect.

The research also analyzed over 65,000 observations across 1,457 sites between 1989 and 2018, using data from the Environment Agency. Researchers found that the decline in metal pollution was primarily driven by several factors, including a reduction in coal burning, a decline in heavy industry, and changes in household product compositions that reduced metal discharge into sewage systems. These improvements have contributed to the recovery of aquatic ecosystems, with macroinvertebrate populations showing a marked increase in diversity and abundance.

However, despite these positive trends, the study also noted that biodiversity improvements have plateaued since the early 2000s. This stagnation is attributed to persistent high metal concentrations in certain areas, particularly downstream of abandoned mines, where historical pollution continues to impact water quality. Recognizing this ongoing challenge, the UK government has set a target under its Environmental Improvement Plan to halve the length of rivers affected by metal pollution by 2038.

The findings highlight the need for continued policy enforcement, improved wastewater treatment, and targeted remediation efforts in historically polluted areas. The study underscores the broader ecological benefits of pollution control measures, demonstrating how reductions in specific contaminants can lead to significant ecosystem recovery and increased resilience of freshwater biodiversity.

Source: Eco Watch