Trout Develop Distinct Genes in Mine-Polluted Rivers

June 5, 2024 By: Spencer Durrant

A fascinating new study out of the United Kingdom shows that trout living in mine-polluted rivers are genetically different than trout living in clean water. According to an article by the University of Exeter at Phys.org, a recent study conducted at 71 sites in Britain and Ireland shows a distinct genetic difference in brown trout that live in mine-polluted rivers.

In short, when some rivers were polluted with mine waste (heavy metals such as copper), the trout that were able to survive that change in their environment quickly became genetically distinct from brown trout that lived in non-polluted water. Brown trout that have developed the tolerance to live with heavy metals in their water are effectively genetically isolated, since trout without that tolerance will die when entering polluted water.

It’s a fascinating, albeit worrying, development because it leaves those populations living in polluted rivers at risk for extirpation.

“So, while these fish may be healthy where they are, the genetic diversity that allowed them to adapt to this rapid change in their environment is now lacking—leaving them more vulnerable to future changes,” said Professor Jamie Stevens, from the University of Exeter.

The exchange of genetics across trout populations is incredibly important for maintaining healthy fish. It allows for increased resistance to disease, healthier offspring, and often, larger, healthier fish. To make a pop culture reference, consider the Targaryen family from Game of Thrones. A lack of genetic diversity in their marriages led to the madness that was their downfall, and that same problem plays out in wildlife when enough genetic diversity isn’t present.

This study continues to highlight the importance of protecting our wildlife from the many threats they currently face, and should serve as more evidence for continued conservation. While it’s heartening that trout do have the ability to adapt to living with heavy metals, it’d be far better if they never had to in the first place.