Did Pollution Drive Fish’s Evolution?

While I was searching for an article to write my current events assignment on I came across a very interesting adaptation one.   The article I have chosen is about the killifish, also known as the mummichog.   The mummichog is a small 2-3 inch long fish that lives in Virginia’s Elizabeth River.

The Elizabeth River is one of the most polluted rivers in North America, according to the news report.   The mummichog was used in an experiment by Richard T. Di Giulio to test the effects of pollution on the animals that inhabit such a polluted place, such as the Elizabeth River.   When Di Giulio took some of the fish home to study them many of them died in the new, clean tank that he provided for their new home.   He thinks that at least 50 generations of this small fish have survived in the polluted waters, and that they have adapted to the pollution.   While studying the fish he also noticed that they are unable to protect themselves from fungal disease and some bacteria.   Di Giulio believes that they are unable to protect themselves from such diseases because the pollution in the river killed the diseases that would normally be found in the water, so the mummichog’s immune system adapted and stopped fighting the diseases and bacteria because they were no longer present in their environment.   Some of the fish also had liver cancer that Di Giulio thinks is from the carcinogens in the river.

Some of the fish that were brought home and put in clean tanks did survive, and had offspring.   Di Giulio studied the offspring and noticed that by the third generation they had lost approximately half of their resistance to some toxins, therefore not all adaptations altered the mummichog’s genome.   He did notice some genetic changes though, such as the mummichog’s susceptibility to changes in the oxygen levels in the water throughout generations.   Di Giulio suggests that we are changing the evolution of organisms, in this case through pollution.   I found this article very interesting, yet very terrifying.   There are efforts to rid the Elizabeth River of toxins, but it will take many years.


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3 thoughts on “Did Pollution Drive Fish’s Evolution?”

  1. Goodness, that is terrifying! However, I also find it hopeful that these little creatures can adapt so efficiently (or at all!) in a world that we humans have so corrupted and polluted. Thank you for posting!


  2. Interesting, however I am skeptical; evolution occurs on vast time scales and though these fish may be selecting for some level of toxin immunity, I wonder if they were inadvertently shocked when brought back to the lab. I’d be interested in seeing the peer-reviewed journal article. Great post; sparked some thought and conversation~

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