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Mankind’s actions constantly affect the ecosystems around us and just like in The Simpsons ^[4] where the nuclear power plant produced three-eyed fish, so the Hudson River ^[5] has spawned a species of bottom-feeding fish that has genetically developed an immunity to polychlorinated biphenyls (PCBs) ^[6]. The discovery was made by a team of New York University ^[7] scientists who have been conducting a decade-long study at the Institute of Environmental Medicine in Tuxedo. Their studies found that Atlantic tomcod ^[8]have evolved (much more quickly than expected) to withstand the effects of pollutants in the river.

Speaking about the discovery, Issac Wirgin ^[9], a lead geneticist on the team, said: “I knew we had something big here. You don’t often get to see evolution, because it usually takes tens of thousands or millions of years.”

Image © wuestenigel ^[10]

It seems the Hudson River has a unique effect on its inhabitants as a similar discovery was made in 1989. At that time, scientists found that a mud-dwelling worm had evolved an immunity to cadmium thanks to the large amounts of waste dumped by the Millennium Battery Company. Despite the fact that the metal is poisonous, it was found that the worms had developed an immunity to it. It is the same with the tomcod, but in their case, large amount of polychlorinated biphenyls, or PCBs, that have been dumped in the river are the contaminant of choice.

While there are many culprits, General Electric ^[11], who is reportedly responsible for dumping 1.3 million pounds of the neurotoxic chemical into the Hudson over 30 years (ending in 1977) is at the top of the list. The tomcod, who feed on the bottom of the river, soaked up the PCBs. Fish in other parts of the country were found to react negatively – either dying or being born with mutations. However that wasn’t the case for the tomcod in the Hudson.

“With tomcod from the Hudson River estuary, there was absolutely no effect,” Wirgin said. “You could blast them with PCB and they’d be fine and dandy.”

Why? Well it seems the Hudson River tomcod were missing a little piece of their genetic code and that has stopped the PCBs from killing them.  Wirgin said it was the first time any scientist had documented a genetic cause of toxin immunity and it was ‘proof’ that evolution was in action in the Hudson River.

It’s truly a case of the fittest surviving, but it is quite the test and unfortunately one that we have inflicted on the local wildlife.

+ New York University ^[7]

Via Record Online ^[9]

Lead image © Mark Mattson, Normandeau Associates, Inc.