Killifish thrives in polluted environment

Killifish are common in brackish waters of the Americas

New research published on February 14 in BMC Evolutionary Biology explains that changes in the genes of Killifish allow them to have genetic resistance against high pollution levels.  Mark Hahn and his team of researchers at Woods Hole Oceanographic Institution discovered that several populations of the non-migratory killifish Fundulus heteroclitus have successfully adapted to environments with heavy-metal pollutants.

The Atlantic Killifish are common estuarine fish that grow to be only three inches long.  Researchers have been solving the mystery of these organisms because they have evolved to thrive in such a toxic environment.   Killifish can be found around the world, but are most common in the Americas.

Killifish don’t migrate which means that their whole lives are spent in the same area.  They are in the same location year round and spend the winters burrowed into contaminated sediment.

Typically, when marine organisms are exposed to toxic pollutants, their bodies are capable of breaking down the chemicals at small exposures.  When animals are constantly exposed to these contaminants, their cellular functions are disrupted leading to toxicity.  In the New Bedford Harbor, scientists have discovered that the killifish have evolved to become resistant to this effect.

Mark Hahn, a lead researcher in the study stated that “the killifish have managed to shut down the pathway which is an example of how some populations are able to adapt to changes in their environment- a snapshot of evolution at work2”.


Journal Reference:

1. Adam M Reitzel, Sibel I Karchner, Diana G Franks, Brad R Evans, Diane Nacci, Denise Champlin, Verónica M Vieira, Mark E Hahn. Genetic variation at aryl hydrocarbon receptor (AHR) loci in populations of Atlantic killifish (Fundulus heteroclitus) inhabiting polluted and reference habitats. BMC Evolutionary Biology, 2014; 14 (1): 6 DOI: 10.1186/1471-2148-14-6

2. Woods Hole Oceanographic Institution. “Solving an evolutionary puzzle: Atlantic killifish thriving in highly polluted water.” ScienceDaily. ScienceDaily, 12 February 2014. <




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