The Cardiotoxic Effects of Oil on Fish Embryos

by Julia Newman (’19)

Fig. 1: Haddock are important to both their ecosystems and our commercial industries.

Recent oil spills in the North Atlantic are currently causing detrimental effects not only on the water’s safety for humans, but also on the millions of fish species that live there. One species in particular, the Atlantic haddock, has shown a decreased survival correlated with the oil spills. This is a concern for both the ecosystems the fish are a part of and the many fishing industries. As a result, Dr. Elin Sørhus, at the Institute of Marine Research in Bergen, Norway, developed haddock embryos in order to determine how they react to the exposure of toxins commonly found in crude oil.

Across all of his studies, Dr. Sørhus found that haddock embryos exposed to the crude oil toxins showed extremely damaging heart defects. Furthermore, the more recently the egg was fertilized, the more the development of the embryo was affected. Even studies using short exposure times of just twenty-four hours showed abnormalities, because the haddock’s thin eggshell structures have a unique ability to bind together droplets of oil, prolonging the uptake of toxins. Specifically, the toxin polycyclic aromatic hydrocarbon (PAH) was shown to cause a disruption of excitation-contraction coupling, which is a process responsible for the proper functioning of heart muscle cells. PAHs found in the haddock embryos cause defects in both the contraction of the heart and also the organ’s rate and rhythm of beating. Although a counter to this deadly toxin has not yet been found, the discovery of its responsibility in harming heart function may aid further attempts at reversing the disastrous effects of oil spills.



  1. Sørhus, J. Incardona, Crude oil exposures reveal roles for intracellular calcium cycling in haddock craniofacial and cardiac development. Springer Nature 6 (2016).
  2. Photo retrieved from:

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