Crude Oil Exposure Harms Developing Fish Embryos

Researchers have found that exposure to crude oil causes serious developmental issues in fish embryos. The findings are in a paper just published in the journal Scientific Reports.

Oil spills can cause serious environmental problems, especially when they occur in spawning areas for fish. As oil operations continue to expand, there are concerns that an oil spill could devastate commercially important species at fisheries. One such expansion has been proposed for parts of Northern Norway, a region with spawning areas for Atlantic haddock, cod, and herrings.

Researchers from Norway collaborated with the Northwest Fisheries Science Center in Seattle. The team wanted to assess the risk of a potential oil spill in Northern Norway. Previous research had already shown that a component of crude oil, polycyclic aromatic hydrocarbons, causes heart defects in developing fish embryos.

The team exposed fertilized fish eggs to different doses of oil. They found that even small doses caused defects in the developing fish embryos. Oil exposure was especially deadly to embryos in early developmental stages. Common compounds found in oil disrupt muscle signaling in fish embryos, leading to a variety of developmental defects. The researchers found that the Atlantic haddock (Melanogrammus aeglefinus) was vulnerable to even the tiniest doses. Haddock eggs in early stages of development attract and stick to oil droplets, possibly due to a protein coating the shell. Eggs that were exposed to low oil concentrations for 24 hours developed head and facial abnormalities, most of which were fatal.

The researchers concluded that an oil spill in Northern Norway would negatively affect the fish in the area. Atlantic haddock, an important commercial species, would be very vulnerable to even low concentrations of crude oil. Oil droplets stick to haddock eggs and cause serious, usually fatal, developmental defects. Herrings and cod would also be impacted; all of the studied fish developed abnormalities after oil exposure. Expanding oil production operations to Northern Norway may put important fisheries at risk.


Elin Sørhus et al. Crude oil exposures reveal roles for intracellular calcium cycling in haddock craniofacial and cardiac development. Scientific Reports (2016).

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