Two separate studies published in early 2014 have shown links between exposure to crude oil and fish health problems. One study compared Gulf killifish (Fundulus grandis) from areas oiled during the Deepwater Horizon spill with killifish from unoiled areas. The second study looked at the mechanism behind crude oil heart toxicity in juvenile yellowfin (Thunnus albacares) and bluefin tuna (Thunnus thynnus).
The killifish study found increased changes in gene expression in liver and gill tissue, as well as other developmental abnormalities, in fish from the affected areas when compared to those from unoiled areas. These abnormalities continued to be found more than a year after the spill.
A study of juvenile yellowfin and bluefin tuna cardiac cells, conducted as part of the ongoing Deepwater Horizon Natural Resource Damage Assessment, found that heart cells exposed to oil did not beat effectively, as the oil interfered with the signaling system that controls heart cell contraction and relaxation.
The results make sense given that similar impacts of oil on heart rates of fish embryos were seen after the Exxon Valdez (salmon) and Cosco Buscan (herring) oil spills. Salmon spawned after Exxon Valdez had slower heart rates and many embryos developed abnormally shaped heart chambers. After the Cosco Buscan incident in 2007, which happened just as herring spawning season began, herring numbers immediately dropped and the following year the spawning biomass was the lowest on record. The population began to recover in 2010.
The killifish study also built on previous findings that oil affects fish embryo development. The newest findings contribute to the growing concern about the wider implications of exposure to oil. In addition to the direct impact on fish populations, some of which are declining for a variety of reasons, there are potential implications for other species. The possibility that oil can contribute to genetic and developmental abnormalities has not yet been studied in depth in other animals, including people.
Other resources:
Scientists Discover Cause of Heart Failure in Fish Exposed to Oil Spills