Oil pollution toxicity to marine fish
Fish exposed to these PAHs exhibit an array of toxic effects including genetic damage, morphological deformities, altered growth and development, decreased body size, inhibited swimming abilities and mortality.
[1][2][3] The morphological deformities of PAH exposure, such as fin and jaw malformations, result in significantly reduced survival in fish due to the reduction of swimming and feeding abilities.
[4] The difficulty in finding a specific toxic mechanism is largely due to the wide variety of PAH compounds with differing properties.
[5] Pacific herring were just beginning to spawn in late March when the spill occurred, resulting in nearly half of the population's eggs being exposed to crude oil.
Pacific herring spawn in the intertidal and subtidal zones, making the vulnerable eggs easily exposed to pollution.
[7] Approximately 171 million gallons of crude oil flowed from the seafloor into the Gulf of Mexico, exposing the majority of the surrounding biota.
[7] The Deepwater Horizon oil spill also coincided directly with spawning window of various ecologically and commercially important fish species, including yellowfin and Atlantic bluefin tuna.
Once PAHs enter the marine environment, fish can be exposed to them via ingestion, ventilation of the gills, and dermal uptake.
For instance, bottom-dwelling fish still showed elevated levels of low molecular weight PAH metabolites 10 years after Exxon Valdez oil spill.
[12] These anthropogenic sources include residential heating, asphalt production, coal gasification, and petroleum usage.
One study on found that Pacific herring eggs exposed to conditions mimicking the ‘’Exxon Valdez’’ oil spill resulted in premature hatching of eggs, reduced size as fish matured and significant teratogenic effects, including skeletal, cardiovascular, fin and yolk sac malformations.
[1] The teratogenic malformations in the dorsal fin and spine, and in the jaw were observed to effectively decrease the survival of developing fish, through the impairing of swimming and feeding ability respectively.
[3] In a study focused on the uptake of PAHs by fish, salmon embryos were exposed to crude oil in three various situations, including via effluent from oil-coated gravel.
From the results, it was determined that fish embryos near the Exxon Valdez spill in Prince William Sound that were not directly in contact with oil still may have accumulated lethal levels of PAHs.
