Title: Gulf spill harmed small fish, studies indicate
Source: Science News
Author: Janet Raloff
Date: November 19, 2012
[...] Among oil constituents that most threaten sea life are polycyclic aromatic hydrocarbons, or PAHs. Through a process known as weathering, lighter-weight chemicals evaporate off of fresh oil, rendering what’s left progressively heavier and sludgy. New chemical analyses show that weathering reduces oil’s propensity to shed PAHs into water, finds Damian Shea of North Carolina State University in Raleigh. The bottom line, he concludes: Weathering reduces oil toxicity.
“But in our hands, weathered oil is more toxic,” said Andrew Esbaugh, a fish physiologist at the University of Texas at Austin’s Marine Science Institute who directly tested the effects of weathered oil on fish. Along with a broad team of researchers from several universities and the National Oceanic and Atmospheric Administration in Seattle, he compared the relative toxicity of weathered oil to fresh BP oil in newly hatched, lab-reared Gulf cobia and mahi mahi.
To simulate how waves disperse oil constituents, his team put oil and seawater into a blender and then spun the mix. They measured the amounts and types of PAHs that entered the water in each batch before exposing hatchlings to the mix for 48 to 96 hours.
Half of the baby fish died after exposure to water containing 5 to 10 micrograms per liter of weathered oil and its PAHs. To achieve the same kill rate with water hosting fresh BP oil, Esbaugh reported, it took concentrations four to eight times higher. [...]
Published: December 5th, 2012 at 4:43 pm ET