On the left is a typical graph for the survivorship curve of a Kemp’s Ridley Sea Turtle, and on the right is what it might look like for the...

Of all the species of sea turtles affected by the Gulf oil spill, the Kemp's Ridley sea turtle stood to be impacted the most.  It was the most endangered species in the world, and adding an oil spill to it's habitat did nothing to better it's chances for survival.  For the graph on the right, the curve for the "Before the spill" category should probably reflect the graph on the right, with a high starting point for hatchlings, then reflecting a sharp downward curve, as few turtles make it from being hatched to adulthood.  The graph for the "After the spill" category should have a lower starting point, as the number of hatchlings will likely decrease.  The number of hatchlings encountering oil on beaches and in surface waters will also increase the death count.  So the curve would start lower and have a sharper drop as age on the x-axis progressed.  The resource I have attached points out a five-fold increase, specifically on the Kemp's Ridley sea turtles, on reported beach strandings.  This is what one would expect to see in terms of impact of an oil spill on the environment.