Something mysterious is killing thousands of dolphins in Peru. Since January, an estimated 2,800 of the sea creatures have been found dead on Peru's northern beaches, reports Scientific American. Experts believe the mass die-off could be caused by acoustic interference stirred up by oil testing or possibly a virus. If acoustic impact affected the dolphins, "they would become disoriented" and "would have intense pain" before getting beached and likely dying on land, says a veterinarian.
Around 20 of the dead dolphins were probed and displayed hemorrhage in the ear, lung lesions, and blood bubbles—symptoms that one scientist links to acoustic impact, but other researchers say there's not yet enough evidence to confirm a cause. With animal die-offs, “there might be a smoking gun, but often we find that it’s two or three or four factors,” says an expert. Stress or toxic chemicals could also be contributing factors as they make marine creatures more susceptible to viruses.