"Diseases from land animals are killing marine mammals at an alarming rate. Can we stem the flow of feces?"
"Pádraig Duignan snaps on a pair of latex gloves in the Marine Mammal Center’s necropsy lab. Located north of San Francisco, California, the lab occupies a space behind a large metal garage door; the door is open on this chilly October day and Pacific Ocean fog surges past. Spread out on a steel table before Duignan are the carcasses of two California sea lions. With a scalpel, he carefully cuts a section of muscle away from the ribs of one of the carcasses and holds a glistening membrane to the lights.
“This is what the diaphragm of a healthy sea lion looks like,” he says, tracing a finger over the tissue. Tight patterns of muscle fibers are interlaced with a mesh of small blood vessels that supply them with oxygen. For a sea lion, an animal capable of diving to depths of over 300 meters, a strong, healthy diaphragm is critical. Duignan reaches below his workstation and retrieves a clear plastic bag. Inside is another slice of diaphragm tissue, different in appearance from the first, taken from an animal suffering from a disease called sarcocystosis.
“Notice the striations,” he says, tracing a finger along the bag. The slab of tissue, suspended in formalin preservative, appears tiger striped, with bright white lines cutting through the dark red muscle fibers. Sarcocystosis can trigger an autoimmune response that causes white blood cells to attack and degrade the body’s muscle cells. “This animal slowly suffocated because its diaphragm was too weak to allow it to breathe,” he says."
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