Researchers have linked human activities to rising numbers of illnesses in marine animals – from cancer in Pacific sea lions to toxoplasmosis in West Coast otters to blooms of “red tide” off of Florida’s Gulf Coast that suffocate manatees.
Marine scientists said the troubling developments are coming from a variety of locations, but indicate things that humans do on land are having a profoundly harmful impact on the coastal waters, and mammals who live near the waters’ edge.
And that’s bad news for people, too, they said in a presentation at the annual meeting of the American Association for the Advancement of Science.
“The manatee really is a 2,000-pound canary,” said Gregory Bossart, a veterinary pathologist at Harbor Branch Oceanographic Institution in Ft. Pierce, Fla., in a statement. “It’s a good sentinel for environmental health.”
Bossart was among a panel of marine researchers who detailed their recent findings during a briefing at the conference. Among them:
• Bossart said “a global pandemic” of red tide blooms, many in the Gulf Coast, have led to marine mammal die-offs since 1991.
• Frances Gulland, a veterinarian at the Marine Mammal Center in Sausalito, Calif., said 10,000 seals and sea lions have been examined over the years; among adult sea lions which die at the center, over 17 percent have cancer. A likely culprit: PCBs.
• Off the central Pacific Coast of the United States, sea otters are falling victim to toxoplasmosis, a brain disease spread by parasites found in cat feces. The exposure to otters results from a booming population of domestic and feral cats on land, and on storm run-off that carries their feces into the ocean, said Patricia Conrad, of the University of California, Davis.
“What the sea otters are trying to tell us about this land-sea connection is a very important message,” Conrad told reporters. “It’s not just what we do but what our pets do on the land can affect not only us but animals in the sea, like sea otters.”