The dumping of human sewage into the ocean and rainfall runoff containing pet wastes may be threatening the continued survival of the endangered Galapagos sea lion, new research from the Zoological Society of London (ZSL) has found.
The research has found that the immune systems of the sea lions which live near human populations are in “overdrive” as a result of human activity — impairing their health, making them less able hunters, and making them more prone to starvation. “The Galapagos sea lions — Zalophus wollebaeki — are more prone to starvation because of exposure to human influences like pets and pollution.”
The work was done by researchers who “spent more than eighteen months on the Islands of San Cristobal, which is inhabited by humans, and Santa Fe, where there are no humans, dogs, cats, mice or rats. They tagged 60 Galapagos sea lions from each island and monitored their behaviour and physiology.”
ZSL’s Institute of Zoology Director, Professor Tim Blackburn states: “We are increasingly aware of the threats of infectious diseases to wildlife around the world, from amphibians in the tropics to the birds in British gardens. It is worrying that we are now potentially seeing such threats to sea lions in the supposedly pristine wilderness of the Galapagos Islands.”
ZSL’s Dr. Paddy Brock, author on the new research paper, states: “A tell-tale sign of an unhealthy sea lion is a thinner than normal layer of blubber, which is what we saw in the sea lions on San Cristobal. This was all the more notable as we didn’t notice these patterns in sea lions on Santa Fe, where they live without the presence of people or pets. The immune systems of San Cristobel sea lions were more active, perhaps indicating a threat of infectious disease, which could mean human activity is increasing the chance of potentially dangerous diseases emerging in the Galápagos sea lions.”
The Zoological Society of London provides background:
Despite laws designed to protect the unique wildlife found on the Galapagos, pets are regularly imported to the islands, which increases the risk of new diseases arriving and spreading to local species. In addition, dumping of sewage into the bay on San Cristobal where the sea lions live may be increasing their exposure to germs and bacteria associated with humans.
The new research was just published June 28th in the journal PLOS ONE.