Investigation and monitoring of marine iguana deaths in Tortuga Bay
November 15, 2013
Following the discovery of a dead marine iguana at Tortuga Bay in September, the Galapagos National Park Directorate (GNPD) has recorded the death of 18 additional marine iguanas. The deaths appear to be linked to a digestive problem, although the exact cause is unknown. An analysis of the water ruled out any kind of chemical contamination at the site, so the problem may have natural origins.
Veterinarians and biologists from the ABG and GNPD carried out initial necropsies on the dead marine iguanas, which revealed stomachs full of undigested red and green algae (their normal food source) and inflammation and hemorrhaging of the small intestine. However, additional analyses were needed in order to identify the exact cause of death. Galapagos Conservancy is funding specialized laboratory testing of tissue samples, which have been sent abroad to be analyzed by experts in reptile pathology, microbiology, and toxicology.
A park ranger monitors a marine iguana colony on Santa Cruz Island.
The GNPD, in collaboration with the Agency for Regulation and Control of Biosecurity and Quarantine for Galapagos (ABG), has designed rapid monitoring protocols for park rangers, scientists, and naturalist guides to implement during their visits to different sites along the archipelago. In addition to any dead marine iguanas they come across, guides are as asked to report individuals with any kind of abnormal behavior.
Park Ranger Washington Tapia, head of Applied Research at the GNPD, commented, “The collaboration of guides, scientists, and the park rangers allows us to obtain systematic information about the state of the rest of the colonies, given that the archipelago is large and the marine iguanas are distributed throughout all the islands—making it physically impossible to be at all sites all the time.”
The environmental authority has increased monitoring on Isabela, San Cristóbal, Española and Floreana Islands, but has not yet found anything out of the ordinary. All colonies found around Santa Cruz have been checked, and the problem currently appears to be concentrated in the Tortuga Bay area—which has a recorded population of 775 living marine iguanas.
Monitoring the marine iguanas is critical while we await results of the specialized laboratory tests. Galapagos Conservancy will be at the forefront of efforts to develop an appropriate conservation strategy once information on the specific cause of death is revealed.