http://www.galapagos.org/conservation/invasive-species/
“Since the discovery of Galapagos in 1535, humans have brought many alien species to the islands—some intentionally, including goats, pigs, cats, and both ornamental and food plants (vegetables and fruits), to name a few—while others, including rodents, insects, and weedy plants, have been carried to the islands accidentally.” They have had to go through great effort to preserve the environment for future generations.
More Sources:
http://www.galapagosislands.com/galapagos-conservation/galapagos-enviroment.html
http://www.darwinfoundation.org/en/science-research/ecological-restoration/
http://www.theguardian.com/artanddesign/gallery/2013/sep/16/postcards-galapagos-islands-in-pictures#/?picture=417421750&index=4