Heron Island is located at the sourthern end of Australias 2,050 km-long Great Barrier Reef. Surrounded by coral reef and home to over 1000 species of fish, scuba divers and scientists alike are drawn to the islands resort and research station. The true-color image above was taken by Space Imagings Ikonos satellite with a resolution of 4 meters per pixelhigh enough to see individual boats tied up at the small marina. The narrow channel leading from the marina to the ocean was blasted and dredged decades ago, before the island became a national park. Since then the Australian government has implemented conservation measures, such as limiting the number of tourists and removing or recycling, instead of incinerating, all trash. One of the applications of remote sensing data from Ikonos is environmental monitoring, including studies of coral reef health.
Named Isla de Aves in Spanish, (meaning “Island of the Birds”) Aves Island lies west of the Lesser Antilles in the Caribbean. It provides a nesting site to green sea turtles (Chelonia mydas) and, of course, birds. Because the abundant bird droppings, known as guano, could be used in fertilizer and gunpowder, guano miners worked on the island until they depleted the supply. Since its discovery by Europeans, likely in the late 16th century, Aves Island was subsequently claimed by several European nations. The island is currently claimed by Venezuela, although disputes about ownership of the island, and the surrounding exclusive economic zone in the Caribbean, continue today.
Howland Island is a United States possession located in the north Pacific between Australia and the Hawaiian Islands. Prior to 1890, organic nitrate (guano) was mined from the island by both the United States and the British. This tiny island (1.6 km²) is currently part of the U.S. National Wildlife Refuge system, and provides nesting areas and forage for a variety of birds and marine wildlife. The island is composed of coral fragments and is surrounded by an active fringing reef. White breakers encircling the island indicate the position of the reef. Astronauts aboard the International Space Station photograph numerous reefs around the world as part of a global mapping and monitoring program.