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Laysan Island (25° 46' N - 171° 44' W)
Laysan Island, located approximately 940 miles (1,741 km) from Honolulu, is a low lying sand island, basically oval in shape, about a mile wide and just under two miles long, with a highest elevation of about 40 feet (12 m). It is approximately 1,000 acres in size (3.7 km2), which makes it the largest natural island in the Northwestern Hawaiian Islands (NWHI). Laysan Island is surrounded by a 1,119,387 acre (4,530 km2 ) shallow-water coral reef ecosystem. The island and its surrounding coral reefs were formed approximately 17 million years ago, when the underlying shield volcano and a portion of the associated coral reef bank were lifted above sea level. The surface of the island is composed of loosely packed coral sand, with beds of coral reef and phosphate rock on the southern and western sides. The beaches rise from the water's edge to a height of 15 to 18 feet (4.6 to 5.5 m), then flatten out to a maximum height of 30 to 40 feet (9.0 to 12.0 m), and then slope gradually downward to a central depression, part of which is occupied by a shallow, land-locked, 173 acre (0.7 km2) hypersaline lake (water with a salinity above 35 percent). It is the only lake in the NWHI, and one of only five natural lakes in all of Hawai‘i.
IKONOS satellite imagery of Laysan Island (Photo: NOAA)
Reef habitats and biology
Most of the shallow water reef habitat is in a protected embayment on the southwestern side of the island, while most other reef areas are in deeper waters. These reef habitats are mostly spur and groove formations. The northern section is heavily eroded with many caves, overhangs, and large holes on a sloping reef with small sand channels. Twenty-seven species of reef-building stony corals are recorded from Laysan. There are some large massive and encrusting corals (Porites and Pavona) found on the sandy floor of the sub-lagoon of the shallow embayment on the southwestern side of the island. Several species of branching corals in the genus Pocillopora are common. Some rare species of coral are also found in the Laysan reefs. Some common invertebrates, other than corals, include rock-boring sea urchins and encrusting coralline algae in all shallow wave-washed habitats. Of the 75 native invertebrate species found on Laysan Island, 15 are endemic.
The large black area is a shallow land-locked hypersaline lake (0.7 km2). It is the only lake in the NWHI, and one of only five natural lakes in all of Hawai'i. (Photo: NOAA)
Aerial view of Laysan Island (Photo:George H. Balazs/NOAA)
The Hawaiian monk seal, Monachus schauinslandi.
Birds and monk seals
The island is home to an estimated two million birds, including thousands of boobies, frigatebirds, terns, shearwaters, and two endangered endemic land birds, the Laysan finch and the Laysan duck. The island is also an important breeding ground for Hawaiian monk seals.
Native species of plants include Eragrostis (a bunch grass important for supporting bird burrows), Chenopodium (goosefoot), Ipomea (a morning glory), Sesuvium, and Makaloa (Cyperus), in which the laysan ducks and finches like to hide, and Mariscus, an endemic sedge on the endangered species list.
Eragrostis growing on Laysan Island (Photo: Bishop Museum)
Laysan's endangered endemic plant, Mariscus.
Laysan's ecosystem was severely altered by the effects of human habitation and exploitation in the late 19th century. The island was extensively mined for bird guano, used as a fertilizer. Later, feather collectors killed birds by the hundreds of thousands. Rabbits released in 1903 ate the island's plants, driving to extinction three species of land birds that relied upon these plants: the Laysan Rail, the Laysan Honeycreeper, and the Laysan Millerbird. These events caused a public outcry which led to the creation of the Hawaiian Islands Bird Reservation by President Theodore Roosevelt in 1909. Successful efforts by the U.S. Fish and Wildlife Service have eliminated most pests, such as rats, rabbits, and weeds, and restored much of the native vegetation. As a result, Laysan finch and Laysan duck populations are increasing.
A shy Laysan duck protects her brood in long grass near the interior lake (Photo: Tom Ordway, Ocean Futures Society [http://www.oceanfutures.org])
Albatross amidst native grass and sand on Laysan Island (Photo: Nan Marr, Ocean Futures Society [http://www.oceanfutures.org])
Jean-Michel Cousteau is seen walking along the beach at Laysan Island, littered with marine debris. In the background are remnants of a shipwreck and rusting Japanese long liner that sank, but is still visible in the sand lake. (Photo: Tom Ordway, Ocean Futures Society [http://www.oceanfutures.org])
Scientists carry jugs of fresh water up the Laysan beach to the camp they will occupy for several months. The NOAA ship OSCAR ELTON SETTE sits at anchor three quarters of a mile west of the island. (Photo: NOAA)
Link to metadata and data held by CoRIS
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