Coral Bleaching on Reefs in the Remote U.S. Pacific Islands of the Central Pacific By

James E. Maragos, Pacific Remote Islands National Wildlife Refuge Complex U.S. Fish and Wildlife Service, Honolulu

ABSTRACT:

Ten low reef islands or atolls under U.S. jurisdiction are remotely located in the Central Pacific Ocean: a) Johnston Atoll south of Hawaii and north of the Line Islands; b) Kingman Reef, Palmyra Atoll, and Jarvis Island in the Northern Line Islands; c) Howland and Baker Islands, northern outliers of the Phoenix Islands; d) Swains Island and Rose Atoll, respectively in northern and eastern American Samoa; e) Midway Atoll in the Northwestern Hawaii Islands (and covered in a separate report); and Wake Atoll, north of the Marshall Islands. Except for Swains, all are beyond state or territorial control, and all except Wake and Swains are now protected as National Wildlife Refuges. All were uninhabited at the time of their western "discovery" over the past 2 centuries, and most are still uninhabited except for a few residents at Swains and Palmyra, and small military bases at Wake and Johnston. Despite their relatively undisturbed status, all have experienced recent coral bleaching: a) reported in the literature or observed at Johnston, Kingman, Swains, Rose and Wake; b) strong evidence (dead standing coral) of recent bleaching at Jarvis, Howland, and Baker; and c) deduced via time series observations over the past 2 decades at Palmyra. A1993 ship grounding nearly coincided with the 1994 bleaching event at Rose, exacerbating adverse impacts to reefs and corals. Military dredging and filling at Palmyra greatly extended bleaching to lagoon and down-drift reefs, and may have similarly elevated bleaching at Wake and Johnston. These findings reveal that even the most protected and least disturbed reefs under U.S. jurisdiction are not immune from coral bleaching and possibly other effects of global climate change.