1.1 Ecological Studies of Caroline Atoll, 



Republic of Kiribati, South-central Pacific 

 Ocean 



Part 1. History, Physiography, Botany, and Islet Descriptions 



ANGELA K. KEPLER , CAMERON B. KEPLER 1 , and DAVID H. ELLIS* 



*t/5 Fish & Wildlife Senice, Patuxent Wildlife Researeh Center, Southeast Research Station, Athens, Georgia, USA 

 X US Fish & Wildlife Senice, Patuxent Wildlife Research Center, Laurel, Maryland, USA 



Introduction 



On 26 July 1988, the Soviet research vessel Akademik 

 Korolev sailed from Vladivostok enroute to Dutch Harbor, 

 Alaska. There, Soviet oceanographers joined their American 

 colleagues to investigate the Gulf of Alaska and the Chukchi 

 Sea in the Third Joint US-USSR Eering & Chukchi Seas 

 Expedition. When the arctic research was completed in early 

 September, the ship headed toward the central Pacific. A 

 rendezvous for a second contingent of Americans took place in 

 Hilo, Hawaii, on 9 September. Six Americans joined the ship, 

 which set sail on a cruise track of 14,892 km that terminated 



6 weeks later in Singapore. An important part of the expedition 

 was research in and around little-known Caroline Atoll, at the 

 southeastern edge of the Line Group. On Christmas Island, we 

 picked up Katino Teeb'aki, a conservation officer for the 

 Republic of Kiribati, who represented his government and 

 helped our land-based research efforts. After landing on 

 Caroline on 22 September, we camped in 2 locations for 



7 nights, surveying the terrestrial plants and animals on all 

 39 islets. Caroline is a remarkably pristine atoll with its native 

 plant communities nearly intact on all but three islets, and 

 teeming seabird communities that, collectively, are second in 

 the Line Group only to Christmas Island ( Kiribati ) in diversity. 

 For several historical reasons, the natural values of this 

 spectacular blend of marine and terrestrial resources have been 

 overlooked. 



Caroline Atoll (Chapter Frontispiece) is situated at 10°00'S 

 latitude and I50°13'W longitude in the south-central Pacific 

 Ocean. Caroline is the southeasternmost of the Southern Line 

 Islands, a group of three islands that also includes Vostok and 

 Flint, lying 230 km to its west and southwest, respectively. 

 Although anthropologically and geographically within 

 Polynesia, Caroline is owned by the Republic of Kiribati 

 (formerly Gilbert and Ellice Islands). 



Caroline, 9.7 km long, 2.3 km wide at its widest point, and 

 26.9 km in circumference, is a crescentic coral ring with 

 39 islets centered on a continuous reef enclosing a relatively 

 shallow lagoon. Its total land area above high water is 399 ha, 

 with islets ranging in size from 0.02 to 107.5 ha. Islets 

 extend along 55% of the reef perimeter. The closed lagoon, 

 rich in marine life, contains a maze of patch reefs and remarkably 

 clear water. 



The island was "discovered" by de Quiros in 1606. 

 Although remnants of an ancient Tuamotuan culture still exist, 

 the atoll apparently never supported a long-term permanent 

 population and has been less affected by man than most Pacific 

 islands. Its European history includes guano export, a 

 multinational expedition to observe a solar eclipse, and copra 

 production. It has been uninhabited since the early 1930's (a 

 factor contributing to its relatively undisturbed ecology), except 

 for the presence of one family from 1987 to 1991. The primary 

 factors responsible for its lack of permanent settlement are 

 remoteness, apparent absence of usable ground water, the 

 repeated failure of its coconut plantations, absence of a passage 

 into the lagoon, a paucity of safe boat anchorages, and an 

 abundance of rats. 



Until the 1988 US-USSR Expedition on the Akademik 

 Korolev, only one fairly accurate map was available, which 

 named seven islets. We have drafted an accurate map based on 

 this field work and recent aerial photographs, also naming 32 

 previously unnamed islets, 4 islet groups, and an inlet. During 

 8 days of intensive field work, we surveyed all 39 islets, 

 walking 33 km in systematic cross-islet transects and around 

 islet perimeters. 



Soils, of coral and molluscan origin, are categorized into 

 five types, from barren coral rubble to rubble mixed with 

 humus and guano. Caroline provides an excellent example of 

 soil development through different age and size classes of 

 motus. 



Caroline's near-pristine, lush native vegetation supports 

 27 species of plants organized into 7 plant communities — 

 6 natural and 1 anthropogenic. The atollwide distribution of 

 each plant species is mapped. Its insular flora, typical of central 

 equatorial islands in their natural state, is 85% indigenous 

 (possibly up to 93% ), an extremely high figure for anywhere in 

 the world. Though Caroline's islets are covered with 

 extensive tracts of native woodland, the Pisonia grandis 

 forests, up to 25 m high, are particularly notable as they 

 constitute some of the best groves left in the Pacific. Toumefortia 

 argentea is abundant, and Cordia subcordata, becoming 

 quite rare elsewhere, is present on most islets. Cocos is 

 present, but only dominates one islet; 22 islets harbor wholly 

 indigenous vegetation. 



