HARLES H. LAMOOREW No. 86 February 28, 1965 BOTANY DEPT. UNlVERSllY OF HAWAII HONOLULU 14. HAWAII ATOLL RESEARCH BULLETIN Geography and land ecology of CZ;Pperton Idand by ~arie-H6l;ne Sachet Issued by THE PACIFIC SCIENCE BOARD National Academy of Sciences-National Research Council Washington, D.C., U.S.A. ATOU RESEARCH lNlUXTN ---..------------- NO. 86 Geography and land ecology of Clipperton Island by Marie -&'lbne Sachet Issued by PACITE EClENCE BOARD National Academcy of Sciences-4?a'tlonal Research Council Washington, D. C. February 28, 1962 It is a pleasure to conmend the far-sighted policy of the Of'fice of Naval Research, with its emphasis on basic research, as a result of which a grant has made possible the continuation of the Coral Atoll Program of the Pacific Science Board. It is of interest to note, historically, that much of the f'unda- mntal Infomaation on atolls of the Pacific was gathered by the U. S. Navy's South Pacific Exploring Ekpedition, over one hundred years ago, under the cormnand of Captain Charles kfillres. The continuing nature of such scientific interest by the Navy is shotm by the support for the Pacific Science Board ' s research programs during the past fourteen years. me preparation and issuance of the Atoll Research Bulletin is assisted by fbds from Contract N70nr-2300(12). The sole responsibility for all statements made by authors of papers in the Atoll Research Bulletin rests with them, and they do not necessarily represent the views of the Pacific Science Board or of the editors of the Bulletin. Editorial Staff F. R, Fosberg, editor M. -H. Sachet, assistant editor Correspondence concerning the Atoll Research Bulletin should be addressed to the above Pacific Vegetation -Project $ Natioml Research Council 2101 Constitution Avenue, N. W. Washington 25, D. C., U.S.A. CONTENTS INTRODUCTION ....................03 Geographic location. general description .......3 istorical sketch ..................4 WEATHERANDCmTE ..e.eee..eeeeee e.9 Temperatme .....................9 Atm~phericpress- ................10 Winds .......................810 Tropical storms and hurricanes ...........12 Rainfall ......................20 Aixmspheric humidity ................24 Cloudiness and visibility .............024 HYDROGRAPRY .....................25 Surfacecurrents ..................25 ........................26 Tides ........................27 ocean temperatures .................28 SUBMARINETOPOGRAPHY .e***.eeeee.e.. e29 Ocean floor. Clipperton Ridge ............29 Ocean bottom ....................29 Undersea mountain ..................30 Upper slopes and terraces ..............31 Interpretation .................32 Reef ........................32 SURFACE FEAWS OF LAND STRIP ...........35 Owter shore ....................-35 Beaches ....................35 Beach Rock ...................36 md........................ 38 Beach ridges ..................38 Land surface ..................39 Unconsolidated material ..........39 The ledges ................39 Exposed pavements .............40 Lagoon shores ....................41 Lagoon cliffs .................41 Other lagoon shore types ............41 ClippertonRock ...................42 .Analysis of Clipperton lagoon water ......46 Lagoon level ..................47 Lagoon.depth and nature of bottom ....... 48 Lagoon reefs and islets 49 LITHOLOGY... ................m0.51 Loose sediments ....................51 Boulder and cobble gravel ...........52 Fine gravels. sands. silts. and mixtures of these ..............53 Beach conglomerates ..............58 Phosphatic conglomerates ...~.~~.~..-58 Pumice and other extraneous materials ....... .65 Analyses of Clipperton Island samples 66 . iii PHYSIOGFUPHIC CHANGES. .............. 69 Geological change .............. 63 Historicjl. change due to natural causes ... 69 Recent changes due to man .......... 72 GENERALLAUDIEOLOGY ............... 75 ET8bikL-t .....................* 75 ~azld iota .................... 76 put life .................. 76 Vegetation of the lagoon ........ 79 Animal life ................. 79 Marrrm&ls ................. 79 BWLS .................. 80 Reptiles ................ 84 Invertebra-tes .............. 84 Ecological history ................ 86 CATALOGUE OF LAND AND LAGOON PLANTSAND ANIMALS . 89 Plants ...................... 89 AnWs ...................... 94 BIBLIOGRELW ................... 103 PREFACE During the Iilternational Geophysical Year, Scripps Institution of' Oceanogaphy, a branch of the University of California, organized several research cruises in the Pacific, as part of the world-wide propaiii, Several previous cruises had called attention to Clipperton Island, and during the Doldrums Expedition of the surntner of' 1958 it was decided to study the biogeography of this little-lmo~misland. A Zroup of 13 per- sons were left on the island by the Research Vessel Spencer F. Baird on August 7, 1958 and were taken aboard aaain on August 26, excFpt for four who remained until September 25 to contime their studies of sharks. I had the great zood forbe to be one of the group and to study plant life on the island. In addition I made observations on the land fauna and seology, and some collections of animals, soils and rocks. It will not be easy to thank adequately the uany persons who have contributed to the success of my work on C~ipperton. In the first place of course I 17a11t to express my gratitude for this unique opportunity to Scripps Institution of Oceanog-aphy and to its Director, Dr. Roger Revelle. I owe xuch also to Dr. Carl Hubbs, froi whom the invitation rms received, to I@. John A. Knauss, leader of tlle Doldr~li~~s3:yedition, to the late Conrad Limbau~h, chief of the Clipperton field party, to all my companions in the field and to the Master and crew of the Baird. Our visit could not have taken place vithout the authorization of the French Goverrxent, and without the intervention of Dr. Jean Delacour, then Director of the Los Angeles County N~~se~lmand Professor Roger Heim, Director of the Ivluse/unl National d Histoire Naturelle in Paris, rho helped procure this author- ization. The French Embassy and the Office of the Naval ~ttachgin Vasn- ington vere also very helpful, For penilittins me to join the expedition and. encouraging ~ileto work up the material, I wish to thank my superiors in the U. S. Geological Survey and in the Pacific Science Board, fiJationa1 Academy of Sciences-- National Research Council. The Acadeioy also provided very welcoule help in the fom of a grant froii! tlle Joseph Hznry Fund. I cannot nac!e here all the persons who have contributed identifications, analyses, and suz- zestions and .to whom I am deeply grateful. They will be mentioned in the course of the paper. In assembling biblioeraphic material and photographs I have benefited from the facilities of many individuals and several or- ganizations: the U. S. Navy's Naval History Division, Hydrographic Office and Office of Naval Research, the Service Historique de la Nariile Na- tionale of France, the U. S. Weather Bureau, the U. S. National IG~seur,, the U. S. National Archives, the Library 02 Congress, the California Acaderkv of Sciences, and the ~iblioth&ueNationale of France. Miss Evelyn L. Pruitt, Head. of the Geography Bra~ch,Office of Naval Research, gave me much help i3 searching for photographs and d.oc~ments in the U. S. Navy files. Nessrs. E. C. Allison, Ted. Arnow, Willard Bs- corn, A. I. Coopeman, A. S, Hambly, Lester F. Hubert, W. L. Klatre, Job1 Knauss, H. S. Lad.d, Conrad Limbaugh, W. E. Nalone, H. 2. Naude, C. S. Rali~age, Waldo Schdtt and R. E. Snodgrass gave me unpublished information, lent me photographs and documents, or read and criticized parts or all of the urnnuscript. Mr. V. A. Rossi gave me advice and help ~iiththe il- lu~trations,alld. Dr. Gilbert, Corwin examined the samples of volcaric rocks. I wish to make specid mention of Mr. Obermiiller, ~e'olo~ueen Chef de la France dfOutre-Mer, who worked on Clipperton a few mnths before I went there and gave me copies of his reports even before their publi- cation, as well as samples of his rock collections. Finally I wish to express my appreciation and gratitude to Dr. F. R. Fosberg who helped and encouraged me in every step of this work. The appearance of this paper has been delayed by various circumstances, as has that of a more extensive and profusely illustrated memoir on Clip- perton (sachet, in press). Geographic location, general description Clipperton Island (~ig.l), one of the few oceanic islands in the Faatern Pacific, excites the interest and curiosity of naturalists especia3ly because it is the only coral island in that part of the ocean The nearest atoll, Arkapuka in the Eastern Tumotus, lies 2300 nautical miles to the southwest. Here are some other figures that will give an idea of the isolation of Clipperton, the coordinates of which are 10ol8'N and 10g013'W (adjusted position for Astro 1957, a monument placed by the U. S. Hydrographic Office on the northeast side: 10~18~41"N, 109Ol2' 34"~). The nearest land is the Mexican west coast, 600 nautical miles to the north-north-east. The nearest islands ta the north are the ReviUagigedo Islands of which Soccoro is 530 miles from Clipperton. The Galapagos lie 1300 miles to the southeast and Easter Island 2250 miles due south. In its general form, Clipperton is a low closed ring of coral lime- stone, but the island does not exactly qualify as an atoll as a small volcanic rock rises at the end of a short peninsula in the lagoon. This typ of island has been called an "al~~~st-atoll,"but