Zircon Xenocrysts From Easter Island (Rapa Nui) Reveal Hotspot Activity Since the Middle Jurassic

Eight species of Collembola are reported from recent collections made in caves on the Polynesian island of Rapa Nui (Easter Island). Five of these species are new to science and apparently endemic to the island: Coecobrya aitorererere n. sp., Cyphoderus manuneru n. sp., Entomobrya manuhoko n. sp., Pseudosinella hahoteana n. sp. and Seira manukio n. sp. The Hawaiian species Lepidocyrtus olena Christiansen & Bellinger and the cosmopolitan species Folsomia candida Willem also were collected from one or more caves. Coecobrya kennethi Jordana & Baquero, recently described from Rapa Nui and identified as endemic, was collected in sympatric association with C. aitorererere n.sp. With the exception of F. candida, all species are endemic to Rapa Nui or greater Polynesia and appear to be restricted to the cave environment on Rapa Nui. A key is provided to separate Collembola species reported from Rapa Nui. We provide recommendations to aid in the conservation and management of these new Collembola, as well as the other presumed cave-restricted arthropods.

Chapter 5 - The cultural landscape of Rapa Nui (Easter Island, Chile)

This article examines evolving linguistic practices in the Spanish-Rapa Nui (Polynesian) bilingual community of Easter Island, Chile, and in particular the transformation of Rapa Nui Spanish speech styles. The island's rapid integration into the national and world economy and a vibrant indigenous movement have profoundly influenced the everyday lives of island residents. Although community-wide language shift toward Spanish has been evident over the past four decades, the Rapa Nui have in this period also expanded their speech style repertoire by creating Rapa Nui Spanish and syncretic Rapa Nui speech styles. Predominantly Spanish-speaking Rapa Nui children who have imperfect command over Rapa Nui are today adopting a new Rapa Nui Spanish style. Ethnographic and linguistic analysis of recorded face-to-face verbal interactions are utilized to analyze the development, structure, and social significance of Rapa Nui Spanish varieties and to locate them within the complex process of language shift.I wish to express my appreciation to the Rapa Nui and other residents of Easter Island for so kindly welcoming me into their homes and allowing me to participate in their daily life. I would also like to thank my research assistant, Ivonne Calderón Haoa, who helped me record and transcribe speech events. This article is based on field research supported by the National Science Foundation (Grant No. SBR-9313658), the Wenner-Gren Foundation (Grant No. 5670), the Andrew W. Mellon Foundation, Yale University, and the Institute for Intercultural Studies. Parts of this article were presented at the 2004 meeting of the Linguistic Society of America and the 2004 meeting of the Association for Social Anthropology in Oceania. I thank those who offered comments on earlier versions, in particular two anonymous reviewers, Jane Hill, Robert and Nancy Weber, Christine Jourdan, Niko Besnier, Jean Mitchell, and Lamont Lindstrom.

The history of the Polynesian civilization on Rapa Nui (Easter Island) over the Common Era has come to exemplify the fragile relationship humans have with their environment. Social dynamics, deforestation, land degradation, and climatic shifts have all been proposed as important parts of the settlement history and societal transformations on Rapa Nui. Furthermore, climate dynamics of the Southeast Pacific have major global implications. While the wetlands of Rapa Nui contain critical sedimentological archives for reconstructing past hydrological change on the island, connections between the island’s hydroclimate and fundamental aspects of regional climatology are poorly understood. Here we present a hydroclimatology of Rapa Nui showing that there is a clear seasonal cycle of precipitation, with wet months receiving almost twice as much precipitation as dry months. This seasonal cycle can be explained by the seasonal shifts in the location and strength of the climatological south Pacific subtropical anticyclone. For interannual precipitation variability, we find that the occurrence of infrequent, large rain events explains 92% of the variance of the observed annual mean precipitation time series. Approximately one third (33%) of these events are associated with atmospheric rivers, 21% are associated with classic cold-front synoptic systems, and the remainder are characterized by cut-off lows and other synoptic-scale storm systems. As a group, these large rain events are most strongly controlled by the longitudinal position of the south Pacific subtropical anticyclone. The longitudinal location of this anticyclone explains 21% of the variance in the frequency of large rain events, while the remaining variance is left unexplained by any other major atmosphere-ocean dynamics. We find that over the observational era there appears to be no linear relationship between the number of large rain events and any other major climate phenomena. With the south Pacific subtropical anticyclone projected to strengthen and expand westward under global warming, our results imply that Rapa Nui will experience an increase in the number of dry years in the future.

Rano Raraku, the crater lake constrained by basaltic tuff that served as the primary quarry used to construct the moai statues on Rapa Nui (Easter Island), has experienced fluctuations in lake level over the past centuries. As one of the only freshwater sources on the island, understanding the present and past geochemical characteristics of the lake water is critical to understand if the lake could have been a viable freshwater source for Rapa Nui. At the time of sampling in September 2017, the maximum lake depth was ~1 m. The lake level has substantially declined in the subsequent years, with the lake drying almost completely in January 2018. The lake is currently characterized by highly anoxic conditions, with a predominance of ammonium ions on nitrates, a high concentration of organic carbon in the water-sediment interface and reducing conditions of the lake, as evidenced by Mn/Fe and Cr/V ratios. Our estimates of past salinity inferred from the chloride mass balance indicates that it was unlikely that Rano Raraku provided a viable freshwater source for early Rapa Nui people. The installation of an outlet pipe around 1950 that was active until the late 1970s, as well as grazing of horses on the lake margins appear to have significantly impacted the geochemical conditions of Rano Raraku sediments and lake water in recent decades. Such impacts are distinct from natural environmental changes and highlight the need to consider the sensitivity of the lake geochemistry to human activities.

BackgroundRapa Nui (Easter Island = Isla de Pasqua) is of volcanic origin, best known for about 900 man-made stone statues known as moai. It is one of the most isolated inhabited islands on Earth and studies on the diatoms of Rapa Nui are very few.MethodsLight (LM) and electron microscopic (SEM) observations of a single sample collected from Rapa Nui are presented. The samples (mix of soil and organic detritus) were collected from ground of cave entrance.ResultsThe samples were characterized by low diatom diversity and strongly dominated by terrestrial (soil) forms. Among the taxa present in the material studied were cosmopolitan forms of the genera Humidophila, Nitzschia, Angusticopula, Orthoseira, Tryblionella and Luticola. Whereas most of taxa of the enumerated genera were identifiable, only one among four Luticola species distinguished in the samples studied was identified. This taxon was L. ectorii, a cosmopolitan species known previously from South America (Brazil) and Asia (China). The three remaining species could not be assigned to any established species. Therefore, based on external and internal morphological features from light and scanning electron microscopic analysis, we describe here three species new to science, including: L. georgzizkae, L. rapanuiensis and L. moaiorum. All three taxa new to science are compared to established Luticola species and their significance for the global distribution of the genus is discussed.

Easter Island (Rapa Nui) is well known for the enigmas surrounding its unique megalithic statues, the moai, and the prehistoric (i.e., pre-European contact) Rapanui society that built them. These enigmas include, among others, the time of the island’s settlement, the geographical origin of the first settlers, the technology associated with moai transportation and emplacement, the occurrence (or not) of an ecological and cultural collapse linked to the island’s deforestation, and the potential influence of climatic shifts on ecological and cultural changes. Until recently, most explanations for prehistoric developments invoked anthropogenic causes, but the progressive development of paleoecological studies has incorporated a new perspective in which climate change and climate-human synergies have gained momentum. This paper reviews all paleoecological studies published to date and their contribution to a better understanding of Easter Island’s prehistory, with a focus on four main aspects: (i) the discovery and settlement of the island, (ii) the eventual occurrence of climatic changes and its potential influence on landscape changes, (iii) spatiotemporal deforestation patterns, and (iv) the relationship between environmental, ecological and cultural shifts. Paleoecological research on Easter Island has proceeded through three main phases: a pioneer phase (1977–1992), a transitional phase (1993–2004) and a revival phase (2005–2020). During the pioneer and transitional phases, the paradigm of a self-induced prehistoric socioecological collapse known as the “ecocidal” hypothesis dominated the scene. However, new empirical evidence obtained during the revival phase highlighted the potential importance of climate change in prehistoric ecological and cultural developments. In addition, paleoecological records have provided novel insights into the initial discovery and occupation of Easter Island before Polynesian settlement. Paleoecological evidence has suggested or supported that (i) the island would have been discovered and sporadically/intermittently settled, possibly by Amerindian cultures, long before Polynesian colonization; (ii) climatic changes, especially centennial-scale droughts that occurred during the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA), would have influenced ecological trends and cultural developments; (iii) deforestation was not a synchronous island-wide process but occurred at different times and at different rates according to the catchment considered; and (iv) both climatic and anthropogenic drivers, along with feedbacks between them, would have been responsible for the prehistoric socioecological developments on Easter Island. A general conclusion is that Easter Island’s prehistory is complex and cannot be resolved using simplistic and deterministic approaches from isolated disciplines. Rather, uncovering this prehistory requires an integrated framework with contributions from complementary research fields such as anthropology, archaeology, ethnography, history and paleoecology, among others. This paper explains the potential contributions of paleoecology, in the hope that researchers in other disciplines will be able to incorporate the available paleoecological knowledge into their own studies. From a paleoecological point of view, further coring is needed and the use of novel biomarkers is highly recommended. General recommendations are to increase the amount of raw data available in public repositories, to develop a multidisciplinary database for Easter Island and to adopt a problem-solving attitude focused on the main topics of interest.

In situ U-Pb and geochemical evidence for ancient Pb-loss during hydrothermal alteration producing apparent young concordant zircon dates in older tuffs

The disappearance of the bird species involved in the bird-cult of Rapa Nui (Easter Island) was examined. The cult was a contest in which the winner gathered the first seabird egg of the year from a near-shore islet, allowing the winner to become the Tangata Manu, or Birdman. This title provided a heightened status, bringing social and economic benefits and a way of being closer to their gods. Three seabird species were involved in the bird-cult: Great Frigatebird Fregata minor, Sooty Tern Onychoprion fuscatus, and the Spectacled Tern Onychoprion lunatus, none of which currently breed in the area. Rock art suggests that frigatebird eggs were initially used in the bird-cult. However, when frigatebirds ceased to nest due to overexploitation of eggs and feathers, there was a switch to more numerous Sooty Tern eggs to satisfy the bird-cult. Spectacled Terns have probably never bred at Rapa Nui, though they do visit, and any relationship to the bird-cult is due to confusion with the Sooty Tern. The bird-cult itself was diminished by a decrease in seabird numbers, but also by two sociological factors: (1) enslavement of the islanders by Peruvian raiders, including the King and the most educated members of society; and (2) by the imposition of a new religion in which there was no need to idolatrize the old gods. The bird species involved in the bird-cult disappeared due to a combination of factors: (1) the restriction (tapu) on the number of eggs and birds that could be collected for feathers and food—which was in place when the ritual was active—was removed as the cult diminished; (2) modernization brought better tools that facilitated gathering of eggs and feathers (e.g., canoes and then outboards motors in a land without trees); and (3) the introduction of a hunter-scavenger hawk, the Chimango Caracara Milvago chimango, put further pressure on seabird species that were already in decline. There is currently an urgent need to eradicate the hawk from the island because it continues to depredate large numbers of nestling seabirds.

ABSTRACTThe invasive Argentine Ant, Linepithema humile, is known to prey on land bird chicks, but there are few reports of the ants’ impacts on breeding seabirds. We conducted a manipulative study using hen eggs to estimate the potential Argentine Ant recruitment to pipping eggs in the Red-tailed Tropicbird, Phaethon rubricauda, at Rapa Nui (Easter Island), Chile. Hen eggs were experimentally opened to simulate pipping eggs and control eggs were left unopened. The eggs were monitored for 90 min. The time elapsed until the arrival of the first ant did not differ between experimental and control eggs. None of the control eggs were visited by more than two ants. In contrast, the inferred cumulative number of ants that arrived at experimental eggs varied from 1 to >450. Simulated pipping eggs attracted a high number of ants in a short period of time, and the probability of an egg being attacked by ants after 5 and 60 min of exposure was 75% and 99%, respectively. A long-term monitoring study is needed to determine the actual Argentine Ant recruitment rate on pipping eggs, and the potential effects on the post-fledging survival rate of this native seabird which is threatened by a number of introduced species.

The mysteries of Easter Island (Rapa Nui) have gripped the imagination of explorers, scientists, and the public for more than a century. The origin of the Rapanui people and the rise and fall of their advanced prehistoric culture raise many important scientific questions. Who were the Rapanui ancestors? Did they come to this remote island as part of a single Polynesian migration or multiple ones? Were all of these early inhabitants Polynesian or were some of them of South American origin? What forces were involved in the rise, decline, and eventual collapse of this unique culture? Answers to these questions could explain much about human mobility, resourcefulness, and adaptability. Explorations of Easter Island within the modern era began largely with archaeological investigation. Beginning with the Norwegian Expedition of 1955–56, under the direction of the world-famous explorer, Thor Heyerdahl, an international team of archaeologists began the process of scientific inquiry (Heyerdahl and Ferdon, 1965). They excavated a number of well-documented sites, and at most of them encountered well-preserved human skeletons. Thousands of additional human bones were seen by these archaeologists since they existed in open caves and partially exposed burial chambers within ahu platforms (i.e., the platforms that support the giant Easter Island statues, or moai ). These men realized the importance of human skeletons to future scientific investigation, and also the risk of their loss in the not too distant future as this tiny island would most certainly, in time, begin to open up to the outside world. The 1981 Easter Island Anthropological Expedition, which resulted in the successful recovery, protection, and initial study of these threatened human bones, and which eventually allowed for many of the studies presented in this book, was inspired and assisted in many ways by these members of the original Heyerdahl team (especially William Mulloy, Gonzalo Figueroa G-H, and Thor Heyerdahl himself). This connection will be discussed in more detail below.

By whatever name it is called, Easter Island, Isla de Pascua, or Rapa Nui, this small (ca. 106 km2) spot of land in the central Pacific Ocean (27° 08’S, 109°20’W) has the distinction of being perhaps the most isolated spot on earth. It is approximately 3800 km from the South American mainland to the east, and over 2200 km from it’s nearest neighbor to the west, Pitcairn Island. The closest landmass is tiny Sala y Gomez 415 km to the east, a bleak uninhabited rock. Easter Island is, of course, most famous for its anthropological history, and the numerous stone statues (moai) that dot the landscape. Not surprisingly, most of the preservation effort directed at Easter Island in this century has been towards these archaeological and cultural artifacts. That the biological component of the island has received less attention is also not surprising, given the relatively depauperate fauna and flora reported on and around the island. What animals lived on the island in historical times is unknown and the few terrestrial species living there today, from the common isopods to the ubiquitous hawks, were introduced either on purpose (hawks from Chile for rodent control; see Klemmer and Zizka, 1993) or by accident (cosmopolitan isopod species brought in on plants). Of the terrestrial invertebrate fauna, only the insects have been studied in any detail (Compos & Pena, 1973); there are no comprehensive published accounts of the sparse isopod, mollusk, or flatwork freshwater faunas to date (see Kuschel, 1963; Klemmer and Zizka, 1993).

Reviewed by: Stanley’s Dream: The Medical Expedition to Easter Island by Jacalyn Duffin Warwick Anderson Jacalyn Duffin. Stanley’s Dream: The Medical Expedition to Easter Island. Carleton Library Series, no. 247. Montreal: McGill-Queens University Press, 2019. 576 pp. Ill. $39.95 (978-0-7735-5710-9). Not surprisingly, I see the specter of D. Carleton Gajdusek stalking the Canadian-led medical expedition to Rapa Nui or Easter Island in 1964–65. The scrappy, quarrelsome research team displayed the same fascination with so-called primitive groups, the same naiveté about supposed isolation, the same blundering in local politics, the same assumption of its rights and duties to investigate Indigenous people as it saw fit. Whether in Gajdusek’s contemporary studies of kuru in New Guinea or in Stanley Skoryna’s research on Rapa Nui, described so well in Stanley’s Dream, personal acrimony and recrimination abounded. Both Gajdusek and Skoryna boasted links to the new International Biological Programme (IBP), although their connections often proved tenuous, more aspirational than consequential. The major difference between the New Guinea and Rapa Nui expeditions is that Gajdusek was awarded the 1976 Nobel Prize in physiology or medicine for his discovery of the first “slow virus,” later found to be a prion, a wholly new mechanism of human disease causation, whereas Skoryna was awarded nothing at all. Despite Jacalyn Duffin’s admirable efforts to find some positive outcome of the expedition to Rapa Nui, we are left with the impression of a disorderly, bickering rabble, unprepared for the investigation, ignorant of Pacific history, stumbling around on an alluring island, unsure of what they were doing there. If Gajdusek’s expedition was ultimately a case study in tragedy—for both him personally [End Page 269] and the Fore people—then Skoryna’s trip to Rapa Nui provides us instead with a rollicking farce. Perhaps unintentionally, Duffin delivers a highly readable postcolonial critique of the assumptions of sovereignty and claims to competence of the modern scientific expedition. The first third of Stanley’s Dream is a compelling (mis)adventure story; the middle section brings to mind both Lord of the Flies and Fawlty Towers, an inventive amalgam; while the final third assemblies a meticulous, if ultimately unconvincing, inventory of the expedition’s “achievements.” Inspired by the postwar Pacific exploits of Thor Heyerdahl, McGill gastroenterologist Skoryna proposed a medical jaunt to Rapa Nui in 1964, hoping to document the health and biological status of the Polynesian inhabitants before an international airport was opened. He imagined an isolated population, inbred and primitive, about to be exposed to the ravages of civilization, the pathologies of progress. Little did he know that the islanders already were thoroughly mixed in ancestry and more cosmopolitan than many of his fellow Quebecois. Nor was he aware of extensive Chilean medical research on the islanders. Skoryna quickly convened a ragtag bunch of investigators, mostly from Canada, including microbiologists, physiologists, ecologists, and a trainee sociologist. A biological anthropologist and a nutritionist agreed to come along but soon dropped out. The two Chilean participants found themselves in conflict with the North Americans, and they too fled. Remarkably, Skoryna managed to acquire funding for the expedition from the WHO and the Canadian government. Duffin places this research project within the context of emerging concerns about human adaptability in a changing biosphere, which found expression around the world in expanding ecological inquiries, often organized after 1964 through the IBP. She claims that Skoryna, who had studied medicine in Vienna, was immersed in studies of general biology and fascinated by F. Macfarlane Burnet’s speculations on disease ecology. (Another parallel since Burnet happened to be Gajdusek’s disaffected mentor.) Apparently, Hungarian-Canadian micro-biologist Georges L. Nógrády, another expedition leader, also was enthralled by ecosystems thinking and issues of planetary sustainability, hoping to learn something on Rapa Nui about how humans might adapt genetically and sociologically to environmental degradation and increasing interconnection. But the research team as a whole had little or no experience investigating human adaptability and displayed indifference to the burgeoning literature on the topic. It was never clear how these patchy opportunistic studies would elucidate any of the issues that engaged human ecologists more...

The endangered green sea turtle (Chelonia mydas; hereafter C. mydas) plays a crucial role in maintaining the balance of marine ecosystems. However, its populations are highly vulnerable to various threats, including marine pollution. Rapa Nui (Easter Island), an isolated location in the southeastern Pacific, provides vital foraging habitats for both morphotypes of Pacific C. mydas (black and yellow). In this study, we examined the demographic structure (morphotype, life stage, sex) and health status (based on blood analytes and mercury-Hg concentration) of C. mydas on Rapa Nui during 2018 and 2023. Turtles from various life stages and sexes were observed, with a predominance of yellow morphotype juveniles, likely recently recruited or emerging from brumation. Haematological analyses revealed low levels of several key analytes (e.g. cholesterol, calcium, phosphorus, total protein, globulins), suggesting poor nutritional status, potentially related to the brumation process, limited food availability or poor food quality in the region. Alterations in both red and white blood cell lines, including anaemia and lymphopenia, indicate ongoing inflammatory states and infections, consistent with clinical observations. Rapa Nui turtles exhibited some of the highest blood Hg concentrations globally. Abnormalities in blood profiles, along with correlations between various analytes and blood Hg concentrations, suggest altered immune function and probable renal and liver dysfunction, likely resulting from both natural and anthropogenic sources of this heavy metal. Additionally, a very high body condition index in turtles with carapace lesions suggests a negative impact from human food subsidies in local bays, particularly from high-trophic-level fish, which may also serve as a pathway for Hg accumulation, both for the turtle aggregation and the human population. Our findings underscore the urgent need for long-term mercury monitoring and turtle movement studies to identify pollution sources, inform effective conservation strategies for this endangered species, and address potential public health concerns on this remote Pacific island.

The Quaternary East Eifel volcanic field (EEVF) comprises three major evolved, phonolitic to trachytic centers (from old to young: Rieden, Wehr, and Laacher See) in addition to ~80 scoria cones. The prominent Laacher See eruption ca.13.000 years ago ranks among the largest Quaternary volcanic events in Europe, with the phonolitic Laacher See tephra (LST) being widely dispersed and of great relevance as a tephrochronological marker horizon1. Magmatic activity as recorded by zircon indicates that evolved magma was present underneath Laacher See at least 50 ka prior to its eruption. Continuous degassing and deep low-frequency earthquakes presumably related to fluid migration in the crust hint at ongoing magmatic activity.Multiple eruptive phases characterize the older volcanic complexes of Rieden and Wehr, and it is therefore relevant to compare them to Laacher See center with presently only one eruption. Here, we focus on three eruptions that are associated with the Wehr depression or nearby centers, and where existing eruptive geochronology based on 40Ar/39Ar suggest eruptions <116 ka, bridging the transition of activity from Wehr to Laacher See. Three composite pumice samples were collected from previously established type localities (Dachsbusch, Herchenberg) comprising the Hüttenberg Tephra (HT), Glees Tephra (GT), and Dümpelmaar Tephra (DT). Whereas HT and GT are generally attributed to the Wehr depression, DT is presumably sourced from a small vent west of the Herchenberg scoria cone2.These trachytic-phonolitic magmas evolved from parental basanite, similar to LST, although there are major and trace element as well as isotopic differences3.SIMS U-Th zircon crystallization ages for HT ( ka; MSWD= 0.83; n=27, uncertainties 1σ) and GT ( ka, MSWD= 1.71; n=32) are nominally older than published 40Ar/39Ar eruption ages2 by at most 15 ka, but zircon crystallization and eruption ages overlap within uncertainty. The U-Th zircon age for DT of  ka (MSWD= 1.02; n=33) also overlaps with the published 40Ar/39Ar age (116 ±16 ka), but this is only based on two sanidine analyses with the lowest ages that were interpreted as maximum eruption age2. Crustal zircon xenocrysts are common in all pumices, but morphologically distinguishable from the juvenile zircon population dominated by dipyramidal morphology. Glass geochemistry indicates high abundances of Zr, which is a pre-requisite for zircon saturation in highly alkaline melts.In contrast to 40Ar/39Ar ages for individual K-feldspar crystals that display significant age heterogeneity2, in part exceeding the onset of volcanism in the EEVF, juvenile zircon crystals from HT, GT, and DT define a single population based on their individual isochrons. No carry-over of older zircon crystals into younger eruptions was detected, suggesting either eruption from distinct magma reservoirs, or complete resorption of pre-existing crystals between eruptive pulses. Future (U-Th)/He zircon geochronology will further constrain the temporal evolution of the evolved EEVF complexes.1Bogaard, v. d. P., Schmincke, H.-U., 1985. Geol. Soc. Am. Bull. 96, 1554–1571.2Bogaard, v.d. P., Hall, C.M., Schmincke, H.-U., York, D., 1989. Nature 342, 523–525.3Wörner, G. et al., 1988. N Jb Miner Abh, 159, 73–99.