Project

Inventory, Conservation and Management of Endemic Insects on Rapa Nui (Easter Island)

Goal: Rapa Nui (Easter Island) has undergone extensive environmental change. Today, all native terrestrial vertebrates and most native plants have gone extinct. Today, the island ecosystem is dominated by a community of nonnative animals and plants. Insects are that remain of the endemic native fauna. By sampling caves, cliff faces, rocky and sandy shorelines and crater lake shorelines, we will increase the number of endemic insects known to the island.Through improving our knowledge of the extent of endemic insects on the island, we can better manage and protect them.

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Jut Wynne
added a research item
Hawaiioscia rapui Taiti & Wynne, 2015 was first described from two caves on Rapa Nui and considered a potential island endemic and disturbance relict (i.e., an organism that becomes a relict species due to anthropogenic activities). As this species was not subterranean-adapted, it may have had an island-wide distribution prior to the arrival of the ancient Polynesians to Rapa Nui. We report new records for Hawaiioscia rapui beyond its type locality. These findings extend this animal’s range to the closest neighboring island, Motu Motiro Hiva (MMH), 414 km east by northeast of Rapa Nui. We also report information on this animal’s natural history, discuss potential dispersal mechanisms, identify research needs, and provide strategies for management. Our discovery further underscores that MMH likely harbors a unique and highly adapted halophilic endemic arthropod community. Conservation policies will be required to prevent alien species introductions; additionally, an inventory and monitoring program should be considered to develop science-based strategies to manage the island’s ecosystem and species most effectively.
Jut Wynne
added a research item
Background: Salas y Gómez is a small, volcanic island largely untouched by humans due to its diminutive size and remoteness. Since the waters surrounding Salas y Gómez were established as Motu Motiro Hiva Marine Park in 2010, marine investigations have been the primary research focus. Secondarily, nesting seabird communities have been censused since 2011. Methods and findings: In 2016, terrestrial arthropods were sampled on the island. Two observers sampled two locations for 30 min per site. Fifteen morphospecies were identified including at least one likely undescribed species. Conclusions: Our work represents the most comprehensive terrestrial arthropod inventory of Salas y Gómez island to date. We are hopeful the recommendations provided will spur additional research to both characterize the island's arthropod community, as well as identify species of management concern.
Jut Wynne
added 2 research items
The arthropod fauna of Salas y Gómez is essentially uncharacterized. Past biological inventory work was largely centered upon marine life and pelagic birds. We present the results of the most comprehensive terrestrial arthropod inventory of Salas y Gómez island to date. At least 16 morphospecies across 11 coarse taxonomic groups are now known. We also provide recommendations to guide future research and management.
Jut Wynne
added a research item
Aim: Identify the optimal combination of sampling techniques to maximize the detection of diversity of cave-dwelling arthropods. Location: Central-western New Mexico; northwestern Arizona; Rapa Nui, Chile. Methods: From 26 caves across three geographically distinct areas in the Western Hemisphere, arthropods were sampled using opportunistic collecting, timed searches, and baited pitfall trapping in all caves, and direct intuitive searches and bait sampling at select caves. To elucidate the techniques or combination of techniques for maximizing sampling completeness and efficiency, we examined our sampling results using nonmetric multidimensional scaling (NMDS), analysis of similarity (ANOSIM), Wilcoxon signed-rank tests, species richness estimators and species accumulation curves. Results: To maximize the detection of cave-dwelling arthropod species, one must apply multiple sampling techniques and specifically sample unique microhabitats. For example, by sampling cave deep zones and nutrient resource sites, we identified several undescribed cave-adapted and/or cave-restricted taxa in the southwestern United States and eight new species of presumed cave-restricted arthropods on Rapa Nui that would otherwise have been missed. Sampling techniques differed in their detection of both management concern species (e.g., newly discovered cave-adapted/restricted species, range expansions of cave-restricted species and newly confirmed alien species) and specific taxonomic groups. Spiders were detected primarily with visual search techniques (direct intuitive searches, opportunistic collecting and timed searches), while most beetles were detected using pitfall traps. Each sampling technique uniquely identified species of management concern further strengthening the importance of a multi-technique sampling approach. Main conclusions: Multiple sampling techniques were required to best characterize cave arthropod diversity. For techniques applied uniformly across all caves, each technique uniquely detected between ~40% and 67% of the total species observed. Also, sampling cave deep zones and nutrient resource sites was critical for both increasing the number of species detected and maximizing the likelihood of detecting management concern species.
Jut Wynne
added a research item
Nine species of terrestrial isopods are reported for the Polynesian island of Rapa Nui (Easter Island) based upon museum materials and recent collections from field sampling. Most of these animals are non-native species, but two are new to science: Styloniscus manuvaka sp. n. and Hawaiioscia rapui sp. n. Of these, the former is believed to be a Polynesian endemic as it has been recorded from Rapa Iti, Austral Islands, while the latter is identified as a Rapa Nui island endemic. Both of these new species are considered ‘disturbance relicts’ and appear restricted to the cave environment on Rapa Nui. A short key to all the oniscidean species presently recorded from Rapa Nui is provided. We also offered conservation and management recommendations for the two new isopod species.
Jut Wynne
added a research item
the spiders of rapa nui have not been assessed in over two decades. During this time, additional nonnative alien species introductions would be expected due to increased tourism visitation and the steady influx of commercial goods imported from mainland Chile. Prior to our work, only one endemic species (Tetragnatha paschae Berland, 1924) was known to occur on the island. We conducted multiple research trips (from 2008–2012) and examined 15 different study sites on rapa nui to search for both this species and other endemic ground-dwelling arthropod species including spiders. Tetragnatha paschae was not detected during our survey. We suggest this spider is probably extinct. our sampling yielded 26 unique spider morphospecies (representing 15 families and at least 20 genera). Based on our research and previous work, we complied a list of 47 morphospecies known to rapa nui – including six new island records. nearly half of these alien morphospecies (n = 23) have cosmopolitan or pantropical distributions. importantly, we detected one potentially endemic and possibly undescribed spider, Tetragnatha sp., which is probably restricted to the native vegetation within one crater lake. the areas with highest spider diversity are likely due to high habitat heterogeneity. We also provide recommendations to expand the search for endemic spider species on rapa nui.
Jut Wynne
added a research item
Caves are considered buffered environments in terms of their ability to sustain near-constant microclimatic conditions. However, cave entrance environments are expected to respond rapidly to changing conditions on the surface. Our study documents an assemblage of endemic arthropods that have persisted in Rapa Nui caves, despite a catastrophic ecological shift, overgrazing, and surface ecosystems dominated by invasive species. We discovered eight previously unknown endemic species now restricted to caves—a large contribution to the island's natural history, given its severely depauperate native fauna. Two additional species, identified from a small number of South Pacific islands, probably arrived with early Polynesian colonizers. All of these animals are considered disturbance relicts—species whose distributions are now limited to areas that experienced minimal historical human disturbance. Extinction debts and the interaction of global climate change and invasive species are likely to present an uncertain future for these endemic cavernicoles.
Jut Wynne
added 4 research items
The spiders of Rapa Nui have not been assessed in over two decades. During this time, additional nonnative alien species introductions would be expected due to increased tourism visitation and the steady influx of commercial goods imported from mainland Chile. Prior to our work, only one endemic species (Tetragnatha paschal Berland, 1924) was known to occur on the island. We conducted multiple research trips (from 2008–2012) and examined 15 different study sites to search for both this species and other endemic ground-dwelling arthropod species including spiders. Tetragnatha paschae was not detected during our survey. We suggest this spider is probably extinct. Our sampling yielded 26 unique spider morphospecies (representing 15 families and at least 20 genera). Based on our research and previous work, we complied a list of 47 morphospecies known to Rapa Nui – including six new island records. Nearly half of these alien morphospecies (n = 23) have cosmopolitan or pantropical distributions. Importantly, we detected one potentially endemic and possibly undescribed spider, Tetragnatha sp., which is probably restricted to the native vegetation within one crater lake. The areas with highest spider diversity are likely due to high habitat heterogeneity. We also provide recommendations to expand the search for endemic spider species on Rapa Nui.
Caves are considered buffered environments in terms of their ability to sustain near-constant microclimatic conditions. However, cave entrance environments are expected to respond rapidly to changing conditions on the surface. Our study documents an assemblage of endemic arthropods that have persisted in Rapa Nui caves, despite a catastrophic ecological shift, overgrazing, and surface ecosystems dominated by invasive species. We discovered eight previously unknown endemic species now restricted to caves—a large contribution to the island's natural history, given its severely depauperate native fauna. Two additional species, identified from a small number of South Pacific islands, probably arrived with early Polynesian colonizers. All of these animals are considered disturbance relicts—species whose distributions are now limited to areas that experienced minimal historical human disturbance. Extinction debts and the interaction of global climate change and invasive species are likely to present an uncertain future for these endemic cavernicoles.
We define the genus Cyptophania with characters that clearly separate it from other genera of the Family Lepidopsocidae in which wing reduction has occurred. We redescribe the generotype, C. hirsuta Banks (Hawaii, presumably introduced), and describe three new species, C. australica n.sp. (Queensland, Australia), C. costalis n.sp. (Gulf of Mexico and Caribbean), and C. pakaratii n.sp. (Rapa Nui = Easter Island, probably endemic). The latter species is described from both sexes and presents the first males known for the genus. One female of this species presents a large spermatophore protruding from the genital chamber, thus indicating the mode of sperm transfer in sexual members of this genus. A key to the known species is included. All of the species of Cyptophania are highly neotenic, but differences in the level of neoteny are noted among the species studied. We question the synonymy of the genus Ptenocorium Enderlein with Cyptophania on the basis of several characters illustrated in the original description of Ptenocorium. We note similarities of Cyptophania to the entirely macropterous genus Lepidopsocus Enderlein and suggest a possible close relationship between the two genera.
Jut Wynne
added 10 research items
Eight species of Collembola are reported from recent collections made in caves on the Polynesian island of Rapa Nui (Eas-ter 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 Wil-lem 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.
Jut Wynne
added 3 research items
Este trabajo representa el primer esfuerzo por muestrear las zonas profundas de las cavernas de Rapa Nui en busca de artrópodos troglomórficos. Las cuatro cavernas de tubo de lava más grandes dentro del flujo de lava de Roiho fueron seleccionadas debido a la presencia de zonas profundas. Identificamos al menos 17 morfoespecies, incluyendo la identificación de especies de nivel para cinco artrópodos que se encontraron dentro de las zonas profundas de las cavernas. Se identificó dos especies nuevas durante este estudio – un especie de isópodo (Styloniscidae: Styloniscus n. sp.?) y una especie de Symphyla (Myriapoda: Symphyla n. sp.?) y cinco especies representan nuevos registros en la isla. Cuando se comparó la información de la detección de artrópodos, el muestreo por cebo dio como resultado la detección de una cantidad más grande de especies que el de una búsqueda intuitivamente dirigida de tiempo y las estaciones de cebo que utilizaban entrañas de pescados y pollos dio como resultado una detección de 65% de insectos. La información de la temperatura recolectada en los lugares de muestreo reveló bajas fluctuaciones diurnas y sugieren que nuestros lugares de muestreo fueron seleccionados correctamente dentro de las zonas profundas de las cavernas. Todos los artrópodos identificados hasta ahora parecen ser especies invasivas, no nativas. Aunque no se confirmó la presencia de artrópodos troglomórficos durante este estudio, no podemos descartar la posibilidad de su existencia. Nosotros en vano intentamos recolectar un ácaro potencialmente adaptado a las cuevas. Las zonas de cavernas profundas de Rapa Nui permanecen bajo muestreo y existen varias áreas que ameritan investigación adicional.
Jut Wynne
added a research item
Rapa Nui (Easter Island) has undergone an environmental transformation over the past several hundred years. Today, no stands of native vegetation remain and all terrestrial vertebrates have gone extinct. The recent discovery of 10 endemic cave-restricted arthropods (including eight new species) prompted an island-wide search for endemic arthropods in areas somewhat sheltered from human activities, livestock and rats, as well as within patches of native vegetation. We sampled 47 sites across the island including 20 caves, 10 cliff faces, the three crater lakes, eight rocky coastlines, the two main beaches, four control sites, and two inland surface areas containing patches of native ferns. Less than 2% of the ~20,000 specimens have been examined. From the examined materials, at least 32 distinct morphospecies have been identified including nine potentially undescribed (i.e., new and potentially endemic) species, three new island records of nonnative species, and the range expansions for three well-established invasive species. We provide recommendations for future research and monitoring, as well as a framework for managing the area supporting the 10 previously discovered endemic species.
Jut Wynne
added a research item
https://blogs.scientificamerican.com/guest-blog/the-hunt-for-endemic-insects-on-easter-island/
Jut Wynne
added an update
Rapa Nui (Easter Island) has undergone an environmental transformation over the past several hundred years. Today, no stands of native vegetation remain and all terrestrial vertebrates have gone extinct. The recent discovery of 10 endemic cave-restricted arthropods (including eight new species) prompted an island-wide search for endemic arthropods in areas somewhat sheltered from human activities, livestock and rats, as well as within patches of native vegetation. We sampled 47 sites across the island including 20 caves, 10 cliff faces, the three crater lakes, eight rocky coastlines, the two main beaches, four control sites, and two inland surface areas containing patches of native ferns. Less than 2% of the ~20,000 specimens have been examined. From the examined materials, at least 32 distinct morphospecies have been identified including nine potentially undescribed (i.e., new and potentially endemic) species, three new island records of nonnative species, and the range expansions for three well-established invasive species. We provide recommendations for future research and monitoring, as well as a framework for managing the area supporting the 10 previously discovered endemic species.
Wynne, J.J. F. Ika, S. Yancovic Pakarati, L. Gonzales, P. Lazo Hucke, S. Manuheuroroa, L. Pakarati, D. Bristow, R. Rodríguez Brizuela, E. Fies, N. Glover, W. L. Hicks, D. Kisner, I. Marinakis, B. Shipley, B. Yeager, C. Villagra, E. Tucki, and R. Scherson. 2016. Island-Wide Search for Endemic Ground-dwelling Arthropods in Extreme Environments of Rapa Nui: Final Report. On File with The Explorers Club, New York, NY. Pp. 28.
 
Jut Wynne
added a project goal
Rapa Nui (Easter Island) has undergone extensive environmental change. Today, all native terrestrial vertebrates and most native plants have gone extinct. Today, the island ecosystem is dominated by a community of nonnative animals and plants. Insects are that remain of the endemic native fauna. By sampling caves, cliff faces, rocky and sandy shorelines and crater lake shorelines, we will increase the number of endemic insects known to the island.Through improving our knowledge of the extent of endemic insects on the island, we can better manage and protect them.