Activity Record: Biological Sampling of Rapa Nui Caves, Explorers Club Flag Report (Flag #52) J. Judson Wynne 1 , Armando Azua-Bustos 2 , Peter J. Polsgrove 3 , Knutt Peterson 4 , and Sergio Rapu 5 1 Merriam-Powell Center for Environmental Research, Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA, jut.wynne@nau.edu; 2 Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; 3 Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA; 4 Department of Geography, University of New Mexico, Albuquerque; 5 Department of Anthropology, University of Hawai’i, Mânoa, current address: Tupa’a Hotel, Easter Island, Chile Introduction Caves support some of the most fragile ecosystems on Earth (Elliott, 2000; Wynne and Pleytez, 2005; Wynne et al., 2007). Because many troglomorphic (i.e., obligate cave-dwelling) organisms are endemic to a single cave or region (Reddell, 1994; Culver et al., 2000; Christman et al., 2005), and are generally characterized by low population numbers (Mitchell, 1970; Krajick, 2001), many populations are considered imperiled (Reddell, 1994; Culver et al., 2000). Despite this, cave ecosystems in general remain poorly understood (Wynne and Pleytez, 2005; Wynne et al., 2007). We conducted a literature review searching on “cave biology,” “cave ecology,” “cave” and “arthropods” using “Easter Island,” “Rapa Nui” and “Isla de Pascua” as secondary search terms. Literature searches were conducted via Northern Arizona University’s Cline Library’s scientific collections, the scientific collections at Pontificia Universidad Católica de Chile, Santiago, Chile and Google Scholar. Our review revealed no published information on cave biological investigations on Rapa Nui. It is imperative we begin to document and inventory the biodiversity of Rapa Nui caves because (i) there is no published information regarding these cave ecosystems, (ii) the potential for sensitive and/ or endemic cave-dwelling organisms exists, and (iii) continued unregulated tourism use may place many of these systems and the undiscovered sensitive species they may harbor at risk. Information on biodiversity and endemism on a per cave basis will ultimately provide resource managers with the information necessary to make well- informed decisions to best conserve and manage these fragile resources. Figure 1. This organism has been tentatively identified as belonging to the family Polydesmidae. We are uncertain whether this millipede is cave-limited or if its coloration is due to polymorphism. Credit: J. Wynne. Objectives This work represents the first effort to investigate cave biodiversity on Rapa Nui. Our objectives were to: (a) inventory arthropods and microorganisms present using an array of sampling techniques; (b) identify vertebrate use of caves; and, (c) identify endemic and/ or cave- adapted arthropods.