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Authors: Zarders, Jorden Alexander
Advisor: Eiben, Jesse A.
Keywords: Entomology
Conservation biology
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Issue Date: Jun 2018
Abstract: Risks posed to ecosystems by invasive species are dependent on the unique characteristics of the environment and the specific species that may be introduced. This study assesses the ability to detect non-native species threats, evaluates the risks posed by these species, and tests the recommendations to mitigate risks posed by non-native arthropods to alpine habitats on Maunakea, Hawaiʻi. Such non-native species have the potential to drastically alter populations of native biota, affect ecological processes, and impact human health. This work is intended to facilitate improved management capacity on Maunakea while increasing the body of knowledge for addressing management of non-native arthropod species in general.
The occurrence of non-native arthropod taxa collected during 2015-2016 at the subalpine-alpine region (2,800-4,000 m elevation) and lower elevation sites (below 2,800 m) associated with regulated human activities occurring on the mountain are documented in this study. I assessed and recorded sampling effort, arthropod species and morphospecies diversity and trapping techniques at subalpine (Halepōhaku, 2,800 m) and alpine (Astronomy Precinct, 4,000 m) ecosystems on the south slope of the mountain at proposed astronomy facility construction areas. These proposed construction areas and staging sites were surveyed for arthropods over an 11-month monitoring period. I also sampled for and recorded potential invasive non-native species found at lower elevations (20-2,000 m) that may be transported to the subalpine and alpine areas by official users of facilities associated with astronomy-related activities on the summit regions of Maunakea. At the mountain alpine and subalpine areas, potential arthropod invasive species detections consisted almost entirely of spiders for all sampling efforts, with the notable exception of a single ant species found twice at the 2,800 m Subalpine site. Sampling efforts effective at detecting ecosystem or human health threat non-native taxa (as defined in management plans) and non-threat taxa are evaluated through species accumulation curves. Non-threat arthropod taxa accounted for approximately 50% of trap captures, and occasional new morphospecies detections continued throughout the duration of the sampling period. Baited sticky traps detected threat taxa at greater rates than other trapping techniques and this method accounted for 80% of the total threat taxa captured; whereas non-threat taxa were captured more often and in greater numbers using baited sticky and yellow pan traps than other trapping techniques. Regular monitoring throughout the year using the methods tested will be likely to record many rare events of potential threat taxa introduction so that mitigation efforts (via physical, chemical, or biological control methods) could be enacted to reduce the overall threat risks associated with invasive arthropods. Furthermore, the sampling efforts did not detect some types of threat taxa identified by land management authorities that are known in the areas surveyed (social wasps, Vespula pensylvanica), which provides insight into the potential shortcomings of current sampling effort methods. This suggests further study and refinement of invasive arthropod monitoring protocols will require refinement to account for arthropod threats at the Maunakea summit region.
Currently, regular potential invasive species inspection of facilities and locations directly associated with telescope or land management activities on Maunakea is limited to University of Hawai‘i (UH) managed lands at the summit region and subalpine (Halepōhaku) and does not include sites elsewhere around the island. This study also explores the presence of ant occurrence at these non-high elevation support facilities and surveyed vehicles as possible pathways for invasive species movement associated with telescopes and land management activities on UH managed lands. To evaluate potential invasive arthropod threat introduction from source point sites, surveys were conducted using ant-targeted baited vials, hand searches, and vehicle sampling events as evaluations to compare threat taxa incidence rates between vehicles and facilities typically being used by high elevation telescope support staff. Ant occurrence and sampling techniques were evaluated to determine species presence at all astronomy related support facilities below 2,800 m and if vehicles may be a pathway for species movement between sites. Surveys of sites below 2,800 and facilities revealed ant presence primarily in developed urban locations in Hilo and Waimea, and the numbers of species present were very limited at 2,000 m elevation sites on the southern flank of Maunakea. The dominant ant species found at these 2,000 m elevation sites, the Argentine ant (Linepithema humile) although currently not found within the 2,800+ m habitats, is the greatest threat species to the summit region, as it is known to survive high elevation alpine temperatures and ecosystems in other locations (~3,000 m). L. humile was found as high as 2,150 m along the sole road that can be traveled to the summit.
Evaluations of practices to prevent transport of species between lower and upper elevation sites included vehicle pathway assessments which revealed that vehicles subject to management authority-recommended decontamination procedures have fewer incidences of threats, that threat Formicidae species were detected using multiple sampling methods, and these methods should be used to increase threat ant species detection. The surveys revealed that threat species of ants do occur at low elevation telescope facility sites and that regular decontamination of vehicles reduced the occurrence of ants. Regular washing of vehicles that drive primarily between Maunakea subalpine and alpine facilities and low elevation support facilities is associated with less threat taxa on or in vehicles. Regular vehicle decontamination and prophylactic bait treatments would be more likely to interrupt establishment and lifecycles of threat taxa in vehicles that occasional undergo episodic cleanings or treatments, therefore regular decontaminations and treatments are recommended.
Pages/Duration: 63 pages
Appears in Collections:Tropical Conservation Biology and Environmental Science

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