TCBES Theses

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INTRASPECIFIC VARIATION IN HOME RANGE SIZE, OVERLAP, AND MOVEMENT BEHAVIORS OF ‘IO - THE HAWAIIAN HAWK (BUTEO SOLITARIUS)
(University of Hawaii at Hilo, 2024-05) Durham, Amy; Ostertag, Rebecca; Tropical Conservation Biology & Environmental Science
‘Io (Buteo solitarius) is the only endemic hawk species across the Hawaiian archipelago and their range is restricted to Hawai‘i Island. Their federal delisting in 2020, alongside their cultural and ecological significance, emphasizes the importance of sustained long-term population monitoring efforts. However, existing home range estimates for the species are outdated, and research on their spatial behaviors remains deficient. This study aimed to update ‘io home range estimates while providing insights into their movement strategies and space-use sharing patterns. From June 2022 to October 2023, solar GPS-GSM transmitters tracked 43 ‘io on the east side of Hawai‘i Island. Using continuous-time stochastic process (CTSP) models and an autocorrelated kernel density estimator (ADKE), the estimated median home range size for the population was 616 hectares, which is larger than previous estimates obtained using traditional tracking and analysis methods. Although no significant difference in home range size existed across sex and age groups, it varied based on movement strategy. Birds whose movement patterns remained within a distinct range had smaller home ranges overall than those engaging in an occasional foray or commuting between multiple ranges. Additionally, all individuals within the population shared on average 10% of space, with up to 97% observed between presumed breeding pairs. A high likelihood of pairwise encounters was predicted to occur not only along home range boundaries but also within core areas, indicating a high potential for intraspecies interactions. This study provides new insights into ‘io spatial behaviors and highlights the importance of advanced technology and analytical tools to aid species conservation.
ʻAmakihi kaulana i ka hoʻōla maʻi: Assessing the long-term impacts of chronic infection with avian malaria in Hawai‘i ‘amakihi
(University of Hawaii at Hilo, 2024-05) Stierhoff, Emma; Hart, Patrick; Tropical Conservation Biology & Environmental Science
The introduction of avian malaria (Plasmodium relictum) to Hawai‘i has decimated native forest bird populations, driving many species to extinction, and threatening those that remain. However, one native honeycreeper, the Hawaiʻi ‘amakihi (Chlorodrepanis virens, hereafter referred to as ‘amakihi), has shown resilience against acute infection with avian malaria. ‘Amakihi who survive the acute stage remain chronically infected with low parasitemia levels. Although immediate costs of acute malarial infection have been closely studied, the long-term costs of chronic infection are poorly understood in this species. I assessed the impact of chronic infection on the physiological condition of ‘amakihi near ‘Ᾱinahou Ranch in Hawai‘i Volcanoes National Park. During biweekly banding sessions from May 2022 to August 2023, ‘amakihi were banded, measured for tarsus and wing chord, and weighed, and a blood sample was collected for each bird. Using the blood samples, I measured hematocrit, triglycerides, and reactive oxygen metabolites (ROMs) to assess physiological condition, and I determined disease status (undetermined or positive) using qPCR. There were no detectable differences in hematocrit, triglycerides, nor ROMs based on disease status. Body condition was slightly higher in birds that could be confirmed chronically infected than those that were undetermined, but this difference did not persist when accounting for all infected birds. Although acute infection with avian malaria has been shown to have significant costs, this study suggests that ‘amakihi surviving acute infection may not have negative long-term fitness impacts. These results further demonstrate the resilience ‘amakihi have against avian malaria and set the foundation for future research to determine factors facilitating this resilience and how that knowledge might be applied to protect more threatened honeycreeper populations.
Targeting Infection at the Source: evaluating the efficacy of semiochemical repellent compounds in the management of rapid ʻōhiʻa death-associated ambrosia beetles
(University of Hawaii at Hilo, 2024-05) Mikros, Dan; Hart, Patrick J.; Tropical Conservation Biology & Environmental Science
Rapid ʻōhiʻa death (ROD) is a highly virulent and aggressive fungal disease that has been devastating ʻōhiʻa forests on Hawai‘i Island since the mid 2010s. ʻŌhiʻa (Metrosideros polymorpha) is the dominant keystone tree species in native Hawaiian wet forests and its decimation could lead to an ecological collapse. . Therefore, management strategies for preventing ROD transmission are crucial. Ambrosia beetles have been implicated as the primary dissemination agents of environmental inoculum and have the capacity to directly transmit the pathogens as well. Currently, the only widely endorsed management recommendation is to fell and tarp infected trees, thereby physically isolating beetles and inoculum from the environment. But this is often neither practical nor does it offer a preventative strategy for inoculum production. Alternatively, non-toxic semiochemical repellents, which exploit the beetles’ chemical communication system, have been shown to be effective against similar ambrosia beetle species, and may be useful in regards to ROD. I tested the efficacy of two semiochemical repellents, SPLAT Verb® (10% verbenone) and SPLAT Beetle Guard® (10% verbenone + 10% methyl salicylate) for their ability to reduce beetle attack, colonization, and frass production when applied to felled ROD-Ceratocystis infested ʻōhiʻa wood in order to examine the products’ utility as an alternative post-felling management solution. Verbenone alone displayed the capacity to reduce new beetle gallery formations and frass production, but not beetle emergence. Verbenone + MeSA also exhibited the ability to reduce galleries, more so than verbenone in one of the trials, and reduced beetle emergence and frass production. As beetle attack and frass production are the primary concern to inoculum dissemination, both products show a strong potential for use as an active ROD management treatment. After felling trees, new beetle attacks subsided to near zero across all treatments by week 10 in both trials, suggesting a single application of repellent is suitable to protect target trees for the extent of their host-suitability period post-felling. Semiochemical beetle repellents will play a pivotal role in the multifaceted management approach that is needed to manage the disease, and the findings from this project support the growing body of evidence surrounding their use within the ROD pathosystem. Due to the products’ accessibility and ease of use, they offer a comparatively simple management strategy which can be widely employed by land managers and the general public to reduce infectious material in the environment and restrict ROD transmission.
High-Resolution Satellite Imagery: An Alternative Method for the Detection and Monitoring of Rapid ‘Ōhi‘a Death in Hawai‘i
(University of Hawaii at Hilo, 2024-05) Odachi, Nai'a; Perroy, Ryan; Tropical Conservation Biology & Environmental Science
Rapid ‘Ōhi‘a Death has caused extensive mortality of endemic ‘ōhi‘a (Metrosideros polymorpha) across the Hawaiian Islands. First detected on Hawai‘i Island, the responsible Ceratocystis pathogens have now spread to Kaua‘i, O‘ahu, and Maui. Multiple remote sensing efforts such as RGB aerial imagery, laser spectroscopy, and Digital Mobile Sketch Mapping have been successful in identifying mortality outbreaks, although each method has temporal, spatial, or fiscal limitations. In this thesis I explore the utilization of high-resolution satellite imagery with a spatial resolution of £ 0.5 m for individual symptomatic tree identification for field sampling and laboratory testing of the Ceratocystis pathogen. I also analyze landscape scale annual patterns of mortality across East Hawai‘i and compare my findings to annual helicopter- based Digital Mobile Sketch Mapping (DMSM) surveys. Lastly, I created an object detection model using NV5’s ENVI Deep Learning for suspect tree identification and compared the results to DeepForest object detection using the same datasets for training. Results showed that of the individual suspect trees visited in the field (n = 55), 94.5% were successfully located with imagery. Of the trees located (n = 52) using satellite imagery suspects, 98.1% were correctly identified as ‘ōhi‘a. From the subset sampled (n = 35), 40% resulted in a Ceratocystis lukuohia detection. Annual patterns of mortality were found to be similar between satellite-identified and DMSM survey datasets and showed rapid increases in mortality patterns in initial infection years. Temporal and spatial differences between datasets limit direct comparisons due to the short duration of the red phase that strongly signifies ROD-related mortality. Used jointly, these two datasets provide a comprehensive picture of annual mortality trends across East Hawai‘i. Finally, DeepForest models (F1-score = 0.32 and mAP = 0.73) were significantly better overall compared to ENVI models (F1-score = 0.04 and mAP = 0.017) and were promising for automatically identifying tree mortality in new satellite imagery. These results indicate that high-resolution satellite imagery complements existing remote sensing efforts and can help to create a robust and comprehensive monitoring system. This research documents the utilization of high-resolution satellite imagery for landscape-scale ecological monitoring of forest pathogens in Hawai‘i. These results provide annual mortality trends of Hawai‘i Island and share a pathway for future automated identification of new outbreaks which can be inform land management decisions and be implemented on other islands.
FOREST RESTORATION TECHNIQUES IN A SUB-ALPINE FOREST ON HAWAIʻI ISLAND, KANAKALEONUI, MAUNA KEA.
(University of Hawaii at Hilo, 2023-12) Pigao, Amberly K.; Price, Jonthan P.; Tropical Conservation Biology & Environmental Science
Climate change in Hawaiʻi stands to alter forest succession with native bird populations being threatened by mosquito-borne avian disease, forested corridors may create a path to higher elevation habitats with less disease threat. Areas with an abundance of fog may be key in forest self-regeneration but because many of these areas have turned into degraded grasslands, water capture by trees and subsequent regeneration is not occurring. An enclosed 514 acre (208 ha) area, Kanakaleonui Bird Corridor (KBC), located on the east slope of Mauna Kea, is a unique transition zone from a Tropical Montane Cloud Forest (TMCF) to a colder, drier subalpine forest. We conducted two separate experiments at two elevation zones (a lower site at 2,200 m; 7,150 ft. and an upper site at 2,400 m; 7,900 ft.) to understand how fog water capture may facilitate seedling growth. For the first experiment Acacia koa and Sophora chrysophylla were used as nurse trees to both capture fog and buffer seedlings from high and low temperatures. For the second experiment synthetic fog structures were built along existing fence lines to capture moisture as fog passes through. Experimental plantings involved seedlings of five species: māmane (Sophora chrysophylla) naʻenaʻe (Dubautia arborea), ʻaʻaliʻi (Dodonaea viscosa), pāwale (Rumex giganteus), and ʻāweoweo (Chenopodium oahuense). These were planted under nurse trees, along a fence with 40% and 63% shade cloth, along a fence without shade cloth, and in control plots away from nurse trees and fences. ZENTRA soil moisture probes and HOBO temperature gauges were installed at each experiment. Species survival and growth responses to each treatment were generally higher in fence and nurse designs than in control plots (although survival was significant and growth was not significant). Seedings in the lower site still survived in control plots, but seedlings in the upper site, which is drier, had a high mortality rate in control plots. The results indicate that shade cloth and nurse trees facilitate fog water capture at KBC where fog is frequent. Future restoration efforts can benefit from fog capture strategies to successfully restore native Hawaiian forest.
Signal Interactions Between Native and Introduced Forest Birds of Hawaiʻi Island and Predicting Distance of Signals from Their Energy
(University of Hawaii at Hilo, 2023-12) Hunt, Noah James; Hart, Patrick J.; Tropical Conservation Biology & Environmental Science
Passive acoustic monitoring using autonomous recording units (ARUs) offers uniqueopportunities to investigate both theoretical and applied ecological questions. I used Song Meter SM4s to answer: (1) whether native and introduced birds in Hawaiʻi are dividing acoustic space in time and frequency, and (2) whether wildlife managers can improve their density estimates of bird species by achieving unbiased distance measurements from ARUs. First, using recordings I collected from a diversity of vegetation types, I compared the observed overlap between introduced and native bird vocalizations from what was expected under a null model of 500 vocalization randomizations. I found that overlap did not differ from the null distribution and was unaffected by community composition nor vegetation type, suggesting that introduced birds are not having a strong impact on native forest bird communication. Second, using field recordings collected while observing vocalizing birds, I modeled distances between birds and the ARUs, measured from range finders as a function of the random effects of maximum power level (amplitude) of bird vocalizations, the orientation of the bird to the microphone, and wind and rain levels, with the species and call type as fixed effects. Overall, there was no strong relationship between distance and any of the random effects. However, when modeling within individual call types, I found four call types among four species showing relationships between distance and sound power level, suggesting that while this method has potential for wildlife monitoring, it requires further refinement.
EFFECTS OF CLIMATE CHANGE AND FISHING PRESSURE ON CIGUATERA PREVALENCE IN HAWAIIAN REEF FISHES: IMPLICATIONS TO PUBLIC HEALTH IN A CHANGING CLIMATE
(University of Hawaii at Hilo, 2024-01) Rodriguez, Nikola Deborah; Grabowski, Timothy B.; Tropical Conservation Biology & Environmental Science
Ciguatera fish poisoning (CFP) is caused by consuming reef fishes containing toxins produced by epiphytic dinoflagellates in the genus Gambierdiscus. Changing reefscapes due to climate change and altered reef fish assemblages from overfishing may increase the range of and habitat available to Gambierdiscus spp. while altering how ciguatoxins (CTX) move through coral reef food webs. However, it is not clear how these factors may interact to influence the probability of ciguatoxic fishes and thus the risk of CFP to local communities dependent upon these fisheries. Therefore, the objectives of this study are to 1) evaluate the relationship between a suite of habitat characteristics at multiple spatial scales, including those related to changing temperature regimes and fishing pressure on the probability of fish testing positive for CTX; 2) evaluate the relationship of the same habitat characteristics on the concentration of CTX; and 3) assess the degree to which local fishing communities practices and beliefs that are used to limit risk of CFP agree with the findings of the first two objectives. I evaluated the presence and concentration of ciguatoxins in two common reef fish species: the high-level predator, Peacock Grouper (Cephalopholis argus), hereafter referred to by its Tahitian name – Roi, and a frequently sought-after herbivore, Goldring Bristletooth (Ctenochaetus strigosus), known as Kole in Hawaiian, sampled bi-annually across four sites along west Hawaiʻi Island. For Roi, both the probability of testing positive for CTX and CTX concentration exhibited a positive relationship to length and negative relationship to the number of days under a coral bleaching alert and fishing pressure. For Kole, the probability of testing positive for CTX was negatively related to length, the number of coral bleaching alert days, effluent, fishing pressure. The concentration of CTX in Kole was also negatively related to length, effluent, fishing pressure, and mean percent live coral cover. Most anglers and spearfishers are unlikely to restrict their fishing activity in response to CFP risk, instead tending to avoid species, size classes, or fishing areas perceived as high risk. However, my results suggest that fish behaviors are likely to become less effective as changing temperature regimes, loss of live coral cover, and human fishing pressure may be altering the prevalence and distribution of ciguatoxic fishes. The results of the study will allow resource managers to better communicate the risk of CFP to anglers and spearfishers so they can mitigate the dangers of ciguatera fish poisoning in a fast-changing climate.
Behavior, infestation, and molecular characterization of Cryptophlebia spp. (Lepidoptera: Tortricidae) associated with macadamia nut in Hawai'i
(University of Hawaii at Hilo, 2023-12) de Rocquigny, Nathalie Brigitte Marie; Arancon, Norman Q.; Tropical Conservation Biology & Environmental Science
Macadamia nut (Macadamia integrifolia Maiden & Betche, 1899), one of Hawai'i’s largest agricultural commodities, is susceptible to attacks by several insect pests that reduce yield and profit. Among these pests are two species of Tortricid moths, Cryptophlebia illepida and C. ombrodelta, which cause significant damage to the husk and kernel of macadamia nuts. Currently, growers in Hawai'i have limited options for managing these pests. This limitation is due to their feeding behavior that renders insecticide applications ineffective, their persistence in the orchards year-round due to the phenology of macadamia nut and presence of alternative hosts, and the lack of comprehensive research on these pests. This study aims to investigate Cryptophlebia’s spatial and temporal trends across the macadamia nut growing season to facilitate the development of pest management strategies. Delta traps baited with sex pheromone mixture were utilized to assess male Cryptophlebia populations within and around two macadamia nut orchards in Kea'au and Kapa'au, Hawai'i. Immature nuts were collected and examined from the tree and mature nuts from the ground were sampled to assess for oviposition and injury during the 2022 macadamia nut growing season, spanning from May to October. The numbers of hatched eggs, injury per nut, and total injury of nuts were greater in the exterior of the orchards, than the interior of the orchard. Moreover, male moths and eggs were more abundant in May, June, and July, suggesting that Cryptophlebia mating occurs mostly during the flowering stage of macadamia and egg laying happens shortly thereafter. Furthermore, molecular analysis using DNA barcoding was conducted on collected larvae to determine the species composition of Cryptophlebia in Hawaiian macadamia nut orchards. The species composition was compared to the proportion of adult C. ombrodelta and C. illepida moths caught in delta traps to determine if populations of the endemic C. illepida had decreased since the last time Cryptophlebia were assessed in the field, approximately 30 years ago. These findings provide valuable insights that will guide producers to adhere to a timely and focused integrated pest management (IPM) plan to decrease production inputs such as cost of labor and application of chemicals.
CONDUCTING REEF FISH SURVEYS THROUGH A NEW LENS: THE TRANSFORMATIVE POTENTIAL OF INNOVATIVE TECHNOLOGIES AND COMMUNITY-BASED MONITORING METHODS.
(University of Hawaii at Hilo, 2023-12) Taylor, Zach Thomas; Burns, John HR; Tropical Conservation Biology & Environmental Science
Coral reef fishes in Hawai‘i are economic pillars both as subsistence and commercial food sources, and for ecotourism, with greater than 70% of the value being associated with subsistence activities. Current monitoring efforts are heavily focused on using a single method of open circuit (OC) SCUBA diving by certified scientific divers. These methods have been scrutinized in recent years for potential biases, and perhaps more importantly, for excluding many fishers in the community from collecting data that is useful for the management of nearshore fisheries. This thesis describes a comprehensive methods analysis of the standard OC SCUBA-based coral reef fish surveys in comparison to innovative approaches including permanent live-streaming remote underwater video (RUV) system, snorkeling, and freediving. This approach was designed to address the need for more accurate methodology that can be incorporated into inclusive community survey efforts to enhance reef monitoring. We utilized advanced statistical approaches to directly compare species richness, size estimation, and abundance among these different methodologies. Results from principal component analysis (PCA) and linear mixed effects models (LMM) showed that RUV, snorkeling, and freediving offer robust alternatives to OC SCUBA-based surveys and provide accurate data collection without the necessity of SCUBA. The novel live-streaming RUV approach displayed promising capabilities for enabling in-depth insights into ecological processes on coral reefs and continuous data acquisition. Snorkeling and freediving showcased their suitability in sizing and counting fish in shallow reef environments, and the potential for encouraging community engagement and local knowledge integration. This study highlights the transformative potential of innovative methods, encouraging collaboration between researchers and communities for effective coral reef conservation through advancement of coral reef fish monitoring efforts.
FISH MEAL REPLACEMENT BY MICROBIALLY FERMENTED BLACK SOLDIER FLY (Hermetia illucens) LARVAE MEAL IN DIETS FOR JUVENILE MIXED SPECIES TILAPIA (Oreochromis niloticus/O. aureus)
(University of Hawaii at Hilo, 2023-12) Dye, Matthew; García-Ortega, Armando; Tropical Conservation Biology & Environmental Science
One of the primary objectives of sustainable aquaculture is to reduce the use of marine resources like fish meal (FM) and fish oil (FO) traditionally utilized in aquafeeds. A promising alternative protein source used for aquafeeds is the protein meal from the black soldier fly larvae (BSFL), though, presently, full replacement of protein from FM with insect meals has not been achieved. This study aimed to elucidate the potential of kōji (Aspergillus oryzae) fermented black soldier fly larvae (fBSFL) meal to replace FM at cumulative substitution levels in diets for juvenile mixed sp. tilapia (Oreochromis niloticus/O. aureus). A Control diet (FM-100) based on commercially produced FM was used as a reference and three experimental diets were prepared to replace FM with fBSFL meal at levels of 10% (INS-LOW), 25% (INS-MED), and 50% (INS-HIGH), respectively. All diets were formulated to contain 45% crude protein and 10% crude lipid. A fish feeding trial in a recirculating aquaculture system was performed. The diets were fed to triplicate groups of 10 fish (0.5 ± 0.0 g) twice a day for 57 days. Final fish weight, specific growth rate (SGR), and survival of mixed sp. tilapia fed the experimental diets showed no significant differences (P > 0.05) compared to the Control diet. There were significant correlations (P < 0.05) in total omega-3 (n-3) fatty acids (FA) between diets and fish whole body FA composition. The results of this study suggest that the replacement of up to 50% of FM with fBSFL in diets for juvenile mixed sp. tilapia does not significantly affect fish growth, SGR or survival rate. Further studies should evaluate the refinement and digestibility of fBSFL proteins used in this study to optimize feeds for juvenile mixed sp. tilapia.
Shifts in Carbon Flux from a Hawaiian Watershed due to Climate Change
(University of Hawaii at Hilo, 2023-12) Boger, Walter Loc-Ming; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental Science
Climate change is affecting the quantity, quality, and sources of riverine carbon (C) that are exported from terrestrial ecosystems to coastal waters. While tropical islands in Oceania comprise 3% of the Earth’s land mass, they contribute 21% to 38% of total organic carbon (OC) flux to the world’s oceans. This study focuses on climate change induced shifts in carbon exports on the Wailuku River, Hawai‘i, USA. Concentrations of coarse particulate organic carbon (CPOC), fine particulate organic carbon (FPOC), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) were measured as well as carbon: nitrogen (C:N) ratios, CPOC composition, δ13C values for different carbon forms and species, and δ18O- and δ2H of H2O to identify carbon sources and quality. Concentration and discharge data were used in LOADEST to calculate current monthly and annual carbon fluxes, as well as potential future fluxes impacted by climate change. Concentrations of all carbon forms were affected by discharge, except CPOC. The primary source of OC to the river was leaf litter, and the source of DIC was basalt weathering; neither changed with discharge. Wailuku river δ18O and δ2H values of H2O decreased with increasing river discharge. Although a large variation in C:N was observed, the quality of FPOC decreased with increased discharge. Shifts in total carbon fluxes were linked to climate change driven variations in baseflow, which in turn caused significant variations in DIC, but not in CPOC, FPOC, and DOC. To best advise public policy and take adaptive management actions to mitigate the effects of climate change, a better understanding of Oceanic river contributions to the global carbon flux is needed. An important step in that direction is to quantify the different forms of carbon that contribute to the riverine carbon budget.
SEA TO DIGITAL REALITY: COMPARATIVE ANALYSIS OF UNDERWATER STRUCTURE FROM MOTION PHOTOGRAMMETRY PLATFORMS AND THEIR INTEGRATION INTO AN IMMERSIVE AUGMENTED REALITY APPLICATION
(University of Hawaii at Hilo, 2023-08) Spengler, Alexander J.; Burns, John HR; Tropical Conservation Biology & Environmental Science
Underwater 3D reconstruction tools play an important role in advancing the study and preservation of coral reef environments. This study assessed the viability of small action cameras, such as the GoPro Hero4, to serve as a comparable image collection platform to entry level DSLRs like the Canon 60D. The sensor and optical characteristics of a given camera system influence the accuracy and quality of 3D reconstructions. Examining the performance characteristics of action cameras is critical for assessing if these cheaper and simpler platforms can produce comparable data to the larger DSLR systems. . The findings from this study indicate that the GoPro Hero4 falls short in several key aspects compared to the Canon 60D, challenging its potential as a viable alternative. The Canon 60D's larger sensor size and lens allow for higher resolution and visually rich images, both of which are essential for accurate 3D reconstructions. The GoPro Hero4’s small sensor and short lens introduce chromatic aberration, distortion, overexposure, and color accuracy issues which compromise the quality and precision of resulting 3D models. These limitations, along with disparities in quantitative metrics, highlight the challenges associated with using action cameras as DSLR replacements. However, for research objectives that are less dependent on fine detail, such as habitat structure metrics, small action cameras may offer comparable performance to established platforms like DSLRs. Identifying the performance thresholds of camera systems can provide useful information for scientists and organizations planning to integrate 3D reconstruction techniques into their research and monitoring of coral reefs.This study also introduces an augmented reality (AR) application that allows users to explore and learn about underwater coral reefs and historical shipwrecks in the Pacific Ocean. The application leverages underwater photogrammetry data captured during scientific expeditions to create accurate 3D models of these environments. The Unity game engine and Vuforia AR engine are used to develop an interactive and immersive application. The AR app not only provides virtual access to these underwater environments but also incorporates educational content, interactive annotations, and informative overlays to enhance the user experience. The study also discusses the methods used for data acquisition and photogrammetry, application development, and publishing. The effectiveness of the AR application is evaluated through user feedback and performance testing. The app has been well-received, with positive ratings and downloads on both iOS and Android platforms. The study concludes that the app has successfully bridged the gap between scientific data and the general public, fostering engagement, experiential learning, and environmental awareness. Future improvements could focus on expanding the number of targets and reducing the app's file size to enhance user engagement and accessibility.
ʻO KE KAHUA MA MUA, MA HOPE KE KŪKULU: INVESTIGATING THE RELATIONSHIP BETWEEN THE FUNCTIONAL TRAITS OF LEAF LITTER AND LITTER-DWELLING ARTHROPODS
(University of Hawaii at Hilo, 2023-05) Robins, Casey Anuhea; Ostertag, Rebecca; Tropical Conservation Biology & Environmental Science
The interactions between leaf litter and litter-dwelling arthropods are often overlooked in restoration strategies, despite their importance in facilitating key ecosystem processes and functions. It is also unclear how plant community composition affects our litter-dwelling faunal communities, and the factors governing these relationships. Trait-based ecology presents a good opportunity to study the interactions between leaf litter and litter-dwelling arthropods, and can be useful in uncovering the underlying principles behind their community assemblage patterns. I studied the relationship between the traits of leaf litter and litter-dwelling arthropods in a Hawaiian lowland wet forest (Hilo, Hawai‘i) by 1) identifying how arthropod community composition and functional traits differ between native and introduced plant species, 2) determining if there are correlations between the traits of leaf litter and litter-dwelling arthropods, and 3) comparing the litter-dwelling arthropod functional trait variation of different plant community assemblages used in restoration. I collected leaf litter samples from 20 plant species and four plant communities to quantify their arthropod community composition, and compared their functional trait relationships. For the species litterbags, a total of 14,347 individuals were collected, with 151 different morphospecies. For the treatment litterbags, a total of 73,976 individuals were collected, with 219 different morphospecies. Overall, plant species and their traits were found to influence arthropod community composition. Plant species with traits tending towards the slow, conservative end of the spectrum were found to be strongly associated with larger, more predatory arthropods; and plants with moderate, more acquisitive traits were strongly associated with smaller arthropods lower in trophic positions. Introduced plant species were shown to have similar arthropod abundance and richness as native plant species, emphasizing the potential benefit of including introduced plant species in the restoration of highly degraded ecosystems. Results also showed no difference in arthropod trait variation between plant community assemblages with complementary and redundant plant functional trait profiles, suggesting that resource functional diversity does not support higher niche availability for consumers. Establishing significant linkages between the traits of leaf litter and litter-dwelling arthropods can deepen our understanding of principles governing these relationships, and guide restoration managers in creating strategies that are inclusive to species interactions on a micro-scale.
Pockets and Pathways to Invasion: Developing Improved Mosquito Monitoring in High Elevation Forests on Hawaiʻi Island
(University of Hawaii at Hilo, 2023-05) Mladinich, Stephanie K.; Hart, Patrick J.; Tropical Conservation Biology & Environmental Science
A diverse and globally prevalent disease, avian malaria (Plasmodium relictum Grassi and Feletti) is transmitted by the introduced southern house mosquito, Culex quinquefasciatus Say (Diptera: Culicidae) and is the primary driver of rapidly declining populations and extinctions of native Hawaiian forest birds. The urgency and severity of the threat to native Hawaiian forest birds has served as the impetus for studies to understand the dynamic context of the invasion and establishment of mosquito populations and disease transmission into increasingly higher elevations in the context of climate change. In recent years, the focus has shifted from documenting the invasion of mosquitoes and the decline of the bird populations, to implementing solutions that have the potential to safeguard the birds from further decline and extinction, such as landscape-level mosquito control. However, in order to effectively implement these solutions, robust and detailed mosquito surveillance data is needed, particularly in high elevation forests. My thesis research leveraged conventional mosquito monitoring methods alongside climate monitoring and innovative environmental DNA techniques to enhance mosquito monitoring in remote sites across the Hawaiian Islands. In my first chapter, I explored a three-tier, low-cost, continuous surveillance approach for monitoring adult mosquito populations, feral pig-created larval mosquito habitat, and climate suitability conditions for the invasion and establishment of the avian malaria vector, C. quinquefasciatus, in two high elevation forests on Hawaiʻi Island. I found little evidence of invasion by C. quinquefasiatus at either site, despite suitable climate conditions for both vector and parasite development present over half of the year, alongside variable larval habitat between fenced and unfenced sites. In my second chapter, I developed an environmental DNA assay that targets the cytochrome oxidase subunit I (COI) gene for the detection of C. quinquefasciatus in aquatic larval habitat. I found the primer-probe set to be highly efficient in the detection of known presence of C. quinquefasciatus from lab samples and performed the foundational steps for the assay to be tested in a field setting as a tool for detection. My work emphasizes the importance of continuous monitoring and contributes to the continued enhancement of reliable and rigorous methods for monitoring the spatial and temporal distribution and abundance of mosquito populations, along with environmental conditions for population establishment that are critical for vector and disease management.
Characterization of Queensland Longhorn Beetle (Acalolepta aesthetica Olliff) Distribution, Host Selection Preference, and Environmental Correlations in Puna District, Hawai‘i County, Hawai‘i.
(University of Hawaii at Hilo, 2022-12) Miles, Blake Jonathan; Arancon, Norman Q.; Tropical Conservation Biology & Environmental Science
Queensland longhorn beetle (QLB; Acalolepta aesthetica Olliff) is an invasive polyphagous plant-boring insect of Hawai’i County, Hawai’i, native to Australia (including Queensland). QLB presence in Hawai’i County was first reported circa July 2009 in a Hawaiian Acres residental property in Puna district. Current distribution range of QLB in Hawai’i County is believed to be expanding at a slow rate across Puna and into neighboring districts. Effective management of QLB constitutes region-specific studies including biology, ecology, life history, and reproductive behavior that are largely undescribed at present. Without effective management, unabated expansion to QLB population range and density in Hawai’i County may lead to disruptive environmental, economic, and cultural impacts, as well as heightened risk of QLB introduction to surrounding counties and United States mainland. A total of 1,087 trees – consisting of kukui (Aleurites moluccanus), breadfruit (Artocarpus altilis), trumpet tree (Cecropia obtusifolia), citrus (Citrus spp.), and cacao (Theobroma cacao) – were surveyed and analyzed to assess: (1) current distribution from October 2020 to March 2021; (2) host selection preferences; and (3) infestation-environmental correlations associated with the local QLB population. Analyzed plant taxa were situated among 20 private properties in Puna district (East Puna, Keaau, Kurtistown, Mountain View, Pāhoa); were sampled a minimum of 15 times; and were represented by at least five individuals infested with QLB larvae. Host range of QLB in Queensalnd, Australia is not known. Access to host species density data pertinent to Puna district were not available. Survey data was analyzed using R software (version 4.0.3) via mixed effects logistic regression modeling, multiple comparisons of means post-hoc analysis (Tukey contrasts), and DHARMa (R package model diagnostic tool). Mapping of active QLB infestations did not indicate presence of significant distribution, irrespective of host species. QLB distribution could be influenced by a combination of opportunistic infestation; host condition and stress; and aggregation pheromone synergism. Kukui was significantly preferred by QLB over trumpet tree, citrus, and breadfruit. Cacao was also significantly preferred by QLB over trumpet tree, citrus, and breadfruit. Preferred host selections could be driven by reception to specific and complex phytochemical motifs, many of which contain phenolic and terpenoid compounds. QLB infestation among cacao and breadfruit trees correlated strongly and positively with annual precipitation (mm), with breadfruit infestation also correlating strongly and positively with elevation (m). Attraction to breadfruit and cacao trees may be attributed to host physiological stress from excess precipitation exposure. Relationship of precipitation in influencing QLB infestation is possibly variable. Influence of elevation in influencing breadfruit infestation is unclear. Overall, observations from this study are preliminary but hope to help further ongoing efforts between addressing biological and ecological knowledge gaps surrounding QLB and devising invasive species management plans.
Development of new bioacoustics tools to monitor and better understand populations of two critically endangered bird species on Maui
(University of Hawaii at Hilo, 2022-12) Kekiwi, Erika; Hart, Patrick J.; Tropical Conservation Biology & Environmental Science
Bioacoustic monitoring using automated recording units (ARUs) offers an alternative method to monitor vocalizing wildlife compared to traditional methods. Some benefits of using ARUs include flexible scheduling, infinite replayability, and the ability to collect large datasets with minimal effort. Still, a drawback is the time-consuming nature of reviewing recordings for target species. Automatic detection algorithms can expedite ARU data analysis; however, automated detection algorithms are not well-developed for Hawaiian forest bird species. Here, I focused on using automated tools to improve monitoring protocols for two critically endangered Hawaiian forest birds: the kiwikiu (Pseudonestor xanthophrys) and the ʻākohekohe (Palmeria dolei). My first objective was to gather training data for the automatic detection algorithm (BirdNET) and use it to examine the differences in vocalization characteristics in my target species in three distinct areas of their population. I deployed ARUs at The Nature Conservancy’s Waikamoi Preserve, Manawainui, and upper Kīpahulu Valley in Haleakalā National Park. For kiwikiu, I found significant differences in the mean length and frequency variability in songs between locations. For ʻākohekohe, I found a significant difference in the mean length of their “squirtle” calls. However, I did not find differences in repertoire sizes or diversity among locations in either species. For kiwikiu songs, I observed that shared syllables occurred most frequently in the same locations, suggesting variation in songs between the sub-populations of kiwikiu. ʻĀkohekohe vocalizations may also vary between the sub-populations. These results demonstrate that some vocalizations vary by location and may indicate the presence of dialects in these species. My second objective was to train the BirdNET algorithm to detect kiwikiu and ʻākohekohe and to test whether the newly trained algorithm could accurately detect kiwikiu and ʻākohekohe in soundscape recordings. This testing occurred in two phases, an efficacy phase, where the identifications BirdNET produced were compared to previously annotated files, and an expansion phase, where BirdNET identified vocalizations in unannotated files. For BirdNET identifications over a 0.50 confidence threshold, BirdNET accurately identified ʻākohekohe 65.8% of the time, and kiwikiu 27.4% of the time. My results demonstrate the potential for using BirdNET to analyze recording data for kiwikiu and ʻākohekohe and improve the tools available to conduct future bioacoustic research for these species.
Colorimetric determination of glyphosate in water using ozonolysis followed by spectrophotometric analysis of phosphate product with molybdenum blue reagent: a simple, fast and inexpensive assay of glyphosate.
(University of Hawaii at Hilo, 2022-12) Criscione, Rose; Platz, Matthew; Tropical Conservation Biology & Environmental Science
A simple and inexpensive assay for quantifying glyphosate in aqueous environments using ozonolysis followed by spectrophotometric analysis of phosphate product with the molybdenum blue reagent has been developed. Glyphosate was oxidized with ozone gas in the presence of sodium hydroxide (1*10-3M) and then reacted with the molybdenum blue reagent to yield a colorimetrically quantifiable phosphate product. The absorbance of the heteropoly blue color complex was measured at 830 nm. The concentration of glyphosate was determined using a standard phosphate calibration curve concentration range from 10-4 to 10-8M in the presence of NaOH (1*10-3M). The reliable detection limit of glyphosate in aqueous environments when using ozonolysis and spectrophotometric methods was found to be 1*10-5M. The method developed in this study may be applicable in aquatic environments such as streams and estuaries and can be used by high school students, undergraduates, and field workers to obtain quantitative data.
A COMPARATIVE CO2 LIFE CYCLE ANALYSIS OF THREE NUTRIENT SOURCES FOR A NOVEL OFFSHORE MACROALGAE FARM IN HAWAI’I
(University of Hawaii at Hilo, 2022-12) Chambers, Trevor; Hopkins, Kevin; Tropical Conservation Biology & Environmental Science
Large-scale offshore seaweed cultivation systems using novel technologies have the potential to sequester large amounts of CO2, potentially decreasing ocean acidification, while producing biomass that could be converted into fuel. However, low nutrient concentrations in offshore sea surface water (SSW), such as those seen surrounding Hawai’i Island, are a primary constraint to seaweed growth. Nutrient enhancement through the upwelling of deep-sea water (DSW) and artificial fertilization (AF) could provide the additional nutrients required to increase seaweed growth rates, but it is unknown if these novel systems are sustainable. Therefore, the objective of this study was to model the growth of three seaweed species: Ulva lactuca, Gracilaria parvispora, and Halymenia hawaiiana, to determine the potential CO2 sequestration capacity. Deterministic models were used to estimate the CO2 emissions of the various nutrient sources and CO2 sequestration potential of the three species, using 4 different Specific Growth Rates (SGRs), on the hypothetical 1000 hectare offshore farm. Regardless of SGR and species, SSW had the lowest net CO2 impact over a 10-year lifespan (sequestration ranged from 234,658 – 923,011 MT of CO2); DSW showed the greatest net CO2 impact (sequestration ranged from 234,323 – 1,720,416 MT of CO2), and the AF system was almost the same as DSW (sequestration ranged from 226,617 to 1,712,709 MT of CO2). Although all systems sequestered more CO2 than they produced, questions regarding economic viability of each nutrient source must be answered by future research
INVESTIGATING SPINNER DOLPHIN PRESENCE ALONG THE WINDWARD COAST OF HAWAI‘I ISLAND THROUGH BOTH PASSIVE ACOUSTIC MONITORING (PAM) AND BOAT-BASED VISUAL TECHNIQUES
(University of Hawaii at Hilo, 2022-12) Alvarez, Petrisha; Pack, Adam A.; Tropical Conservation Biology & Environmental Science
Spinner dolphins (Stenella longirostris) in Hawaiian waters are known for their predictable diel patterns of feeding offshore during nighttime hours and returning to bays and shallow coastlines to rest during daytime hours. They have been studied extensively since the late 1970s, largely along the leeward coasts of the main Hawaiian islands. In stark contrast, little effort has been dedicated to studies of spinner dolphins occurring along the windward coasts, although dorsal fin photo-identification mark-recapture studies and aerial surveys have confirmed the species’ presence. Here, I provide the first comprehensive study of spinner dolphins along the windward coast of Hawai‘i Island utilizing long-term passive acoustic monitoring (PAM) complemented by boat-based visual and acoustic surveys. Four bottom-moored Soundtrap underwater acoustic recorders were positioned along the Hilo coastline from Onomea Bay to Kealoha beach park (12.6 km²) within 16-25 m, recording 24 hour/day on a 10% duty cycle capturing 30s every 5 minutes from July 1- December 31, 2020. Throughout this period, 10 boat-based surveys were conducted bimonthly spanning 15 km² over the recording locations to confirm species identification and determine behavioral states. During these surveys, the dorsal fins of individual dolphins were photographed for the purposes of identification, and dipped hydrophone recordings of vocalizations were made to compare with spinner dolphin acoustic signaling recorded on the Soundtraps. Single species pods of spinner dolphins were encountered on 60% of boat surveys, with a mean group size of 73.2 (SE = ± 10.2) (mean minimum = 50.6 ± 6.9 SE; mean maximum = 92.7 ± 11.3 SE) comprised of mixed age classes, including calves of the year (mean = 3.2 ± 0.5 SE). Spinner dolphins were observed in Hilo Bay for as long as 4.5 hours. Behavioral states included milling and traveling with individual behaviors including those that had an aerial and/or percussive characteristics, nursing, and intercourse. The analysis of +8,000 hours of acoustic data captured from Soundtraps revealed the presence of spinner dolphins across the study area for 150 days of the 180 day recording period (83%). Spinner dolphin vocalizations were recorded on each Soundtrap with a greater detection rate per day along the Northern coast at Onomea Bay and Honoli‘i beach as compared to the Eastern locations along Keaukaha. Significantly greater acoustic presence was detected during the morning hours between 0600 – 1155 h, compared to the afternoon between 1200 - 1755 h. Overall, these findings reveal significant habitat usage by spinner dolphins of all age classes for resting and socialization purposes along the windward coast of Hawai‘i Island. To the extent that individual spinner dolphins using windward coastlines are distinct from those using leeward areas, future abundance estimates of spinner dolphins off Hawai‘i Island should consider both leeward and windward coastlines.
Sewage Pollution in Keaukaha, Hawaiʻi, U.S.A. : An Area Impacted by Cesspools and Offshore Wastewater Outfall
(University of Hawaii at Hilo, 2022-08) Waiki, Shayla Marie Pualani; Colbert, Steven; Tropical Conservation Biology & Environmental Science
Sewage pollution in coastal waters is concerning for the health of coastal ecosystems and communities worldwide. Sewage enters the environments directly from sewage spills and treated effluent from sewage outfall pipes, or indirectly through groundwater discharge as treated or untreated effluent from on-site sewage disposal systems (OSDS) and injection wells. The presence of sewage pollution in coastal waters can lead to nutrient enrichment impacting coastal water quality and human exposure can also cause health problems. Keaukaha, Hawaiʻi, is an area susceptible to sewage pollution due to the presence of two sewage pollution sources: OSDS and the Hilo Wastewater Treatment Plant (HWTP) sewage outfall pipe. Conducting dye tracer tests, the use of a multi-indicator approach, and including a citizen science survey (the Pilau-meter) the goals of this study were to: 1) identify the connectivity of OSDS to nearshore waters, 2) characterize water quality from HWTP inlet to outfall, 3) compare water quality of OSDS-impacted springs to HWTP outfall plume, and 4) document the intensity of sewage and other smells encountered in Keaukaha using the Pilau-meter and indentify envrionmental factors associated with the presence of specific smells. Dye tracer tests found that sewage from OSDS reached shoreline springs within 20 h – 3 d, with faster flow rates than reported elsewhere in Hawai’i. HWTP influent samples were an order of magnitude higher in FIB concentrations compared to effluent samples, supporting the effectiveness of the wastewater treatment process. Nutrient concentrations increased from influent to pre-outfall samples, while DOC concentrations were three times lower. Shoreline stations were higher in nutrients except for NH4+ and DOC compared to the sewage plume. Sewage smells reported on the Pilau-meter were associated with HDOH advisories on two occasions. Our study confirms the effectiveness of using dye tracers test to determine the travel of OSDS contaminants to nearby shorelines, highlights the effectiveness of chlorination as a wastewater treatment mechanism for reducing FIB, and expands the field of odor science and using the sense of smell in research.

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