Browsing by Author "Hart, Patrick"
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Item FURTHER INVESTIGATION OF THE DENDROCHRONOLOGICAL POTENTIAL OF MĀMANE (SOPHORA CHRYSOPHYLLA) ON MAUNA KEA, HAWAI‘I(2019-05) Uehana, Shea Takeo; Hart, Patrick; Tropical Conservation Biology & Environmental ScienceIn order to better understand and predict the future effects of global climate change, researchers must utilize methods that allow accurate interpretation of pre-instrumental environmental conditions. Dendrochronology is especially useful because of its ability to utilize climate proxies spanning tremendous spatial and temporal scales in the form of tree rings. The construction of a global network of tree-ring chronologies is already well underway, but temperate bias has resulted in an under representation of the tropics. The Hawaiian Archipelago provides a unique opportunity to gather tree ring data from an under sampled region of the eastern tropics. I used classical dendrochronological methods to expand on previous research on Hawai‘i Island, adding trees from an additional site at a subalpine forest at Pu‘u La‘au, and extending the tree-ring chronology for māmane (Sophora chrysophylla) from 86 years to 173 years. I also investigated the growth-climate relationship of māmane at Pu‘u La‘au and found that rainfall is a poor predictor for tree growth.Item Genetic Variation, Population Structure, and Morphology of an Endemic Bat, Lasiurus cinereus semotus (Chiroptera: Vespertilionidae) Across the Hawaiian Islands(2019-08) Pinzari, Corinna Anne; Hart, Patrick; Price, Donald; Tropical Conservation Biology & Environmental ScienceDetermining the connections between islands and assessing subpopulations are required to effectively manage an endemic, seasonally migrant bat species with an observed archipelago wide distribution. An innovative technique to characterize the connectivity among populations is to evaluate the genetic similarity between individuals sampled from among and within islands. By combining mitochondrial and nuclear DNA markers (or genetic variants), we can identify how island groups may differ between populations, sexes, and estimate relative abundances. One mitochondrial gene and six nuclear microsatellite loci were used to explore genetic connectivity among and within three islands inhabited by the endangered Hawaiian hoary bat (Lasiurus cinereus semotus). Employing the resources of an existing collection of bat tissue samples (~140) from the four major islands (Kaua`i, Hawai`i, Maui, and O`ahu) and applying classical population genetics analyses, I tested for population structure; quantified levels of genetic variation, genetic distance, and gene flow in bats among and within the Hawaiian Islands; estimated both historical long-term female effective population size, and contemporary effective population size; and examined the data for patterns of past bottleneck events. In order to accurately measure degree of population structure and phenotypic variation with respect to sex, I conducted genetic sex determination tests on bat samples from both live and desiccated specimens. I also examined the morphological characteristics of bat skull and wing size on 23 individuals to determine differences with respect to island, mitochondrial clade, and sex. This project provides the most current data set of population level information, describing the genetic diversity and geographic structure of Hawai`i’s only endemic terrestrial land mammal. This study contributes demographic information, sex determination techniques, and banking of diverse DNA samples available for future genomic sequencing, to support management and recovery of an endangered species. Research results may provide support to state and federal agencies tasked with balancing the demands of sustainable wind generated energy and wildlife conservation in Hawai`i.Item Investigating the growth periodicity, stable carbon isotope trend and climate reconstruction potential of 'Akoko (Euphorbia olowaluana), A native Hawaiian C4 tree on Mauna Kea, Hawaii, using tree ring analysis(2016-05) Ben, Tishanna; Hart, Patrick; Tropical Conservation Biology & Environmental ScienceTree ring patterns provide one of the best records of historical climate variability. I evaluated growth increment periodicity and the stable isotope ratios of carbon in two woody plant species using the C3- and C4-photosynthetic pathway. The investigated species, Māmane (Sophora chrysophylla, C3) and ʻAkoko (Euphorbia olowaluana, C4), are small endemic Hawaiʻian trees sampled from a rather dry, high elevation habitat on the ridge between Mauna Loa and Mauna Kea on the island of Hawaiʻi, USA. A relatively strong correlation in ring patterns was found within the ʻAkoko and the Māmane individuals as well as with ring-width patterns from a nearby population of introduced Deodar Cedar (Cedrus odorata) trees that serve as a reference. This is evidence that the C4-plant ʻAkoko may form annual growth rings. In addition to being the first demonstration of annual growth rings in a C4 plant, our findings have important implications for future climate change research in Hawaiʻi. Unlike plants with a C3-photosynthetic pathway, C4 plants do not show strong bias against 13C during the photosynthetic fixation of CO2. Thus, ʻAkoko may provide a record of past atmospheric CO2 concentration that can be compared with, and possibly supplement, the well-known Keeling curve produced by the nearby Mauna Loa Atmospheric Observatory. Regression analysis indicates a significant relationship between ʻAkoko δ13C averages and atmospheric δ13C values. Furthermore, time series of tree ring data from both species provide long-term information on the response of C3 and C4-plants to increasing atmospheric CO2 concentrations and climate change. Trends in 13C (intrinsic water-use efficiency) of the two species show similar responses in that both demonstrate an increase in iWUE over time and with increased CO2atm. ‘Akoko and Māmane iWUE curves are different however, in that the ‘Akoko (C4) curve is non-linear and a significant increase could only be observed post 1975, while the Māmane curve shows a distinct linearly increasing trend throughout the observation period.Item North Hilo (Hilo Palikū) Coastal Fishery Assemblages: Global Climate Change Impacts Modeled Along a Highly Constrained Hydrological and Precipitation Gradient(2017-05) Akau, James Jacob; Hart, Patrick; Tropical Conservation Biology & Environmental ScienceFor centuries coastal fish communities have sustained human populations throughout the Hawaiian archipelago. Fish populations not only provide sustenance, but have also been and continue to be a source of inspiration for Hawaiian culture. The advent of global climate change and corollary increases in sea level temperature has compromised coral reef health and disrupted the ecological stability of nearshore systems. Global climate change and associated elevated atmospheric carbon dioxide has affected watershed function, especially rainfall magnitude and frequency. Since 1958 average rates of precipitation have decreased from 5 to 40 %. Coastal and estuarine environments are especially sensitive to runoff and stream discharge, which affect food availability for fishes, juvenile recruitment, benthic substrate, salinity levels, and fish community composition. To examine the effects of global climate change on coastal ecosystems, I’ve compared salinity levels, benthic substrate, fish community assemblages, species relative abundances, and food web structure across a precipitation gradient from Pepe‘ekeo (6000mm rain/yr) to Laupahoehoe (300mm rain/yr) along the Hilo Paliku (North Hilo), Hawai‘i coastline. To investigate the effects of variable fresh water inputs to near shore fishery assemblages, I compared recorded fish biodiversity, species relative abundances, and benthic substrate at Pepe‘ekeo and Laupāhoehoe using fish visual surveys on SCUBA and free diving. While free diving, I also used a Hobo data conductivity logger to measure salinity levels spatially and over time at Pepe ‘ekeo, Kolekole, and Pepe‘ekeo. Corals, which provide habitat and food for fishes, are sensitive to extreme fluctuations in salinity. Most corals have a salinity tolerance range between 28.7. Coral percent cover and fish biodiversity was significantly greater at Laupāhoehoe when compared to Pepe‘ekeo (P < 0.001). This demonstrates that more coral provide a more variable habitat for greater fish diversity, and that changes in rainfall and coastal salinity levels are important to maintain this diversity. With an understanding of how decreased stream flow will impact near-shore fish communities, we can begin to develop adaptive management strategies to maintain stream flow during periods of drought or return water to streams from diversions. This information can help to develop and support effective near-shore fisheries management at the community and legislation level. Keywords: precipitation gradient, fishery assemblage, food web dynamicsItem SOCIAL LEARNING AND FORAGING PROFICIENCY OF PALILA (LOXIOIDES BAILLEUI) IN AN AVIARY SETTING(2024-12) Kluzak, Christopher Zdenek; Hart, Patrick; Tropical Conservation Biology & Environmental ScienceItem ʻAmakihi kaulana i ka hoʻōla maʻi: Assessing the long-term impacts of chronic infection with avian malaria in Hawai‘i ‘amakihi(2024-05) Stierhoff, Emma; Hart, Patrick; Tropical Conservation Biology & Environmental Science