Global Environmental Science Theses

Permanent URI for this collectionhttps://hdl.handle.net/10125/60447

The Bachelor of Science Degree Program in Global Environmental Science (GES) is administered by the department of Oceanography in the School of Ocean and Earth Science and Technology of the University of Hawai‘i.

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Ola I Ka Wai - The Barriers of Implementing a One Water Approach on O'ahu
(University of Hawaiʻi at Mānoa, 2022) Thelle, Jakob; Milz, Dan; Oceanography; Global Environmental Science
The Hawaiian Islands are on course for a water crisis. Currently, water supplies face challenges deriving from overconsumption of water and a growing world population increasing the demand. Furthermore, climate change causes detrimental impacts to water resources by reducing water quality and quantity, urging planning efforts to integrate climate science within water management practices. In 2020, the City and County of Honolulu stated their intention to adopt a One Water (OW) approach, which aims to manage water resources in Hawai'i in a holistic and collaborative way. Through this research, we will identify the barriers of implementing the OW framework on O'ahu to encourage strategies in effectively integrating the framework to O'ahu's water management practices. The research follows a qualitative research design collecting data through conducting interviews with key stakeholders and professionals in the field of water resources management. We found the main barriers posing the implementation of the One Water framework to be; (1) siloed systems (2) funding and budget constraints, (3) political and social-buy in, and (4) socio-cultural understanding. Strategic action to overcome the addressed barriers will be key towards effectively implementing a One Water approach in the process of preserving Hawai'i's waters for the benefit of the people.
The Use of Groundwater Geochemistry to Prospect for Blind Geothermal Resources in the State of Hawaii
(University of Hawaiʻi at Mānoa, 2018) Dudoit, Tineill; Lautze, Nicole; Oceanography; Global Environmental Science
The principle goal of this study was centralized on the use of groundwater geochemistry to prospect for blind geothermal resources throughout the State of Hawaii by the collection of water samples, analysis of water geochemistry data, and highlighting of wells that contained chemical signatures indicative of elevated subsurface heat. Water samples were collected in ten locations across the State of Hawaii that were identified as areas of potential geothermal resource in a recent geothermal prospect assessment, and analyzed for temperature, major and minor chemical species, and trace metals. A total of 61 samples were collected: 60 from existing wells and 1 spring was sampled in an area where no wells exist. The aqueous geothermal indicators: silica concentration, chloride/magnesium, sulphate/chloride, and temperature, were chosen because of the relative success as geochemical indicators in Hawaii. Additionally, thresholds were determined, based on compiled historical data and research, as chemical signatures that could signify subsurface heat under Hawaii conditions. As a result, various anomalies were detected on four islands within the State of Hawaii based on the criteria set within the project as potential indications of subsurface heat, and a potential geothermal source was identified on the Island of Lanai. However, positive indications of a subsurface heat anomaly based on this assessment could have an alternative non-thermal explanation. Given that these aqueous geochemical indicators can be affected by both natural and anthropogenic processes, further investigation is necessary. Furthermore, data collected could assist the Hawaiʻi State Legislature to address the state’s growing energy demands through the identification, exploration, and use of available geothermal sources. The subsequent report provides the latest comprehensive water geochemistry data that may be used as a geothermal exploration tool for the State of Hawaiʻi.
Glutamate-Cysteine Ligase Modifier Subunit as a Possible Modulating Factor in Methylmercury-Inducedn Developmental Toxicity
(University of Hawaiʻi at Mānoa, 2004) White, Sally; Berry, Marla; Schoonmaker, Jane; Oceanography; Global Environmental Science
The US EPA recently released a fish-consumption advisory, recommending that pregnant mothers reduce their intake of certain fish. Concentrations of methylmercury (MeHg) in commonly consumed fish have raised concern for the health of women of childbearing age and their developing children. Previous experiments have implicated glutathione (GSH), an endogenous, tri-peptide antioxidant, as an ameliorative factor in MeHg toxicity. GSH biosynthesis is rate-limited by glutamate-cysteine ligase (GCL), a heterodimeric enzyme consisting of a catalytic and a modifier subunit (GCLC and GCLM, respectively). To examine the roles of GCLM and GSH synthesis in MeHg- induced developmental toxicity, experiments were conducted employing Gclm knockout and hemizygous mice. Eight breeding pairs were established and on gestational day 14, females were inoculated with MeHg or sesame oil vehicle. The animals were sacrificed on gestational day 17, with dissection of the embryos, placenta, and yolk sacs, and maternal brain, liver, and kidney. The genotype of each embryo was determined and tissues were assayed for Gclm transcription and GCLM protein expression. While the scale of this experiment was found to be insufficient for definitive assessment of the roles of GCLM and GSH biosynthesis in MeHg toxicity, the work described here may provide pilot data for the design of future experiments. Additional results from such experiments should provide a better understanding of the fundamental processes involved in MeHg-induced developmental toxicity, and suggest public health strategies for protecting developing children from such injury.
Impact of Sea Level Rise on Aging Population's Accessibility to Essential Services in Honolulu, Hawai'i
(University of Hawaiʻi at Mānoa, 2022) Liu, Dingyi; Shen, Suwan; Oceanography; Global Environmental Science
Demographic studies have shown two trends: (1) elderly population is growing as a consequence of longer life expectancy; (2) population in low elevation coastal zones will significantly increase. One of the potential risks of living in low elevation coastal zones is the projected sea level rise. As sea level rises, more and more frequent flooding can cause disruptions and damage to the roadways in coastal areas. Seniors could be especially vulnerable to such disruptions given their need for emergency services, which could also increase because of the adverse impacts climate change has on health. This study aims to investigate the impacts of sea-level rise on the aging population’s accessibility to essential services and its implication for long term adaptation planning using Honolulu, Hawai’i as a case study. Using Cohort Change Ratio (CCR), the study projects the elderly population in each Traffic Analysis Zones (TAZs) in future decades. Road segments and essential facilities (grocery stores, police stations, fire stations, and hospitals and clinics) at risk under different sea-level rise scenarios (1.1 feet, 2.0 feet, and 3.2 feet) are identified. Network connectivity from each TAZs to nearest essential services are analyzed. The results show that while the physical impacts on infrastructures are mild, some vulnerable communities’ access to essential services will be greatly affected even under 1.1 feet sea-level rise scenarios. Especially some areas with a high projected density of the elderly population will be cut off to essential services due to transportation bottlenecks. For the rest of the population, sea level rise could significantly reduce the number of people with timely access to essential services. The results not only urge transportation network planners to take actions to make sure transportation connectivity to vulnerable elder population at-risk are protected, but also suggest that over the long-term land use planning would be one of a key factors to adapt to climate change. These findings have broad implications for other coastal locations with similar development and growth patterns, and the methodology used could be easily adapted to be used in a variety of other metropolitan areas across the country to conduct similar vulnerability analyses to aid in adaptation planning in practice. Also, audience will learn the emergent needs of sea level rise adaptation planning.
Extreme Sea Levels in Guam: Incorporation of Wave-Driven Setup and Runup into the Analysis of Fluctuations in Extreme High Waters at the Ipan Reef
(University of Hawaiʻi at Mānoa, 2012) Yasui, Sarah; Merrifield, Mark; Oceanography; Global Environmental Science
Changes in mean sea levels influence the coast by aﬀecting the height and frequency of extreme high waters. Tide-gauge records are often used to study fluctuations in the timing and severity of extreme sea levels because these records are relatively long and accessible. However, there are two main limitations to analyzing sea-level extremes using tide-gauge observations: 1) Tide gauges are often protected from wave energy, and therefore do not account for the elevation of water levels due to setup, and 2) instruments with sampling frequencies of several minutes to an hour may not correctly identify the most extreme sea level. Here it is found that sea-level extremes documented by tide gauges at Pago Bay and Apra Harbor, located in eastern and western Guam, respectively, diﬀer significantly in height when the observations are evaluated alongside a high-frequency (1 Hz) sea-level record from Ipan that has been modified to include the influences of setup and extreme runup. The disparity between water levels with and without wave eﬀects is especially pronounced (as high as 1.5 m) during large wave events (>2 m). Extreme high waters appear to be correlated to a surge in southwesterly monsoon winds in Apra Harbor and the passage of tropical cyclones close to (<370 km) the island in Pago Bay and Ipan. The sea-level response to the passage of a tropical cyclone over Guam does not appear to be correlated to storm intensity or proximity.
Critical Review of Utilizing Constructed Wetlands to Sustainably Treat Petroleum Industry Wastewater
(University of Hawaiʻi at Mānoa, 2018) Kelly, William; Cooney, Michael; Oceanography; Global Environmental Science
Current practices regarding the treatment of petroleum industry wastewater rely on high energy consumption and the effluent maintains high nutrient levels. Post treatment, the high nutrient wastewater is discharged into local waterways and can lead to eutrophication in surrounding waters, thereby making the treatment process an environmentally, socially and economically damaging process. Both the high energy demand and elevated nutrient levels in the effluent are reasons to explore new methods to sustainably treat the petroleum industries wastewater. While the majority of industry uses the high energy process, some utilize constructed wetlands. A constructed wetland is a low energy treatment process that produces effluent with very low nutrient levels. In this study, a sustainability analysis of the two treatment processes showed the constructed wetland to be more sustainable. The analysis weighed metrics to fully understand the complete environmental, social and economic impacts of each process. The constructed wetland proved most sustainable in the economic and social categories, due to low associated costs and contributing to Hawai’i’s sustainability initiative. Relatively closer scores in the environmental category showed both were efficient in hazardous component removal but lacking in nutrient reduction. The low energy demand and low waste produced by the constructed wetland were responsible for showing improved sustainability in the environmental category.
Temporal and Spatial Variability of Nitrifying Archaea in the Pacific Ocean
(University of Hawaiʻi at Mānoa, 2010) Wai, Brenner; Church, Matthew; Oceanography; Global Environmental Science
Crenarchaea are putative ammonia oxidizers in the marine environment. The nitrifying role that these microorganisms play is an integral component of the marine nitrogen (N) cycle. Here we present two separate, but very similar studies to assess both the temporal and spatial dynamics of ammonia oxidizing Crenarchaea. One study looked at the seasonal variability in the abundances and distributions of ammonia oxidizing Crenarchaea over a four-year time scale at the same location in the North Pacific Ocean (Station ALOHA). We found total crenarchaeal gene abundances typically increased three to four orders of magnitude between the near-surface (~5m) ocean and the epi- mesopelagic boundary (200 m), decreasing about an order of magnitude throughout the rest of the mesopelagic zone, and staying relatively constant in the bathypelagic water. Annual occurrences of 10,000 fold increases in crenarchaeal abundances in near-surface waters appeared linked to winter mixing, while during summer months, a predominately upper ocean dwelling Crenarchaea increased in abundance in upper mesopelagic waters coincident with periods of increased particulate nitrogen flux to the deep sea. Our other study examined meridional distributions of crenarchaeal ammonia monooxygenase (amoA) genes and transcripts across a vast (~5200 km) region of the central Pacific Ocean. Throughout the transect, crenarchaeal amoA genes showed a nearly identical depth-dependent distribution when compared to estimates at Station ALOHA. Crenarchaeal amoA transcripts typically increased one to two orders of magnitude between 100 m and the epi- mesopelagic boundary (200 m), before decreasing throughout the mesopelagic zone. When normalized to gene abundances, amoA transcripts revealed elevated expression in the upper ocean waters (0-100m), where crenarchaeal abundances were low and transcript abundances decreased throughout the mesopelagic zone as crenarchaeal gene abundances increased. Both studies suggest that throughout the entire water column, ammonia oxidizing Crenarchaea are dynamic contributors to the marine nitrogen cycle in the Pacific Ocean.
Environmental and Economic Benefits of Locally Grown Versus Imported Agriculture: A Case Study of Sumida Farm
(University of Hawaiʻi at Mānoa, 2024) Thepsenavong, Ariel; Burnett, Kimberly; Oceanography; Global Environmental Science
The state of Hawaiʻi relies heavily on food imports in order to feed its residents. In return, the state is highly impacted by food chain issues and fuel surcharges. In order to determine the benefits of supporting local agriculture in Hawaiʻi, this study analyzes the impacts of “local” food using Sumida Farm, a local watercress farm, as a case study. In addition, this study will also characterize some of the key environmental and economic benefits of locally produced versus imported produce. These will be shown by (1) calculating the price differential between local and imported watercress, (2) calculating the greenhouse gas emissions of local and imported watercress, and (3) describing and illustrating the social reach and community impact of Sumida Farm. We find that the cost of imported watercress for the residents of Hawaiʻi is more than double the cost of local watercress, and residents would need to pay about $3 million more per year for imported watercress. We also find that the total greenhouse gas emissions associated with imported watercress is over 50 times the emissions of local watercress. Finally, we find that although most of Sumida Farm’s community presence is on the island of Oʻahu, their impact can be felt throughout most islands across the state.
Assessment of the Wind Resource at the Grace Pacific Quarry Site in Kapolei, Oahu
(University of Hawaiʻi at Mānoa, 2013) Tu, Jiayu; Businger, Steven; Oceanography; Global Environmental Science
The goal of this research project is to determine the feasibility of building a wind farm at Grace Pacific Quarry (GPQ) in Kapolei. This location was chosen because wind maps for Oahu suggest that the location of GPQ has a sufficient wind resource for a wind farm. Meteorological data from Grace Pacific Wind Towers were used to analyze the quality of the wind resource at GPQ. The people who work at First Wind in Hawaii were interviewed, and the wind resource at their wind farms was compared with that at GPQ. Finally, the thesis discusses local and political considerations and environmental impact studies needed to assess the feasibility of constructing a wind farm in Hawaii.
Updating Historical Shoreline Change Rates of North Kā'anapali, Honokōwai, and Kahana, West Maui
(University of Hawaiʻi at Mānoa, 2019) Tran, Cuong; Fletcher, Charles; Oceanography; Global Environmental Science
Tracking shoreline movement across the main Hawaiian Islands provides empirical data to assist in the development of better coastal management practices. We, the University of Hawaiʻi at Mānoa Coastal Geology Group, use empirical data to calculate shoreline change rates on the islands of Kauaʻi, Oʻahu, and Maui. In this study, 2015 raw satellite imagery, provided by World View 3, was used to update the historical shoreline database of North Kāʻanapali, Honokōwai, and Kahana, West Maui. We calculated 2015 shoreline change rates and analyzed differences compared to an earlier database in 2007. The satellite imagery we used was orthorectified using ArcGIS and PCI Geomatica Inc., the low water mark and coastal vegetation line were digitized, and shoreline position locations were measured from transects spaced 20 meters alongshore. These locations were modeled using linear regression to identify long-term rates of change at each transect. Including the 2015 shoreline, the data revealed that 77% of all transects were erosional, compared to 73% in 2007. With regard to beach loss, the 2007 dataset experienced a loss of 80 meters whereas the 2015 dataset showed a loss of 920 meters. The expansion of eroding shoreline over the period 2007 to 2015 is consistent with the expected influence of rising sea level and continued coastal hardening. However, a full analysis that would have identified whether the changes were due to short-term variability or a valid statistical trend was not conducted.
Beach Loss, Seawall Construction, and Land-Use Patterns at Odds with Coastal Zone Policy - East O'ahu, Hawai'I 1928-2015
(University of Hawaiʻi at Mānoa, 2017) Summers, Alisha; Fletcher, Charles; Oceanography; Global Environmental Science
Protecting and preserving beaches is critically important to the economy, ecosystem, culture, and lifestyle of the Hawaiian Islands. However, within the last century, beaches on Oʻahu have narrowed and are increasingly vanishing altogether. In response to federal incentives, a desire to better manage population growth and development along the shoreline, a need to protest coastal resources, and locally significant erosion problems, the State of Hawaiʻi enacted a Coastal Zone Management (CZM) program in 1977 as part of the policy framework created under the U.S. Congress’ Coastal Zone Management Act of 1972. Under the Hawaii Costal Zone Management program (HCZMP), the State has delegated the authority to regulate shorelines to the Counties. Over the intervening decades, the four counties have adopted different types of construction setback laws: Maui and Kauaʻi have erosion rate-based setbacks, and Hawaiʻi and the City & County of Honolulu (C&C) use a fixed distance of 20-60 feet depending on specific parcel conditions. The stated purpose of C&C setback policy is primarily for preservation and protection of the natural shoreline, public access, and open space. Maintaining wide healthy beaches are critical to achieving all three of these goals. Despite this, across O’ahu, structures continue to be built close to the shoreline, seawalls continue to be constructed, and beaches continue to disappear. We present data from the east-facing shores of Oʻahu between 1928 to 2015 that document changing shoreline positions and beach widths concurrent with expanding coastal development that is at odds with the goals of presiding coastal policy. Over the study timeframe of 1928 to 2015 seawall and revetment construction increased by 54%, concurrent to net shoreline change shifting from quasi-stable to erosional along 74% of the coast. Before the enactment of CZM policy in 1975, the shoreline was quasi-stable with headland regions eroding at an average change rate of -0.05 ± 0.09 m/yr and embayed regions accreting at an average rate of 0.14 ± 0.05 m/yr. Following 1975, the average headland and embayed region shoreline change rate became erosional at -0.08 ± 0.06 m/yr and -0.21 ± 0.09 m/yr, respectively. We reveal that historical seawall and revetment construction to protect eroding lands has caused a narrowing and loss of beach from 1928 to 2015 even while both the Hawai’i CZM program and C&C policy have been in force with laws specifically designed to protect the coastline, ensure open space, and enhance public access.
Quantifying Coral Reef Cryptofauna Diversity of O'ahu and Kaua'I Islands Using Autonomous Reef Monitoring Structures
(University of Hawaiʻi at Mānoa, 2013) Garcia, Monica; Drazen, Jeffrey; Reardon, Kerry; Timmers, Molly; Oceanography; Global Environmental Science
Coral reefs are hugely productive ecosystems supported in large part by the cryptic biota that inhabit them. Appropriately dubbed “cryptofauna,” these invertebrate populations are highly understudied reef dwellers that comprise the majority of coral reef biodiversity. Quantifying biodiversity of cryptofauna is critical to monitoring changes in these communities caused by anthropogenic-driven environmental change, particularly in coral reef-dependent islands like that of the Hawaiian archipelago. This study attempts to quantify samples of the cryptofauna that occupy Kauai and Oahu coastal reefs. Seventy percent of the 1.2 million people of Hawaii live on Oahu. Thus, this investigation will attempt to determine if the conversion to a highly urbanized system—Oahu—will result in differences in coastal cryptofauna community of a relatively undisturbed system—Kauai. The use of Autonomous Reef Monitoring Structures (ARMS) was employed to mimic complex coral habitats. A total of 16 ARMS units were deployed at both islands at depths of 12-15 m (spaced 3-5 m apart) for two years. Upon retrieval of the units, a total of 5,889 specimens were collected, counted, and taxonomically identified to the lowest possible taxon. Results using PRIMER-6 showed slight differences in community composition between Oahu and Kauai when considering the sampling effort. However, there was no statistical significant difference in the taxa diversity and abundance between the two islands. Thus, results were inconclusive of comparative effects of anthropogenic environmental degradation. Nonetheless, it was evident that the use of ARMS units was excellent to census cryptofauna communities, and thus should be implemented in greater proportions for better data.
Environmental Influences on Vibrio Vulnificus Abundance in the Ala Wai Canal
(University of Hawaiʻi at Mānoa, 2012) Giancaterino, Shaun; Steward, Grieg; Oceanography; Global Environmental Science
Vibrio vulnificus is a potentially fatal human pathogen indigenous to coastal ecosystems worldwide. This free-living bacterium is ubiquitous in the Ala Wai Canal in Honolulu, Hawaii, and can pose a significant threat to human health when found in elevated concentrations. Two major routes of infection are direct ingestion of contaminated seafood and direct exposure of open wounds to contaminated seawater. Many of Honolulu’s recreational waters and beaches (e.g., Waikiki beach, Ala Moana Beach Park) are located close to the Ala Wai Canal, and thus it is critical to understand when and where environmental pathogens such as Vibrio vulnificus are most prevalent there. Correlations between environmental variables and the abundance of V. vulnificus have been described for temperate and subtropical environments. Unfortunately, these correlations have little predictive power, may not apply in tropical waters, and ignore differences among strains of V. vulnificus. In this study, I measured how the growth rates of two strains of V. vulnificus are affected by varying organic matter concentrations, and by variations in temperature and salinity, under controlled conditions in the laboratory using basal media derived from natural stream and harbor waters. Preliminary experiments showed that the basal medium, or medium supplemented with 0.2 µm glucose, contained insufficient organic matter to promote robust growth. I found that the addition of organic carbon in the form of protein digests did result in measurable changes in optical density in the cultures. Data from the subsequent experiments show that both A-type and B-type strains of V. vulnificus were strongly affected by temperature in the range typically observed in coastal waters of Hawaii (24 to 36 °C), with warmer temperatures resulting in higher growth rates. Both strains had a very broad tolerance to salinity. Growth rates increased most significantly when salinity was increased from around 5 to 10, but the growth rates were indistinguishable in the salinity range of 10 to 35. These results will contribute to the development of a coupled biological-physical model describing the dynamics of V. vulnificus in coastal waters. Such a model can then serve as the basis for quantitative microbial risk assessments to better understand and manage the risks of infection in coastal recreational waters.
Towards Development of a Trace Element Sampling System: In Situ Pre-Concentration Using a Bi-Directional Pump
(University of Hawaiʻi at Mānoa, 2016) Harmon, Nathaniel; Measures, Chris; Hatta, Mariko; Oceanography; Global Environmental Science
A method to pre-concentrate iron (Fe) from seawater samples in the laboratory has been developed. The expectation is eventual deployment in unattended platforms in hard to access regions as well as to act as an alternative to the current rosette-based sampling system for trace elements. The system consists of a bi-directional pump (milliGAT), a holding coil, a multi-position selection valve, and external columns packed with a Toyopearl AF-Chelate-650® resin. From measurements of iron spiked water samples before and after pre-concentration on the resin, it was found that the iron present in the sample was successfully adsorbed on to the resin. The pre-concentration efficiency of the resin is 97.47% ± 0.82%, and the maximum capacity of the resin measured during experiments is 446.71 ± 3.76μmol Fe L-1. A detection limit for the analytical method of 355pM Fe was obtained.
Phytoplankton Community's Response to Open Ocean Fish Farming in Tropical Warm Water
(University of Hawaiʻi at Mānoa, 2004) Mauriac, Romain; Bidigare, Robert; Oceanography; Global Environmental Science
In 1998, the University of Hawai‘i and the Oceanic Institute started the first offshore aquaculture experiment for the grow-out of Pacific Threadfin. One of the goals of the project was to assess the environmental viability of the cage. To do so, samples were taken once a month for water chemistry, and for analysis of the algal community in and around the cage. Virtually no nutrient increase was observed in the water column downstream from the cage. Two explanations for the lack of observed nutrient increase include immediate uptake by phytoplankton and/or rapid dilution by mixing in the surrounding water column. These alternative hypotheses are assessable through examination of the algal community. In this experiment, the responses of the algal community to the addition of nutrients from fish excretion and fish feed, and to the grazing pressure from heterotrophic microorganisms, were examined. Four samples were taken per day between September 26 and October 27, 2003, two in clear polycarbonate bottles and two in dark bottles. In addition, triplicates were taken to support statistical analysis. Sampling was performed upstream from the cage (one clear and one dark bottle) and downstream. Clear bottles were incubated 24 to 48 hours at the cage while brown bottles were brought back to the lab to be filtered immediately and conserved in liquid nitrogen. All samples were filtered using 47 mm GF/F filters and pigment composition was investigated using high performance liquid chromatography (HPLC). Pigment analysis allowed an accurate representation of the phytoplankton community. Comparison of samples taken upstream and downstream allowed estimation of nutrient uptake from the cage by algae. Clear bottles were used to estimate the response from the phytoplankton community after 24 or 48 hours, regardless of mixing effects and currents. Monthly samples examined the long term impact of the fish cage whereas daily samples allowed investigation of the transitory effect due to daily feeding and fish excretion.
Hazardous Marine Algal Toxins: Training, Overview, and Experimental Work
(University of Hawaiʻi at Mānoa, 2011) Molina, Jonathan; Bienfang, Paul; Oceanography; Global Environmental Science
This GES thesis project consisted of three facets. The first was the development and application of practical skills to isolate dinoflagellates from nature, and subsequently bring them into in vitro culture. As a prelude, an educational component came in the form of attendance at the GEOHAB Benthic Hazardous Algal Bloom conference and subsequent workshop that were held in Honolulu, Hawaii in June, 2010. This training was followed by repeated isolation of benthic dinoflagellates, principally Gambierdiscus spp., from Hawaiian coastal waters and their subsequent establishment in culture. This required demonstrating clinical proficiency in the collection, separation, isolation, and cleaning techniques as well as media preparation, sterilization, and culture monitoring. The second facet involved assembling a summary of nine naturally-occurring marine toxins of algal origin. Ciguatoxin, one of a number of natural marine toxins produced by dinoflagellates and poorly understood generally, is a principle focus of research at the Pacific Research Center for Marine Biomedicine (SOEST, University of Hawaii). This effort required proficiency in electronic literature searches, reference management (e.g., EndNote, Zotero), and formatting of collected information into a succinct document. The marine toxins addressed included azaspiracids, BMAA, brevetoxin, ciguatoxin, Cochlodinium polykrikoides, domoic acid, palytoxin, saxitoxin, and yessotoxin. For each of these toxins, information was assembled regarding the causative organism(s), morphology/taxonomy, size, and cyst production capability of putative organism(s), toxin structure, mode(s) of pharmacological activity, geographic range of incidence, marine food web impact, economic impacts, and human health impacts. The third component was an experimental effort designed to determine if Gambierdiscus cells could survive the exposure to the ballast water of shipping vessels and remain viable; this has obvious implications for possibility for such cells to be transferred between geographic locals. Gambierdiscus cells were placed in recently collected ballast water at various temperatures and regularly monitored over time. Cells were counted using an electronic particle counter every three days at each temperature to determine growth rates from the time series of biomass abundance. Results showed that Gambierdiscus concentrations increased over time following exposure to ballast water. The positive growth rates observed following exposure indicates the absence toxicity of ballast water to these epiphytic dinoflagellates.
Developing Soil Water Retention Curves to Guide Irrigation Needs for the Soils of Pioneer Farm, Waialua, Oahu
(University of Hawaiʻi at Mānoa, 2018) Matsuda, Candice; Deenik, Jonathan; Oceanography; Global Environmental Science
Improper management of water is a waste of a scarce and valuable resource as well as posing a threat to the environment. To improve irrigation scheduling in Hawai‘i, a web-based irrigation scheduling tool which incorporates real time weather data and soil moisture data will be implemented to guide farmers with their irrigation management. Soil moisture data is a key component to determine a proper irrigation recommendation, however there is little soil moisture data available for Hawai‘i’s important agricultural soils. In this research, I developed soil water retention curves (SWRC) for three agricultural soils to estimate a soil moisture threshold, which is used to calculate plant available water (PAW) in cropping systems. We collected three soils, two Mollisols (Pulehu and Ewa series) and an Oxisol (Lahaina series) with varying physical properties from the Pioneer Farm in Waialua, Oahu, and developed SWRCs for each soil. We demonstrated that soil texture and bulk density affected soil water retention where the Pulehu soil with a high sand content and the Ewa soil with a high bulk density showed less water retention and a lower amount of PAW compared to soils with a high clay content and pseudosand properties (Lahaina). The soil moisture threshold was -20 kPa for the Pulehu soil, -40 kPa for the Lahaina soil, and -70 kPa for the Ewa soil. Using the threshold, we estimated the time intervals between irrigation events using a generalized potential evapotranspiration rate that was not crop specific. We determined that the Pulehu and Ewa soils retained the least amount of PAW requiring daily irrigation applications. On the other hand, the Lahaina soil with a high clay content and high porosity retained the most PAW and a longer interval between irrigation events.
Marine Debris Deposition Rates in the North Pacific Relative to Forcing Factors
(University of Hawaiʻi at Mānoa, 2013) Agustin, Alyssa; Merrifield, Mark; Potemra, Jim; Oceanography; Global Environmental Science
Marine debris is becoming more abundant in the ocean and it is difficult to predict its pattern of movement resulting in wide ranges of deposition patterns along coastlines. This study investigated the relationships between physical forcing factors and marine debris deposition on an island in the central North Pacific, Tern Island (23.870°N 166.284°W). Data collected by the National Oceanic and Atmospheric Administration Marine Debris Program was classified into types (i.e. floating or saturated) and analyzed annually, seasonally, and biweekly. Debris was found to appear in large sporadic events as opposed to following seasonal or interannual patterns. Some of the large debris events at Tern Island were found to correlate with changes in the location of Ekman transport convergence. Ekman convergence, as estimated by the line of zero zonally-averaged meridional Ekman transport, typically occurs between 26°N to 30°N. The analysis shows during certain times, this line shifts south to near the latitude of Tern Island, and this is sometimes coincident with large marine debris deposition events.
The Upper Layer Structure and Variability of an Antarctic Glacio-Marine Fjord: Andvord Bay, Western Antarctic Peninsula
(University of Hawaiʻi at Mānoa, 2017) Christensen, Katy; Merrifield, Mark; Oceanography; Global Environmental Science
Glacio-marine fjords on the Western Antarctic Peninsula (WAP) are relatively unstudied, rapidly changing systems of high biological productivity. The goal of this research is to characterize the upper layer physical structure and variability of a representative fjord, Andvord Bay, to determine how it changes in time and space in response to external forcing on seasonal and shorter time scales. To analyze the upper layer of Andvord Bay, CTD (Conductivity/Temperature/Depth) profiles and shipboard thermosalinograph data are used from two cruises in the National Science Foundation (NSF) supported project, Fjord ECO. First, the mixed layer depth (MLD) is determined using two different methods: higher order weighting and vertical differences of density above threshold with different commonly used threshold values. The variability of the upper layer salinity, temperature, density, and MLD are analyzed in relation to changes in space, time, and wind forcing. The threshold method using a threshold value of ∆σ = 0.03 kg/m3 is used to define the MLD, with inaccuracies in detection primarily due to the presence of weakly stratified layers at the surface. In the variability analysis, results show that seasonal heat flux is the largest factor impacting the changes in the upper layer of WAP fjords, although wind forcing does play an occasional role. Geographic influences are less prominent and are only relevant between the inside and outside of the fjord. Understanding the upper layer is an important part of understanding the water column dynamics, the chemical characteristics, and the biological diversity of glacio-marine fjords along the WAP.
He'eia Coastal Wetland as a Sink for Nitrogen, Phosphorus, and Polychlorinated Byphenyls in Waters Entering Kane'ohe Bay
(University of Hawaiʻi at Mānoa, 2001) Kobayashi, Kamalana; Mackenzie, Fred; Oceanography; Global Environmental Science
He’eia Coastal Wetland was monitored over several months to document its potential to remove nitrogen, phosphorus, and polychlorinated biphenyls (PCBs) from He’eia Stream water. He’eia Wetland is classified as a free-water natural wetland, with Honohono grass (Commelina diffusa) as the dominant vegetation. Its total area is about 80 ha., and the mean depth of the ponds is less than 1 meter. The wetland receives the majority of its water from He’eia Stream. Water samples for nutrient analysis were collected in two-week intervals from various locations upstream and downstream of the wetland over a period of four months in 2000. The samples were analyzed for nitrate and phosphate concentrations. A United States Geological Survey (USGS) station at the highest elevation sample site provided flow data for that site that were correlated to nitrate and phosphate concentrations. There was a decrease in both nitrate and phosphate after stream water passed through the wetland. Two soil samples were collected in He’eia Wetland and one core sample was collected in He’eia Fishpond during the study period. These samples were analyzed for PCBs. The results suggest that the He’eia freshwater wetland is a sink for nitrogen, phosphorus and PCBs.

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