Recent Submissions

  • Mesoscale modeling study of a polar low in the Chukchi and Beaufort Seas

    Moreira, Paula Doubrawa; Zhang, Xiangdong (2011-12)
    Polar lows are intense mesoscale maritime cyclones, often associated with strong winds that can damage high-latitude coastal environments and infrastructure. These systems have been historically infrequent in the Chukchi and Beaufort seas, but this behavior is expected to change along with the amplified changes in Arctic climate. This study investigates the unusual occurrence of a polar low in this region on October 9-10, 2009. Sensitivity experiments with the Weather Research and Forecasting model indicate that using ERA-Interim as large-scale forcing and performing spectral nudging at all simulation hours yield the most realistic simulation. The simulations are highly sensitive to physical parameterizations, where Morrison rnicrophysics and Yonsei University boundary layer produce the smallest errors. Surface forcings were not important for the polar low development and their influence could not extend above 850 hPa due to a stable lower atmosphere. A convergence zone between the Aleutian Low and the Beaufort High established a southerly flow that created favorable conditions by continuously adverting heat and moisture from lower latitudes. The polar low had a hybrid development and was likely triggered by the interaction between a deep-penetrating upper-level potential vorticity anomaly and a low-level baroclinic zone, which were driven northward by the jet stream.
  • A Bayesian mixed multistate open-robust design mark-recapture model to estimate heterogeneity in transition rates in an imperfectly detected system

    Badger, Janelle J.; McIntyre, Julie; Barry, Ron; Goddard, Scott; Breed, Greg (2020-12)
    Multistate mark-recapture models have long been used to assess ecological and demographic parameters such as survival, phenology, and breeding rates by estimating transition rates among a series of latent or observable states. Here, we introduce a Bayesian mixed multistate open robust design mark recapture model (MSORD), with random intercepts and slopes to explore individual heterogeneity in transition rates and individual responses to covariates. We fit this model to simulated data sets to test whether the model could accurately and precisely estimate five parameters, set to known values a priori, under varying sampling schemes. To assess the behavior of the model integrated across replicate fits, we employed a two-stage hierarchical model fitting algorithm for each of the simulations. The majority of model fits showed no sign of inadequate convergence according to our metrics, with 81.25% of replicate posteriors for parameters of interest having general agreement among chains (r < 1.1). Estimates of posterior distributions for mean transition rates and standard deviation in random intercepts were generally well-defined. However, we found that models estimated the standard deviation in random slopes and the correlation among random effects relatively poorly, especially in simulations with low power to detect individuals (e.g. low detection rates, study duration, or secondary samples). We also apply this model to a dataset of 200 female grey seals breeding on Sable Island from 1985-2018 to estimate individual heterogeneity in reproductive rate and response to near-exponential population growth. The Bayesian MSORD estimated substantial variation among individuals in both mean transition rates and responses to population size. The correlation among effects trended positively, indicating that females with high reproductive performance (more positive intercept) were also more likely to respond better to population growth (more positive slope) and vice versa. Though our simulation results lend confidence to analyses using this method on well developed datasets on highly observable systems, we caution the use of this framework in sparse data situations.
  • Analysis of GNAC Volleyball using the Bradley-Terry Model

    Karwoski, Daniel; Short, Margaret; Goddard, Scott; McIntyre, Julie; Barry, Ron (2020-05)
    Ranking is the process by which a set of objects is assigned a linear ordering based on some property that they possess. Not surprisingly, there are many different methods of ranking used in a wide array of diverse applications; ranking plays a vital role in sports analysis, preference testing, search engine optimization, psychological research, and many other areas. One of the more popular ranking models is Bradley-Terry, which is a type of aggregation ranking that has been used mostly within the realm of sports. Bradley-Terry uses the outcome of individual matchups (paired-comparisons) to create rankings using maximum-likelihood estimation. This project aims to briefly examine the motivation for modeling sporting events, review the history of ranking and aggregation-ranking, communicate the mathematical theory behind the Bradley-Terry model, and apply the model to a novel volleyball dataset.
  • Simulating distance sampling to estimate nest abundance on the Yukon-Kuskokwim Delta, Alaska

    Gallenberg, Elaine; Barry, Ron; Short, Margaret; Goddard, Scott; McIntyre, Julie (2020-05)
    The U.S. Fish and Wildlife Service currently conducts annual surveys to estimate bird nest abundance on the Yukon-Kuskokwim Delta, Alaska. The current method involves intensive searching on large plots with the goal of finding every nest on the plot. Distance sampling is a well-established transect-based method to estimate density or abundance that accounts for imperfect detection of objects. It relies on estimating the probability of detecting an object given its distance from the transect line, or the detection function. Simulations were done using R to explore whether distance sampling methods on the Yukon-Kuskokwim Delta could produce reliable estimates of nest abundance. Simulations were executed both with geographic strata based on estimated Spectacled Eider (Somateria fischeri) nest densities and without stratification. Simulations with stratification where more effort was allotted to high density areas tended to be more precise, but lacked the property of pooling robustness and assumed stratum boundaries would not change over time. Simulations without stratification yielded estimates with relatively low bias and variances comparable to current estimation methods. Distance sampling appears to be a viable option for estimating the abundance of nests on the Yukon-Kuskokwim Delta.
  • Multiple imputation of missing multivariate atmospheric chemistry time series data from Denali National Park

    Charoonsophonsak, Chanachai; Goddard, Scott; Barry, Ronald; McIntyre, Julie; Short, Margaret (2020-05)
    This paper explores a technique where we impute missing values for an incomplete dataset via multiple imputation. Incomplete data is one of the most common issues in data analysis and often occurs when measuring chemical and environmental data. The dataset that we used in the model consists of 26 atmospheric particulates or elements that were measured semiweekly in Denali National Park from 1988 to 2015. The collection days were alternating between three and four days apart from 3/2/88 - 9/30/00 and being consistently collected every three days apart from 10/3/00 - 12/29/15. For this reason, the data were initially partitioned into two in case the separation between collection days would have an impact. With further analysis, we concluded that the misalignments between the two datasets had very little or no impact on our analysis and therefore combined the two. After running five Markov chains of 1000 iterations we concluded that the model stayed consistent between the five chains. We found out that in order to get a better understanding of how well the imputed values did, more exploratory analysis on the imputed datasets would be required.
  • Climate drivers of Interior Alaska wildland fire

    Bukhader, Maryam; Bhatt, Uma S.; Mölders, C. Nicole; Panda, Santosh; Rupp, T. Scott (2020-05)
    This study focused on the climate drivers of wildfire in Interior Alaska that occurred in summer season, JJA, during periods in 1994 to 2017. Analysis results presented in this paper provide identify links between meteorological variables and area burned, in the context of spatial and temporal variability at the PSA level. Warmer temperatures caused higher chance of wildland fires as in summer 2004 (26797 km2) where the temperature reached the highest levels compared to all years of study. In addition, this study has shown that temperatures have the same seasonal cycle in all PSAs level; where the temperature increase begins in June, peaks in July and then gradually decline, consistent with the fire season. Although precipitation limits the increase in forest fires, the accompanying lightning increases the chance fires which gives precipitation a double role in influencing the risk of fire. This can be seen clearly in both Upper Yukon valley (AK02) and Tanana Zone South (AK03S) where the largest number of lightning strikes over Interior Alaska occur (17000 and 11000 strikes, respectively). In addition, these two PSAs have the greatest area burned (1441.2 and 1112.4 km2).There is an upward trend in both temperature and precipitation in all months especially in May and September which indicates a decline in the snow season and an increase in the length of the fire season. A similar pattern was documented between PSAs in eastern versus western Alaska. Eastern PSAs receive the highest amount of precipitation in July, (AK01W , AK01E, AK02, AK03N, AK03S) , and western PSAs in August, (AK04, AK05, AK07). The years 2004, 2015, 2005 and 2009 display the largest values for area burned with extremely warm and dry condition especially in 2004 with approximately 26797 km2 (6.6 m acres).
  • Terrestrial invertebrate prey for juvenile chinook salmon: abundance and environmental controls in an Interior Alaska river

    Gutierrez, Laura; Wipfli, Mark S.; Blanchard, Amy L.; Rosenberger, Amanda E. (2011-12)
    Terrestrial prey subsidies can be a key food source for stream fish, but their importance and environmental controls on their abundance have not been widely documented in high latitude ecosystems. This study investigated terrestrial invertebrate prey availability and predation by age-0+ juvenile chinook salmon (Oncorhynchus tshawytscha), overlap between terrestrial infall and drift to diet, and the relationship between diet to stream temperature and discharge in the Chena River, Interior Alaska. Terrestrial infall, drift, and juvenile chinook diet varied widely through the summers (May-September) of 2008 and 2009. Drift was comprised of 33% terrestrial and 67% aquatic invertebrate mass, while juvenile chinook diet contained 19% terrestrial, 80% aquatic, and 1% unidentifiable invertebrate mass. The proportion of terrestrial invertebrate mass consumed increased through summer and, at times, made up to 39% of total diet. Low similarity of invertebrates in diet and infall, and diet and drift suggested that fish were, in part, prey-selective, selecting hymenopterans and chironomid midges (Diptera). In both years, prey mass consumed and discharge varied inversely, but no correlation was found between proportion of terrestrial invertebrates consumed and discharge. However, the two sampling dates with the highest proportion of terrestrial invertebrates consumed occurred shortly after a 60-year flood, indicating that terrestrial invertebrates may be important during rain and associated high water. This study found that, although terrestrial infall and drift are highly variable, terrestrial invertebrates are an important prey resource for rearing chinook salmon in this high latitude riverine system, especially later in the summer.
  • Novel fungal taxa in an Alaskan boreal forest: phylogenetic affinities, ecologies, and ribosomal RNA secondary structures

    Glass, Daniel; Taylor, D. Lee; Olson, Link E.; Takebayashi, Naoki; Duffy, Lawrence (2011-12)
    Phylogenetic analyses suggest that a novel DNA sequence (NS1) found in a boreal forest soil-clone library belongs to the fungal kingdom but does not fall unambiguously within any known class. In order to determine if NS1 codes for an authentic ribosomal RNA (rRNA) gene-copy, I modeled ribosomal RNA secondary structure for four gene regions. Such analyses have never been used on environmental ribosomal sequences before. It appears that NS1 does code for an authentic gene-copy and is not a biological or lab artifact. I also elucidated the habitat preferences, horizon preferences, and fine-scale spatial structure of NS1 using molecular methods. I determined that NS1 was associated with spruce and was found in both the organic and mineral soil horizons. It appears to have a clumped distribution on the scale of a few meters and its spatial distribution shows little inter-annual variability. Together these findings suggest that NS1 does represent an authentic gene-copy and also shed light on the ecology of this putative taxon. I hope future efforts will expand our understanding of both its identity and function.
  • Reproductive ecology and morphometric subspecies comparisons of Dunlin (Calidris alpina), an arctic shorebird

    Gates, Heather River; Powell, Abby N.; Hunter, Christine M.; Lanctot, Richard B. (2011-12)
    The Arctic region provides globally important breeding and migratory habitat for abundant wildlife populations including migratory shorebirds. Due to their remote breeding locations, basic information on breeding ecology, annual productivity, and factors that regulate their populations are poorly studied. Wildlife biologists managing migratory bird populations require detailed information on avian breeding biology, in addition to information on migration ecology including connectivity of migratory stopover and wintering locations. To address information gaps in fecundity, I conducted an experimental study investigating the renesting ecology of Dunlin (Calidris alpina arcticola) by removing clutches at two stages of incubation and by following adults marked with radio transmitters to their replacement clutch. In contrast to predictions for arctic-breeding species, Dunlin had high (82-95%) rates of clutch replacement during early incubation and moderate (35-50%) rates during late incubation. Female body condition and date of clutch loss were important variables explaining propensity for females to replace a clutch; larger females that lost their nest early in the season were more likely to renest than smaller females who lost their nest later in the season. To delineate Dunlin subspecies in areas where they overlap, I used morphological and molecular approaches to determine sex and subspecies of five subspecies of Dunlin breeding in Alaska and eastern Russia. This analysis yielded discriminant function models to correctly classify unknown individuals to sex (79-98%) and subspecies (7385%) via morphometric measures. Correct classification of mixed assemblages of subspecies improved when sex, determined though molecular techniques, was known. The equations I derived using discriminant function models can be used to identify the sex and subspecies of unknown Dunlin individuals for studies investigating breeding and migration ecology.
  • Regional modeling of Greenland's outlet glaciers with the parallel ice sheet model

    Della-Giustina, Daniella N. (2011-12)
    The most recent report from the Intergovernmental Panel on Climate Change cites ice sheet dynamics as the greatest source of uncertainty for predicting current and future rates of sea level rise. This has prompted the development and use of ice sheet models that are capable of simulating the flow and evolution of ice sheets and their corresponding sea level contribution. In the Arctic, the Greenland ice sheet appears to be responding to a warming climate more quickly than expected. In order to determine sea level contribution from Greenland, it is necessary to capture the regional dynamics of the fast flowing outlet glaciers that drain the ice sheet. This work has developed a novel regional model capable of simulating an outlet glacier, and its associated drainage basin, as a mode of using the Parallel Ice Sheet Model. Specifically, it focuses on modeling the Jakobshavn Isbrae as a demonstration. The Jakobshavn Isbrae is one of the world's fastest flowing outlet glaciers, and accounts for nearly 5% of ice loss from the Greenland Ice Sheet. Additionally, the Jakobshavn Isbrae has been widely studied for several decades, and a wealth of remotely sensed and in situ data is available in this region. These data are used as model input and for model validation. We have completed a parameter study in this work to examine the behavior of the regional model. The purpose of this study was not to tune the model to match observations, but rather to look at the influence of parameter choices on the ice dynamics. Model results indicate that we have identified the subset of the model parameter space that is appropriate for modeling this outlet glacier. Additionally, we are able to produce some of this more interesting features that have been observed at Jakobshavn, such as the development and disintegration of a floating ice tongue and the distribution of observed surface velocities. We validate these model results by comparison with recent spatially rich measurements of ice surface speeds, as well as ice geometry.
  • The response of plant community structure and productivity to changes in hydrology in Alaskan boreal peatlands

    Churchill, Amber C.; McGuire, A. David; Nettleton-Hollingsworth, Teresa; Turetsky, Merritt (2011-12)
    Northern peatlands have been a long-term sink for atmospheric CO₂, and have had a net cooling effect on global climate for the last 8,000 to 11,000 years. Across Alaska, peatlands face increased effects of climate change through hydrologic disturbance, both drying and flooding, and these conditions alter the ability of peatlands to accumulate carbon. Here, I examined the influence of changing hydrology in a moderate rich fen and a bog located in the discontinuous permafrost zone of interior Alaska. In both sites, I quantified how changing hydrology affected vegetation composition and ecosystem carbon uptake. At the fen, drying via a lowered water table treatment caused larger changes in vegetation composition and primary productivity than flooding via a raised water table treatment. In the bog, an area of recent permafrost thaw (collapse scar) had increased rates of understory net primary production and gross primary production, relative to an adjacent but older collapse scar and the surrounding permafrost plateau. Together, results from these studies highlight possible community responses to projected change in water availability, whether through drying or flooding, and demonstrate initial mechanisms for community responses altering ecosystem processes.
  • Remote sensing and GIS analysis of the spatial and morphological changes of thermokarst lakes: Kolyma lowlands, northeast Siberia

    Tillapaugh, Meghan L. (2011-05)
    Thermokarst lakes develop when changes in the permafrost thermal regime cause degradation leading to surface subsidence and ponding. The degree of thermokarst development depends upon permafrost characteristics, topography, and geology. Changing thermokarst lake dynamics affect arctic ecosystems, hydrological patterns, albedo, and the carbon cycle through the mobilization of organic matter in the permafrost. This study used remote sensing and GIS techniques to relate lake dynamics in the Kolyma Lowlands, Siberia, to geology, elevation, geomorphological features, hydrology, and air temperature. Highest limnicity and largest lake sizes were found in regions with low elevation, limited alluvial processes, high ground-ice content, and lithologies with small particle sizes. New lake development and erosion occurred as well. One subregion studied showed lake area increases (Cherskii: +7.6%) while another showed a decrease (Duvanny Yar: -5.2%). Differences are attributed to variations in elevation and fluvial influences. A major cause of drainage was river tapping of lakes. Lake coalescence, flooding during river water level high stands, and lakeshore erosion were the main causes of lake expansion. The Kolyma Lowland soils have high ice and organic matter contents as well making the monitoring of thermokarst lake dynamics important as large amounts of freshwater and carbon could potentially be released.
  • Mobility and chemical fate of antimony and arsenic in historic mining environments of Kantishna Hills, Denali National Park and Preserve, Alaska

    Ritchie, Vanessa J. (2011-05)
    Oxidative weathering processes of acid-forming sulfide minerals, such as pyrite (FeS₂), and associated arsenopyrite (FeAsS) and stibnite (Sb₂S₃), can have a significant impact on water quality associated with current and legacy mining operations. Concentrations of toxic metals and metalloids, such as antimony (Sb) and arsenic (As), in acid mine drainage can exceed drinking water quality standards by orders of magnitude. This study provides a detailed hydrogeochemical assessment of the mobility and chemical fate of antimony and arsenic in streams draining from historic antimony mines within Denali National Park and Preserve, Alaska. Antimony and arsenic concentrations in stream water reach up to 720 parts per billion (ppb) and 239 ppb, respectively. Aqueous phase antimony and arsenic speciation was determined using liquid chromatography coupled to an inductively coupled plasma mass spectrometer. Antimony in all water samples is predominantly found as Sb⁵ whereas arsenic was detected as mixtures of As³ /As⁵⁺ . Elevated antimony concentrations extend over 8 km downstream from the source, whereas arsenic quickly attenuates within 1.5 km. High correlation between antimony/arsenic and iron concentrations in fine-fraction streambed sediment indicates that sorption and (co)precipitation with iron (hydr)oxides is an important pathway for the attenuation of antimony and arsenic in natural waters.
  • The molecular basis of aerobic metabolic remodeling in threespine stickleback in response to cold acclimation

    Orczewska, Julieanna Inez (2011-05)
    Increases in mitochondrial density during cold acclimation have been documented in many fish species, however the mechanism regulating this process is not understood. The present study sought to characterize metabolic changes in response to cold acclimation and identify how these changes are regulated in oxidative muscle, glycolytic muscle and liver tissue of threespine stickleback, Gasterosteus aculeatus. Fish were warm (20°C) or cold (8°C) acclimated for 9 weeks and harvested during acclimation. Mitochondrial volume density was quantified using transmission electron microscopy and aerobic metabolic capacity assessed by measuring the maximal activity of citrate synthase and cytochrome c oxidase. The molecular mechanism mediating changes in aerobic metabolic capacity were assessed by quantifying transcript levels of aerobic metabolic genes and known regulators of mammalian mitochondrial biogenesis using quantitative real-time PCR. Our results indicate that while the maximal activity of aerobic metabolic enzymes increased in all tissues, mitochondrial biogenesis only occurred in oxidative muscle. Our results also suggest that the time course of metabolic remodeling is tissue specific. Lastly, we identified differences in the magnitude and timing of transcriptional and co-transcriptional activators driving metabolic remodeling between each tissue. These results suggest aerobic metabolic remodeling may be triggered by different stimuli in different tissues.
  • Body condition and reproductive strategies of female lesser scaup in the boreal forest of Alaska

    DeGroot, Kristin A.; Lindberg, Mark; Barboza, Perry; Schmutz, Joel (2011-05)
    In many waterfowl species, body condition of breeding females can contribute to reproductive success by influencing factors such as egg size, clutch size and ability to incubate eggs. In turn, changes in female condition at the population level could affect population growth rates. Large-scale declines in populations of Lesser Scaup (Aythya affinis) raised concerns that poor female body condition was contributing to declines by reducing reproductive output. However, little was known about changes in body condition over time and about the contribution that stored body reserves make to egg production, especially in boreal forest regions where most scaup breed. My objectives were: 1) examine temporal changes in body condition of pre-breeding female lesser scaup on the Yukon Flats National Wildlife Refuge, Alaska and the relationship between body condition and breeding status; 2) examine the role of body reserves (protein and lipid) in egg production using stable isotope techniques. I found no evidence for a decline in female body condition as compared to historic measures. However, females that had entered rapid follicle growth (the early stages of egg production) were significantly fatter than birds that were not currently producing eggs. In addition, I found that female lesser scaup use both body reserves and dietary nutrients for production of egg yolk.
  • Insights into deep structure and evolution of Alaska based on a decade of observations of shear wave splitting and mantle flow

    Bellesiles, Anna K. (2011-05)
    This thesis covers shear wave splitting results from a decade of temporary networks deployed throughout Alaska. The analysis and interpretation of data from the MOOS (Multidiscipline Observations Of Subduction) and ARCTIC (Alaska Receiving Cross Transect for the Inner Core) PASSCAL (Program for Array Seismic Studies of the Continental Lithosphere) deployments, combined with the previously published BEAAR (Broadband Experiment Across the Alaska Range) results provide anisotropy and flow observations across the state. In south central Alaska, a region dominated by the subduction of the Pacific plate under the North American plate, fast directions are dominantly in the direction of convergence (NNW-SSE), or trench-normal. This is either due to entrained flow below the subducting portion of the Yakutat block, or anisotropy within the block itself. Farther north above the mantle wedge the shear wave splitting results are dominated by fast directions along the strike of the subducting slab (NE-SW), due to along strike flow within the mantle wedge. North of the mantle wedge, fast directions transition into a more NNE to SSW orientation which is the Brooks Range and North slope are in the direction of absolute plate motion.
  • An exposition on the Kronecker-Weber theorem

    Baggett, Jason A. (2011-05)
    The Kronecker-Weber Theorem is a, classification result from Algebraic Number Theory. Theorem (Kronecker-Weber). Every finite, abelian extension of Q is contained in a cyclotomic field. This result was originally proven by Leopold Kronecker in 1853. However, his proof had some gaps that were later filled by Heinrich Martin Weber in 1886 and David Hilbert in 1896. Hilbert's strategy for the proof eventually led to the creation of the field of mathematics called Class Field Theory, which is the study of finite, abelian extensions of arbitrary fields and is still an area of active research. Not only is the Kronecker-Weber Theorem surprising, its proof is truly amazing. The idea of the proof is that for a finite, Galois extension K of Q, there is a connection between the Galois group Gal(K/Q) and how primes of Z split in a certain subring R of K corresponding to Z in Q. When Gal(K/Q) is abelian, this connection is so stringent that the only possibility is that K is contained in a cyclotomic field. In this paper, we give an overview of field/Galois theory and what the Kronecker-Weber Theorem means. We also talk about the ring of integers R of K, how primes split in R, how splitting of primes is related to the Galois group Gal(K/Q), and finally give a proof of the Kronecker-Weber Theorem using these ideas.
  • Ecological effects of invasive European bird cherry (Prunus padus) on salmonid food webs in Anchorage, Alaska streams

    Roon, David A.; Wipfli, Mark; Prakash, Anupma; Wurtz, Tricia (2011-08)
    Invasive species are a concern worldwide as they can displace native species, reduce biodiversity, and disrupt ecological processes. European bird cherry (Prunus padus) (EBC) is an invasive ornamental tree that is rapidly spreading and possibly displacing native trees along streams in parts of urban Alaska. The objectives of this study were to: 1) map the current distribution of EBC along two Anchorage streams, Campbell and Chester creeks, and 2) determine the effects of EBC on selected ecological processes linked to stream salmon food webs. Data from the 2009 and 2010 field seasons showed: EBC was widely distributed along Campbell and Chester creeks; EBC leaf litter in streams broke down rapidly and supported similar shredder communities to native tree species; and EBC foliage supported significantly less terrestrial invertebrate biomass relative to native deciduous tree species, and contributed significantly less terrestrial invertebrate biomass to streams compared to mixed native vegetation, but riparian EBC did not appear to affect the amount of terrestrial invertebrate prey ingested by juvenile coho salmon (Oncorhynchus kisutch). Although ecological processes did not seem to be dramatically affected by EBC presence, lowered prey abundance as measured in this study may have long-term consequences for stream-rearing fishes as EBC continues to spread over time.
  • Separation, identification, and quantification of low molecular weight nitrogen containing compounds in fish byproducts

    Nigg, Jonathan; Rasley, Brian; Bechtel, Peter J.; Green, Thomas K. (2011-08)
    There is interest by the fish processing industry in the identification and eventual extraction of higher valued low molecular weight nitrogen compounds from fish byproducts such as stickwater, hydrolysates, fish tissues, and other byproducts. A hydrophilic interaction liquid chromatography (HILIC) method was developed for the separation and quantification of amino acids, small nitrogenous acids and bases, as well as, other nitrogen containing metabolites. The HILIC method developed is a robust and non-derivatizing method for the analyses of aqueous compounds found in freeze dried red salmon whole fish and red salmon byproducts (pretreated stickwater, post-treated stickwater, and fishmeal). Triplicate samples of all byproducts were obtained from commercial processors in Kodiak, AK. Byproduct samples were extracted and centrifugally filtered through 3000 MW membranes. The identification of low molecular weight compounds in different fractions of fish byproduct showed the partitioning of unbound components during fishmeal processing. Several aqueous nitrogen containing compounds were quantified and comparisons were made of these components in different fish byproduct fractions. This study suggests that creative, creatinine, taurine, and hypoxanthine are found in elevated concentrations in stickwater and are preferentially partitioned into the stickwater fraction.

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