• Observations and generation mechanisms of slow-mode waves in the magnetosheath

      Yan, Ming; Lee, Lou; Craven, John; Hawkins, Joseph; Sentman, Dave; Watkins, Brenton (1995)
      The interaction of solar wind with the geomagnetic field leads to the formation of the bow shock, magnetosheath, and magnetopause. Magnetohydrodynamic (MHD) slow-mode structures with a plasma density enhancement and magnetic field depression have been observed to appear frequently in the inner magnetosheath. In addition, the slow-mode structures usually consist of slow-mode waves with a smaller length scale. These slow-mode structures and waves are studied in this thesis through satellite observations and numerical simulations. We find, through satellite observations, that some of the slow-mode structures are associated with Alfven waves in the solar wind. On the other hand, simulations show that slow-mode waves are generated through the interactions between the bow shock and interplanetary shocks, magnetosonic waves, rotational discontinuities, or Alfven waves. The generated slow-mode waves stay in the inner magnetosheath for a long time (about 15 minutes) before the wave energy is convected away tailward. Of particular importance are the interactions between the bow shock and interplanetary rotational discontinuities or Alfven waves. These interactions generate a region with an enhanced plasma density and depressed magnetic field, which is very similar to the slow-mode structures observed in the inner magnetosheath. Based on observations and simulations, it is suggested that the interactions of various types of solar wind fluctuations with the bow shock may lead to the frequent appearance of slow-mode structures and waves in the inner magnetosheath. The generated slow-mode structures have strong pressure variations, and may impinge on the magnetopause as strong pressure pulses.
    • Observations Of Metal Concentrations In E-Region Sporadic Thin Layers Using Incoherent-Scatter Radar

      Suzuki, Nobuhiro; Watkins, Brenton (2006)
      This thesis has used incoherent-scatter radar data from the facility at Sondrestrom, Greenland to determine the ion mass values inside thin sporadic-E layers in the lower ionosphere. Metallic positively-charged ions of meteoric origin are deposited in the earth's upper atmosphere over a height range of about 85-120 km. Electric fields and neutral-gas (eg N2, O, O2) winds at high latitudes may produce convergent ion dynamics that results in the re-distribution of the background altitude distribution of the ions to form thin (1-3 km) high-density layers that are detectable with radar. A large database of experimental radar observations has been processed to determine ion mass values inside these thin ion layers. The range resolution of the radar was 600 meters that permitted mass determinations at several altitude steps within the layers. Near the lower edge of the layers the ion mass values were in the range 20-25 amu while at the top portion of the layers the mass values were generally in the range 30-40 amu. The numerical values are consistent with in-situ mass spectrometer data obtained by other researchers that suggest these layers are mainly composed of a mixture or Mg +, Si+, and Fe + ions. The small tendency for heavier ions to reside at the top portion of the layers is consistent with theory. The results have also found new evidence for the existence of complex-shaped multiple layers; the examples studied suggest similar ion mass values in different layers that in some cases are separated in altitude by several km.
    • Obstacle detection with Kinect V2 on a ground robot

      Fisher, Laurin; Lawlor, Orion; Hartman, Chris; Genetti, Jon (2018-12)
      This paper is about determining whether using a Kinect V2 (Xbox One Kinect) mounted on a LAYLA ground robot can be used to detect obstacles, by generating a heightmap with the depth data. We take several factors into consideration including: framerate, power consumption, field of view, and data noise.
    • The occurrence and characteristics of plastic pollution in Alaska's marine birds

      Day, Robert H. (1980-05)
      Major aspects of the occurrence and variation of plastic particles in the stomachs of marine birds in Alaska were examined. A total of 448 of 1 ,968 individuals and 15 of 37 species of marine birds contained plastic. Species feeding primarily by pursuit-diving and surface-seizing had the highest incidence of plastic. Crustaceanand cephalopod-feeders had a higher incidence of plastic than did fish-feeders. Birds from the Aleutian Islands averaged more particles than did birds elsewhere in Alaska. No sexual differences in plastic ingestion were found, but subadults averaged more plastic than did adults. There was a general increase in plastic ingestion between 1969 and 1977. An annual cycle of plastic ingestion was recorded, with the greatest ingestion in mid-summer. No overt effects of plastic on the physical well-being of the birds were found, but non-breeding in the Parakeet Auklet may have been caused by high plastic ingestion.
    • Occurrence patterns of whistler mode (WM) echoes observed by RPI/IMAGE and their relation to geomagnetic activity

      Reddy, Amani (2007-12)
      This thesis presents an analysis of whistler mode (WM) echoes observed at altitudes less than 5,000 km by the Radio Plasma Imager (RPI) on the IMAGE satellite. WM echoes are generated either by specular reflection (SR) of RPI signals at the Earth-ionosphere boundary (~90 km) or by magnetospheric reflection of RPI signals [...] at altitudes greater than 1,000 km [Sonwalkar et al., 2004; Sonwalkar et al., 2006]. These echoes are further influenced by field aligned irregularities (FAI) and are categorized into discrete, multipath or diffuse SR- and MR- WM echoes, based on their characteristic spectral forms. A survey of WM echoes observed during January 2004- December 2005 showed that WM echoes occurred at all latitudes and under moderate geomagnetic conditions. Occurrence patterns of WM echoes observed in August-December 2005 during geomagnetically quiet and disturbed periods indicate that geomagnetic storms lead to significant changes in FAI that affect the propagation of WM echoes. Our results help (1) in better understanding propagation and generation mechanisms of naturally occurring WM waves, and (2) in planning future WM wave injection experiments in space.
    • Ocean Wilderness In Theory And Practice

      Barr, Bradley W.; Kruse, Gordon; Kliskey, Andrew; Alessa, Lilian; Koester, David (2012)
      Wilderness preservation has been an important focus of resource conservation since the dwindling number of wild places was perceived by some as losing a valued part of our collective natural and cultural heritage. While wilderness preservation efforts have been almost entirely focused on the land, recently there has been growing interest in "ocean wilderness." However, implementation has been constrained by the lack of a common vision of how "wilderness" is applied to the ocean, and how such areas should be managed and preserved. The purpose of this work was to identify and evaluate potential definitions of ocean wilderness and the values and qualities such areas possess, and to determine how they might be effectively identified and managed to preserve their wilderness character. This research focused on articulating a robust definition for "wilderness waters," within the context of how wilderness is currently conceived and articulated in law and policy, as well as evaluating how such areas might be most appropriately identified and managed. Extensive inventories were conducted of existing ocean wilderness areas, focused on North America, to determine what currently exists, how these areas are managed, and how future ocean wilderness designations should be prioritized. A survey was conducted, targeting resource managers and scientists, to identify preferences and perceptions of ocean wilderness and its potential stewardship. The survey results suggested that coastal waters possessed considerable values and qualities of wilderness, particularly areas adjacent to existing designated wilderness, that certain human uses might be appropriately permitted, and that there was much support for expanding the area of coastal waters designated as wilderness. The research also suggested that the North American Arctic might offer many opportunities for preserving ocean wilderness, in close collaboration with the Indigenous communities in this region. A number of recommendations were offered including that priority should be given to evaluating and designating areas adjacent to designated coastal wilderness areas, that the existing legal and policy framework in North America can be effectively used to expand the "wilderness waters" system, and that more work needs to be done to build the constituencies of support essential to accomplish this task.
    • Oceanic emissions of sulfur: Application of new techniques

      Jodwalis, Clara Mary; Benner, Richard L. (1998)
      Sulfur gases and aerosols are important in the atmosphere because they play major roles in acid rain, arctic haze, air pollution, and climate. Globally, man-made and natural sulfur emissions are comparable in magnitude. The major natural source is dimethyl sulfide (DMS) from the oceans, where it originates from the degradation of dimethysulfonioproprionate (DMSP), a compound produced by marine phytoplankton. Global budgets of natural sulfur emissions are uncertain because of (1) the uncertainty in the traditional method used to estimate DMS sea-to-air flux, and (2) the spatial and temporal variability of DMS sea-to-air flux. We have worked to lessen the uncertainty on both fronts. The commonly used method for estimating DMS sea-to-air flux is certain to a factor of two, at best. We used a novel instrumental technique to measure, for the first time, sulfur gas concentration fluctuations in the marine boundary layer. The measured concentration fluctuations were then used with two established micrometeorological techniques to estimate sea-to-air flux of sulfur. Both methods appear to be more accurate than the commonly used one. The analytical instrument we used in our studies shows potential as a direct flux measurement device. High primary productivity in high-latitude oceans suggests a potentially large DMS source from northern oceans. To begin to investigate this hypothesis, we have measured DMS in the air over northern oceans around Alaska. For integrating and extrapolating field measurements over larger areas and longer time periods, we have developed a model of DMS ocean mixing, biological production, and sea-to-air flux of DMS. The model's main utility is in gaining intuition on which parameters are most important to DMS sea-to-air flux. This information, along with a direct flux measurement capability, are crucial steps toward the long-term goal of remotely sensing DMS flux. A remote sensing approach will mitigate the problems of spatial and temporal variability. The new developments in methodology, field sampling, and modeling put forth in this thesis are tools we have used to better understand and quantify sulfur gas emissions from northern oceans, which appear to be a significant source of sulfur to the global atmosphere.
    • Odors And Ornaments In Crested Auklets (Aethia Cristatella): Signals Of Mate Quality?

      Douglas, Hector D., Iii; Springer, Alan M. (2006)
      Crested auklets (Aethia cristatella) are small colonial seabirds that display an ornamental feather crest and emit a citrus-like odorant during the breeding season. In this study odors and ornaments were investigated as possible signals of mate quality. Crest size was negatively correlated with the stress hormone corticosterone in males, but this was not the case in females. Body condition was negatively correlated with corticosterone in females, but this was not the case in males. Corticosterone levels were interpreted as an index of physiological condition, and it was concluded that males with longer crests were more competent at meeting the social and energetic costs of reproduction. I hypothesized that the crested auklet odorant: (1) functions as a chemical defense against ectoparasites, (2) is assessed as a basis for mate selection, (3) is facilitated by steroid sex hormones. Laboratory and field experiments showed that synthetic replicas of the crested auklet odorant repelled, impaired, and killed ectoparasites in a dose-dependent fashion. Chemical concentrations in plumage were at least sufficient to repel and impair ectoparasites. Chemical emissions from breeding adult crested auklets peaked at the time of egg hatching when young are most vulnerable to tick parasitism. In males, chemical emissions were correlated with crest size, a basis for mate selection. Presentation of synthetic aldehydes elicited behaviors similar to those that occur during courtship. Captive crested auklets responded preferentially to synthetic replicas of their odor, and the highest frequency of response occurred during early courtship. These results show that the chemical odor could be a basis for mutual mate selection. Production of the chemical odorant may be facilitated by steroid sex hormones since octanal emission rates were correlated with progesterone in males. Finally it was determined that the chemical composition of odorants in crested auklets and whiskered auklets (A. pygmaea) differed in three key respects. This suggests that an evolutionary divergence occurred in the odorants of the two species similar to what has been suggested for ornamental traits. In conclusion, crested auklets appear to communicate with odors and ornaments, and these signals may convey multiple messages regarding condition, quality, and resistance to parasites.
    • Oil and wildfire effects on nutrient cycling and microbial diversity in subarctic mineral soils

      Garron, Jessica I.; Braddock, Joan; Valentine, David; Lindstrom, Jon (2007-05)
      In 1976 crude oil was experimentally spilled on a plot near Fairbanks, Alaska to mimic an oil pipeline spill. The plot and surrounding area were further disturbed by wildfire in 2004. Although the fire burned organic matter on the plot surface, substantial subsurface oil remained. After the fire, soil samples from oiled/burned, burned, and control plots were collected to evaluate the effects of disturbance on nutrient cycling and soil bacterial communities. Samples were analyzed for total nitrogen (N), soil carbon (C) and N mineralization, N fixation, total bacterial diversity (16S rDNA), and functional genetic diversity (nifH). Inorganic N was low in all soil types. In control and burned soils there was net N mineralization, but in oiled/burned soils there was significant N immobilization. Carbon mineralization was much higher in oiled/burned soils than control or burned soils. While the highest N fixation potential was measured in oiled/burned soils, the diversity of the N-fixing bacterial community in those soils was about the same as that of the control. For 16S rDNA, diversity was higher in control and burned soils than in oiled/burned soils. Overall, the type of disturbance and the length of time since disturbance both affected microbial function and diversity
    • On interannual variability and climate change in the north Pacific

      Salmon, David Kurt (1992-05)
      Long term changes in the atmospheric and oceanic environment of the North Pacific were investigated for the period 1946-1991. A climatology of North Pacific wind stress curl was developed because of the relevance of changes in wind stress curl to both oceanic and atmospheric variability. The dominant scales of spatial and temporal wind stress curl variability were determined and examined within the context of observed changes in North Pacific air temperature, sea surface temperature (SST), sea ice cover, oceanic mass transport and the occurrence of blocking anticyclones. Relationships between these variables and indices of tropical Pacific variability were also determined on interannual time scales. During 1976-1988, phase relationships were very strong between long term mean anomalies of wind stress curl, SST, air temperature, sea ice cover, The Pacific North American index, the Southern Oscillation Index (SOI), and tropical Pacific SST. Long term mean anomalies of these parameters did not change sign during 1976-88. These strong phase relationships did not occur amongst these variables during any other period of the record. The 1976-1988 period is characterized by intensified storminess, the decreased occurrence of blocking anticyclones, and decreased sea ice cover in the subarctic North Pacific. Intensified atmospheric circulation also occurred in the western Pacific subtropical anticyclone. Anomalously low SST occurred across the central and western North Pacific during this period while anomalously high SST was present in the eastern North Pacific adjacent to North America. Changes in the sign of the long term mean anomalies of wind stress curl, central North Pacific SST and the SOI suggest that this climate regime ended or relaxed after 1988. After 1975, long term changes in anomalies of the Southern Oscillation Index, tropical Atlantic wind stress, Sahel rainfall, and Greenland Sea ice cover have characteristics similar to those observed in the North Pacific. It is suggested that the climate anomalies observed in the North Pacific during 1976-1988 occurred as part of a hemispheric or global scale climate regime.
    • On the biology of eelgrass in Alaska

      McRoy, C. Peter (1970-05)
      A collection of essays is presented that are a contribution toward a biology of eelgrass (Zostera marina L.) in Alaska. Eelgrass is the most abundant seagrass on the coast of Alaska. The distribution of the plant in Alaska is disjunct and extends from Kotzebue Sound to the southern border of the state. The present circumboreal distribution is thought to be the result of dispersal from a west Pacific origin around the Pacific rim and through the Arctic into the Atlantic. Ten widely scattered eelgrass populations in Alaska have been sampled for quantitative comparison. The highest standing stocks (1510 g dry wt/m²) were found in Kinzarof and Izembek lagoons on the Alaska Peninsula. The caloric content, chlorophyll a concentration, turion density, and leaf size varied greatly among the populations. The eelgrass in Safety Lagoon survives the arctic winter under one meter of sea ice in conditions of extremely low light intensity and anoxic water. In chemical composition, eelgrass is similar to other angiosperms, but it also reflects adaptation to the marine environment. Trace elements are accumulated in the plant in proportion to their concentration in the sea. The roots as well as the leaves function as the sites for the uptake of phosphate. Using radioactive phosphate it was shown that phosphate was absorbed greatest in the light and transported throughout the plant; a portion of the phosphate removed from solution by the roots was lost across the leaves. The metabolism of eelgrass in the dark is extremely dependent on temperature. Physiological differences exist between shallow water and deep water plants and between summer and winter plants. A depressed rate of respiration in winter is an adaptation enhancing survival in high latitudes.
    • On the detection of virtual machine introspection from inside a guest virtual machine

      Marken, Brandon Ashlee; Lawlor, Orion; Price, Channon; Barry, Ronald; Hartman, Christopher; Genetti, Jon (2015-12)
      With the increased prevalence of virtualization in the modern computing environment, the security of that technology becomes of paramount importance. Virtual Machine Introspection (VMI) is one of the technologies that has emerged to provide security for virtual environments by examining and then interpreting the state of an active Virtual Machine (VM). VMI has seen use in systems administration, digital forensics, intrusion detection, and honeypots. As with any technology, VMI has both productive uses as well as harmful uses. The research presented in this dissertation aims to enable a guest VM to determine if it is under examination by an external VMI agent. To determine if a VM is under examination a series of statistical analyses are performed on timing data generated by the guest itself.
    • On the dynamics of the Alaska coastal current

      Luick, John Leonard; Royer, Thomas C. (1988)
      The Alaska Coastal Current (ACC) in the northern Gulf of Alaska is a wind- and buoyancy-driven near-surface jet primarily maintained by the horizontal salinity gradient due to fresh water entering at the coast. It serves as the major source of fresh water to the North Pacific Ocean. The buoyancy driving force is the major focus of this investigation. The study area is situated just "downstream" of Prince William Sound (PWS), a large estuary whose surface outflow is seen to occupy a narrow inshore band after joining the ACC. The effect of this band appears to be the formation of an occasional double maximum in the ACC. The period focused on in this study was selected on the basis of weak windstress but large fresh water input in order to emphasize the buoyancy forcing. The TS characteristics and a water mass tracing technique are used to separate the thermal and haline signals in the buoyancy forcing and to track the origin and fate of the source waters of the study area. The buoyancy driving force is shown to be primarily haline, with temperature playing a secondary, moderating role. Because of the large topographic variability and sloping density interfaces, and in order to exploit the available data, a diagnostic model retaining the baroclinicity and bottom topography terms was chosen to study the dynamics. Model premises are verified by results from hydrographic surveys, moored current meters, and a profiling current meter. The model predicts a midshelf region of negligible sealevel gradient, with a nearshore ($\approx$70 km wide) band over which the sealevel changes by about 25 cm. The sloping surface drives a strong ($\approx$100 cm/s) surface flow, which decreases to zero and reverses below about 100 m due to the opposing baroclinic pressure gradient. The flow splits around a shoal region. The onshore portion joins the outflow from PWS and accelerates downstream forming a double maximum. The offshore segment forms a large meander before rejoining the rest of the ACC, advecting midshelf water shoreward. The momentum balance is dominated by the JEBAT terms, which primarily determine the flow along and across contours of f/H.
    • On the frontal ablation of Alaska tidewater glaciers

      McNabb, Robert Whitfield; Hock, Regine; Bueler, Edward; Motyka, Roman; Pettit, Erin; Truffer, Martin (2013-08)
      Sea level rise is a major problem that society will face in the coming century. One of the largest unknown components of sea level rise is frontal ablation (the sum of mass loss through calving and subaqueous melting) from glaciers and ice sheets. Using estimates of ice thickness, rates of glacier length change, and glacier velocities, we present a record of frontal ablation over the period 1985-2012 for 20 Alaska tidewater glaciers. We also present a new method for estimating ice thickness by solving the continuity equation between adjacent flowlines. Because of the wealth of data available, we apply this method to Columbia Glacier, Alaska. The mean ice thickness and volume of Columbia Glacier were approximately halved over the period 1957-2007, from 281 m to 143 m, and from 294 km�_ to 134 km�_, respectively. Using bedrock slope and considering how waves of thickness change propagate through the glacier, we conclude that the rapid portion of this tidewater glacier's retreat is likely nearing an end. We present a 64 year record of length change for 50 Alaska tidewater glaciers, over the period 1948-2012. Most (31) glaciers retreated over the period. Examination of the onset of glacier retreats indicates a correlation between high summer sea surface temperature and the triggering of retreat. Finally, we present a 27 year record of surface velocity for 20 Alaska tidewater glaciers derived from Landsat imagery. Surface velocities vary by as much as 80% throughout the year, indicating that using measurements from one time of year may bias estimates of frontal ablation. The total mean rate of frontal ablation for these 20 glaciers over the period 1985-2012 is 16.2 � 6.5 Gt a����_. Extending this to the remaining 30 Alaska tidewater glaciers yields an estimate of frontal ablation of 18.3 � 7.3 Gt a����_, approximately 50% of the climatic mass balance of the region. This indicates the important, non-negligible role frontal ablation can play in regional mass balance, even where tidewater glaciers cover a small fraction of the total area.
    • On the Klein-Gordon equation originating on a curve and applications to the tsunami run-up problem

      Gaines, Jody; Rybkin, Alexei; Bueler, Ed; Nicolsky, Dmitry (2019-05)
      Our goal is to study the linear Klein-Gordon equation in matrix form, with initial conditions originating on a curve. This equation has applications to the Cross-Sectionally Averaged Shallow Water equations, i.e. a system of nonlinear partial differential equations used for modeling tsunami waves within narrow bays, because the general Carrier-Greenspan transform can turn the Cross-Sectionally Averaged Shallow Water equations (for shorelines of constant slope) into a particular form of the matrix Klein-Gordon equation. Thus the matrix Klein-Gordon equation governs the run-up of tsunami waves along shorelines of constant slope. If the narrow bay is U-shaped, the Cross-Sectionally Averaged Shallow Water equations have a known general solution via solving the transformed matrix Klein-Gordon equation. However, the initial conditions for our Klein-Gordon equation are given on a curve. Thus our goal is to solve the matrix Klein-Gordon equation with known conditions given along a curve. Therefore we present a method to extrapolate values on a line from conditions on a curve, via the Taylor formula. Finally, to apply our solution to the Cross-Sectionally Averaged Shallow Water equations, our numerical simulations demonstrate how Gaussian and N-wave profiles affect the run-up of tsunami waves within various U-shaped bays.
    • On the nature and shape of noctilucent cloud particles

      Chao, Jih-Kwin (1965-05)
      The exact theory of the scattering of light from spheres, double-layer spheres, infinite long cylinders and coaxial cylinders is presented here in detail. The theory of scattering from spheres and infinite long cylinders is then applied to the noctilucent Cloud (NCL) problem. The intensity and polarization versus scattering angle, particle size, and wavelength for spherical particle scattering with index of refraction 1.33 (corresponding to ice and stone) were calculated with an IBM 1620 electronic computer and the results are compared with the available experimental data. The experimental data was also compared with the results of Deirmendjian, Clasen, etc., allowing conclusions with regard to the possibility of spherical pure metallic particles. The results indicate that the NLC particles are either stony dust or ice coated stony dust rather than pure metallic in nature. Consideration is given to the possibility of detecting through polarization and spectrographic studies the possible growth of NLC particles resulting from the formation of ice on them. If the NLC become visible only as a result of an increase of the number of particles, then the shape of the polarization versus scattering angle curve will not change, and the intensity versus wavelength curve will not change in shape but only in amplitude. However, if particle growth is responsible for the NLC becoming visible, then the shape of the polarization versus scattering angle curve will change. Careful experimental observations of these quantities should then answer this question about particle growth. A detailed analysis of the NLC particle sampling data obtained in Sweden during 1962 is made. A particle size distribution of the form Nα(diameter)⁻⁴ is required for the sampling data to be consistent with the polarization measurements that have been made.
    • On the physical oceanography of Bristol Bay 1969-1970

      Myers, Richard L. (1976-08)
      The examination of hydrographic data obtained in Bristol Bay 1969-1970 allowed oceanographic conditions in this region to be described for shorter time periods (several weeks) than previous studies (several months). This data revealed that during early spring Bristol Bay was homogeneous both vertically and horizontally in temperature and vertically in salinity. During late spring, a steep thermocline developed in the offshore regions and was present throughout summer, while the salinity structure remained vertically homogeneous. Salinity and bottom temperature contours tended to follow isobaths and indicated a cyclonic circulation in the bay. Summer surface temperature distributions are characterized by regions of cold water. These regions are believed to be maintained by upwelling of cold bottom water due to a subsurface convergence in the bottom Ekman layer. Data from 1970 showed that low temperature and high salinity water was much more extensive in that year than in 1969. This is attributed to deeper water from outer Bristol Bay surfacing in central Bristol Bay.
    • On the willingness-to-pay for Elodea removal in the Fairbanks North Star Borough

      Kaczmarski, Jesse I.; Little, Joseph; Greenberg, Joshua; Fix, Peter (2018-05)
      The empirical research conducted herein addresses a public need for the funding of a project that would eradicate Elodea in the Fairbanks North Star Borough (FNSB). The eradication project has been outlined and approved by State and Federal agencies and has gathered funding to begin the eradication process. The study aims to develop a mean willingness-to-pay value for survey participants by shifting the funding burden to property tax payers. This body of work includes a primer on Elodea in the borough, an overview of contingent valuation, a parametric approach to willingness-to-pay, and results of the study conducted on Fairbanks property owners. The average willingness-to-pay per survey respondent is $50.32. In addition, 72% of survey respondents voted for the enactment of the program at their proposed cost level. These financial burdens took values of $10, $30, $60, or $120 per year for 4 years to fund the proposed program. A penalized maximum log-likelihood estimation found that the most significant predictors for the likelihood of a yes vote are the respondent's perceived risk to the ecosystem and recreational opportunities. Additionally, the respondents concern for the use of herbicides in the borough to treat the Elodea infestation is highly significant. The high level of prior knowledge throughout the survey indicates that respondents had established view on Elodea prior to the survey.