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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Phenology and management of triploid flowering rush (Butomus umbellatus L.)

Turnage, Lee Gray, Jr. 30 April 2021 (has links)
Flowering rush (Butomus umbellatus L.) is a perennial wetland/aquatic plant that is native to Eurasia but has invaded North America and spread across Southern Canada and the Northern U.S. where it thrives along wetlands, shallow shorelines, and in submersed habitats of lakes, ponds, streams, rivers, and reservoirs. Little is known about the life cycle of flowering rush in its invaded range as only one study has investigated flowering rush phenology in Minnesota, USA. As flowering rush continues to expand its range southward in the U.S. it is imperative that resource managers 1) better understand the plants life cycle, 2) identify more aggressive and 3) selective herbicide strategies, and 4) utilize adaptive management protocols. In a mesocosm experiment, flowering rush grown in southern climates produced less overall biomass but produced more buds than recorded in northern populations. A second mesocosm study using one to four biweekly sequential diquat (0.37 mg L-1) treatments reduced flowering rush biomass and rhizome bud density by 62 to 100% one year after treatment. Additionally, there were no differences among diquat treatments suggesting that more aggressive diquat protocols may not be useful. In field trials, flowering rush was selectively reduced 92 to 99% by diquat treatments over two years, while hardstem bulrush was not affected. In mesocosms, flowering rush and hardstem bulrush were exposed to the contact herbicides diquat, endothall, copper, carfentrazone-ethyl, and flumioxazin; endothall (3.0 mg L-1) selectively reduced aboveground biomass of flowering rush by 69% and diquat (0.19 mg L-1) selectively reduced belowground biomass by 77%. None of the other herbicides affected flowering rush. In a Minnesota field project to identify adaptive control strategies, treatment sites were designated as having very-low, low, or high flowering rush prevalence with each receiving no, one, or two diquat treatments (0.37 mg L-1), respectively. Flowering rush did not increase after single diquat applications in low prevalence sites while prevalence declined in high prevalence sites. This suggests that single diquat applications are suitable to maintain control of sites with low flowering rush prevalence allowing resource managers to allocate unused resources elsewhere.
2

Recreational Water Users, Aquatic Invasive Species and Fish Disease: Examining the Usage of Tailored Messaging to Increase Environmental Responsible Behaviors

Grant, Lionel DeShaun 01 August 2012 (has links)
The purpose of this study was to discover how to efficiently use tailored messaging to increase recreational water users' behavioral intentions to perform specific behaviors that prevent the spread of Aquatic Invasive Species (AIS) and Viral Hemorrhagic Septicemia (VHS). The objectives were to identify the most effective message structure and message order for signs targeting seven behaviors that reduce the spread of AIS and VHS, and to examine the moderating effect of AIS and VHS knowledge and awareness on behavioral intentions. The population of this study consisted of students 31 years of age and younger attending Southern Illinois University Carbondale (μ = 21.06; n = 680). The study design tested messages according to the Optimal Arousal Theory. The respondents completed an 11-item questionnaire that measured knowledge, awareness, and behavioral intentions, and included one of 34 sign treatments. When asked how knowledgeable respondents were about AIS and VHS, 48% of respondents indicated that they were not knowledgeable. Respondents were also asked the extent to which they believed AIS is a problem in Illinois; 43% reported AIS to be a "moderate" problem. Seven (7) items on the questionnaire measured intention to perform specific behaviors that may reduce the spread of AIS and fish disease between water bodies. Knowledge and awareness (only when interacting with knowledge) were found to be covariates of behavioral intentions. Complex results were revealed regarding the most effective tailored message, as no one sign significantly increased all seven behavioral intentions and the number of treatments significantly increasing behavioral intentions varied by behavior (i.e., 11 treatments had a significant influence on the behavioral intention for "visual inspections;" 4 treatments had a significant influence on the behavioral intention for "drain water;" 8 treatments had a significant influence on the behavioral intention for "avoid bait release;" 6 treatments had a significant influence on the behavioral intention for "remove plants and animals;" 4 treatments had a significant influence on the behavioral intention for "flush motor;" and, 11 treatments had a significant influence on the behavioral intention for "rinse boat". Results suggest mainly positively phrased messages works best when trying to stimulate environmentally responsible behavior (ERB). The recommendations from this study encourage strategic use of communication to enhance natural resource management as this study yielded gains in predicted behaviors of respondents to reduce the spread of AIS and VHS. The study also demonstrates the need to increase recreational water users' AIS and VHS knowledge improve the likelihood that they will perform desired behaviors.
3

Modeling Ballast Water Management Strategies for Slowing the Secondary Spread of Aquatic Invasive Species on the Laurentian Great Lakes

Kvistad, Jake T. January 2018 (has links)
No description available.
4

Age-0 Walleye Diet Shift Reflects Food Web Changes in Western Lake Erie

Yang, Touhue 11 July 2022 (has links)
No description available.
5

Ports, Prosperity, and Pests: Assessing the Threat of Aquatic Invasive Species Introduced by Maritime Shipping Activity in Cuba

O'Brien, Charleen 22 November 2016 (has links)
Aquatic invasive species (AIS) are biological pollutants that cause detrimental ecological, economic, and sociological effects on non-native communities. With increasing globalization through maritime trade, coastal ports are vulnerable to AIS introductions transported by commercial vessels. As Cuba’s Port Mariel becomes a competitive transshipment hub within the Caribbean, it is essential to identify the potential threat that AIS may pose with a likely increase in shipping activity. It is equally important to understand the status of established AIS in Cuba and control measures presently being implemented by the country. This information can provide guidance for establishing or improving Cuban AIS preventative and remedial actions. For this study, publically accessible information was used to conduct threat assessments of present and potential AIS in Cuba and to identify feasible international donors of AIS due to trade with Port Mariel. Fifteen species were identified as established Cuban AIS, eight of which were associated with harmful impacts to the environment, economy, and human health. Only one established AIS, Perna viridis (the Asian green mussel), was recorded as having repeated, negative influences in Cuba. Regional trade partners of Port Mariel were identified as the most likely donors of AIS due to ecological similarity and minimal voyage duration between countries. These trade partners also represented the busiest ports and transshipment hubs in the wider Caribbean region and, therefore, could expose Port Mariel to ‘stepping-stone’ invasions. Five species associated with international trade partners were identified as potentially detrimental to Cuba if introduced into Port Mariel. There were no significant differences between the salinity and temperature tolerances of the AIS already established in Cuba and the possible AIS of concern, suggesting that these potential invaders could survive the environmental conditions of Port Mariel and subsequently become established throughout Cuba. The results presented herein are a preliminary assessment of AIS threats in Cuba and emphasize the importance of prioritizing AIS prevention and management. This study also establishes a baseline inventory of potential AIS in Cuba and a methodology that can be followed for future analyses outside of the study region.

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