Parasitological Data as Monitors of Environmental Health

When an appropriate fish host is selected, analysis of its parasites offers a useful, reliable, economical, telescoped indication or monitor of environmental health. The value of that information increases when corroborated by another non-parasitological technique. The analysis of parasites is not necessarily simple because not all hosts serve as good models and because the number of species, presence of specific species, intensity of infections, life histories of species, location of species in hosts, and host response for each parasitic species have to be addressed individually to assure usefulness of the tool. Also, different anthropogenic contaminants act in a distinct manner relative to hosts, parasites, and each other as well as being influenced by natural environmental conditions. Total values for all parasitic species infecting a sample cannot necessarily be grouped together. For example, an abundance of numbers of either species or individuals can indicate either a healthy or an unhealthy environment, depending on the species of parasite. Moreover, depending on the parasitic species, its infection, and the time chosen for collection/examination, the assessment may indicate a chronic or acute state of the environmental health. For most types of analyses, the host should be one that has a restricted home range, can be infected by numerous species of parasites, many of which have a variety of additional hosts in their life cycles, and can be readily sampled. Data on parasitic infections in the western mosquitofish (Gambusia affinis), a fish that meets the criteria in two separate studies, illustrate the usefulness of that host as a model to indicate both healthy and detrimentally influenced environments. In those studies, species richness, intensity of select species, host resistance, other hosts involved in life cycles, and other factors all relate to site and contaminating discharge.

Arctic Report Card 2007: Tracking Recent Environmental Changes

Collectively, the observations indicate that the overall warming of the Arctic system continued in 2007. There are some elements that are stabilizing or returning to climatological norms. These mixed tendencies illustrate the sensitivity and complexity of the Arctic System. Atmosphere: Hot spot shifts toward Europe Ocean: North Pole Temperatures at depth returning to 1990s values Sea Ice: Summer extent at record minimum Greenland: Recent warm temperatures associated with net ice loss Biology: increasing tundra shrub cover and variable treeline advance; up to 80% declines in some caribou herds while goose populations double Land: Increase in permafrost temperatures The Arctic Report Card 2007 is introduced as a means of presenting clear, reliable and concise information on recent observations of environmental conditions in the Arctic, relative to historical time series records. It provides a method of updating and expanding the content of the State of the Arctic Report, published in fall 2006, to reflect current conditions. Material presented in the Report Card is prepared by an international team of scientists and is peer-reviewed by topical experts nominated by the US Polar Research Board. The audience for the Arctic Report Card is wide, including scientists, students, teachers, decision makers and the general public interested in Arctic environment and science. The web-based format will facilitate future timely updates of the content.

Essays on Industrial Organization and Environmental Economics

This dissertation studies environmental regulation issues in the hog production industry as well as forces behind the reorganization of the industry during the past two decades. Federal and State-level environmental regulations imposed on U.S. hog production during the year 2003 are examined in Chapter 1. Based on the number of regulations passed by the Federal government and states, the 2003 regulatory index is constructed. The regulatory stringency index suggests that state-level regulations vary across states and have increased over the years. In addition, state-level regulations are more stringent than federal regulations. Chapter 2 develops an empirically implementable theoretical model which allows us to investigate the long-run effects of environmental regulations on the U.S. hog industry. Hog feeding operations (HFOs) are divided into large feeding operations (LHFOs) and small feeding operations (SHFOs). The impact of the presence of a large number of LHFOs on the entry and exit of CHFOs is also examined. Results of this study suggest that: Increased state-level regulation stringency significantly lowers the output of SHFOs; increased state-level regulation stringency significantly lowers the output of LHFOs; increased state-level regulation stringency significantly lowers the number of SHFOs; SHFO output rises significantly in states that have a greater number of LHFOs; LHFO output rises significantly in states that have a greater number of LHFOs; the number of SHFOs significantly increases in states that have a greater numbers of LHFOs; regulation increases the average SHFO size; and regulation decreases the average LHFO size. Chapter 3 examines the importance of input availability, market attractiveness, agglomeration economies and environmental regulations on the reorganization of U.S. hog production for a panel of 22 U.S. hog producing states which include, Northern states, Southern states and Midwest states for the period 1994-2006. Results from this study suggest that: Hog production in a state is positively affected by hog production in a nearby state, confirming the presence of agglomeration economies; Environmental regulations and high corn price have negative effects on state-level U.S. hog production; High hog prices, and favorable labor cost, and land values attract hog production; and transportation cost has no effect on hog production. Advisors: Azzeddine Azzam and Karina Schoengold