Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item Conserving Pollinators: An Interdisciplinary Approach to Evaluating the Ecological, Economic and Cultural Value of Native Bees in Mid-Atlantic Sustainable Agriculture(2008-04-25) Meredith, Annette May; Paolisso, Michael J.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Certain pollinator populations are threatened globally due to habitat fragmentation and alteration, pesticides, disease and infestations by parasites. Localized population declines have prompted interest on the part of various stakeholders in restoring and maintaining pollinator-friendly habitats on working landscapes, particularly private agricultural lands. Recommendations from the National Research Council's report, Status of Pollinators in North America, include informing the agricultural community about ways to manage pollinators and conducting studies to improve restoration protocols and to understand land managers' willingness to adopt pollinator-friendly practices (NRC 2007). Interdisciplinary in nature, this research follows NRC's recommendations and incorporates methods from environmental science, ecology and anthropology to investigate and evaluate the opportunities and challenges to native bee conservation in Mid-Atlantic sustainable agriculture. I censused sustainable agriculture farms to assess the diversity of bees in different habitats and collected and identified over 3100 individuals representing five families, 26 genera and 81 species. Native bee abundance measures indicated a temporal shift in foraging among habitats with more bees moving into crops in mid-summer. I investigated floral constancy and visitation rates among native bees at Blandy Experimental Farm in Boyce, VA and found that bees move primarily among conspecific flowers and that particular flowers are more attractive to certain bee genera. I also investigated pollination of okra (Abelmoschus esculentus) and bell pepper (Capsicum annuum) and examined importance of native bees to Mid-Atlantic vegetable crops. Additionally, I conducted a survey to examine similarities and differences in beliefs and values of Mid-Atlantic sustainable agriculture producers and pollinator scientists/managers in relation to native bee conservation. Sustainable agriculture farmers already hold beliefs, values and knowledge about ecosystem services conservation; therefore to formulate effective outreach, there is a need to understand how these beliefs differ or align with those of pollinator advocates. Although sustainable agriculture producers and pollinator scientists/managers share certain beliefs and values, enough differences were detected to impact outreach efforts. Results from the research can be used to develop feasible conservation approaches for native bees in this region.Item Age, growth and recruitment of Hudson River shortnose sturgeon (Acipenser brevirostrum)(2005-08-10) Woodland, Ryan Jordan; Secor, David H.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Shortnose sturgeon (Acipenser brevirostrum), an Endangered Species, has experienced a several-fold increase in abundance in the Hudson River in recent decades. Age structure and growth were investigated to evaluate the hypothesis that improvements in water quality during the late 1970s stimulated population recovery. Specimens were captured using gill nets bi-monthly 2003 to 2004. Annuli in fin spine sections were determined to form at an annual rate and yielded age estimates of 5-30 years for sizes 49-105cm Total Length (n=554). Hindcast year-class strengths, corrected for gill net mesh selectivity and cumulative mortality indicated high recruitments (28,000-43,000 yearlings) during 1986-1992, which were preceded and succeeded by c. 5 year-periods of lower recruitment (5,000-15,000 yearlings). Results indicated that Hudson River shortnose sturgeon abundance increased due to the formation of several strong year-classes occurring about five years subsequent to improved water quality in important nursery and forage habitats in the upper Hudson River estuary.Item THE EVOLUTION, PHYLOGEOGRAPHY, AND CONSERVATION OF THE GOLDEN LANGUR (Trachypithecus geei) IN BHUTAN(2005-04-15) Wangchuk, Tashi; Inouye, David W; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The golden langur (<i>Trachypithecus geei</i>) is an endangered endemic species of primate in Bhutan. Conservation of this species is addressed here through phylogeographic and habitat management tools. I hypothesize that rivers and mountains in Bhutan isolated a population of capped langurs (<i>Trachypithecus pileatus</i>) and that this population later speciated into the morphologically distinct golden langur. <i>Trachypithecus</i>, the genus to which both capped and golden langurs belong, spread north from a paleo-refuge in south China and <i>Semnopithecus</i> (grey langurs) spread east and northward from a refuge in south India. My results show that these two genera both arrived in Bhutan but could not mix since the Sunkosh River and Pelela range form a biogeographic barrier. Likewise, a population of capped langurs isolated from parental populations by rivers speciated into the distinct golden langur. I conducted field surveys covering the entire range of langurs in Bhutan, confirming the distribution and isolating barriers among the three langurs. Grey langurs and golden langurs are isolated from each other by the Sunkosh River and Black Mountain range in west Bhutan. In the east, the Manas river system (Manas-Mangde-Chamkhar) served as a barrier between golden and capped langurs. However, this barrier has been broken in the last 30 years due to the construction of bridges over the Chamkhar river. A hybrid zone was found and the implications are discussed. A cyt b phylogeny showed the grey langur of Bhutan grouping into a distinct clade with other congenerics of Semnopithecus. The south-Indian clade of grey langurs is more ancient, with the Bhutan and Nepal grey langurs having diverged later. The golden and capped langur from Bhutan grouped with <i>Trachypithecus</i> from South East Asia. Finally, I explore conservation of golden langur habitat in Bhutan and estimate available habitat at 3,089 km2 and an estimated population of about 6,000 individuals. I also find that the most viable strategy for conservation of langur habitat is to give ownership of the forests to local people, with monitoring by the Department of Forestry.