1,721,097 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Establishment and Growth of a Sea Turtle Rookery: the Population Biology of the Leatherback in Florida.
No full textDespite facing threat of extirpation in the eastern Pacific, the critically endangered leatherback turtle (Dermochelys coriacea) appears to be thriving in the Atlantic. The purpose of my dissertation was to establish a baseline of biological data for the leatherback at the northern limit of its nesting range in the northwestern Atlantic (Florida) to inform management. From six years of empirical field data collected on nesting female leatherbacks, I addressed four major objectives of the Federal (US) Recovery Plan for the east coast of Florida. 1) I determined the rate of increase in observed nest numbers since standardized nest surveys began in 1979. From these data collected at 70 beaches and using a multilevel modeling approach, I found a dramatic increase of 11.3 ± 1.9% each year in the number of nests. 2) By tagging and recapturing individual females as well as marking nests for inventories at one high-density nesting beach, I determined several critical population parameters. The annual survival rate was 95.6% for nesting females and the yearly nesting population size was 71 ± 23 turtles at my Juno Beach study site (19.4 km); statewide the estimate will be higher. The average remigration interval was 2.2 +/- 0.5 years, clutch frequency was 4.1 +/- 0.9 nests/season, and the average clutch size was 69.0 +/- 18.2 eggs/female. 3) I used novel GPS tags and conventional tag returns to discover the full nesting range and true clutch frequency of individual turtles. Leatherbacks in Florida exhibit weak nest site fidelity by nesting at broad spatial scales, distributing at least five nests within a single season up to 139.8 km from first encounter. 4) Finally, I used microsatellites and mtDNA to determine the relatedness of leatherbacks in Florida and found few family groupings, indicating that this rookery has been established through immigration and not through a founding event, as there is no evidence of a genetic bottleneck. Although the Florida population is relatively small compared to other Caribbean mainland rookeries, it has the potential to contribute to further increases of leatherbacks in the Atlantic as well as contributing genetic variation, thereby achieving objectives of the US Recovery Plan
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Shifts in the Benguela ecosystem and recommendations for protecting Namibia’s fishery economy
No full textNatural and anthropogenic disruptions in the flow of energy through
marine food webs can result in systematic changes which have implications
for ecosystem-based fisheries management. A recent biological regime shift
in the N. Benguela current has resulted in an alternate stable state in fish
abundance. Many of the depleted stocks are considered forage fish, species
of fish preyed upon by top predators like large piscivorous fish and marine
mammals. I will present three case studies which demonstrate some of the
consequences of depleted forage. I will then highlight documented and
probable changes to the N. Benguela as a result of depleted forage species.
Decreasing abundance of forage fish and increased abundances in jellyfish
could inhibit the system from returning to its previous state. In light of
these ecological changes, I will examine Namibia’s fisheries management
plan and the nation’s dependence upon its fisheries for economic
development. I offer short-term adaptive management strategies focused on
the restoration of depleted forage fish stocks, and improved development
opportunities. I also make recommendations for long-term strategies aimed
at an ecosystem-based management perspective with protections for top
predators that will likely undergo declines as a result of a lack of forage
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Establishing a Socioeconomic Baseline of Sea Turtle Ecotourism in Baja California, Sur
No full textBaja California Sur provides vitally important habitat to five of seven species of sea turtles. All five species have long been subject to direct and indirect exploitation in the region, and federal intervention has largely failed to address conservation goals. A powerful opportunity exists to incentivize sea turtle conservation by means of ecotourism, as locals can use turtles non-consumptively to their socio-economic benefit. However, ecotourism is a complex multi-faceted endeavor built upon a mix of social, economic, and environmental factors. Community participation, a central component of ecotourism, depends on local perceptions and realities, but is often overlooked in ecotourism implementation. The purpose of my research is to describe and contextualize community perception and involvement in sea turtle ecotourism, with existing infrastructure and resources in the region. To achieve this goal, oral surveys, semi-structured interviews, and participant observation techniques were administered in communities throughout Baja California Sur during the summer of 2008. My findings suggest that local perceptions of ecotourism are highly optimistic but vary significantly between communities, as do existing tourism infrastructure and resources. Current local participation is low, but desire to participate is high among communities. Drivers to participate are based on a variety of economic, social and conservation factors. These findings will advise on proper implementation of sea turtle ecotourism in the region in order to maximize community involvement, and will provide a baseline from which to measure future successes and failures of sea turtle ecotourism
Influence of Substrate on Coral Reef Fish Communities
No full textCoral reef fish coexist in a state of high diversity that has not been successfully explained by niche diversification, larval supply, differential mortality, or a suite of other proposed factors. These processes are all occurring on a diverse substrate that would be expected to affect the abundance and distribution of fish by directing habitat preferences as well as affecting competitive and predatory success. I conducted correlational studies on healthy and degraded Caribbean reefs that addressed fish abundances at the levels of community, species, and age class. I also experimentally tested habitat preferences in two ways: choice experiments on adults of common species that determined preferences for live coral and rugosity in an isolated environment, and monitoring of artificial reefs differing in live coral cover that tested habitat selection of adults and juveniles in the field. These observations all show that live coral had no effect on community parameters such as abundance or diversity, but that rugosity was positively related to species richness. However, these measures of the community masked differences at the species and age class level. A handful of species exhibited positive or negative preferences for live coral, but these selections did not follow a taxonomic or trophic-level classification. Species within the genus Stegastes, for example, could either aggregate towards or avoid live coral. One species even reversed its habitat preference as it matured. Field distributions were not determined solely by these habitat preferences, but inclusion of competitive interactions into a multi-factorial model explained distribution of some species. Results suggest that changes in live coral cover, an increasingly common phenomenon, would not affect fish at a community level, but could affect a few species through changes to recruitment or alteration of competitive interactions.</p
Linking Prey to Predator: Scale Dependence and Oceanographic Influence in Marine Food Webs
No full textIncreased pressure has been placed on researchers to focus on processes at an ecosystem level. However, ecological processes operate at multiple scales from an individual predator up to ocean basin migrations, and research across these scales is extremely difficult. More accurate and detailed understanding of prey distributions relative to physical and biological features can greatly aid in understanding top predator distributions and ultimately ecosystem functioning. High resolution acoustic data is a critical tool that can be used to investigate food web linkages at many spatial scales. At a broad scale, migratory top predators are often modeled relative to oceanographic structure as a proxy for the distribution of their prey. At a fine scale, combining novel technologies including fisheries acoustics, real time oceanographic sensors, and digital tags allows examination of decisions made by an individual foraging whale. In the Gulf of Mexico, fish distributions at fine scales (both horizontal and vertical) were examined relative to hypoxic bottom waters to understand potential ecosystem effects. Forage fish distribution (sand lance, Ammodytes spp.) were measured relative to physical features and oceanographic processes up to the decision making of a top predator, the humpback whale (Megaptera novaeangliae). The effect of geostrophic currents and environmental regimes on the deep scattering layers of the central tropical pacific were examined relative to sightings of marine mammals in the area. Analyses across trophic levels and at multiple scales is an important step towards understanding community ecology and ecosystem processes in pelagic systems.</p
Navigating Our Way to Solutions in Marine Conservation
Get PDFNavigating Our Way reflects the broader insights and diverse voices revolutionizing marine conservation. This volume brings together an array of scholars, practitioners, and experts from multiple fields, creating a network of trans-disciplinary and multi-cultural perspectives to address the complex problems in marine conservation. Larry B. Crowder, a leading voice in the field, has curated contributions on a wide range of topics, including critically endangered species in the Bahamas, Argentinian penguins, and the ecosystems of our coral reefs. The book delves deeply into human relationships with nature, the development of climate-smart solutions, and the governance of collective action. Committed to inclusivity, this volume also includes conversations across the disciplines of natural sciences, social sciences, and governance, incorporating both Western and Indigenous knowledge traditions. This volume is highly relevant to marine conservation scholars, practitioners, managers, and students, and anyone interested in preserving our marine environment
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