1,721,160 research outputs found
The impact of excessive protein consumption on human wastewater nitrogen loading of US waters
No full textTotal and per capita protein consumption rates in US diets, whether from plant or animal sources, rank among the highest in the world. When protein consumption outpaces physiologic protein demands, excess amino acids are degraded in the human body and nitrogen (N) is excreted and released to the environment, mainly in the form of urea. Such excess reactive N can enter downstream environments, thereby impairing human and ecosystem health as well as contributing to economic losses. We show that matching protein consumption with physiologic requirements would reduce US hydrologic N losses to aquatic ecosystems by 12% and overall (atmospheric and hydrologic) N losses to ecosystems by 4%. Were US citizens to consume protein at recommended rates, projected N excretion rates in 2055 would be 27% less than they are today, despite population growth. Optimizing US protein consumption to levels that meet human health standards has environmental benefits on par with improving wastewater treatment using existing technology, while also generating impactful economic benefits
Cataloguing and mapping cumulative human impacts on marine biological and functional diversity to inform conservation management
Full text linkPeople around the world depend on healthy oceans for sustenance, employment, culture, and identity, among other valuable ecosystem services. Anthropogenic impacts from human activity on land and sea, coupled with increasing effects of climate change, drive declines in the health of marine biodiversity throughout the world’s oceans, which puts at risk those ecosystem services we value. Effective marine conservation efforts depend on understanding where and to what degree anthropogenic stressors are impacting marine ecosystems. In this dissertation, my colleagues and I catalogued and compared the activities and stressors contributing to marine biodiversity loss, noting those stressors imposing the greatest impacts and those for which risk of impact is poorly understood. We then mapped the footprint of cumulative impacts across ranges of 1,271 threatened and near-threatened marine species on a global scale from 2003 to 2013. We found that on average, species are substantially affected by human stressors across more than half their range, and these impact footprints expanded in scale and increased in intensity over the study period. Building upon a trait-based framework for estimating species vulnerability to human stressors, we expanded our mapping methodology to 21,267 marine animal species, examining patterns of impact through lenses of species richness, functional vulnerability, and representative habitats. I conclude by examining the current literature on applying machine learning methods to estimate species conservation status based on information on species traits, stressors, and environmental conditions. Using a value of information framework, I explore the improvement in expected outcome of conservation management decision based on incorporating additional predictor data or increasing the number of species used to train the model. The resulting conceptual model can help identify optimal investment in data collection and formal assessment of currently data-deficient species to accelerate our understanding of extinction risk of marine biodiversity. In all, the concepts and methods presented here can inform effective, equitable, and ecologically representative conservation efforts toward the goals proposed in the draft of the United Nations Convention on Biological Diversity Post-2020 Global Biodiversity Framework
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
No branch left behind: tracking terrestrial biodiversity from a phylogenetic completeness perspective
Full text linkBiodiversity is ultimately the outcome of millions of years of evolution; however, due to increasing human domination of the Earth, biodiversity in its multiple dimensions is changing rapidly. Here, we present “phylogenetic completeness” (PC) as a concept and method for safeguarding Earth's evolutionary heritage by maintaining all branches of the tree of life. Using data for five major terrestrial clades, we performed a global evaluation of the PC approach and compared the results to an approach in which species are conserved or lost at random. We demonstrate that under PC, for a given number of species extinctions, it is possible to maximize the protection of evolutionary innovations in every clade. The PC approach is flexible, may be used to conduct a phylogenetic audit of biodiversity under different conservation scenarios, complements existing conservation efforts, and is linked to the post-2020 UN Convention on Biodiversity targets.Fil: Pinto Ledezma, Jesús N.. University of Minnesota; Estados UnidosFil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Halpern, Benjamin S.. University of California; Estados UnidosFil: Khoury, Colin. San Diego Botanic Garden; Estados Unidos. Centro Internacional de Agricultura Tropical; ColombiaFil: Cavender Bares, Jeannine. University of Minnesota; Estados Unido
Variations on the Author
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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UNDERSTANDING FISH AND FISHER BEHAVIOR IN CORAL REEF ECOSYSTEMS
Full text linkHuman activities are increasing in intensity, duration, and spatial extent. As a result, humans play an increasingly influential role in nearly all of the planet’s ecosystems. In order to maintain ecosystem function alongside growing human impacts, we must first understand the nature and drivers of these impacts, and, just as importantly, understand how to manage them. Behavior is a critical consideration in addressing this two-part challenge. Animal behaviors that underlie ecosystem function can be affected by human activities, and human behaviors determine human impacts and management outcomes. This thesis integrates ecological and social approaches to improve our understanding of both animal and human behavior in the context of ecosystem management, with a particular focus on Caribbean coral reef systems. I begin with a comprehensive assessment of the potential pathways in which human activities may influence ecosystem outcomes through impacts on animal behavior across aquatic and terrestrial ecosystems. While such impacts have been increasingly documented, the implications of these behavior changes for ecosystem function remain understudied. Through synthesis of empirical evidence and ecological theory, I find that human-induced animal behavior change has the potential to alter ecosystems through numerous pathways. Whether or not these pathways are realized will depend on several factors, primarily the nature and distribution of human activities and the ecological role of an altered species’ behavior. To better understand potential variations in ecologically critical animal behaviors, in my second chapter I examine the feeding behaviors of herbivorous fish in coral reef ecosystems experiencing different human disturbance. Herbivory on coral reefs is a keystone driver of ecosystem health through facilitation of coral survival, growth, and recruitment by suppressing otherwise dominant algal competitors. Across thirteen reef sites in three Caribbean islands with varying levels of coral reef health and anthropogenic impacts, I find that the grazing behavior of herbivorous fish varies significantly. Feeding rates, or the number of bites taken per minute, varied as much as nine-fold across sites, while the grazing intensity, or number of consecutive bites taken while feeding, varied as much as six-fold. I present several hypotheses for these trends and discuss theoretical links to human impacts such as fishing that can guide future studies. In my third chapter, I evaluate the outcomes of efforts to shift human fishing behavior off of coral reefs and onto less exploited pelagic resources through a case study of the Guadeloupe fishery, a mixed-gear small-scale fishery in the Caribbean. I find that these efforts, namely the introduction of moored fish aggregating devices (MFADs), have allowed more vessels to specialize in exclusively offshore fishing and likely facilitated an increasing proportion of landings coming from pelagic species, but that they have also made offshore fishing less accessible to certain portions of the fleet. These findings suggest the importance of understanding human behavior in modifying human impacts on threatened ecosystems
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