1,720,991 research outputs found
The legacy of past disturbance: chronic angling impairs long-term recovery of marine epibenthic communities from acute date mussel harvesting.
No full textTwo major concerns affect the way we perceive impacts: first, no ecosystem can still be considered pristine
and second, stressors may interact. Untangling the effects of broad-scale anthropogenic stressors is
complicated as appropriate unimpacted areas at relevant scales are usually unavailable for contrast with
impacted regions. Although the perfect study design in the traditions of small-scale manipulative experiments
may not always be possible, many human impacts and the mechanisms associated with ecosystem
responses have been highlighted in literature allowing contrasting predictions on expected patterns
to be tested. We applied such an approach to the Marine Protected Area of Bergeggi (Ligurian Sea, NW
Mediterranean). Our study aimed at assessing the effects of recreational angling (a presumed chronic
stress) on the recovery of epibenthic communities following historical date-mussel harvesting (an
extreme disturbance) by making and testing alternative predictions on the structure of epibenthic communities
that should be apparent depending on the importance of specific mechanisms. Effects of datemussel
harvesting were still visible 20 years after its cessation, mostly because recovery is hampered by
persistent sea-urchin grazing. We hypothesized that fish biomass removal by angling favours high sea
urchin abundance. Based on these premises, we assembled information on angling pressure, sea urchin
abundance and substratum cover by different trophic guilds to test our predictions. Our study indicates
that the interaction between date-mussel harvesting and angling produced a shift, from autotrophicdominated
to consumer-dominated communities as a consequence of cascading trophic effects. Such
an outcome implies that chronic recreation fishing pressure is blocking recovery in locations previously
impacted by date-mussel harvesting. Testing predictions proved efficient in describing the interaction
among stressors when system history is known and represents a valuable approach to provide scientifically
sound insight for improved conservation management
Colonization Processes and the Role of Coralline Algae in Rocky Shore Community Dynamics
No full textRecovery from disturbance is an important attribute of community dynamics. Temperate rocky shores will expe- rience increases in both the type and intensity of impacts under future expected global change. To gauge the community response to these potential changes in the disturbance regime it is important to assess space occu- pancy and the temporal dynamics of key species over the recovery process. We experimentally disturbed repli- cated 1 m2 plots in the lower intertidal at 5 sites along the Ligurian rocky coast (North-western Mediterranean) and assessed early succession processes over 18 months. To identify colonisation processes and role of key spe- cies in affecting species richness on recovery trajectories, we monitored species composition at the cm-scale along fixed transects within the plots. Our results highlighted the role of a limited number of taxa in driving the recovery of species richness across sites, despite site variation in community composition. Settlement of new propagules and overgrowth were the principal pathway of space occupancy. We detected an important role for coralline algae, particularly the articulated Corallina elongata, in promoting the colonisation of a diverse range of colonists. The present study highlights the important role played by calcifying coralline macroalgae as substrate providers for later colonists, favouring recovery of biodiversity after disturbance. This pivotal role may be compromised in a future scenario of elevated cumulative disturbance, where ocean acidification will likely depress the role of coralline algae in recovery, leading to a general loss in biodiversity and community complexit
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Forecasting the limits of resilience: integrating empirical research with theory
No full textDespite the increasing evidence of drastic and profound changes in many ecosystems, often referred to as
regime shifts, we have little ability to understand the processes that provide insurance against such change
(resilience). Modelling studies have suggested that increased variance may foreshadow a regime shift, but
this requires long-term data and knowledge of the functional links between key processes. Field-based
research and ground-truthing is an essential part of the heuristic that marries theoretical and empirical
research, but experimental studies of resilience are lagging behind theory, management and policy
requirements. Empirically, ecological resilience must be understood in terms of community dynamics
and the potential for small shifts in environmental forcing to break the feedbacks that support resilience.
Here, we integrate recent theory and empirical data to identify ways we might define and understand
potential thresholds in the resilience of nature, and thus the potential for regime shifts, by focusing on
the roles of strong and weak interactions, linkages in meta-communities, and positive feedbacks between
these and environmental drivers. The challenge to theoretical and field ecologists is to make the shift from
hindsight to a more predictive science that is able to assist in the implementation of ecosystem-based
management
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