1,721,105 research outputs found
Simulations and interpretations of cumulative trophic theory
Full text linkExamining marine ecosystems in a distinct way can produce new ecological, theoretical and applied insights. The common “S” and “hockey stick” -shaped curves, which result from examining the cumulative biomass and trophic level and the cumulative production and cumulative biomass curves of marine ecosystems, have strong potential to elucidate the mechanisms of marine food webs. These curves are based on the cumulative trophic theory, which can be summarized as the integration of biomass and production across trophic level that results from the relatively simple trophic transfer equation. Here we test the behavior of this theory via modeled simulations of the transfer equation under a variety of common mechanisms that can influence marine ecosystems. The simulated scenarios we present and evaluate here explore bottom-up driven changes (production, growth), internal dynamics (transfer efficiency) or top-down driven changes (mortality, selectivity), as well as multi-mechanism scenarios (overfishing and eutrophication) that are commonly experienced in marine ecosystems. We explore these scenarios at high, medium or low levels of change for each feature to ascertain how they can result in major changes to the realized trophodynamics of a marine ecosystem. Our results lend credence to the generality of the cumulative trophic theory by predicting the empirically observed “S” and “hockey stick” -shaped curves under a wide range of possible mechanisms. Given that common, repeatable and predictable dynamics is a key hallmark of increasingly robust theories, the application of cumulative trophic theory in managing marine ecosystems enables more repeatable and predictable responses across a wide range of conditions
“VALLI DA PESCA” AND ECOSYSTEM SERVICES ASSESSMENT: A NEW PERSPECTIVE
No full textThe evaluation of ecosystem services (ES) has been proven to be an effective method to highlight
natural capital and its contribution to human well-being. Notwithstanding the studies about the
ES provided by transitional water environments are numerous, data about the assessment of ES in
the Venice lagoon are scarce and mainly focused on just one single ecosystem service at once.
Recently, as part of the project Venezia 2021, a new perspective has started to be developed,
which will quantify both the potential capacity of the lagoon to provide ES and the actual flow of
them from the environment towards the human society.
The present analysis aims to apply the same perspective to evaluate ES provided by the “valli da
pesca”, which are enclosed fishing ponds typically located in the Venice lagoon.
These environments, albeit very similar to the natural lagoon ecosystem, could be considered
“anthropic environments”: they were created centuries ago by local populations and are
completely depending on human actions, both in terms of physical maintenance and functioning
(e.g. regulation of fresh and saltwater flows). All this imitates the functioning of the real lagoon
ecosystem, aimed to maximize the exploitation of fish and birds. Fishing and hunting activities
represent two of the main ES provided by transitional water environments and here we indagate
how their maximization could influence other ES, either the regulating and cultural ones.
Furthermore, thanks to the multiple ES approach, a preliminary analysis to individuate the link
between the structure of the environment, its ecological status, and its capability to provide ES will
be suggested
Mosaic of submerged habitats in the Venice lagoon shows signs of marinization
Full text linkThe relationships between habitat patterns and ecosystem functioning have been widely explored in terrestrial ecosystems, but less in marine and coastal ecosystems, calling for further research in this direction. This work focuses on the mosaic of submerged habitats in the Venice lagoon, Italy. It aims to describe the habitats’ spatial patterns at multiple spatial scales, and to explore their linkages with the ecological status defined according to the EU Water Framework Directive (WFD, 2000/60/EC). The submerged habitats’ mosaic has been analysed by calculating a set of seascape metrics at different spatial scales. These metrics have been linked with the biological quality elements (BQEs) that are monitored in the lagoon in compliance to the WFD. The results show that the habitats’ spatial patterns differ between the areas of the lagoon with marine-like features and the areas which still retain more lagoon characteristics. The similarity between the pattern found in the whole lagoon and those found in marine-like areas suggests a general loss of lagoon characteristics at the lagoon scale. Regarding the ecological status, every BQE seems to be associated with a different habitat configuration at the water body scale. This does not facilitate the joint improvement of the BQEs, as required by the Directive. If we cannot achieve that, at some point we will probably have to choose what to prioritize. On a broader perspective, this calls for a reflection on what lagoon we want for the future, a vision that should be shared and account for the lagoon’s complexity, current trends and challenges
EST: an exploratory model for Ecosystem Services in the Venice lagoon
No full textThe Venice lagoon is a complex socio-ecological system, where Ecosystem Services (ES) and benefits for people
result as emergent properties from the interactions between ecological processes and human activities. Such
a complex system is threatened by several drivers of change, including those connected to resource
exploitation and ecosystem fruition, along with climate related drivers. EST (Ecosystem Services Screening
Tool) is an exploratory numerical model based on dynamic system theory, aimed at investigating the
interactions among the different ES, the lagoon resources and the social dynamics, and compare possible
scenarios of evolution of the whole socio-ecological system. The conceptual model was inspired by the “Socialecological systems framework” and considers 13 Ecosystem Services, along with the biophysical component,
represented by specific macrohabitats characterizing the lagoon seascape and key faunal groups, and the main
groups of actors involved in services fruition. Increase in water temperature and relative sea level rise were
provided as external forcings in the model, which also attempted to account for the feedbacks on services
produced by the regulation of lagoon high tides through the closure of mobile gates. EST was implemented in
Simile v. 6.1 software environment, as an attempt to improve its applicability for participatory modelling
applications. Model development and parameterization is presented, and contrasting tendency scenarios are
preliminarily explored, considering a 50 year time horizon. Scenarios included both changes in climate-related
forcings and in governance choices aimed at preserving the biophysical component, ensuring ES sustainability
Comparative production of fisheries yields and ecosystem overfishing in African Large Marine Ecosystems
No full textMarine capture fisheries in African Large Marine Ecosystems (LMEs) are important from economic, cultural, social, and food provision perspectives. These African fisheries have a long history of high exploitation in the context of data-limited situations. There is a growing, global movement (both in terms of management requirements and scientific efforts) to develop measures of ecosystem overfishing (EOF) that detect overfishing of an entire ecosystem using readily available data and based on widely repeatable patterns. These EOF indicators extend the thinking beyond single stock overfishing to an entire ecosystem and are largely based on well-established trophic theory. Moreover, they need to be germane for data limited situations, easily interpretable, and simple to calculate. Here we introduce and present the results of several of these indicators—the Ryther index, Fogarty index, and Friedland index—as well as indices based on cumulative biomass-Trophic Level curve parameters for eight African LMEs. Significantly, all these EOF indicators also have thresholds beyond which EOF is indicated, particularly when coupled with other evidence. These thresholds were applied to the African LME EOF indicators to determine the degree to which EOF may be occurring. Five out of eight African LMEs exhibited symptoms of EOF, one with significant EOF, with at least one LME still currently experiencing EOF, and three more that may be close to EOF thresholds. One LME exhibited evidence of recovering trends. Additionally, EOF indicators detected changes in the LMEs five-ten years prior to major impacts that would be identified by piecing together fishing impacts on a stock-by-stock basis. We conclude that if EOF is detected, at the very least these relative simple measures should be monitored and means to mitigate total fishing pressure in an ecosystem should be explored
Ecosystem services for supporting coastal and marine resources management, an example from the Adriatic sea (Central Mediterranean sea)
No full textEcosystem Services (ESs) assessment is increasingly considered the constitutive metric to embrace the social, ecological, and economic spheres. Spatially explicit ES assessments can integrate and standardize different types of information, making them comparable. In this context, a multiple coastal and marine ESs assessment in the Northern-Central Adriatic Sea was carried out, considering seven ESs. Two cultural (tourism and recreational boating), two regulating (carbon sequestration and coastal erosion prevention potential), and three provisioning (mussel, whitefish aquaculture, and industrial fishery) ESs have been measured. The spatial analysis described (un)sustainable human uses of ecosystems in the area. (De)coupling of ES capacities and flows and synergies and tradeoffs among ESs were analyzed. Results indicate spatial agreement for capacities, while contrasting results emerged from the analysis across flows and of the capacity-flow balance. The evidence of a geographical pattern and areas of high, medium, and low capability to provide ESs across the study area was highlighted, suggesting the need for implementing the natural resources management. Some coastal provinces maximize a single ES at the detriment of other ESs, and other provinces built mimics of Nature through artificial facilities. These strategies are not far-sighted in the view of conserving the supply of the whole ESs set. These findings might be useful in the context of the Marine Strategy Framework Directive (MSFD), and for the implementation of the Maritime Spatial Planning (MSP) in the Northern-Central Adriatic Sea
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
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