1,721,019 research outputs found
Farm‐scale models in fish aquaculture – An overview of methods and applications
Full text linkModels are important tools to address sustainability challenges associated with developing aquaculture at farm, regional and global scales. Farm-scale models (FSMs), which are integrated mathematical models developed to simulate farm operations, can quantify energy, mass or economic input flows and predict a variety of outputs such as fish biomass, waste and by-products. The variety of farming systems, equations available to build the models, and objectives of applications and intended users has resulted in the publication of wide range of FSMs. We performed a narrative review of 36 fish FSMs published from 1985–2021 to address several questions: Can the main characteristics of these models be defined? How do the farming system studied and the objectives of the study influence model development? What are the main modelling techniques available to simulate the main processes of a fish farm, and what are their advantages and disadvantages? How can FSMs help address sustainability challenges of aquaculture? This review discusses advances, limitations and future lines of research related to FSMs to help select existing models, or develop new ones, that are suitable for their intended use and users. The article is structured according to the main steps of the modelling process: (i) definition of scope and objectives; (ii) process formulation and model selection at individual, cohort and farm levels; (iii) implementation and evaluation; and (iv) applications (e.g. precision fish farming, IMTA modelling, supporting spatial management, life cycle assessment). At each step, recommendations are provided and research needs are stated
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
Bioremediation of fish solid wastes by a polychaete detritivore in integrated multi-trophic aquaculture context
No full textLes systèmes intégrés d’aquaculture multi-trophique (IMTA) proposent de limiter les rejets dans l’environnement en associant la culture d’espèces de niveaux trophiques différents et le recyclage des déchets. Les détritivores sont un groupe trophique intéressant car ils permettent l’extraction de matière organique particulaire. Hediste (Nereis) diversicolor est un polychète qui connait un intérêt croissant du fait de sa capacité de bioturbation dans les sédiments et de sa haute valeur commerciale en tant qu’appât et nourriture potentielle pour animaux. L’objectif principal de cette thèse est d’évaluer le potentiel d’ H. diversicolor dans la bio-remédiation des rejets solides en système IMTA. Plus spécifiquement, l’étude a eu pour objectifs : i) de calibrer une nouvelle méthode de mesure des composés organiques des rejets (azote, carbone, phosphore, lipides), ii) d’évaluer l’activité métabolique (respiration) d’H. diversicolor nourries aux fèces de Dicentrarchus labrax en fonction de leur taille et de différentes températures, et iii) d’utiliser un modèle bioénergétique pour simuler croissance, respiration et excrétion d’H. diversicolor selon différents scenarios IMTA.Pour obtenir une caractérisation rapide des composés organiques, une méthode novatrice (NIRS) a été calibrée. Les composés des rejets ont varié entre 44-77% de matière organique, 2-5% d’azote organique total, 11-51% de carbone organique total, 9-26 de rapport carbone/azote, 1-3% phosphore total and 2-12% de lipides (% de matière sèche).Les taux métaboliques de H. diversicolor nourries aux fèces ont été estimés par consommations d’oxygène à différentes températures (11, 17, 22 and 27°C). Les effets de la température et de la taille du ver sur les consommations en oxygène ont été significatifs, mais ces niveaux de respiration (12.3 µmol g-1 de poids sec h-1 à 20°C) correspondaient probablement à un métabolisme basal dû aux conditions expérimentales (jeun et obscurité).Les simulations du modèle DEB H. diversicolor ont été comparées aux données expérimentales de taux de croissance, de respiration et d’excrétion, ce qui a permis de corroborer les prédictions du modèle. Le modèle DEB a permis de tester différents scenarios pour prédire les réponses métaboliques, la croissance, la maturité et la reproduction d’ H. diversicolor à différentes températures (5 à 25°C) et disponibilité alimentaire (f variant de 0.5 à 1, correspondant à la disponibilité des fèces). Le modèle DEB s’est avéré être un outil utile pour prédire les réponses physiologiques sous différentes conditions environnementales dans un contexte IMTA.Integrated Multi-Trophic Aquaculture (IMTA) systems are based on the concept of limiting aquaculture discharges associating species of different trophic levels to reuse wastes. Deposit-feeders are one trophic group that has gained attention for the extraction of particulate organic matter. Hediste (Nereis) diversicolor is a polychaete species that has gained increasing interest for its bioremediation capacity through bioturbation activity in sediments, and high commercial value as fish bait and animal food sources. The main objective of this thesis was to evaluate the fish waste bioremediation capacity of polychaete H. diversicolor in IMTA context. More specifically, i) to predict organic compounds (nitrogen, carbon, phosphorus, lipids) in marine fish waste, ii) to evaluate the metabolic responses - respiration - of H. diversicolor fed with solid waste of seabass Dicentrarchus labrax at different temperatures and body size, and iii) to use a bioenergetic model (DEB) to simulate growth, oxygen consumption and excretion in different IMTA scenarios.To provide fast characterization of organic compounds we used an innovative method based on near infrared reflectance spectroscopy (NIRS). Chemical content of the waste measured by NIRS models after calibration, ranged from 44-77% organic matter, 2-5% total organic nitrogen, 11-51% total organic carbon, 9-26 carbon/nitrogen ratio, 1-3% total phosphorus and 2-12% lipids (% of dry matter).Fish waste fed H. diversicolor metabolic rates were evaluated through oxygen consumption at different temperatures (11, 17, 22 and 27°C). The effect of temperature and worm body size was significant on oxygen consumptions, however these respiration measures (12.3 µmol g-1 of dry weight h-1 at 20°C) may represent basal metabolic rate due to experimental conditions (starvation, darkness).DEB model of H. diversicolor was compared to experimental data on growth, respiration and excretion rates, which corroborated DEB model predictions. DEB was then applied to test different scenarios predicting metabolic responses, growth, maturity and reproduction of H. diversicolor at different temperatures (5 to 25°C) and food levels (f varying from 0 to 1, corresponding to fish waste loading). DEB revealed to be a useful tool in IMTA context, predicting physiological responses in different environmental conditions
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
Influence de la mytiliculture (Mytilus edulis L.) sur les caractéristiques physico-chimiques du sédiment et sur les communautés macrobenthiques
Full text linkRÉSUMÉ : La biodéposition des bivalves, en augmentant les taux de sédimentation, peut
modifier les caractéristiques physico-chimiques du sédiment et affecter les communautés
benthiques sous les sites mytilicoles. Les objectifs de cette thèse étaient: (1) de caractériser
la production, la sédimentation et la dispersion des biodépâts de moules (Mytilus edulis,
L.), (2) d'évaluer les effets de ces biodépâts sur l'environnement benthique, (3) d'évaluer
l'efficacité de différents indices utilisés pour détecter les effets de la mytiliculture et (4) de
déterminer quelle densité de moules induit des changements dans une communauté
benthique et dans les flux biogéochimiques. Les différentes études ont été menées aux Îlesde-
la-Madeleine (Québec) pendant les étés 2003 et 2004. Des observations in situ et des
analyses expérimentales ont permis de tester différentes hypothèses. Les variations
spatiales à petite (10 m - sous et entre filières), moyenne (100 m - sites) et grande échelle
(1 km, culture et site référence) ont été prises en compte, ainsi que les variations liées aux
différences de taux de biodéposition par les cohortes de bivalves présentes dans la culture
(0+ et 1+).
L'étude sur la dynamique de biodéposition (Chapitre 2) a montré que le taux de
production de biodépâts de moules 1+ était 1,6 fois plus élevé que celui des moules 0+. La
vitesse de sédimentation des fèces variait selon la taille des moules. Compte tenu de la
vitesse de sédimentation, de la hauteur des filières et de la vitesse moyenne du courant
pendant l'été, la dispersion initiale des biodépâts a été estimée entre 0 et 7,4 m dans la zone
des moules 1+ et entre 7 et 24,4 m dans la zone des moules 0+. Des mesures in situ ont
montré que les taux de sédimentation étaient plus élevés sur les sites mytilicoles que sur les
sites références, supportant l'hypothèse que la mytiliculture augmente les taux de
sédimentation. Les taux étaient deux fois plus élevés directement sous les filières de moules
1+ qu'entre les filières, 10 m plus loin. L'évaluation des taux de sédimentation le long de
transects autour de la zone de mytiliculture a confirmé la faible dispersion initiale des
biodépâts dans la lagune de Grande-Entrée.
Les caractéristiques physico-chimiques et biologiques du benthos ont été évaluées
(Chapitre 3) aux mêmes échelles spatiales que celles utilisées pour évaluer les taux de
sédimentation. Parmi les mesures chimiques, le potentiel redox diminuait et la
concentration en sulphide augmentait avec la profondeur du sédiment mais aucune
différence significative n'a été observée entre les zones (0+, 1 + et référence) et les positions
(sous et entre). Par contre, des différences significatives de structure de communautés
macrobenthiques ont été observées entre les zones et les positions (1 + sous et 1 + entre). La
communauté était dominée par des espèces opportunistes (Capitella capitata) et présentait
une faible diversité et une faible biomasse. La comparaison à des données historiques
indique que la lagune est un environnement naturellement enrichi. La culture de moules n'a
donc, probablement, qu'un effet très localisé sous les filières de moules.
Différents indices ont été évalués pour détecter l'effet de la mytiliculture sur
l'environnement (Chapitre 4). Les caractéristiques du sédiment (taille de particules, image
du profil sédimentaire-SPI, pourcentage de matière organique) et des communautés
benthiques (abondance, diversité, biomasse, masse individuelle, groupe trophique, structure
de communauté, indice biotique) ont été déterminées dans deux sites mytilicoles: Grande-
Entrée (GE) et à Havre-aux-Maisons (HAM) aux Îles-de-Ia-Madeleine. Les stations
d' échantillonnage étaient positionnées directement sous la filière la plus externe, à 3, 6, 9,
15, 30 m et sur un site contrôle (300-500 m) le long d'un transect partant des deux sites
mytilicoles, dans la direction du courant dominant. L'étude a montré que le choix a priori
des stations d'échantillonnage et des indices avait une grande influence sur l' interprétation.
L'analyse de la structure de communautés et l'analyse du profil sédimentaire ont permis la
détection des effets à la fois proches et éloignés de la mytiliculture, contrairement aux
autres indices.
Une expérience a été menée in situ pour déterminer quelle quantité de biodéposition
pouvait modifier la structure d'une communauté benthique de sable et les flux
biogéochimiques (Chapitre 5). Ces derniers (consommation d'oxygène, flux d'ammonium et
de phosphate), à l'exception des flux de silicates, n'étaient pas corrélés à la densité de
moules. L'abondance totale et le nombre d'espèces ont diminué en fonction de
l'augmentation de la densité de moules, tandis que l'abondance et la biomasse de l'espèce
opportuniste Capitella sp. ont augmenté dans les benthocosmes soumis à la plus forte
densité de moules (764 moules m-2
). À cette densité, l'environnement est passé d'un état
«peu perturbé» à un état «modérément perturbé».
Les résultats de cette thèse contribuent à déterminer la capacité d'assimilation de
l'environnement benthique pour la mytiliculture. ABSTRACT : Bivalve biodeposition may increase natural sedimentation rates, which could induce
changes in the physico-chernical characteristics of the sediment and affect the benthic
communities under culture sites. The objectives of the thesis were: (1) to characterise the
production, sedimentation and dispersion of mussel (Mytilus edulis L.) biodeposits, (2) to
evaluate the effects of biodeposits on the benthic environment, (3) to evaluate the efficiency
of different indices to detect mus sel farm influences and (4) to deterrnine which mus sel
density induce changes in the benthic community structure and biogeochernical fluxes. The
different studies were done during the summer 2003 and 2004 in the Magdalen Islands,
Quebec. Observational and experimental approaches were combined to test the different
hypotheses. The small (l0 m - un der vs. between mus sel lines), intermediate (100 m -
sites) and large (l km, culture vs. reference sites) spatial scale variations were considered,
as weIl as the effects of different mussel cohorts (juveniles 0+ and commercial size 1 +).
The first study (Chapter 2) has shown that the biodeposit production rates of 1 +
mus sel was 1.6 times higher than these of 0+ mussels. The settling velocity of faeces varied
in function of mus sel size. Based on the settling velocity of fecal pellet, the height of the
mussel lines and the average CUITent velocity, the initial biodeposit dispersion was
estimated between 0 and 7.4 m in the 1 + mussel zone and between 7 and 24.4 m in the 0+
mus sel zone. Measurements of sedimentation rates in situ have shown that sedimentation
rates was greater at mussel site than at reference site, supporting the hypothesis that mussel
culture increase the sedimentation rates. Sedimentation rates were twice greater directly
under the 1 + mus sel lines than between the lines, only 10 m distant. The evaluation of
sedimentation patterns along transects leading away from the mus sel farm confirmed the
low initial biodeposit dispersion in Great-Entry lagoon.
The chemical and biological characteristics of the sediment were then evaluated
(Chapter 3) using the same spatial sampling design as outlined above. With regards to
chemical parameters, redox potentials decreased and sulphide concentrations increased with
sediment depth but did not differ among zones or positions. In contrast, a c1ear difference in
macrofaunal community structure was observed between zones (0+, 1+ and reference) and
position (l +under and 1 +between). The benthic community at 1 +under positions was dorninated
by an opportunistic species (Capitella capitata) and had the lowest diversity and biomass.
The mus sel farm contributed, therefore, to local organic enrichment. However, the farm
effect was restricted to directly under the mussellines as a comparison with historical data
indicated that this area of the lagoon is a naturally enriched environment.
A further study (Chapter 4) compared different indicators for their ability to detect
the influence of bivalve farrning on the environment. Both sediment [partic1e size, sediment
profile imaging (SPI), % OM] and benthic community characteristics (abundance,
diversity, biomass, individu al body mass, trophic group, corn munit y structure, and biotic
index) were evaluated at two mus sel farms: Great-Entry- GE and Havre-aux-Maisons -
HAM, in the Magdalen Islands (Quebec). Sampling stations were positioned directly
beneath the outside-most mus sel lines (Om) and at distances of 3, 6, 9, 15, 30 m and at a
control site (300-500 m) along a transect from the two mussel farms in the main water
current direction. Results show very site-specifie effects at the two farms studied. The study
showed that the a priori choice of the sampling station and indicators may have a great
influence on the interpretation. Community structure and SPI appears to detect small and
broader scale influence than other indices.
A manipulative ex periment (Chapter 5) was finally carried out in situ to deterrnine
the level of mussel biodeposition that modifies sandy benthic community structure and
biogeochemical fluxes. Because of high intra-treatment variability, oxygen consumption,
ammonium and phosphate fluxes did not vary significantly between treatments. Only
silicate was positively correlated to mussel density. A decrease of macrofaunal total
abundance and number of species in relation to increased mussel density was observed. An
important increase in abundance and biomass of opportunistic species (Capitella sp.) was
observed at a mussel density of 764 mussels m-2
. At this density, a shift from slightly to
moderately disturbed benthic environment occurred.
Results from this thesis contribute to deterrnine the assimilative capacity of the
benthic environment for mussel aquaculture
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