Academic literature on the topic 'Trophic flow'
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Journal articles on the topic "Trophic flow"
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Ulrich-Baker, M. G., W. R. Smidt, T. S. Gaginella, and D. N. Granger. "Splanchnic blood flow during stimulation of gastrointestinal growth." American Journal of Physiology-Gastrointestinal and Liver Physiology 252, no. 5 (May 1, 1987): G692—G698. http://dx.doi.org/10.1152/ajpgi.1987.252.5.g692.
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The primary objective of this study is to determine whether a relationship exists between the rate of blood flow and the gastrointestinal response to a trophic stimulus. A new prostaglandin E2 (PGE2) derivative, Ro 22-1327, was employed as a growth stimulus. Rats were treated by gavage for 14 days with Ro 22-1327 (0.5 and 5 mg/kg). The vascular and trophic effects of Ro 22-1327 were studied in the gastric antrum and oxyntic gland area, duodenum, jejunum, ileum, colon, liver, and pancreas. Generally, the trophic effects were 1) similar to those reported with other PGE2 analogues, 2) more pronounced in the antrum than in the oxyntic gland area, 3) greatest in the stomach, diminishing toward the colon, and 4) dose dependent. Organ blood flows were largely unaffected by the low-dose treatment, while the high-dose treatment tended to increase blood flow. The changes in blood flow were most pronounced proximally where the trophic responses were maximal. We speculate that the greater trophic response to the high dose of Ro 22-1327 may reduce the vasoconstriction produced by this agent.
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Canning, A. D., and R. G. Death. "Trophic cascade direction and flow determine network flow stability." Ecological Modelling 355 (July 2017): 18–23. http://dx.doi.org/10.1016/j.ecolmodel.2017.03.020.
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Riascos, José M., Marco A. Solís, Aldo S. Pacheco, and Manuel Ballesteros. "Breaking out of the comfort zone: El Niño-Southern Oscillation as a driver of trophic flows in a benthic consumer of the Humboldt Current ecosystem." Proceedings of the Royal Society B: Biological Sciences 284, no. 1857 (June 21, 2017): 20170923. http://dx.doi.org/10.1098/rspb.2017.0923.
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The trophic flow of a species is considered a characteristic trait reflecting its trophic position and function in the ecosystem and its interaction with the environment. However, climate patterns are changing and we ignore how patterns of trophic flow are being affected. In the Humboldt Current ecosystem, arguably one of the most productive marine systems, El Niño-Southern Oscillation is the main source of interannual and longer-term variability. To assess the effect of this variability on trophic flow we built a 16-year series of mass-specific somatic production rate (P/B) of the Peruvian scallop ( Argopecten purpuratus ), a species belonging to a former tropical fauna that thrived in this cold ecosystem. A strong increase of the P/B ratio of this species was observed during nutrient-poor, warmer water conditions typical of El Niño, owing to the massive recruitment of fast-growing juvenile scallops. Trophic ecology theory predicts that when primary production is nutrient limited, the trophic flow of organisms occupying low trophic levels should be constrained (bottom-up control). For former tropical fauna thriving in cold, productive upwelling coastal zones, a short time of low food conditions but warm waters during El Niño could be sufficient to waken their ancestral biological features and display massive proliferations.
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Zanden, M. Jake Vander, Timothy E. Essington, and Yvonne Vadeboncoeur. "Is pelagic top-down control in lakes augmented by benthic energy pathways?" Canadian Journal of Fisheries and Aquatic Sciences 62, no. 6 (June 1, 2005): 1422–31. http://dx.doi.org/10.1139/f05-042.
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Modern food web studies are typically conducted from a trophic dynamic perspective that focuses on combined roles of top-down and bottom-up forces in regulating food web structure. Recognition of spatial food web subsidies in diverse ecosystems highlights the importance of energy flow as a foundation for understanding trophic dynamics. Here, we consider how different energy flow configurations might affect trophic dynamics in north-temperate lakes. A literature review revealed that littoral piscivores exert top-down control on prey fishes. In contrast, analysis of littoral predator diets indicated extensive omnivory and heavy reliance on zoobenthic prey. We explored this uncoupling between trophic dynamics (piscivores regulate prey fish) and energy flow (zoobenthos in piscivore diets) using a biomass dynamic model. This model compared top-down impacts of a piscivore on prey fishes under two scenarios: consumption of prey fish only and consumption of prey fish plus zoobenthos. The model predicted that elimination of zoobenthivory leads to a 50% reduction in piscivore standing stock and concomitant 2.5-fold increase in prey fish abundance (i.e., zoobenthivory plays a key role in mediating pelagic top-down control). These results highlight the role of benthicpelagic linkages in regulating trophic dynamics and underscore the value of whole-ecosystem approaches to the study of food webs.
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Kowalewski, David. "Howling About Trophic Cascades." Australian Journal of Environmental Education 28, no. 1 (July 2012): 17–26. http://dx.doi.org/10.1017/aee.2012.3.
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AbstractFollowing evolutionary theory and an agriculture model, ecosystem research has stressed bottom-up dynamics, implying that top wild predators are epiphenomenal effects of more basic causes. As such, they are assumed expendable. A more modern co-evolutionary and wilderness approach — trophic cascades — instead suggests that top predators, whose effects flow down to fundamental biological processes, are co-equal causes of ecosystem health. Their survival, then, should be supported. This article, based on extensive research including the author's participation in a major field project, provides informational resources for teaching trophic cascades, using wolves as a case study. As charismatic, iconic, thriving but still endangered, well-studied, and terrestrial carnivores, wolves are ideal for enlightening students about what otherwise might be dry abstractions about crucial ecosystem processes. The article ends with student exercises and broader lessons for environmental education.
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Zhao, Yuxi, Xingguo Liu, Ming Lu, Runfeng Zhou, Zhaoyun Sun, and Shuwen Xiao. "Evaluation of Trophic Structure and Energy Flow in a Pelteobagrus fulvidraco Integrated Multi-Trophic Aquaculture System." International Journal of Environmental Research and Public Health 19, no. 19 (September 23, 2022): 12027. http://dx.doi.org/10.3390/ijerph191912027.
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An integrated multi-trophic aquaculture system (IMTA) combined muti-trophic organism cultivation with ecological engineering facilities effectively improves energy utilization efficiency and reduces pollution emission, which promotes the development of the aquaculture industry. In this study, an Ecopath model was used to analyze the Pelteobagrus fulvidraco-integrated multi-trophic aquaculture system (FMRP). The results showed that the effective trophic level range of FMRP was low (1~2.566), and the energy throughput was mainly concentrated in trophic level I (65.39%). The utilization rate of commercial fish feed was high. Due to the lack of predators for detritus and primary producers (Oryza sativa L. and hydrophyte), the energy throughput of detritus and the primary production were not fully utilized. The ascendency/total development capacity (A/TDC) and overhead/total development capacity (O/TDC) were 0.29 and 0.59, respectively, which indicated that the aquaculture system had high elasticity and strong anti-perturbation ability, but the stability could be substantially improved. The results of the carrying capacity assessment showed that the maximal single increments of Pelteobagrus fulvidraco fry and juvenile were 0.12 g/m2 and 0.42 g/m2, respectively, and the maximal common increments of Pelteobagrus fulvidraco fry and juvenile were 0.10 g/m2 and 0.10 g/m2, respectively, which indicated that there was insufficient space for increment. The study showed that the FMRP still needed to be improved in the aspects of polyculture species, energy consumption and stability. It would be necessary for the FMRP to perform further optimization and enhancement on the energy utilization efficiency, system stability and comprehensive benefits.
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Kang, Yun-Ho. "A Preliminary Trophic Flow Model for Gwangyang Bay, Korea." Korean Journal of Fisheries and Aquatic Sciences 38, no. 3 (June 1, 2005): 184–95. http://dx.doi.org/10.5657/kfas.2005.38.3.184.
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Burns, Thomas P., Masahiko Higashi, Sam C. Wainright, and Bernard C. Patten. "Trophic unfolding of a continental shelf energy-flow network." Ecological Modelling 55, no. 1-2 (July 1991): 1–26. http://dx.doi.org/10.1016/0304-3800(91)90061-5.
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Richter, Andreas, Toni Kern, Sebastian Wolf, Ulrich Struck, and Liliane Ruess. "Trophic and non-trophic interactions in binary links affect carbon flow in the soil micro-food web." Soil Biology and Biochemistry 135 (August 2019): 239–47. http://dx.doi.org/10.1016/j.soilbio.2019.04.010.
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Zhang, Wenfeng, Weixiong Huang, Xiao Chen, Xingfen Yang, and Xiaoguang Yang. "Stable carbon and nitrogen isotope evidence for the low biomagnification of mercury in marine fish from the South China Sea." Marine and Freshwater Research 71, no. 8 (2020): 1017. http://dx.doi.org/10.1071/mf19069.
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The low biomagnification of total mercury (THg) and methylmercury (MeHg) in commercially important marine fish from the south coast of China has been demonstrated through the analysis of stable carbon and nitrogen isotopes. In this study, levels of THg, MeHg and stable carbon and nitrogen isotope ratios were determined. Stable isotope signatures of carbon and nitrogen (13C/12C, 15N/14N) were used to trace the carbon flow and reconstruct trophic interactions. Levels of THg and MeHg in fish muscle samples were <220ngg–1. The trophic levels of sampled fish ranged from 2.31 to 5.03. The trophic magnification slopes were ~0.1 for both THg and MeHg, whereas the trophic magnification factor showed that the average biomagnification of THg and MeHg per trophic level was 3.02 and 2.87ngHgg–1 respectively along fish food chains, indicating low biomagnification potential of these mercury species. The low concentrations of MeHg and low biomagnification of mercury in marine fish may result from the trophic levels and habitats of these fish.
Dissertations / Theses on the topic "Trophic flow"
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Ribeiro, Fabianne de Araújo. "Silver nanoparticles flow in an aquatic trophic chain." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/12478.
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Doutoramento em BiologiaSilver nanoparticles (AgNP) have been produced and applied in a variety of products ranging from personal care products to food package containers, clothing and medicine utilities. The antimicrobial function of AgNP makes it very useful to be applied for such purposes. Silver (Ag) is a non-essential metal for organisms, and it has been historically present in the environment at low concentrations. Those concentrations of silver increased in the last century due to the use of Ag in the photographic industry and lately are expected to increase due to the use of AgNPs in consumer products. The presence of AgNP in the aquatic environment may pose a risk for aquatic species, and the effects can vary from lethal to sublethal effects. Moreover, the contact of aquatic organisms with AgNP may not cause immediately the death of individuals but it can be accumulated inside the animals and consequently transferred within the food chain. Considering this, the objective of this work was to study the transfer of silver nanoparticles in comparison to silver ions, which was used as silver nitrate, within an aquatic food chain model. To achieve this goal, this study was divided into four steps: the toxicity assessment of AgNP and AgNO3 to aquatic test-species, the bioaccumulation assessment of AgNP and AgNO3 by Pseudokirchneriella subcapitata and Daphnia magna under different exposure scenarios, and finally the evaluation of the trophic transfer of Ag through an experimental design that included the goldfish Carassius auratus in a model trophic chain in which all the species were exposed to the worse-case scenario. We observed that the bioconcentration of Ag by P. subcapitata is mainly driven by ionic silver, and that algae cannot internalize these AgNPs, but it does internalizes dissolved Ag. Daphnia magna was exposed to AgNP and AgNO3 through different exposure routes: water, food and both water and food. The worse-case scenario for Daphnia Ag bioaccumulation was by the joint exposure of contaminated water and food, showing that Ag body burdens were higher for AgNPs than for AgNO3. Finally, by exposing C. auratus for 10 days through contaminated water and food (supplied as D. magna), with another 7 days of depuration phase, it was concluded that the 10 days of exposure were not enough for fish to reach a plateau on Ag internal concentration, and neither the 7 days of elimination were sufficient to cause total depuration of the accumulated Ag. Moreover, a higher concentration of Ag was found in the intestine of fish when compared with other organs, and the elimination rate constant of AgNP in the intestine was very low. Although a potential for trophic transfer of AgNP cannot be suggested based in the data acquired in this study, there is still a potential environmental risk for aquatic species.
As nanopartículas de prata (AgNP) têm sido produzidas e utilizadas em uma grande variedade de bens de consumo, desde produtos de higiene pessoal a embalagens de alimento e utensílios médicos. A ação antimicrobiana das nanopartículas de prata é o principal fator que as torna úteis e ideais para tais aplicações. A prata é um metal não essencial e pode ser encontrado no ambiente em concentrações ecologicamente irrelevantes. No passado, a atividade de revelação fotográfica era a principal fonte de prata no ambiente. Ultimamente, estas concentrações têm aumentado devido à vasta utilização das nanopartículas de prata na indústria. A presença da prata no ambiente pode constituir um risco para as espécies e os efeitos causados podem ser do tipo letal ou sub-letal. Para além disso, a exposição dos organismos à prata, mesmo que não os leve à morte imediata, pode causar uma acumulação deste metal, e que poderá ser transferido entre os níveis tróficos da cadeia alimentar aquática. Tendo isto em consideração, o objetivo deste trabalho foi estudar a transferência das nanopartículas de prata numa cadeia trófica aquática modelo, e comparar os mesmos processos com a exposição a nitrato de prata (AgNO3). Para alcançar este objetivo, este trabalho foi dividido em quatro estudos: avaliação da toxicidade das AgNP e do AgNO3 para as espécies em estudo, uma posterior avaliação da bioconcentração das AgNP e do AgNO3 pela alga verde P. subcapitata, o estudo da bioacumulação da prata em Daphnia magna, exposta a diferentes vias de contaminação (água, alimento e ambos) e por último a avaliação da transferência das AgNP e de AgNO3 através de um desenho experimental que incluiu o peixe Carassius auratus expostos a água e alimento contaminados. Os resultados obtidos com estes estudos indicam que a bioacumulaçãoo da prata na alga P. subcapitata ocorre devido à internalização dos iões de prata, e não das nanopartículas. Estas aparentemente encontram-se em aglomerados próximas às células das algas, não entrando nas células/algas. Relativamente à Daphnia magna, o maior fator de bioacumulação foi obtido quando estas foram expostas à água e alimento contaminados com AgNP. Finalmente observou-se que os peixes não atingiram um equilíbrio na concentração interna de prata, e que o órgão que apresentou maior bioacumulação de prata foi o fígado. Para além disso, foi verificada no fígado uma taxa de eliminação muito baixa, o que nos pode levar a sugerir que as nanopartículas de prata podem persistir neste órgão. Apesar de não se verificar um potencial para transferência trófica, as nanopartículas de prata podem representar risco para as espécies aquáticas aqui estudadas.
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Whiting, Daniel P. "Macroinvertebrate production, trophic structure, and energy flow along a tallgrass prairie stream continuum /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1967802681&sid=3&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Whiting, Daniel Philip. "MACROINVERTEBRATE PRODUCTION, TROPHIC STRUCTURE, AND ENERGY FLOW ALONG A TALLGRASS PRAIRIE STREAM CONTINUUM." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/120.
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Conceptual models of stream continua predict that energy flow and consumer functional structure change predictably with the physical attributes of a stream. To quantify these relationships in a prairie landscape, I estimated macroinvertebrate production, benthic organic matter standing stocks, and resource consumption and egestion by consumer groups along a longitudinal continuum of Kings Creek, a tallgrass prairie stream draining the Konza Prairie Biological Station in Eastern Kansas. I sampled benthic macroinvertebrates for 1 year from three stream reaches, each bordered by distinct riparian vegetation. Riparian vegetation along the continuum ranged from grassy headwaters to shrubby mid-reaches to lower reaches bordered by gallery forest. Total habitat-weighted production ranged from 31.9 g ash-free dry mass (AFDM) m-2 y-1 in the grassy headwater reach to 9.1 g AFDM m-2 y-1 in the shrubby reach to 17.0 g AFDM m-2 y-1 in the gallery forest. Functional group contributions to production generally were similar along the continuum, with collector-gatherers (40%-56% of total) and Predators (23%-38%) dominating all reaches. Quantitative food webs indicated detrital pathways dominated energy flow in all reaches, with collector-gatherers accounting for most energy flow through primary consumers. Predators were well represented and consumed 75% - 135% of total macroinvertebrate production whereas shredders (2-4%), scrapers (11-15%), and filterers (<1%) consumed a small percentage of their particular resources. High production and consumption estimates for macroinvertebrate predators suggest top-down controls are important in this system. Although functional structure was fairly similar among reaches, changes in energy flow through some groups reflected longitudinal changes in resource availability. Results indicate that this tallgrass prairie stream ecosystem is intermediate in the context of predictions of conceptual stream continua models, and biotic interactions may override some predicted responses to changes in the physical template.
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Iwata, Tomoya. "The roles of fluvial geomorphology in the trophic flow from stream to forest ecosystems." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/86478.
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Pavlaki, Maria. "Bottom-up contamination in marine systems: model trophic levels to predict cadmium flow in marine organisms." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16846.
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Doutoramento em BiologiaCadmium is considered one of the most toxic metals to aquatic organisms. This naturally occurring metal is found in the environment in low concentrations due to natural processes, such as volcanic eruptions, natural crust erosion and also anthropogenic activities, such as mining and smelting. As a by-product of zinc mining, cadmium can reach aquatic environment through leaching or to rainwater runoff from the mine areas. It is a non-essential metal for organisms that even at relatively low concentrations can be toxic and may cause adverse effects due to its high bioaccumulation tendency. Considering this, the objective of this work was to study the toxicity and bioaccumulation potential of cadmium within different model marine trophic levels. To achieve this goal, this work was divided into four studies: i) assess the eco- and genotoxicity of cadmium to three marine test-species, representing different marine trophic levels, ii) determine the bioconcentration potential of cadmium in the calanoid copepod Acartia tonsa under different environmental conditions, such as pH, salinity and temperature, iii) evaluate the uptake and depuration kinetics of cadmium by the estuarine ditch shrimp Palaemon varians considering three different uptake routes: water, diet, water + diet and iv) assess the bioaccumulation patterns of cadmium in the Senegalese sole Solea senegalensis, a final consumer, and the possible risk and implications the consumption of the edible fraction of both shrimps and fish may bear to human health upon Cd exposure. We observed that the toxicity of cadmium is highly influenced by its speciation. Highest sensitivity to cadmium was observed by A. tonsa while the most sensitive endpoint was the Larval Development Ratio (LDR). Cadmium induced DNA damage to all species with increasing concentrations. The bioconcentration of cadmium by A. tonsa is strongly affected by different environmental conditions due to biological processes. The simultaneous exposure of P. varians to cadmium-contaminated water + diet showed that cadmium internal concentration was higher when compared to the individual pathways. Finally, by exposing S. senegalensis for 14 days through contaminated water and diet (supplied as Hediste diversicolor), with another 14 days of depuration phase, it was concluded that the 14 days of exposure were not enough for the fish to reach a steady state on cadmium internal concentration, and neither the 14 days of elimination were sufficient to cause total depuration of the accumulated cadmium in any of the organs. Moreover, a higher concentration of cadmium was found in the intestine of the fish when compared with the rest of the organs, and the elimination rate constant of cadmium in the liver was nule. The Target Hazard Quotient (THQ) and the Estimated Weekly Intake (EWI) values for cadmium for the edible fraction of S. senegalensis were below the acceptable levels set by the European Regulation while for the shrimps both THQ and EWI exceeded the acceptable levels established
O cádmio é considerado um dos metais mais tóxicos para organismos aquáticos, podendo ocorrer naturalmente no ambiente em concentrações muito baixas, devido a processos naturais (e.g., erupções vulcânicas, erosão da crosta natural) mas também devido a atividades antropogénicas, como a atividade mineira. Como um subproduto da exploração mineira de zinco, o cádmio pode ser libertado para o ambiente aquático através de lixiviação ou escorrências. O cádmio é um metal não essencial para os organismos mas, mesmo em concentrações relativamente baixas, pode ser tóxico, provocando efeitos adversos devido à sua elevada tendência para bioacumular. Neste contexto, o objetivo deste trabalho foi estudar a transferência de cádmio em diferentes modelos de níveis tróficos marinhos. O estudo foi dividido em quatro etapas: i) avaliar a eco- e genotoxicidade de cádmio em três espécies marinhas, representando diferentes níveis tróficos marinhos ii) determinar a bioconcentração de cádmio por Acartia tonsa sob diferentes condições ambientais, tais como pH, salinidade e temperatura, iii) a avaliação de toxicocinética de cádmio pelo camarão estuarino Palaemon varians sob três vias de exposição diferentes: água, alimentação e água + alimentação, e iv) avaliar os padrões de bioacumulação de cádmio no linguado Solea senegalensis como consumidor final, e os possíveis riscos e implicações do consumo da fração edível de camarões e peixe que pode ter para a saúde humana, após a exposição a cádmio. Foi observado que a toxicidade de cádmio é influenciada pela sua especiação. A maior sensibilidade ao cádmio foi observada em A. tonsa tendo como parâmetro mas sensível o Índice de Desenvolvimento Larvar (LDR). O cádmio induziu danos no ADN de todas as espécies utilizadas. A bioconcentração de cádmio por A. tonsa é fortemente afetada por diferentes condições ambientais devido a processos biológicos. P. varians foi exposto a cádmio através de diferentes vias de exposição: água ou alimento ou água e alimento. A exposição simultânea de P. varians a água e alimento contaminado com cádmio mostrou que a concentração interna de cádmio foi maior quando comparada com as outras duas vias de exposição. Finalmente, mesmo uma exposição através de água e alimento contaminado (fornecido como Hediste diversicolor) não foi suficiente para que o peixe S. senegalensis atingisse um plateau na concentração interna de cádmio, sendo os 14 dias de depuração insuficientes para que os organismos depurassem totalmente a concentração interna que havia sido acumulada. Adicionalmente, foi encontrada uma maior concentração de cádmio no intestino de S. senegalensis quando comparada com os outros órgãos, e a constante de eliminação de cádmio no fígado foi inexistente. Os valores do Coeficiente de Perigo Alvo (THQ) e o Consumo Semanal Estimado (EWI) para o cádmio estavam abaixo dos níveis aceitáveis estabelecidos em regulamentos europeus para a fração edível de S. senegalensis, enquanto que para P. varians tanto o THQ quanto o EWI excederam os níveis aceitáveis estabelecidos.
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Regester, Kurt Joel. "Ecosystem significance of ambystomatid salamanders : energy flow, habitat subsidies, and trophic interactions associated with their complex life cycles /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1342728871&sid=9&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Guiguer, Karin R. R. A. "Determination of Colpoys Bay (Georgian Bay) benthic community trophic structure and energy flow using stable isotopes and secondary production." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0022/NQ51199.pdf.
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Parreira, de Castro Diego Marcel. "Functional diversity and trophic relationships in benthic communities : a multi-scale spatial approach in neotropical savanna streams." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1092/document.
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Les changements d'intensité dans l'utilisation des sols et la dégradation de l'environnement en raison de activités humaines ont entraîné une forte altération des écosystèmes tropicaux, en particulier dans les cours d'eau de tête de bassin de la savane néotropicale. Les pressions humaines liées à l'expansion agricole et à l'urbanisation ont conduit à une réduction drastique de la couverture végétale indigène, affectant les zones riveraines et altérant le fonctionnement des écosystèmes aquatiques. Il est urgent de quantifier et de prévoir comment les communautés aquatiques répondent aux changements de l'utilisation des sols pour guider les efforts de conservation et de gestion des ressources naturelles. Dans ce contexte, cette thèse visait à évaluer à quelles échelles spatiales la relation entre habitat et communautés de macroinvertébrés benthiques s'exprimait le plus fortement et comment l'intensité d'utilisation des sols affectait les relations trophiques et la composition en traits biologiques des communautés de macroinvertébrés benthiques. Dans le chapitre 1, j'évalue comment l'intensité d'utilisation des sols (représentée par un gradient depuis la végétation autochtone, au pâturage, et à la plantation de canne à sucre et la végétation indigène) influe sur les flux d'énergie et les niches trophiques des macroinvertébrés benthiques. Ensuite, j'ai évalué à quelle échelle spatiale (bassin versant, localité) et pour quelles variables, le lien entre la composition taxonomique et fonctionnelle des assemblages de macroinvertébrés benthiques était le mieux exprimé (chapitre 2). Enfin, j'ai montré que les perturbations anthropiques avait unj impact sur la diversité fonctionnelle des assemblages de macroinvertébrés benthiques (chapitre 3). Les résultats présentés ici montrent que les changements d'intensité de l'utilisation des sols conduisent les assemblages de macroinvertébrés benthiques vers des comportements d'alimentation plus généralistes avec un chevauchement des niches trophiques (chapitre 1). De plus, les variables environnementales à l'échelle locale et du bassin versant expliquent de façon significative les variations de la composition taxonomique et fonctionnelle des assemblages d'Ephéméroptères, Plécoptères et Trichoptères, mais les variables décrivant l'intensité d'utilisation des sols expliquent le mieux les différences de composition fonctionnelle entre les différents sites (chapitre 2). Enfin, J'ai montré que les sites quasi-naturels (dans des conditions de référence) ont des assemblages de macroinvertébrés plus spécialisés comparés aux sites perturbés (chapitre 3). Les résultats corroborent le fait que la biodiversité doit être évaluée en tenant compte de variables agissant à de multiples échelles spatiales et que les éléments fonctionnels des communautés biologiques doivent être considérés, en vue de la conservation et du développement d'outils prédictifs. Cette étude contribue à une meilleure compréhension de la structure et du fonctionnement des cours d'eau dans la savane néotropicale dans le contexte du développement d'outils d'évaluation environnementale. Ces approches contribueront à l'élaboration de mesures de gestion et de conservation plus appropriées et permettront d'examiner les conséquences futures d'une poursuite de la dégradation des conditions écologiques dans les cours d'eau tropicauxChanges in land cover and use and the associated environmental degradation due to human activities have resulted in extreme alterations of tropical ecosystems, especially in headwater streams and their watersheds in the neotropical savanna. Human pressures related to agricultural expansion and urbanization have led to drastic reductions in native vegetation cover, affecting riparian zones and degrading aquatic ecosystem functioning. There is an urgent need to quantify and predict how aquatic communities respond to different intensities of land use to guide conservation and natural resource management efforts. This thesis aims to evaluate how spatial scales influence the relationship between habitat and benthic macroinvertebrate communities and how land use intensity affects the trophic relationships and biological traits of macroinvertebrates. In Chapter 1, we evaluated how the intensity of land use (represented by a gradient moving from native vegetation toward pasture and sugar cane plantations) influences the energy flow and trophic niches of macroinvertebrates. In Chapter 2, we investigated the spatial scales (e.g., catchment, local) that most influence the taxonomic and functional composition of macroinvertebrate assemblages. Finally, in Chapter 3, we examined the impacts of human pressures on the functional diversity of macroinvertebrate assemblages. we showed that the intensity of land use affects benthic macroinvertebrate assemblages, yielding more generalist feeding behaviors with greater overlap of trophic niches (Chapter 1). In addition, environmental variables at the local and catchment scales significantly explained the variations in the taxonomic and functional composition of Ephemeroptera, Plecoptera and Trichoptera assemblages, but land use variables best explained the differences in functional composition among sites (Chapter 2). Finally, we showed that less impacted sites (under reference conditions) had more specialized and more functional diverse macroinvertebrate assemblages compared to disturbed sites (Chapter 3). These results corroborate the idea that biodiversity should be evaluated at multiple spatial scales and that the functional elements of biological communities should be considered when aiming for conservation and the development of predictive tools. This study contributes to a better understanding of the structure and functioning of streams in the neotropical savanna by subsidizing the development of environmental assessment tools. Such approaches will contribute to the development of more appropriate management and conservation measures that will allow for evaluation of the impacts on biota of further degradation of the ecological conditions in tropical streams
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Zhang, Lu [Verfasser], Tillmann [Akademischer Betreuer] Lueders, Tillmann [Gutachter] Lueders, and Ingrid [Gutachter] Kögel-Knabner. "Insights into trophic connectivities and carbon flow through bacterial members of a belowground food web / Lu Zhang ; Gutachter: Tillmann Lueders, Ingrid Kögel-Knabner ; Betreuer: Tillmann Lueders." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1163728713/34.
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Ruiz, Jarrin Diego J. [Verfasser], Matthias [Akademischer Betreuer] Wolff, and Hauke [Akademischer Betreuer] Reuter. "Energy flow and trophic structure of Galápagos shallow rocky reef systems along a gradient of productivity and artisanal fisheries / Diego J Ruiz Jarrin. Gutachter: Matthias Wolff ; Hauke Reuter. Betreuer: Matthias Wolff." Bremen : Staats- und Universitätsbibliothek Bremen, 2015. http://d-nb.info/1077061730/34.
Full textBooks on the topic "Trophic flow"
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North American Conference on Multiphase Technology (1st 1998 Banff, Alta.). 1st North American Conference on Multiphase Technology: Technology from the arctic to the tropics : papers presented at the 1st North American Conference on Multiphase Technology, organized and sponsored by BHR Group Limited. Held in Banff, Canada on 10-11 June, 1998. Bury St. Edmunds: Professional Engineering Publishing, 1998.
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Jacobsen, Dean, and Olivier Dangles. Energy flow and species interactions at the edge. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198736868.003.0007.
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Chapter 7 elucidates the relationships between the structure and functioning of aquatic ecosystems at high altitude through the description of material cycles and food webs. Following the landscape continuum model, material cycling is profoundly influenced by the physical structure of the waterscape (e.g. vegetation cover); as a result a great diversity of energetic pathways characterize high altitude waterscapes, along an autotrophy–heterotrophy gradient. Similarly, high altitude aquatic food webs embrace a great diversity of trophic compartments, feeding strategies, and processes (trophic cascades and terrestrial subsidiarity) that are profoundly shaped by environmental harshness. Harsh conditions also generate stress gradients along which the strength and direction of species interactions (from competition to facilitation) and their functional role (e.g. as ecosystem engineers) are modified. The resulting structural and functional changes affect in turn species coexistence and trigger potential ecosystem shifts.
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Transport, European Commission Directorate-General, ed. Tropic: Traffic optimisation by the integration of information and control. Luxembourg: Office for Official Publications of the European Communities, 1999.
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Dunlop, Storm. 6. Weather in the tropics. Oxford University Press, 2017. http://dx.doi.org/10.1093/actrade/9780199571314.003.0006.
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‘Weather in the tropics’ considers the weather systems between the two subtropical anticyclones, lying at approximately latitudes 30 °N and S. The trade winds consist of air that flows out of the subtropical anticyclones towards the equatorial trough. They are strongest in the winter season, tending to weaken during the summer. The northern and southern hemisphere trade winds converge at the Intertropical Convergence Zone, whose position is variable. The South Pacific Convergence Zone is closely associated with the changes involved in the Walker Circulation and El Niño events. The convergence zones over the Indian Ocean show major changes in location during the northern summer, and these are related to seasonal monsoons.
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(Editor), J. P. Brill, and G. A. Gregory (Editor), eds. Multiphase Technology: Technology from the Arctic to the Tropics (BHR Group Publication 31) (British Hydromechanics Research Group (REP)). Wiley, 1998.
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Jacobsen, Dean, and Olivier Dangles. Ecology of High Altitude Waters. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198736868.001.0001.
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This book brings together current knowledge on patterns and processes in the ecology of streams, lakes, and wetlands situated at more than 3000 m above sea level. The alpine headwaters of the large Asian rivers and Lake Titicaca are both well-known and iconic examples. High altitude waters include more than these systems—they are both numerous and cover many habitat types, organisms, and specializations. The book provides an overview of the variety of aquatic ecosystems and habitats, their environmental features, prominent species, and their functional adaptations to the harsh aquatic environmental conditions through to global diversity patterns along altitudinal gradients, community dynamics, species interactions and dispersal, trophic relations, and energy flows. High altitude waters are ideal systems to address a broad range of topical themes in ecology because patterns and processes are both diverse and singular. The book highlights how key concepts in ecology (e.g. the stress gradient hypothesis, the biodiversity–ecosystem functioning relationship) could find relevant study models in high altitude waters. The usual perception of pristine mountain waters is far from true, particularly in the case of high altitude waters at low latitudes where human population density is often high, and local communities live in intimate contact with, utilize, influence, and exploit these aquatic systems. Climate change effects, extinction risks of mountain populations due to vanishing glaciers, multiple human impacts, management, and conservation are also treated thoroughly. The book is richly illustrated with diagrams and numerous pictures of these poorly known systems and species.
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Clarke, Andrew. Temperature, growth and size. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199551668.003.0013.
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Growth involves two flows of energy. The first is chemical potential energy in the monomers used to construct the proteins, lipids, polysaccharides and nucleic acids forming the new tissue. The second is the metabolic energy (ATP or GTP) used to construct the new tissue; this is the metabolic cost of growth and can be expressed as a dimensionless fraction of the energy retained in the new tissue. Its value is ~0.33. Typical temperature sensitivities for growth in the wild lie in the range Q10 1.5 – 3. Within species there may be evolutionary adjustments to growth rate to offset the effects of temperature, though these involve trade-offs with other physiological factors affecting fitness. Outside the tropics, many mammals and birds exhibit a cline in size, with larger species at higher latitudes (Bergmann’s rule). Carl Bergmann predicted such a cline from biophysical arguments based on endotherm thermoregulatory costs; Bergmann’s rule thus applies only to mammals and birds. Many ectotherms grow more slowly but attain a larger adult size when grown at lower temperatures (the temperature-size rule). The large size of some aquatic invertebrates at lower temperatures (notably in the polar regions and the deep sea) is associated with a higher oxygen content of the water.
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Wang, Bin. Intraseasonal Modulation of the Indian Summer Monsoon. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.616.
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The strongest Indian summer monsoon (ISM) on the planet features prolonged clustered spells of wet and dry conditions often lasting for two to three weeks, known as active and break monsoons. The active and break monsoons are attributed to a quasi-periodic intraseasonal oscillation (ISO), which is an extremely important form of the ISM variability bridging weather and climate variation. The ISO over India is part of the ISO in global tropics. The latter is one of the most important meteorological phenomena discovered during the 20th century (Madden & Julian, 1971, 1972). The extreme dry and wet events are regulated by the boreal summer ISO (BSISO). The BSISO over Indian monsoon region consists of northward propagating 30–60 day and westward propagating 10–20 day modes. The “clustering” of synoptic activity was separately modulated by both the 30–60 day and 10–20 day BSISO modes in approximately equal amounts. The clustering is particularly strong when the enhancement effect from both modes acts in concert. The northward propagation of BSISO is primarily originated from the easterly vertical shear (increasing easterly winds with height) of the monsoon flows, which by interacting with the BSISO convective system can generate boundary layer convergence to the north of the convective system that promotes its northward movement. The BSISO-ocean interaction through wind-evaporation feedback and cloud-radiation feedback can also contribute to the northward propagation of BSISO from the equator. The 10–20 day oscillation is primarily produced by convectively coupled Rossby waves modified by the monsoon mean flows. Using coupled general circulation models (GCMs) for ISO prediction is an important advance in subseasonal forecasts. The major modes of ISO over Indian monsoon region are potentially predictable up to 40–45 days as estimated by multiple GCM ensemble hindcast experiments. The current dynamical models’ prediction skills for the large initial amplitude cases are approximately 20–25 days, but the prediction of developing BSISO disturbance is much more difficult than the prediction of the mature BSISO disturbances. This article provides a synthesis of our current knowledge on the observed spatial and temporal structure of the ISO over India and the important physical processes through which the BSISO regulates the ISM active-break cycles and severe weather events. Our present capability and shortcomings in simulating and predicting the monsoon ISO and outstanding issues are also discussed.
Book chapters on the topic "Trophic flow"
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Pimm, Stuart L. "Energy Flow and Trophic Structure." In Concepts of Ecosystem Ecology, 263–78. New York, NY: Springer New York, 1988. http://dx.doi.org/10.1007/978-1-4612-3842-3_13.
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Ulanowicz, Robert E. "Trophic Flow Networks as Indicators of Ecosystem Stress." In Food Webs, 358–68. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4615-7007-3_35.
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Tamisier, Alain, and Charles Boudouresque. "Aquatic bird populations as possible indicators of seasonal nutrient flow at Ichkeul Lake, Tunisia." In Aquatic Birds in the Trophic Web of Lakes, 149–56. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1128-7_14.
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Zadereev, Egor S., Ramesh D. Gulati, and Antonio Camacho. "Biological and Ecological Features, Trophic Structure and Energy Flow in Meromictic Lakes." In Ecology of Meromictic Lakes, 61–86. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-49143-1_4.
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Gaedke, Ursula, Dietmar Straile, and Claudia Pahl-Wostl. "Trophic Structure and Carbon Flow Dynamics in the Pelagic Community of a Large Lake." In Food Webs, 60–71. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4615-7007-3_6.
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Sarvala, Jouko, Kalevi Salonen, Marko Järvinen, Eero Aro, Timo Huttula, Pekka Kotilainen, Heini Kurki, et al. "Trophic structure of Lake Tanganyika: carbon flows in the pelagic food web." In From Limnology to Fisheries: Lake Tanganyika and Other Large Lakes, 149–73. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-017-1622-2_15.
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Arnaud, Sentis, Kaunisto Kari, Chari Lenin, Morrill André, Popova Olga, Pomeranz Justin, Boukal David, Tüzün Nedim, and Stoks Robby. "Odonata trophic ecology." In Dragonflies and Damselflies, 219–32. 2nd ed. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192898623.003.0016.
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Abstract Trophic interactions are at the core of several key ecological processes and theories as they determine the flow of material and energy within and across communities and habitats. Odonates provide a rich and diverse taxonomic group with several features (e.g. trophic position, hunting behavior, olfaction) that make them a very interesting biological model for the study of trophic interactions in aquatic and terrestrial habitats. Moreover, odonates undergo incomplete metamorphosis with aquatic larvae and terrestrial adults, which provides opportunities to investigate ontogenetic diet variation and trophic links between aquatic and terrestrial systems. They are also important predators regulating prey populations and mediating community processes such as trophic cascades. Finally, recent studies on odonates have pioneered whether local adaptation and phenotypic plasticity can counterbalance the negative impacts of global change on resource acquisition and fitness. This chapter reviews recent studies investigating the trophic features and role of odonates in aquatic and terrestrial ecosystems as well as their importance for investigating the impact of global change on trophic ecology, local adaption, and community processes. Many of the insights highlighted in this chapter go beyond odonates and have helped to advance key concepts in trophic ecology.
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Fogarty, Michael J., and Jeremy S. Collie. "Production at the Ecosystem Level." In Fishery Ecosystem Dynamics, 169–82. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198768937.003.0010.
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The development of ecosystem models can be size-based, species-based, or trophocentric. In all cases, equilibrium mass-balance descriptions of ecosystems can be translated to dynamic models. Linear network models trace the flow of energy through food webs. Starting from the base of the food web, they can be solved from the bottom up to calculate how many predators can be supported for a given level of primary production. Conversely, the food web can be solved from the top down to calculate how much primary production is required to support fisheries yield, given the dietary requirements of top predators. These models typically employ species-level and/or trophic-level designations for the nodes in the model. Biomass-spectrum models in contrast are based on body size dimensions (typically weight) rather than any taxonomic designation. Biogeochemical models provide another approach to developing ecosystem production models by making the connection between the availability of key nutrients and ecosystem production.
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Moore, John C., and Jill Sipes. "Trophic Structure and Nutrient Dynamics of the Belowground Food Web within the Rhizosphere of the Shortgrass Steppe." In Ecology of the Shortgrass Steppe. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195135824.003.0015.
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Belowground organisms are key components of the trophic structure and they mediate the dynamics of nutrients of all terrestrial ecosystems. The interactions among assemblages of belowground microorganisms and their consumers mediate the cycling of plant-limiting nutrients, influence aboveground plant productivity, affect the course of plant community development, and affect the dynamic stability of aboveground communities following natural and anthropogenic disturbances (Clarholm, 1985; Ingham et al., 1985; Laakso and Setälä, 1999; Naeem et al., 1994; Tilman et al., 1996; Wall and Moore, 1999). The influence of belowground organisms on the aboveground plant community is heightened in systems such as the shortgrass steppe (Blair et al., 2000), given the relatively high percentage of plant production that is diverted belowground through plant roots. Many of the human-induced changes that the shortgrass steppe has been subjected to during the past 150 years fall outside the scope of the natural variations in climate and grazing. This conflict between the natural history of the shortgrass steppe and the more recent human legacy forms the backdrop of this chapter. First we present a detailed description of the belowground food web for the native shortgrass steppe and present its structure in terms of the patterns of trophic interactions, the distribution of biomass, the flow of energy, and the strengths of interactions. Second, we explore how three disturbances—managed grazing, agricultural practices, and climate change (altered precipitation and temperature, and elevated CO2)—have altered the structure of the belowground community. We conclude with a synthesis of the common patterns that we observed in the grassland’s response to these disturbances, and speculate on their consequences. Aboveground plant parts provide from 20% to 40% cover with exposed soil between them (Lauenroth and Milchunas, 1991). Much of the aboveground production remains in place as standing dead, rather than falling to the soil surface as litter. The ratio of shoot production to root production is roughly 1:1, contrasting sharply with forests, where far more production is allocated aboveground (Jackson et al., 1996; Milchunas and Lauenroth, 1993, 2000). Hence, in the shortgrass steppe, plant roots provide the major input of carbon to soil. As such, plant roots are the focal point of biological activity in soils (Coleman et al., 1983).
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Kültz, Dietmar. "Anadromous fishes." In A Primer of Ecological Aquaculture, 184–97. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780198850229.003.0014.
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Abstract Anadromous fishes hatch and develop in freshwater (FW) and migrate to seawater where they spend most of their life before returning to FW for spawning. In contrast to trout, most salmon are anadromous. Atlantic salmon (Salmo salar) dominates aquaculture of anadromous fishes and is produced mainly in its native distribution range. Most Pacific salmon are produced in the Southern hemisphere, outside their native distribution range. Salmon aquaculture consists of a FW hatchery phase and a seawater grow-out phase. These different culture phases are required for all anadromous species. The most critical stage of salmon development in a FW hatchery is the alevin stage. At this stage, mortality is highest and yolk sac larvae are trained to consume starter feeds. Smoltification (silvering) is the physiological process of salmon parr transforming to smolts ready to enter seawater. Smoltification is essential for the anadromous life history of salmonids and precedes translocation of aquaculture salmon from FW hatcheries to open marine cages. Rainbow trout (Oncorhynchus mykiss) is the second-most produced salmonid aquaculture species. Most rainbow trout are grown in open, flow-through FW hatcheries and raceways, although anadromous rainbow trout (steelhead trout) are grown-out in mariculture. Salmonids are carnivores that occupy high levels in trophic webs, require high water quality, strong flow, and high-quality feeds. From an ecological sustainability perspective, salmonids are more challenging and more resource-intensive than herbivorous FW fishes. Consumer preference and demand for salmonids is high, which has fuelled research to reduce water usage, minimize waste, and develop more sustainable feeds.
Conference papers on the topic "Trophic flow"
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Zhou, Jinxin, Takero Yoshida, Junbo Zhang, Sanggyu Park, and Daisuke Kitazawa. "Three-Dimensional Physical Environment Modelling for Integrated Multi-Trophic Aquaculture (IMTA) Implementation in Onagawa Bay, Japan." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95672.
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Abstract Continually increasing demands on aquaculture products drive the current monoculture to upgrade and upscale because of not only economic but environmental sustainability reasons. Over the past decade, open water integrated multi-trophic aquaculture (IMTA) practiced as a potential alternative has been demonstratively illustrated from both scientific and public attention. Basing on previous studies of this synergistic aquaculture system, we, here, studied the physical environment in Onagawa Bay as the cornerstone for further IMTA implementation. Onagawa Bay locates in Miyagi Prefecture, Japan, and because of its mature practice on polyculture, it is recognized as a suitable site for IMTA. Unfortunately, the earthquake and tsunami in 2011 caused a huge uncertainty on physical environment changes. Still insufficient researches have been conducted on physical environment study, especially through modelling method. Here, adopting the three-dimensional Marine Environmental Committee (MEC) ocean model, we described the setup and validation for Onagawa Bay in this research. At the present stage, simulation results can best fit observation data on the tidal elevation with the correlation coefficient between observed and simulated tidal elevation reaching 0.96, captured the main characteristic of flow velocity, and exhibited homogenous tendency towards water temperature. Furthermore, through the plot of the residual velocity field and statistical seasonal velocity distribution, potential aquaculture configuration has been discussed spatio-temporally on the hypothesis that high current speeds contribute to the further implementation.
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Okey, T. A., and D. Pauly. "A Mass-Balanced Model of Trophic Flows in Prince William Sound: Decompartmentalizing Ecosystem Knowledge." In Ecosystem Approaches for Fisheries Management. Alaska Sea Grant, University of Alaska Fairbanks, 1999. http://dx.doi.org/10.4027/eafm.1999.45.
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Shannnon, L. J., and A. Jarre-Treichmann. "Comparing Models of Trophic Flows in the Northern and Southern Benguela Upwelling Systems During the 1980s." In Ecosystem Approaches for Fisheries Management. Alaska Sea Grant, University of Alaska Fairbanks, 1999. http://dx.doi.org/10.4027/eafm.1999.39.
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Sivasithamparam, Nallathamby, and Jorge Castro. "A Framework for Versatile Shape of Yield Surfaces for Structured Aniso-tropic Soft Soils." In The 13th Baltic Sea Region Geotechnical Conference. Vilnius Gediminas Technical University, 2016. http://dx.doi.org/10.3846/13bsgc.2016.022.
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A framework based on logarithmic contractancy is proposed to produce versatile shapes of yield surfaces for structured anisotropic clays. The recently proposed constitutive model (E-SCLAY1S) is an extension of existing model called S-CLAY1S, which is a Cam Clay type model that accounts for anisotropy and structure. A new parameter called contractancy parameter is introduced to control the shape of the yield surface as well as the plastic potential (as an associated flow rule is applied). This new parameter can be used to fit the coefficient of earth pressure at rest, the undrained shear strength or the stiffness under shearing stress paths predicted by the model. The model predicts the uniqueness of the critical state line and its slope is independent of the contractancy parameter. The effect of the shape of the yield surface was investigated on computed results of a benchmark embankment constructed on Bothkennar (Scotland) clay by employing the E-SCLAY1S model as a user-defined soil model into the PLAXIS finite element code. The results demonstrate that the contribution of the shape of yield surface (logarithmic contractancy parameter) have a relatively large effect on lateral movement of subsoil beneath the toe of the embankment compared to the settlement of subsoil at the centre of the embankment.
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Ginder, R. B. "Design and Performance of Advanced Blading for a High-Speed HP Compressor." In ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-374.
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A set of advanced blading has been designed for a 5-stage high-speed research core compressor. The blade profiles were aerodynamically-tailored using a sophisticated quasi-3D S1-S2 flow calculation system which was developed at RAE Pyestock. This system involves iteration between blade-to-blade calculations using an inviscid-viscous code, and a streamline-curvature calculation for the pitchwise-averaged throughflow. The design and measured performance of the new compressor are compared with an initial conventionally-bladed 4-stage version. The new design achieved a peak level of poly tropic efficiency approaching 91%, a substantial improvement on the initial version, but showed a shortfall in pressure ratio compared with design intent. Post-test analyses based on measured performance data are used to give further insight into this result and indicate possible improvements in the design approach.
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Dubey, Swapnil, C. S. Soon, Sin Lih Chin, and Leon Lee. "Performance Analysis of Innovative Top Cooling Thermal Photovoltaic (TPV) Modules Under Tropics." In ASME 2016 10th International Conference on Energy Sustainability collocated with the ASME 2016 Power Conference and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/es2016-59075.
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The main focus area of this research paper to efficiently remove the heat generated during conversion of solar energy into electricity using photovoltaic (PV) module. The photovoltaic conversion efficiency of commercial available PV module varies in the range of 8%–20% depending on the type of solar cell materials used for the module construction, e.g. crystalline silicon, thin film, CIGS, organic, etc. During the conversion process, only a small fraction of the incident solar radiation is utilize by PV cells to produce electricity and the remaining is converted into waste heat in the module which causes the PV cell temperature to increase and its efficiency to drop. This thermal energy could be extract using air or water as a heat removal fluid to utilize in heating applications. The purpose of a solar photovoltaic module is to convert solar energy into electricity. The hybrid combination of photovoltaic module and thermal collector called Photovoltaic-thermal (PVT) module. Such PVT module combines a PV, which converts electromagnetic radiation (photons) into electricity, with a solar thermal module, which captures the remaining energy and removes waste heat from the PV module. Cooling of cells either by natural or forced circulation can reduce the PV cell temperature. The simultaneous cooling of the PV cells maintains their PV efficiency at a satisfactory level and offers a better way of utilizing solar energy by generating thermal energy as well. PVT system has higher overall efficiency as compared to separate PV and thermal collector. The heat output of a PVT module can be used for space heating or production of domestic hot water. This paper presents an innovative design of top cooling Thermal Photovoltaic (T-PV) module and its performance under outdoor weather condition of Singapore. T-PV collector is designed to flow fluid over the top of PV panel through a very narrow gap between the solar lens. This process improves heat removal process from PV panel, and hence, improves the electrical output of PV panel as compared to other PVT collector available in the market. By flowing the water from top of the PV panel will also provide better thermal efficiency. A T-PV collector system with storage tank, sensors, pump, flow meters, data logger and controls, have been installed at test-site located in Ngee Ann Polytechnic, Singapore. Performance analysis of T-PV collector system has been evaluated under the tropical climatic conditions of Singapore. It was found that T-PV module could produce additional electrical power as compared to standard PV panel of same capacity by operating at lower temperature. In addition to electricity, T-PV panel also generate the hot water up to 60 deg C at an average thermal efficiency of 41% for usage in residential and commercial buildings. The average thermal energy output was 3.1 kWh/day on typical day’s basis.
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Killing, Steve. "Alpha and Rocker - Two Design Approaches that led to the Successful Challenge for the 2007 International C-Class Catamaran Championship." In SNAME 19th Chesapeake Sailing Yacht Symposium. SNAME, 2009. http://dx.doi.org/10.5957/csys-2009-014.
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In 2007 Canada entered its first challenge for the International C-Class Catamaran Championship and was victorious in capturing the trophy with five straight wins by Alpha CAN 6 over the venerable Cogito from the USA. Two boats were designed for this challenge - the first was Alpha, a wingsail catamaran, which incorporated some new thinking on sail configuration and hull shape. This made it a successful evolutionary, but not revolutionary, step from the current state-of-the-art boats. Compared to Cogito, the main rival, she had a taller, narrower and thinner wing, lighter construction and more circular hull cross section. The second was Rocker, the bold hydrofoil catamaran, using hulls from the same mold as Alpha and an identical wingsail as the driving force. The daggerboard hydrofoils automatically controlled the ride height with trim tabs, while the control of the rudder elevators was left to the helmsman. Although she flew well, was very controllable, and was spectacular to watch, Rocker could not match the 20 knot plus speed of Alpha.