Journal articles: '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.

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Qin, Qiang, Fubin Zhang, Fei Liu, Chunling Wang, and Huanzhang Liu. "Food Web Structure and Trophic Interactions Revealed by Stable Isotope Analysis in the Midstream of the Chishui River, a Tributary of the Yangtze River, China." Water 13, no. 2 (January 15, 2021): 195. http://dx.doi.org/10.3390/w13020195.

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Understanding energy flow and nutrient pathways is crucial to reveal the dynamics and functions of riverine ecosystems and develop appropriate conservation strategies. In this study, we utilized stable isotopes of δ13C and δ15N to examine the fundamental characteristics of trophic position, trophic niche, and carbon source for the food web in the midstream of the Chishui River, a tributary to the Yangtze River. Our results showed that stable isotope signatures among different sorts of basal resources and consumers were significantly distinguishable and that the food chain consisted of four trophic levels, indicating the multiple trophic pathways and long food chain length here. The trophic guilds of fish were classified into four categories, in which herbivorous and carnivorous fish showed greater trophic diversity and omnivorous fish had higher trophic redundancy, which meant that there was a stable trophic niche structure in the study area. Phytoplankton and periphyton presented the largest contributions to consumers, indicating that autochthonous productivity was the dominant carbon source in the midstream of the Chishui River. Since the Chishui River is still in a natural condition without any dam constructions, the autochthonous productivity, stable trophic niche structure, multiple trophic pathways and long food chain length found here demonstrate its high conservation value. Therefore, the strategy to refrain from damming on this river should persist into the future.

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Gascuel, Didier, Yves-Marie Bozec, Emmanuel Chassot, Audrey Colomb, and Martial Laurans. "The trophic spectrum: theory and application as an ecosystem indicator." ICES Journal of Marine Science 62, no. 3 (January 1, 2005): 443–52. http://dx.doi.org/10.1016/j.icesjms.2004.12.013.

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Abstract Trophic spectra represent the distribution of biomass, abundance, or catch by trophic level, and may be used as indicators of the trophic structure and functioning of aquatic ecosystems in a fisheries context. As a theoretical background, we present a simple ecosystem model of biomass flow reflecting predation and ontogenetic processes. Biomass trophic spectrum of total biomass can be modelled as the result of three major factors and processes: trophic efficiency, transfer kinetics, and extent of top-down control. In the simulations, changes in the spectrum highlight fishing impacts on trophic structure and reveal some functional characteristics of the underlying ecosystem. As examples of potential applications, three case studies of trophic spectra are presented. Catch trophic spectra allow description of structural differences among European fishing areas and periods. Abundance trophic spectra of coral-reef fish assemblages display different trophic signatures, characterizing different reef habitats in New Caledonia and highlighting fishing effects in a marine protected area context. Biomass trophic spectra of demersal resources off Northwest Africa show a shift in ecosystem structure that can be attributed to the rapid increase in fishing pressure during the past few decades. Off Senegal, total biomass remained fairly constant, suggesting a strong top-down control linked to fisheries targeting high trophic level species. Off Guinea, exploitation rates are spread over a wider range of trophic levels, and the total biomass of demersal resources tended to decrease. The trophic spectrum is concluded to be a useful indicator describing and comparing systems in time and space, detecting phase shifts linked to natural or anthropogenic perturbations, and revealing differences in ecosystem functioning.

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Thakur, Madhav P. "Climate warming and trophic mismatches in terrestrial ecosystems: the green–brown imbalance hypothesis." Biology Letters 16, no. 2 (February 2020): 20190770. http://dx.doi.org/10.1098/rsbl.2019.0770.

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Anthropogenic climate change can give rise to trophic mismatches in food webs owing to differential responses of consumer and resource organisms. However, we know little about the community and ecosystem level consequences of trophic mismatches in food webs. Terrestrial food webs are broadly comprised of two types of food webs: green food webs aboveground and brown food webs belowground between which mass and energy flow mainly via plants. Here, I highlight that the extent of warming-induced trophic mismatches in green and brown food webs differ owing to a greater stasis in brown food webs, which could trigger an imbalance in mass and energy flow between the two food webs. I then discuss the consequences of green–brown imbalance on terrestrial ecosystems and propose research avenues that can help understand the relationships between food webs and ecosystem functions in a warmer world.

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Meyer, Elisabeth I., and Rainer Poepperl. "Assessing food-web structure, matter fluxes, and system attributes of a Central European mountain stream by performing mass-balanced network analysis." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 9 (September 1, 2004): 1565–81. http://dx.doi.org/10.1139/f04-104.

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Trophic interactions and cycling of matter within the community in a soft-water mountain stream were analyzed on the basis of a compartment food-web model. The model describes (i) the structure of the food web, quantifying biomass, production, and consumption of individual elements as well as of the entire system, and (ii) the flow of matter between compartments as well as trophic levels. Detritus and primary producers sustain a broad variety of invertebrate consumers. Fishes are the top predators; sculpin (Cottus gobio) and a compartment consisting of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) are at the highest trophic level. Heterotrophic microorganisms (227.1 g dry mass (DW)·m2·year1) and aufwuchs algae (150.1 g DW·m2·year1) have the highest production. Secondary production of fishes and macroinvertebrates amounts to 2.56 and 19.9 g DW·m2·year1, respectively. Total consumption amounts to 1136.41 g DW·m2·year1. Main flows occur between the lower trophic levels. Food intake is greatest for microorganisms and Ephemeroptera. A relatively high fraction of invertebrate production is consumed by predators. For 10 of 19 compartments, over 95% of production is used as food by other organisms. Transfer efficiencies are generally low (<10%). A large proportion of matter transfer occurs at the lower discrete trophic levels of the stream.

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Woodson, C. B., J. R. Schramski, and S. B. Joye. "Food web complexity weakens size-based constraints on the pyramids of life." Proceedings of the Royal Society B: Biological Sciences 287, no. 1934 (September 9, 2020): 20201500. http://dx.doi.org/10.1098/rspb.2020.1500.

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Marine ecosystems are generally expected to have bottom-heavy trophic structure (more plants than animals) due to size-based constraints arising from increased metabolic requirements and inefficient energy transfer. However, size-based (allometric) approaches are often limited to confined trophic-level windows where energy transfer is predicted by size alone and are constrained to a balance between bottom-up and top-down control at steady state. In real food webs, energy flow is more complex and imbalances in top-down and bottom-up processes can also shape trophic structure. We expand the size-based theory to account for complex food webs and show that moderate levels of food web connectance allow for inverted trophic structure more often than predicted, especially in marine ecosystems. Trophic structure inversion occurs due to the incorporation of complex energy pathways and top-down effects on ecosystems. Our results suggest that marine ecosystems should be top-heavy, and observed bottom-heavy trophic structure may be a result of human defaunation of the ocean that has been more extreme than presently recognized.

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Lailson-Brito Jr., José, Paulo R. Dorneles, Vera M. F. da Silva, Anthony R. Martin, Wanderley R. Bastos, Claudio E. Azevedo-Silva, Alexandre F. Azevedo, João P. M. Torres, and Olaf Malm. "DOLPHINS AS INDICATORS OF MICROPOLLUTANT TROPHIC FLOW IN AMAZON BASIN." Oecologia Australis 12, no. 03 (October 2008): 531–41. http://dx.doi.org/10.4257/oeco.2008.1203.11.

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Erami, Cauveh, Hua Zhang, Akito Tanoue, Gozoh Tsujimoto, Steven A. Thomas, and James E. Faber. "Adrenergic catecholamine trophic activity contributes to flow-mediated arterial remodeling." American Journal of Physiology-Heart and Circulatory Physiology 289, no. 2 (August 2005): H744—H753. http://dx.doi.org/10.1152/ajpheart.00129.2005.

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Stimulation of α1-adrenoceptors (ARs) induces proliferation, hypertrophy, and migration of vascular smooth muscle cells and adventitial fibroblasts in cell and organ culture. In vivo studies have confirmed this direct trophic action and found that endogenous catecholamines contribute to neointimal formation and wall hypertrophy induced by mechanical injury. In murine carotid artery, these effects are mediated by α1B-ARs, whereas α1D-ARs mediate contraction and α1A-ARs are not expressed. Herein, we examined whether catecholamines also contribute to arterial wall growth in a noninjury model, i.e., flow-mediated remodeling. In wild-type mice or mice deficient in norepinephrine and epinephrine synthesis [dopamine β-hydroxylase knockout (DBH-KO)], all distal branches of the left carotid artery (LC) except the thyroid artery were ligated to reduce flow in the LC and increase flow in the right carotid artery (RC). Twenty-one days later, negative hypertrophic remodeling of the LC [i.e., −20% (decrease) in lumen area, −2% in circumference of the external elastic lamina (CEEL), +98% (increase) in thickness of the intima media, and +71% in thickness for adventitia; P < 0.01 vs. sham ligation] and positive eutrophic remodeling of the RC [+23% in lumen area, +11% in CEEL; P < 0.01 vs. sham ligation] were inhibited in DBH-KO mice [LC: +10% intima media and +3% adventitia; RC: +9% lumen area and +3% CEEL]. This inhibition was associated with reduced proliferation in the RC and reduced apoptosis and leukocyte accumulation in the RC and LC when examined 5 days after ligation. Carotid remodeling in α1D-AR-knockout mice evidenced little or no inhibition, which suggests dependence on α1B-ARs. These findings suggest that catecholamine-induced trophic activity contributes to both flow-mediated negative remodeling and adaptive positive arterial remodeling.

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Aspin, Thomas, Andy House, Alex Martin, and James White. "Reservoir trophic state confounds flow-ecology relationships in regulated streams." Science of The Total Environment 748 (December 2020): 141304. http://dx.doi.org/10.1016/j.scitotenv.2020.141304.

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Lopes, CA, E. Benedito, and LA Martinelli. "Trophic position of bottom-feeding fish in the Upper Paraná River floodplain." Brazilian Journal of Biology 69, no. 2 suppl (June 2009): 573–81. http://dx.doi.org/10.1590/s1519-69842009000300012.

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The δ15N composition of bottom-feeding fish (iliophagous = Apareiodon affinis, Cyphocharax nagelii, Prochilodus lineatus, Steindachnerina brevipinna and S. insculpta; detritivorous = Loricariichthys platymetopon and Liposarcus anisitsi; benthophagous = Satanoperca pappaterra and Hoplosternum littorale) and their primary food sources were investigated in the upper Paraná River floodplain during rainy seasons in different environments (lotic and lentic). Two hypotheses were tested: i) that the trophic position and isotopic values of the investigated organisms (fish and food resources) vary spatially; and ii) that trophic position and isotopic compositions differ among iliophagous, detritivorous and benthophagous fish. C4 macrophytes, periphyton and phytoplankton were isotopically different in sites analyzed. Significant isotopic differences occurred in the species of each trophic category. Spatial differences were observed in the isotopic composition of P. lineatus and L. platymetopon, whose values were more enriched in the Paraná River and Pau Véio Lake. Significant spatial differences in trophic position were observed for L. platymetopon and H. littorale, which presented the highest values in the Paraná and Baía rivers, respectively. Trophic positions were significantly different among the species that composed each trophic category. These findings demonstrate that in energy-flow studies in detrital food chains generalizations concerning the grouping of fish into trophic categories and/or habitats should only be carried out after careful investigations of the local/specific trophic dynamics of the organisms.

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Gurung, Smriti, Babi Kumar Kafle, Bed Mani Dahal, Milina Sthapit, Nani Raut, Chhatra Mani Sharma, Kumud Raj Kafle, and Sushma Manandhar. "Trophic Status of Lake Phewa and Kulekhani Reservoir, Nepal." Asian Journal of Water, Environment and Pollution 18, no. 3 (July 29, 2021): 49–57. http://dx.doi.org/10.3233/ajw210028.

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Eutrophication is one of the growing environmental concerns and is affecting and compromising freshwater bodies across the world making the trophic status assessment of water bodies crucial for their restoration and sustainable use. This paper describes the trophic status of Lake Phewa and Kulekhani Reservoir from Nepal. Sampling was conducted during October 2017 (post-monsoon), April 2018 (Pre-monsoon), July 2018 (Monsoon) and February 2019 (Winter). Trophic State Index (TSI) as given by Carlson (1977) and Trophic State Index Deviation given by Carlson (1991) were estimated to assess trophic status and deviations between the Trophic State Indices. One-way analysis of variance showed significant seasonal variation (p < 0.05) in Secchi depth, total phosphorus (TP), TSI in both the water bodies. Both the water bodies were classified as eutrophic during pre-monsoon and post-monsoon, and hypereutrophic during the monsoon indicating the increased flow of allochthonous inputs from their respective catchments. Non-algal turbidity was found to be the limiting factor for productivity. There is a need for sustainable watershed management in order to reduce the nutrients runoff and accumulation in the water bodies.

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Prestie, Kate, Iain D. Phillips, Douglas P. Chivers, and Timothy D. Jardine. "Effects of ontogeny and invasive crayfish on feeding ecology and mercury concentrations of predatory fishes." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 11 (November 2019): 1929–39. http://dx.doi.org/10.1139/cjfas-2018-0455.

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Lake food web structure dictates the flow of energy and contaminants to top predators, and addition of invasive species can shift these flows. We examined trophic position (TP), proportional reliance on the littoral zone (Proplittoral), and mercury (Hg) concentrations across the life-span of two predatory fishes, walleye (Sander vitreus) and northern pike (Esox lucius), in lakes with and without invasive virile crayfish (Faxonius virilis). The littoral zone was the dominant foraging zone for both species regardless of size, accounting for 59% and 80% of the diet of walleye and pike, respectively. Both species increased in TP and Hg with body size, as did crayfish. Walleye in crayfish-present lakes had lower Proplittoral, TP, and Hg concentrations compared with non-present lakes, but trophic magnification of Hg through the food web was consistent across all six lakes. These findings underscore a strong role for the littoral zone in channeling energy and contaminants to higher trophic levels and how invasive species can occupy new habitats at low abundance while altering food web structure and contaminant bioaccumulation.

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Mahmood, T., J. Fang, Z. Jiang, and J. Zhang. "Carbon and nitrogen flow, and trophic relationships, among the cultured species in an integrated multi‑trophic aquaculture (IMTA) bay." Aquaculture Environment Interactions 8 (April 19, 2016): 207–19. http://dx.doi.org/10.3354/aei00152.

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Liu, Hai-zhen, Lin Luo, and De-ling Cai. "Stable carbon isotopic analysis of amino acids in a simplified food chain consisting of the green alga Chlorella spp., the calanoid copepod Calanus sinicus, and the Japanese anchovy (Engraulis japonicus)." Canadian Journal of Zoology 96, no. 1 (January 2018): 23–30. http://dx.doi.org/10.1139/cjz-2016-0170.

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Japanese anchovy (Engraulis japonicus Temminck and Schlegel, 1846) is a keystone species in the food web of the Yellow Sea and East China Sea ecosystem. To study nutrient flow at intermediate and lower trophic levels, a controlled feeding experiment was carried out on a simplified food chain of the green alga Chlorella Beijerinck, 1890 – the calanoid copepod Calanus sinicus Brodsky, 1962 – E. japonicus. For the whole organism, bulk δ13C was found to be enriched with escalating trophic level, although the intertrophic gap in δ13C was slightly lower than the commonly reported 1.5‰ per increase in level. Furthermore, 15 amino acids (AAs) were detected in the studied organisms. Among them, the δ13C values of 12 AAs were determined and were found to exhibit diverse patterns of variation. The δ13C levels of essential AAs changed very little and were highly correlated across trophic levels, indicating that they underwent little trophic fractionation and were mainly ingested by the consumers from the proteins in their food. In contrast, the δ13C values of nonessential AAs differed greatly across trophic levels, indicating that the nonessential AAs in consumers were synthesized de novo from food proteins. The fractionation pattern of nonessential AAs may depend on the carbon pool and the AA composition of the organism at the lower trophic level.

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Tucker, Marlee A., and Tracey L. Rogers. "Examining predator–prey body size, trophic level and body mass across marine and terrestrial mammals." Proceedings of the Royal Society B: Biological Sciences 281, no. 1797 (December 22, 2014): 20142103. http://dx.doi.org/10.1098/rspb.2014.2103.

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Predator–prey relationships and trophic levels are indicators of community structure, and are important for monitoring ecosystem changes. Mammals colonized the marine environment on seven separate occasions, which resulted in differences in species' physiology, morphology and behaviour. It is likely that these changes have had a major effect upon predator–prey relationships and trophic position; however, the effect of environment is yet to be clarified. We compiled a dataset, based on the literature, to explore the relationship between body mass, trophic level and predator–prey ratio across terrestrial ( n = 51) and marine ( n = 56) mammals. We did not find the expected positive relationship between trophic level and body mass, but we did find that marine carnivores sit 1.3 trophic levels higher than terrestrial carnivores. Also, marine mammals are largely carnivorous and have significantly larger predator–prey ratios compared with their terrestrial counterparts. We propose that primary productivity, and its availability, is important for mammalian trophic structure and body size. Also, energy flow and community structure in the marine environment are influenced by differences in energy efficiency and increased food web stability. Enhancing our knowledge of feeding ecology in mammals has the potential to provide insights into the structure and functioning of marine and terrestrial communities.

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Murphy, E. J., R. D. Cavanagh, K. F. Drinkwater, S. M. Grant, J. J. Heymans, E. E. Hofmann, G. L. Hunt, and N. M. Johnston. "Understanding the structure and functioning of polar pelagic ecosystems to predict the impacts of change." Proceedings of the Royal Society B: Biological Sciences 283, no. 1844 (December 14, 2016): 20161646. http://dx.doi.org/10.1098/rspb.2016.1646.

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The determinants of the structure, functioning and resilience of pelagic ecosystems across most of the polar regions are not well known. Improved understanding is essential for assessing the value of biodiversity and predicting the effects of change (including in biodiversity) on these ecosystems and the services they maintain. Here we focus on the trophic interactions that underpin ecosystem structure, developing comparative analyses of how polar pelagic food webs vary in relation to the environment. We highlight that there is not a singular, generic Arctic or Antarctic pelagic food web, and, although there are characteristic pathways of energy flow dominated by a small number of species, alternative routes are important for maintaining energy transfer and resilience. These more complex routes cannot, however, provide the same rate of energy flow to highest trophic-level species. Food-web structure may be similar in different regions, but the individual species that dominate mid-trophic levels vary across polar regions. The characteristics (traits) of these species are also different and these differences influence a range of food-web processes. Low functional redundancy at key trophic levels makes these ecosystems particularly sensitive to change. To develop models for projecting responses of polar ecosystems to future environmental change, we propose a conceptual framework that links the life histories of pelagic species and the structure of polar food webs.

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Hairston,, Nelson G., and Nelson G. Hairston,. "Cause-Effect Relationships in Energy Flow, Trophic Structure, and Interspecific Interactions." American Naturalist 142, no. 3 (September 1993): 379–411. http://dx.doi.org/10.1086/285546.

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Moreno, François, and Laurianne Laine. "The flow cytometry, a new tool for trophic coastal ecosystem diagnostic." Ecological Indicators 4, no. 3 (September 2004): 161–76. http://dx.doi.org/10.1016/j.ecolind.2004.03.001.

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Bartoszek, Lilianna, Małgorzata Miąsik, and Piotr Koszelnik. "Trophic degradation predispositions and intensity in a high-flow, silted reservoir." PeerJ 8 (June 22, 2020): e9374. http://dx.doi.org/10.7717/peerj.9374.

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The objective of the work was to demonstrate the relationship between the natural environmental characteristics of a reservoir and its catchment and severity of trophic degradation. The shallow, highly-silted Rzeszów Reservoir (SE Poland) was the object of study. The impact on degradation of internal supply from accumulated bottom sediments was also assessed, using water and sediment sampled in 2013 and 2014. A high value for trophic state was identified for the reservoir on the basis of TSI indexes, while assessed natural resilience to degradation and analysis of the catchment as a supplier of biogenic and organic matter both indicate high susceptibility to cultural eutrophication. Obtained values for equilibrium phosphate concentrations under anoxic conditions (EPC-0) point to the possibility of a more intensive process of internal supply in phosphorus. However, the presence of sediments poor in organic matter suggest no major threat of ongoing eutrophication. Desludging and/or dredging are likely to entail elimination from the ecosystem of a large part of the pollutants accumulated in sediments, as well as the internal supply of phosphate to the water column. However, as external sources are responsible for the advanced degradation of Rzeszów Reservoir, any attempts at reclamation within the water will fail to yield persistent effects if appropriate protective procedures in the catchment are not implemented.

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Sánchez-Hernández, Javier. "Reciprocal Role of Salamanders in Aquatic Energy Flow Pathways." Diversity 12, no. 1 (January 17, 2020): 32. http://dx.doi.org/10.3390/d12010032.

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Many species of salamanders (newts and salamanders per se) have a pivotal role in energy flow pathways as they include individuals functioning as prey, competitors, and predators. Here, I synthesize historic and contemporary research on the reciprocal ecological role of salamanders as predators and prey in aquatic systems. Salamanders are a keystone in ecosystem functioning through a combination of top–down control, energy transfer, nutrient cycling processes, and carbon retention. The aquatic developmental stages of salamanders are able to feed on a wide variety of invertebrate prey captured close to the bottom as well as on small conspecifics (cannibalism) or other sympatric species, but can also consume terrestrial invertebrates on the water surface. This capacity to consume allochthonous resources (terrestrial invertebrates) highlights the key role of salamanders as couplers of terrestrial and aquatic ecosystems (i.e., aquatic–terrestrial linkages). Salamanders are also an important food resource for other vertebrates such as fish, snakes, and mammals, covering the energy demands of these species at higher trophic levels. This study emphasizes the ecological significance of salamanders in aquatic systems as central players in energy flow pathways, enabling energy mobility among trophic levels (i.e., vertical energy flow) and between freshwater and terrestrial habitats (i.e., lateral energy flow).

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Barbosa, Ana Paula Dalbem, Ernandes Sobreira Oliveira-Junior, Claumir Cesar Muniz, Wilkinson Lopes Lázaro, Dionei José Silva, and Manoel dos Santos-Filho. "Dynamic of fish trophic guilds in the plateau-plain gradient in the Paraguay River, Northern Pantanal." Papéis Avulsos de Zoologia 62 (August 2, 2022): e202262041. http://dx.doi.org/10.11606/1807-0205/2022.62.041.

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This study aims to evaluate the dynamics of fish trophic guilds according to the longitudinal gradient of the Paraguay River, northern Pantanal, Brazil. Three river segments were sampled: plateau, confluence and plain. These segments have different physical and biological characteristics, with high water flow in forest areas in plateau and slow flow in meanders, with Pantanal typical vegetation. In total, 26,542 individuals distributed in 130 fish species were collected. The sampled species were characterized in seven trophic guilds. From the seven trophic guilds identified, only three were statistically related to the type of the environment; herbivores were more abundant in the plateau, piscivores in the confluence, and invertivores in the plain. According to values of corrected Akaike Information Criteria, the environmental variable that best explains the abundance of piscivorous fishes in the segments sampled in the Paraguay River was water transparency. For herbivores, the model that explained the variation in abundance was composed by temperature, altitude and dense forest proportion. The variable altitude best represented the abundance of invertivores. Water transparency, temperature, altitude, river width and dense forest proportion were determining factors for the distribution of piscivorous, herbivorous and invertivorous fishes as a response to an environmental gradient that meets its ecological requirements. Understanding the trophic relationships is fundamental for management actions, contributing to the maintenance of ecosystem services of different species. Therefore, future research must be taken into account regarding management and ecological relationships.

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Havens, Karl E. "Crustacean Zooplankton Food Web Structure in Lakes of Varying Acidity." Canadian Journal of Fisheries and Aquatic Sciences 48, no. 10 (October 1, 1991): 1846–52. http://dx.doi.org/10.1139/f91-218.

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Crustacean zooplankton food web models were constructed for 25 softwater United States lakes of varying pH (4.7–7.2). Eight lakes on the North Mountain Plateau of Pennsylvania were sampled in 1987, and data from 17 Adirondack Mountain, NY, and White Mountain, NH, lakes were taken from Confer et al. (1983. Can. J. Fish. Aquat. Sci. 40: 36–42). In the most acidic lakes, the zooplankton food webs were simplified, with only two or three crustacean species; the highest pH lakes contained 6–10 species. Positive relationships were found between lake water pH and species richness, total number of predator–prey interactions, average number of interactions per species, and average generalization of predators. Inverse relationships were found between pH and both the degree of omnivory and cannibalism in the webs, perhaps reflecting the adaptiveness of those feeding strategies under circumstances where energy flow from adjacent trophic levels is reduced. Reduced energy flow may limit the number of trophic levels in the most acidic lakes. Lakes of pH < 5 had only two or three modal trophic levels, while lakes of pH > 5 had three, four, or five levels.

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Erami, Cauveh, Hua Zhang, Tina Bleeke, Akito Tanoue, Gozoh Tsujimoto, Steven Thomas, and James Faber. "ARTERIAL REMODELING INDUCED BY EITHER REDUCED FLOW OR INCREASED FLOW BOTH REQUIRE TROPHIC ACTION OF CATECHOLAMINES." Cardiovascular Pathology 13, no. 3 (May 2004): 164. http://dx.doi.org/10.1016/j.carpath.2004.03.494.

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Holmes, Michael J., and Richard J. Lewis. "Origin of Ciguateric Fish: Quantitative Modelling of the Flow of Ciguatoxin through a Marine Food Chain." Toxins 14, no. 8 (August 3, 2022): 534. http://dx.doi.org/10.3390/toxins14080534.

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To begin to understand the impact of food chain dynamics on ciguatera risk, we used published data to model the transfer of ciguatoxins across four trophic levels of a marine food chain in Platypus Bay, Australia. The data to support this first attempt to conceptualize the scale of each trophic transfer step was limited, resulting in broad estimates. The hypothetical scenario we explored generated a low-toxicity 10 kg Spanish mackerel (Scomberomorus commerson) with a flesh concentration of 0.1 µg/kg of Pacific-ciguatoxin-1 (P-CTX-1, also known as CTX1B) from 19.5–78.1 µg of P-CTX-1 equivalents (eq.) that enter the marine food chain from a population of 12–49 million benthic dinoflagellates (Gambierdiscus sp.) producing 1.6 × 10−12 g/cell of the P-CTX-1 precursor, P-CTX-4B. This number of Gambierdiscus could be epiphytic on 22–88 kg of the benthic macroalgae (Cladophora) that carpets the bottom of much of Platypus Bay, with the toxin transferred to an estimated 40,000–160,000 alpheid shrimps in the second trophic level. This large number of shrimps appears unrealistic, but toxic shrimps would likely be consumed by a school of small, blotched javelin fish (Pomadasys maculatus) at the third trophic level, reducing the number of shrimps consumed by each fish. The Spanish mackerel would accumulate a flesh concentration of 0.1 µg/kg P-CTX-1 eq. by preying upon the school of blotched javelin and consuming 3.6–14.4 µg of P-CTX-1 eq. However, published data indicate this burden of toxin could be accumulated by a 10 kg Spanish mackerel from as few as one to three blotched javelin fish, suggesting that much greater amounts of toxin than modelled here must at certain times be produced and transferred through Platypus Bay food chains. This modelling highlights the need for better quantitative estimates of ciguatoxin production, biotransformation, and depuration through marine food chains to improve our understanding and management of ciguatera risk.

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SOARES, Bruno Eleres, Naraiana Loureiro BENONE, Daniela Cristina Oliveira ROSA, and Luciano Fogaça de Assis MONTAG. "Do local environmental factors structure the trophic niche of the splash tetra, Copella arnoldi? A test in an Amazonian stream system." Acta Amazonica 50, no. 1 (March 2020): 54–60. http://dx.doi.org/10.1590/1809-4392201802681.

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ABSTRACT Environmental variation affects the availability of spatial and trophic resources in Amazonian streams and may be important factors structuring the diet of fishes. We analyzed the diet composition and trophic niche breadth of the lebiasinid splash tetra, Copella arnoldi, aiming to evaluate how environmental variation in Amazonian streams affects the species’ trophic niche. Fish were captured and environmental factors were recorded in 20 streams in the Caxiuanã National Forest, in the eastern Amazon, in November 2010. We made a semi-quantitative analysis of stomach contents of 200 individuals. Copella arnoldi exhibited an omnivorous diet composed mainly of detritus and allochthonous invertebrates. Environmental variation (stream width, stream depth, canopy cover and flow) did not affect the diet composition or trophic niche breadth of the species, possibly due to the regional integrity of the forest within the boundaries of the protected area. Riparian cover probably minimizes the effect of the small-scale variations in food resources, thus leading to a locally homogeneous diet composition in the splash tetra C. arnoldi.

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Cuevas Madrid, Homero, Alfonso Lugo Vázquez, Laura Peralta Soriano, Josué Morlán Mejía, Gloria Vilaclara Fatjó, María del Rosario Sánchez Rodríguez, Marco Antonio Escobar Oliva, and Javier Carmona Jiménez. "Identification of Key Factors Affecting the Trophic State of Four Tropical Small Water Bodies." Water 12, no. 5 (May 20, 2020): 1454. http://dx.doi.org/10.3390/w12051454.

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Due to their dimensions, small and shallow water bodies are more sensitive to changes in nutrient load, water flow, and human management. The four water bodies studied are small (area <0.01 km2), constantly supplied by a non-anthropogenic source of nutrients, and these water bodies present different trophic states: mesotrophic, eutrophic, and hyper-eutrophic. The objective of this study was to identify the key environmental factors that created differences in the trophic state of these adjacent shallow urban lakes by modeling chlorophyll-a (Chl a) through the application of the Partial Least Squares Regression (PLSR). The models (n = 36) explain 45.8–60.6% (R2), and predicts 39–52.9% (Q2) of the variance. Environmental variables were identified in the water bodies as critical factors of trophic state determination, water residence time (WRT), ions (e.g., Ca2+), and minerals as hydroxyapatite (HAP). These variables were related to processes that could improve trophic conditions, such as flushing and phosphorous precipitation. Conversely, N-NH3 concentration was associated with nutrient recycling, and found to be able to promote eutrophication.

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Krebs, Charles J., Kjell Danell, Anders Angerbjörn, Jep Agrell, Dominique Berteaux, Kari Anne Bråthen, Öje Danell, et al. "Terrestrial trophic dynamics in the Canadian Arctic." Canadian Journal of Zoology 81, no. 5 (May 1, 2003): 827–43. http://dx.doi.org/10.1139/z03-061.

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The Swedish Tundra Northwest Expedition of 1999 visited 17 sites throughout the Canadian Arctic. At 12 sites that were intensively sampled we estimated the standing crop of plants and the densities of herbivores and predators with an array of trapping, visual surveys, and faecal-pellet transects. We developed a trophic-balance model using ECOPATH to integrate these observations and determine the fate of primary and secondary production in these tundra ecosystems, which spanned an 8-fold range of standing crop of plants. We estimated that about 13% of net primary production was consumed by herbivores, while over 70% of small-herbivore production was estimated to flow to predators. Only 9% of large-herbivore production was consumed by predators. Organization of Canadian Arctic ecosystems appears to be more top-down than bottom-up. Net primary production does not seem to be herbivore-limited at any site. This is the first attempt to integrate trophic dynamics over the entire Canadian Arctic.

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Kang, Yun-Ho. "Analysis of Sinjido Marine Ecosystem in 1994 using a Trophic Flow Model." Sea 16, no. 4 (November 30, 2011): 180–95. http://dx.doi.org/10.7850/jkso.2011.16.4.180.

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38

Price, Elliott L., Mirela Sertić Perić, Gustavo Q. Romero, and Pavel Kratina. "Land use alters trophic redundancy and resource flow through stream food webs." Journal of Animal Ecology 88, no. 5 (February 27, 2019): 677–89. http://dx.doi.org/10.1111/1365-2656.12955.

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39

Santana, ARA, E. Benedito, C. Ducatti, and FA Lansac-Tôha. "Isotopic fractionation and trophic position of zooplankton species in the Upper Paraná River floodplain." Brazilian Journal of Biology 71, no. 1 (February 2011): 71–76. http://dx.doi.org/10.1590/s1519-69842011000100011.

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This study aimed to evaluate the isotopic fractionation and trophic position of three zooplankton species (Notodiaptomus amazonicus, Moina minuta and Bosmina hagmanni) in the Upper Paraná River floodplain. We predict that phytoplankton is the main food resource used by these species. Three zooplankton samples and three phytoplankton samples were taken from each sampling site, with three to four samples collected for each species. The number of individuals for samples varied according to the body size: from 100 to 130 individuals for Notodiaptomus amazonicus; 150 to 200 for Moina minuta; and from 250 to 300 for Bosmina hagmanni. The isotopic values for δ13C and δ15N were determined using mass spectrophotometer. The isotopic fractionation of 13C was performed according to the relationship Δ = δ13Czooplankton - δ13C phytoplankton. To determine the possible trophic position of these species, we used the expression TL = (δ15N zooplankton - δ15N phytoplankton)/Δ+ 1. The species showed high variation in isotopic fractionation and in trophic position in the different environments. We verified that the species use other food resources in addition to phytoplankton. The elucidation and understanding of the trophic position of the organisms based on stable isotopic analysis offers complementary information to traditional techniques. This analysis helps explain the flow of matter and energy in the food chain of floodplain aquatic environments as well as trace the trophic relationships involved in the ecological roles and strategies of distinct species.

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Herwig, Brian R., Daniel A. Soluk, John M. Dettmers, and David H. Wahl. "Trophic structure and energy flow in backwater lakes of two large floodplain rivers assessed using stable isotopes." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 1 (January 1, 2004): 12–22. http://dx.doi.org/10.1139/f03-139.

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Carbon and nitrogen stable isotopes (δ13C and δ15N, respectively) were measured for locally abundant primary producers, detritus, aquatic invertebrates, and fish in backwater lakes of two large floodplain rivers in an effort to understand patterns of energy dependence and trophic structure within these habitats. We observed trophic enrichment values for 15N that were within the ranges observed for other aquatic systems but were often considerably lower than the 3.4 typically assumed in stable isotope studies. Production based on benthic and terrestrial material, combined with planktonic production for larval fish, appears to be an important energy source supporting consumers in backwater lakes of large floodplain rivers. Our isotopic data challenge the conventional wisdom that macrophytes are centrally involved in supplying carbon to aquatic consumers in shallow lakes and that food webs in most lakes are sustained almost exclusively by carbon fixed by phytoplankton.

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Rayner, Thomas S., Bradley J. Pusey, and Richard G. Pearson. "Spatio-temporal dynamics of fish feeding in the lower Mulgrave River, north-eastern Queensland: the influence of seasonal flooding, instream productivity and invertebrate abundance." Marine and Freshwater Research 60, no. 2 (2009): 97. http://dx.doi.org/10.1071/mf08055.

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Wet-season flooding causes dietary shifts in tropical freshwater fish by regulating instream productivity, habitat structure and food availability. These dynamics have been comprehensively documented worldwide, but data are limited for Australia’s Wet Tropics rivers. The aim of the present study was to extend our earlier fish–habitat model for these systems by examining the role of trophic dynamics in determining fish assemblage composition. Chlorophyll a and phaeophytin concentrations, benthic and littoral invertebrates and fish were collected at four sites in the lower Mulgrave River under a range of flow conditions. Wet-season flooding caused significant reductions in instream productivity, whereas habitat disturbance reduced densities and abundances of littoral and benthic invertebrates. However, volumetric gut contents of 1360 fish, from 36 species, revealed seasonal shifts in guild membership by only two species, with fish moving between sites to target their preferred prey items – largely irrespective of differences in habitat structure. As a result, the food consumed by the fish community present at each site closely reflected the seasonal availability of food resources. The present paper questions whether fish community composition in small tropical rivers can be accurately predicted from habitat surrogates alone and encourages consideration of constraints imposed by the trophic dynamics and reproductive ecology of fish.

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Shi, Wenjing, Feng Gui, Manyao Zhang, Xianmin Zeng, Kaida Xu, and Sheng Zhao. "Analysis of Energy Flow in the Sea Area of Zhongjieshan Islands and Assessment of Ecological Capacity of Sepiella Maindroni Based on Ecopath Model." E3S Web of Conferences 350 (2022): 01002. http://dx.doi.org/10.1051/e3sconf/202235001002.

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Sepiella maindroni was once one of the four traditional marine products in our country. In order to evaluate the ecological capacity of Sepiella maindroni in the sea area of Zhongjieshan Islands, this study used Ecopath with Ecosim 6.5 (EwE) software to construct an Ecopath model composed of 17 functional groups in the sea area of Zhongjieshan Islands. The nutrient structure and energy flow characteristics of the sea area of Zhongjieshan Islands are analyzed from the ecosystem level, and the reasonable ecological capacity of the sea area of Zhongjieshan Islands is estimated by the model.The results show that the trophic level of each functional group in the marine ecosystem of the Zhongjieshan Islands is between 1-4.648, total primary production/total respiration is 4.539, the system Connectance Index is 0.478, the System Omnivory Index is 0.389, The trophic level of Sepiella maindroni is 3.562, and the Ecotrophic Efficiency is 0.306, indicating that the Ecotrophic Efficiency of each trophic level in the system is low and the energy is not fully utilized. There is still room for breeding and exile for the Sepiella maindroni. The model estimates that the ecological capacity of Sepiella maindroni is about 2t·km2.

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Morgan, J. Alun W., and Roger W. Pickup. "Activity of microbial peptidases, oxidases, and esterases in lake waters of varying trophic status." Canadian Journal of Microbiology 39, no. 8 (August 1, 1993): 795–803. http://dx.doi.org/10.1139/m93-117.

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The range and activities of microbial enzymes present in lake water were assessed directly in cells concentrated by tangential flow filtration. A total of 108 enzymes were assayed in this study, which included tests for 60 peptidases, 20 oxidases, and 10 esterases, and 18 miscellaneous tests. In general, no trends in the range of enzymes were associated with trophic status of the lakes. However, one lake that was hypereutrophic had a greater range of enzymes than the other lakes tested. An increase in total enzyme activity (activity/mL) was recorded with an increase in trophic status of the water. The relationship between the physical and chemical attributes of each lake and microbial enzyme activities was investigated by principal component analysis. Quantitative changes between lakes in 11 of the 21 variables were shown to be closely related to changes in the enzyme activities of the lakes; total organic carbon, particulate carbon, particulate nitrogen, pH, and chlorophyll a showed the closest relationships.Key words: lake water, enzyme activity, trophic status.

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Insani, Aulia, Herman Yulianto, and Putu Cinthia Delis. "Trophic states assessed from abundance of phythoplankton and chlorophyl-a content in Raman Resevoir Metro, Lampung Province." Tomini Journal of Aquatic Science 2, no. 1 (May 25, 2021): 41–49. http://dx.doi.org/10.37905/tjas.v2i1.10160.

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Raman reservoir is located at north of Metro City, Lampung. The water resources of the reservoir comes from Way Bunut and Way Raman rivers. The Way Bunut and Way Raman rivers flow into the Raman reservoir which is used for a variety of human activities, including fish farming with the floating net cage system, tourism, and agriculture. These activities produce organic and inorganic materials into the waters so that it may cause changes in water quality and trophic states levels, therefore research is carried out on the trophic states based on the abundance of phytoplankton and chlorophyll-a content in the waters of the Raman Reservoir. The purpose of this study was to assess the trophic states of the Raman Reservoir based on the abundance of phytoplankton, chlorophyll-a concentration, and Nygaard Index. This research was conducted in January-March 2020. The data was collected using purposive sampling method. The parameters used in this study were abundance of phytoplankton, chlorophyll-a, primary productivity, brightness, depth, temperature, DO, pH. Trophic states results based on the concentration of chlorophyll-a in the morning range from 0.0007 - 0.0274 mg/L while at noon it ranges from 0.0083-0.0769 mg/L. The results of these measurements can be categorized as chlorophyll-a content in Raman Resevoir was still in the category oligotrophic. The results of trophic states based on the Nygaard index it shows the category of eutrophic.

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Kehrli, Patrik, and Steve D. Wratten. "A Perspective on the Consequences for Insect Herbivores and Their Natural Enemies When They Share Plant Resources." ISRN Ecology 2011 (April 14, 2011): 1–6. http://dx.doi.org/10.5402/2011/480195.

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Thousands of insect species consume both animal and plant-derived food resources. However, little recognition is given to the fact that omnivory is a general feeding strategy common to all higher trophic levels. Species in multitrophic interactions can all directly rely on the same plant resources. Nonetheless, little is known about the effect of a change in the relative abundance of a shared plant resource on trophic dynamics. Here we describe how a relative change of resource availability can affect multitrophic interactions and we emphasise its importance. Changes in multitrophic interactions can be induced by unequal alterations of individual fitness across trophic levels, possibly leading to changes in population structure of interacting species. At least ten ecological mechanisms can be involved and these are explored here. It is concluded that shared plant resources that are differentially used over several trophic levels have the potential to modify community structure and energy flow within food webs and ecosystems in more complex ways than previously recognised. The synthesis presented here provides an understanding of this complexity and can lead to improved deployment of biodiversity when manipulating food webs to protect ecological communities or to enhance ecosystem services such as biological control of agricultural pests.

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Kalinin, R. E., I. A. Suchkov, I. N. Shanaev, and V. A. Yudin. "HEMODYNAMIC DISORDERS IN VARICOSE VEIN DISEASE." NAUKA MOLODYKH (Eruditio Juvenium) 9, no. 1 (March 31, 2021): 68–76. http://dx.doi.org/10.23888/hmj20219168-76.

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Aim. Duplex ultrasound scanning (DUS) is a routine diagnostic procedure in patients with varicose vein disease. DUS mostly evaluates the qualitative (anatomical) parameters of the disease. Still, it is difficult to assess the microcirculatory parameters in trophic disorders based only on the anatomy, therefore assessment of quantitative blood flow parameters is needed. Our aim was to determine the potentials of conventional DUS in assessment of the hemodynamic disorders in patients with varicose disease. Materials and Methods. The study included 583 patients with varicose disease, 348 of which had trophic alterations. The patients were divided into 4 groups according to the CEAP clinical classes. Standard Valsalva and Siegel tests were performed during DUS. The following parameters were assessed in the superficial and deep veins: diameter of veins, antegrade blood flow velocity, retrograde blood flow velocity, reflux time; in the perforator veins (PV) – diameter, maximum velocity and average velocity of reflux. Peripheral resistance index (RI) in the arteries accompanying the PV was also analyzed. Results. A statistically significant difference in the diameter of the GSV was obtained between classes C2 and C3, C3 and C4, but not between class C5, 6 and class C4. Similar findings were observed in the assessment of diameter of the PVs and the velocity of retrograde blood flow through them. A gradual increase in these parameters could be seen with the progression of the disease, but a statistically significant difference was obtained only between classes C2 and C3 for the diameter of the PV and the peak velocity of retrograde blood flow. As for the average blood flow velocity, a statistically significant difference was obtained between classes C2 and C3, C3 and C4. Arteries in the perforator bundles demonstrated low RI which may be attributed to the presence of an arteriolo-venular bypass. Statistically significant differences were obtained for CEAP classes C2 and C3. Conclusions. Ultrasound duplex scanning of the study with use of Superb Micro-Vascular Imaging mode is an effective method in assessing the quantitative and microcirculatory parameters of hemodynamic disorders in patients with varicose vein disease of the lower extremities. Trophic ulcers in varicose vein disease are not an obligatory component of the disease, but only its complication.

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Liakhovskyi, V. І., R. M. Riabushko, and А. V. Sydorenko. "SURGICAL TREATMENT OF COMPLICATED FORMS OF CHRONIC VENOUS INSUFFICIENCY IN LOWER LIMBS (REVIEW ARTICLE)." Актуальні проблеми сучасної медицини: Вісник Української медичної стоматологічної академії 20, no. 4 (December 30, 2020): 209–15. http://dx.doi.org/10.31718/2077-1096.20.4.209.

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Venous diseases of the lower limbs that are accompanied by the development of trophic ulcers are among the medical and social challenges. The vast number of patients is in working age, from 30 to 65 years old. Severe forms of the disease are registered in 27% of the cases; active or healed trophic ulcers are diagnosed in 12.9 % of cases. At present special attention is being paid to the effective surgical treatment of the pathology, to the introduction of the latest surgical interventions, which provide complete radicalism about the causes of trophic ulcers of venous genesis and ensure the maximum cosmetic effect. The aim of this work is to analyze the scientific literature on using the latest surgical techniques in the treatment of venous pathology in patients with trophic ulcers of lower extremities to promote improving the existing and elaborate new surgical interventions in terms of this pathology. Nowadays surgical treatment of patients with chronic venous insufficiency of the lower extremities, especially in case of trophic leg ulcers can be considered as the stage of the integrated treatment of venous trophic disorders. Modern surgical interventions differ in the methods, techniques and tools used, but provide the maximum cosmetic effect and complete radicalism regarding the causes of chronic venous insufficiency. Correction of pathological venous-venous reflux is the main method of eliminating venous hypertension, which underlies the progression of chronic venous insufficiency and promotes the development of trophic disorders, including the ulcers formation. The etiological cause of venous trophic ulcer is the appearance of pathological reflux, which occurs in the superficial, deep and perforating veins and, accordingly, the place of surgery should be those venous segments in which the pathological process is diagnosed. The operation can be performed simultaneously or in two stages: first, the vertical venous-venous reflux is eliminated, followed by the correction of the horizontal reflux. When using modern minimally invasive technologies, adequate and complete correction of venous blood flow in the affected limb is performed simultaneously producing no serious tissue damages to avoid cosmetic effect and to lessen postoperative period. Thus, the analysis of the scientific literatures has shown the unity of views on the strategy of surgical treatment of varicose trophic ulcers that involves the elimination of vertical and horizontal reflux, but the absence of views unity on tactical approaches in solving these issues.

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Litvitskiy, P. F. "Regional blood flow and microcirculation disorders." Regional blood circulation and microcirculation 19, no. 1 (April 6, 2020): 82–92. http://dx.doi.org/10.24884/1682-6655-2020-19-1-82-92.

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The lecture analyzes modern data on the types, etiology, key stages of pathogenesis, manifestations and consequences of typical forms of regional blood flow and microcirculation disorders. The lecturer dwells on typical forms of regional blood flow (in medium vessels): pathological arterial hyperemia, venous hyperemia, ischemia, and stasis. The variants of ischemia associated with increased arterial inflow to tissue or organ are considered as compared to medium-normal inflow. The lecture provides data on typical hemolymph microcirculation disorders, including intravascular, transmural, extravascular disorders, as well as capillary-trophic insufficiency as a final result of one or more microcirculatory disorders. The blood sludge phenomenon is characterized as a pathology of the blood aggregate state, which is either a cause or a consequence of a microhemocirculation disorder. The lecture is recommended for students, medical residents, post-graduate students, and trainees of the system of post-graduate professional education at medical universities.

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Taylor, Marc H., Matthias Wolff, Jaime Mendo, and Carmen Yamashiro. "Changes in trophic flow structure of Independence Bay (Peru) over an ENSO cycle." Progress in Oceanography 79, no. 2-4 (October 2008): 336–51. http://dx.doi.org/10.1016/j.pocean.2008.10.006.

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Gascuel, Didier, Lyne Morissette, Maria Lourdes D. Palomares, and Villy Christensen. "Trophic flow kinetics in marine ecosystems: Toward a theoretical approach to ecosystem functioning." Ecological Modelling 217, no. 1-2 (September 2008): 33–47. http://dx.doi.org/10.1016/j.ecolmodel.2008.05.012.

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Journal articles on the topic 'Trophic flow'

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