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E. Cortés - One of the best experts on this subject based on the ideXlab platform.
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standardized diet compositions and Trophic Levels of sharks
Journal of Materials Science, 1999Co-Authors: E. CortésAbstract:Sharks are marine consumers believed to occupy top positions in marine food webs. But surprisingly, Trophic level estimates for these predators are almost non-existent. With the hope of helping better define the ecological role of sharks in marine communities, this paper presents standardized diet compositions and Trophic Levels calculated for a suite of species. Dietary composition for each species was derived from published quantitative studies using a weighted average index that takes into account sample size in each study. The Trophic level (TL) values of the 11 food types used to characterize the diet (obtained from published accounts) were then used to calculate fractional Trophic Levels for 149 species representing eight orders and 23 families. Sharks as a group are tertiary consumers (TL>4), and significant differences were found among the six orders compared, which were attributable to differences between orectolobiforms (TL<4) and all other orders, and between hexanchiforms and both carcharhiniforms and squatiniforms. Among four families of carcharhiniform sharks, carcharhinids (TL=4.1, n=39) had a significantly higher TL than triakids (TL=3.8, n=19) and scyliorhinids (TL=3.9, n=21), but not sphyrnids (TL=3.9, n=6). When compared to Trophic Levels for other top predators of marine communities obtained from the literature, mean TL for sharks was significantly higher than for seabirds (n=28), but not for marine mammals (n=97). Trophic level and body size were positively correlated (r s =0.33), with the fit increasing (r s =0.41) when the three predominantly zooplanktivorous sharks were omitted, and especially when considering only carcharhinid sharks (r s =0.55).
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Standardized diet compositions and Trophic Levels of sharks
ICES Journal of Marine Science, 1999Co-Authors: E. CortésAbstract:Sharks are marine consumers believed to occupy top positions in marine food webs. But surprisingly, Trophic level estimates for these predators are almost non-existent. With the hope of helping better define the ecological role of sharks in marine communities, this paper presents standardized diet compositions and Trophic Levels calculated for a suite of species. Dietary composition for each species was derived from published quantitative studies using a weighted average index that takes into account sample size in each study. The Trophic level (TL) values of the 11 food types used to characterize the diet (obtained from published accounts) were then used to calculate fractional Trophic Levels for 149 species representing eight orders and 23 families. Sharks as a group are tertiary consumers (TL>4), and significant differences were found among the six orders compared, which were attributable to differences between orectolobiforms (TL
Nina E Fatouros - One of the best experts on this subject based on the ideXlab platform.
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early herbivore alert matters plant mediated effects of egg deposition on higher Trophic Levels benefit plant fitness
Ecology Letters, 2015Co-Authors: Erik H. Poelman, Nina E Fatouros, Foteini G Pashalidou, Joop J A Van Loon, Marcel Dicke, Enric Frago, Eddie GrieseAbstract:Induction of plant defences, specifically in response to herbivore attack, can save costs that would otherwise be needed to maintain defences even in the absence of herbivores. However, plants may suffer considerable damage during the time required to mount these defences against an attacker. This could be resolved if plants could respond to early cues, such as egg deposition, that reliably indicate future herbivory. We tested this hypothesis in a field experiment and found that egg deposition by the butterfly Pieris brassicae on black mustard (Brassica nigra) induced a plant response that negatively affected feeding caterpillars. The effect cascaded up to the third and fourth Trophic Levels (larval parasitoids and hyperparasitoids) by affecting the parasitisation rate and parasitoid performance. Overall, the defences induced by egg deposition had a positive effect on plant seed production and may therefore play an important role in the evolution of plant resistance to herbivores.
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plant volatiles induced by herbivore egg deposition affect insects of different Trophic Levels
PLOS ONE, 2012Co-Authors: Nina E Fatouros, Dani Lucasbarbosa, Berhane T Weldegergis, Foteini G Pashalidou, Joop J A Van Loon, Marcel Dicke, Jeffrey A Harvey, Rieta Gols, Martinus E HuigensAbstract:Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their consequences on insects of different Trophic Levels remain poorly explored. In olfactometer and wind tunnel set-ups, we investigated behavioural responses of a specialist cabbage butterfly (Pieris brassicae) and two of its parasitic wasps (Trichogramma brassicae and Cotesia glomerata) to volatiles of a wild crucifer (Brassica nigra) induced by oviposition of the specialist butterfly and an additional generalist moth (Mamestra brassicae). Gravid butterflies were repelled by volatiles from plants induced by cabbage white butterfly eggs, probably as a means of avoiding competition, whereas both parasitic wasp species were attracted. In contrast, volatiles from plants induced by eggs of the generalist moth did neither repel nor attract any of the tested community members. Analysis of the plant’s volatile metabolomic profile by gas chromatography-mass spectrometry and the structure of the plant-egg interface by scanning electron microscopy confirmed that the plant responds differently to egg deposition by the two lepidopteran species. Our findings imply that prior to actual feeding damage, egg deposition can induce specific plant responses that significantly influence various members of higher Trophic Levels.
Olesia N Makhutova - One of the best experts on this subject based on the ideXlab platform.
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stable isotope composition of fatty acids in organisms of different Trophic Levels in the yenisei river
PLOS ONE, 2012Co-Authors: M I Gladyshev, Nadezhda N Sushchik, Galina S Kalachova, Olesia N MakhutovaAbstract:We studied four-link food chain, periphytic microalgae and water moss (producers), trichopteran larvae (consumers I), gammarids (omnivorous – consumers II) and Siberian grayling (consumers III) at a littoral site of the Yenisei River on the basis of three years monthly sampling. Analysis of bulk carbon stable isotopes and compound specific isotope analysis of fatty acids (FA) were done. As found, there was a gradual depletion in 13C contents of fatty acids, including essential FA upward the food chain. In all the Trophic Levels a parabolic dependence of δ13C values of fatty acids on their degree of unsaturation/chain length occurred, with 18:2n-6 and 18:3n-3 in its lowest point. The pattern in the δ13C differences between individual fatty acids was quite similar to that reported in literature for marine pelagic food webs. Hypotheses on isotope fractionation were suggested to explain the findings.
G. Lassalle - One of the best experts on this subject based on the ideXlab platform.
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lower Trophic Levels and detrital biomass control the bay of biscay continental shelf food web implications for ecosystem management
Progress in Oceanography, 2011Co-Authors: G. Lassalle, Delphine Delmas, C. Hily, Claire Labry, Jacques Lobry, Paco Bustamante, Grégoire Certain, Le F Loch, Christine Dupuy, Le O PapeAbstract:The Bay of Biscay (North-East Atlantic) has long been subjected to intense direct and indirect human activities that lead to the excessive degradation and sometimes overexploitation of natural resources. Fisheries management is gradually moving away from single-species assessments to more holistic, multi-species approaches that better respond to the reality of ecosystem processes. Quantitative modelling methods such as Ecopath with Ecosim can be useful tools for planning, implementing and evaluating ecosystem-based fisheries management strategies. The aim of this study was therefore to model the energy fluxes within the food web of this highly pressured ecosystem and to extract practical information required in the diagnosis of ecosystem state/health. A well-described model comprising 30 living and two non-living compartments was successfully constructed with data of local origin, for the Bay of Biscay continental shelf. The same level of aggregation was applied to primary producers, mid-Trophic-Levels and top-predators boxes. The model was even more general as it encompassed the entire continuum of marine habitats, from benthic to pelagic domains. Output values for most ecosystem attributes indicated a relatively mature and stable ecosystem, with a large proportion of its energy flow originating from detritus. Ecological network analysis also provided evidence that bottom-up processes play a significant role in the population dynamics of upper-Trophic-Levels and in the global structuring of this marine ecosystem. Finally, a novel metric based on ecosystem production depicted an ecosystem not far from being overexploited. This finding being not entirely consistent over indicators, further analyses based on dynamic simulations are required.
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Lower Trophic Levels and detrital biomass control the Bay of Biscay continental shelf food web: Implications for ecosystem management
Progress in Oceanography, 2011Co-Authors: G. Lassalle, Delphine Delmas, C. Hily, François Le Loc'h, Claire Labry, Jacques Lobry, Paco Bustamante, Grégoire Certain, Corinne Dupuy, Olivier Le PapeAbstract:The Bay of Biscay (North-East Atlantic) has long been subjected to intense direct and indirect human activities that lead to the excessive degradation and sometimes overexploitation of natural resources. Fisheries management is gradually moving away from single-species assessments to more holistic, multi-species approaches that better respond to the reality of ecosystem processes. Quantitative modelling methods such as Ecopath with Ecosim can be useful tools for planning, implementing and evaluating ecosystem-based fisheries management strategies. The aim of this study was therefore to model the energy fluxes within the food web of this highly pressured ecosystem and to extract practical information required in the diagnosis of ecosystem state/health. A well-described model comprising 30 living and two non-living compartments was successfully constructed with data of local origin, for the Bay of Biscay continental shelf. The same level of aggregation was applied to primary producers, mid-Trophic-Levels and top-predators boxes. The model was even more general as it encompassed the entire continuum of marine habitats, from benthic to pelagic domains. Output values for most ecosystem attributes indicated a relatively mature and stable ecosystem, with a large proportion of its energy flow originating from detritus. Ecological network analysis also provided evidence that bottom-up processes play a significant role in the population dynamics of upper-Trophic-Levels and in the global structuring of this marine ecosystem. Finally, a novel metric based on ecosystem production depicted an ecosystem not far from being overexploited. This finding being not entirely consistent over indicators, further analyses based on dynamic simulations are required. © 2011 Elsevier Ltd.
Martinus E Huigens - One of the best experts on this subject based on the ideXlab platform.
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plant volatiles induced by herbivore egg deposition affect insects of different Trophic Levels
PLOS ONE, 2012Co-Authors: Nina E Fatouros, Dani Lucasbarbosa, Berhane T Weldegergis, Foteini G Pashalidou, Joop J A Van Loon, Marcel Dicke, Jeffrey A Harvey, Rieta Gols, Martinus E HuigensAbstract:Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their consequences on insects of different Trophic Levels remain poorly explored. In olfactometer and wind tunnel set-ups, we investigated behavioural responses of a specialist cabbage butterfly (Pieris brassicae) and two of its parasitic wasps (Trichogramma brassicae and Cotesia glomerata) to volatiles of a wild crucifer (Brassica nigra) induced by oviposition of the specialist butterfly and an additional generalist moth (Mamestra brassicae). Gravid butterflies were repelled by volatiles from plants induced by cabbage white butterfly eggs, probably as a means of avoiding competition, whereas both parasitic wasp species were attracted. In contrast, volatiles from plants induced by eggs of the generalist moth did neither repel nor attract any of the tested community members. Analysis of the plant’s volatile metabolomic profile by gas chromatography-mass spectrometry and the structure of the plant-egg interface by scanning electron microscopy confirmed that the plant responds differently to egg deposition by the two lepidopteran species. Our findings imply that prior to actual feeding damage, egg deposition can induce specific plant responses that significantly influence various members of higher Trophic Levels.
