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Auteur (up) Javidpour, J.; Molinero, J.-C.; Ramirez-Romero, E.; Roberts, P.; Larsen, T.
Titre Cannibalism makes invasive comb jelly, Mnemiopsis leidyi, resilient to unfavourable conditions Type Article scientifique
Année 2020 Publication Revue Abrégée Commun. Biol.
Volume 3 Numéro 1 Pages
Mots-Clés black-sea; ctenophore mnemiopsis; evolution; growth; impact; kiel fjord; mechanisms; population-dynamics; predation; rates
Résumé The proliferation of invasive marine species is often explained by a lack of predators and opportunistic life history traits. For the invasive comb jelly Mnemiopsis leidyi, it has remained unclear how this now widely distributed species is able to overcome long periods of low food availability, particularly in their northernmost exotic habitats in Eurasia. Based on both field and laboratory evidence, we show that adult comb jellies in the western Baltic Sea continue building up their nutrient reserves after emptying the prey field through a shift to cannibalizing their own larvae. We argue, that by creating massive late summer blooms, the population can efficiently empty the prey field, outcompete intraguild competitors, and use the bloom events to build nutrient reserves for critical periods of prey scarcity. Our finding that cannibalism makes a species with typical opportunistic traits more resilient to environmental fluctuations is important for devising more effective conservation strategies. Javidpour et al. use high-frequency field data, geochemical-isotopic analysis, and modeling of prey-predator dynamics of the comb jelly in the western Baltic Sea to show that adult comb jellies cannibalize their own larvae. This shift to cannibalism allows adults to build nutrient reserves for periods of prey scarcity and sheds light on the ability of this invasive species to thrive amidst environmental fluctuations.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2788
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Auteur (up) Krause, J.; Herbert-Read, J.E.; Seebacher, F.; Domenici, P.; Wilson, A.D.M.; Marras, S.; Svendsen, M.B.S.; Strombom, D.; Steffensen, J.F.; Krause, S.; Viblanc, P.E.; Couillaud, P.; Bach, P.; Sabarros, P.S.; Zaslansky, P.; Kurvers, R.H.J.M.
Titre Injury-mediated decrease in locomotor performance increases predation risk in schooling fish Type Article scientifique
Année 2017 Publication Revue Abrégée Philos. Trans. R. Soc. B-Biol. Sci.
Volume 372 Numéro 1727 Pages 20160232
Mots-Clés animal groups; Behavior; danger; fish schools; geometry; group-living; killer whales; locomotion; organization; Predation; prey interactions; selfish herd; spatial position; spatial positions; vertebrates
Résumé The costs and benefits of group living often depend on the spatial position of individuals within groups and the ability of individuals to occupy preferred positions. For example, models of predation events for moving prey groups predict higher mortality risk for individuals at the periphery and front of groups. We investigated these predictions in sardine (Sardinella aurita) schools under attack from group hunting sailfish (Istiophorus platypterus) in the open ocean. Sailfish approached sardine schools about equally often from the front and rear, but prior to attack there was a chasing period in which sardines attempted to swim away from the predator. Consequently, all sailfish attacks were directed at the rear and peripheral positions of the school, resulting in higher predation risk for individuals at these positions. During attacks, sailfish slash at sardines with their bill causing prey injury including scale removal and tissue damage. Sardines injured in previous attacks were more often found in the rear half of the school than in the front half. Moreover, injured fish had lower tail-beat frequencies and lagged behind uninjured fish. Injuries inflicted by sailfish bills may, therefore, hinder prey swimming speed and drive spatial sorting in prey schools through passive self-assortment. We found only partial support for the theoretical predictions from current predator-prey models, highlighting the importance of incorporating more realistic predator-prey dynamics into these models. This article is part of the themed issue 'Physiological determinants of social behaviour in animals'.
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ISSN 0962-8436 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2161
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Auteur (up) Marques, R.; Darnaude, A.M.; Crochemore, S.; Bouvier, C.; Bonnet, D.
Titre Molecular approach indicates consumption of jellyfish by commercially important fish species in a coastal Mediterranean lagoon Type Article scientifique
Année 2019 Publication Revue Abrégée Marine Environmental Research
Volume 152 Numéro Pages 104787
Mots-Clés Eel; Gut content; Medusae; Polyps; Predation; Quantitative PCR; Seabream; Thau lagoon
Résumé Until recently, jellyfish have been ignored as an important source of food, due to their low nutritional value. Here, quantitative PCR was used to detect and quantify the DNA of the jellyfish Aurelia coerulea in the gut contents of commercially important fish species from the Thau Lagoon. Individuals from five fish species were collected during two different periods: the bloom period, when the pelagic stages of A. coerulea are abundant, and the post-bloom period, when only the benthic stage – polyps – is present in the lagoon. The DNA of A. coerulea was detected in the guts of 41.9% of the fish analysed, belonging to four different species. The eel Anguilla anguilla and the seabream Sparus aurata were important jellyfish consumers during the bloom and post-bloom periods, respectively. These results provide new insights on the potential control of jellyfish populations and on jellyfish importance as a food source for exploited fishes.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2615
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Auteur (up) Maury, O.; Poggiale, J.-C.
Titre From individuals to populations to communities: A dynamic energy budget model of marine ecosystem size-spectrum including life history diversity Type Article scientifique
Année 2013 Publication Revue Abrégée Journal of Theoretical Biology
Volume 324 Numéro Pages 52-71
Mots-Clés biodiversity; Dynamic Energy Budget theory; predation; Schooling; Size spectrum
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ISSN 0022-5193 ISBN Médium
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Notes <p>\textbackslashtextlessp\textbackslashtextgreaterIndividual metabolism, predator–prey relationships, and the role of biodiversity are major factors underlying the dynamics of food webs and their response to environmental variability. Despite their crucial, complementary and interacting influences, they are usually not considered simultaneously in current marine ecosystem models. In an attempt to fill this gap and determine if these factors and their interaction are sufficient to allow realistic community structure and dynamics to emerge, we formulate a mathematical model of the size-structured dynamics of marine communities which integrates mechanistically individual, population and community levels. The model represents the transfer of energy generated in both time and size by an infinite number of interacting fish species spanning from very small to very large species. It is based on standard individual level assumptions of the Dynamic Energy Budget theory (DEB) as well as important ecological processes such as opportunistic size-based predation and competition for food. Resting on the inter-specific body-size scaling relationships of the DEB theory, the diversity of life-history traits (i.e. biodiversity) is explicitly integrated. The stationary solutions of the model as well as the transient solutions arising when environmental signals (e.g. variability of primary production and temperature) propagate through the ecosystem are studied using numerical simulations. It is shown that in the absence of density-dependent feedback processes, the model exhibits unstable oscillations. Density-dependent schooling probability and schooling-dependent predatory and disease mortalities are proposed to be important stabilizing factors allowing stationary solutions to be reached. At the community level, the shape and slope of the obtained quasi-linear stationary spectrum matches well with empirical studies. When oscillations of primary production are simulated, the model predicts that the variability propagates along the spectrum in a given frequency-dependent size range before decreasing for larger sizes. At the species level, the simulations show that small and large species dominate the community successively (small species being more abundant at small sizes and large species being more abundant at large sizes) and that the total biomass of a species decreases with its maximal size which again corroborates empirical studies. Our results indicate that the simultaneous consideration of individual growth and reproduction, size-structured trophic interactions, the diversity of life-history traits and a density-dependent stabilizing process allow realistic community structure and dynamics to emerge without any arbitrary prescription. As a logical consequence of our model construction and a basis for future studies, we define the function Φ as the relative contribution of each species to the total biomass of the ecosystem, for any given size. We argue that this function is a measure of the functional role of biodiversity characterizing the impact of the structure of the community (its species composition) on its function (the relative proportions of losses, dissipation and biological work).\textbackslashtextless/p\textbackslashtextgreater</p> Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 245
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Auteur (up) McKenzie, D.J.; Belao, T.C.; Killen, S.S.; Rantin, F.T.
Titre To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish Type Article scientifique
Année 2015 Publication Revue Abrégée J. Exp. Biol.
Volume 218 Numéro 23 Pages 3762-3770
Mots-Clés african catfish; animal personality; Bimodal respiration; clarias-gariepinus; ecological consequences; Energy metabolism; european sea bass; Hypoxia; individual variation; oncorhynchus-mykiss; Personality; personality-traits; predation risk; Respiratory partitioning; Risk-taking; wild-type zebrafish
Résumé The African sharptooth catfish Clarias gariepinus has bimodal respiration, it has a suprabranchial air-breathing organ alongside substantial gills. We used automated bimodal respirometry to reveal that undisturbed juvenile catfish (N=29) breathed air continuously in normoxia, with a marked diurnal cycle. Air breathing and routine metabolic rate (RMR) increased in darkness when, in the wild, this nocturnal predator forages. Aquatic hypoxia (20% air saturation) greatly increased overall reliance on air breathing. We investigated whether two measures of risk taking to breathe air, namely absolute rates of aerial O-2 uptake ((M) over dotO(2), air) and the percentage of RMR obtained from air (% (M) over dotO(2), air), were influenced by individual standard metabolic rate (SMR) and boldness. In particular, whether any influence varied with resource availability (normoxia versus hypoxia) or relative fear of predation (day versus night). Individual SMR, derived from respirometry, had an overall positive influence on (M) over dotO(2), air across all contexts but a positive influence on % (M) over dotO(2), air only in hypoxia. Thus, a pervasive effect of SMR on air breathing became most acute in hypoxia, when individuals with higher O-2 demand took proportionally more risks. Boldness was estimated as time required to resume air breathing after a fearful stimulus in daylight normoxia (T-res). Although T-res had no overall influence on (M) over dotO(2), air or % (M) over dotO(2), air, there was a negative relationship between Tres and % (M) over dotO(2), air in daylight, in normoxia and hypoxia. There were two Tres response groups, 'bold' phenotypes with Tres below 75 min (N= 13) which, in daylight, breathed proportionally more air than 'shy' phenotypes with Tres above 115 min (N= 16). Therefore, individual boldness influenced air breathing when fear of predation was high. Thus, individual energy demand and personality did not have parallel influences on the emergent tendency to take risks to obtain a resource; their influences varied in strength with context.
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Numéro d'Appel MARBEC @ alain.herve @ collection 1429
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