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Auteur Van Beveren, E.; Fromentin, J.-M.; Bonhommeau, S.; Nieblas, A.-E.; Metral, L.; Brisset, B.; Jusup, M.; Bauer, R.K.; Brosset, P.; Saraux, C.
Titre Predator-prey interactions in the face of management regulations: changes in Mediterranean small pelagic species are not due to increased tuna predation Type Article scientifique
Année 2017 Publication Revue Abrégée Can. J. Fish. Aquat. Sci.
Volume 74 Numéro 9 Pages 1422-1430
Mots-Clés (up) anchovy engraulis-encrasicolus; atlantic bluefin tuna; Energy density; fish condition; fisheries; food-consumption; Proximate composition; sea; thunnus-thynnus; Yellowfin tuna
Résumé Recently, the abundance of young Atlantic bluefin tuna (Thunnus thynnus) tripled in the northwestern Mediterranean following effective management measures. We investigated whether its predation on sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) could explain their concurrent size and biomass decline, which caused a fishery crisis. Combining the observed diet composition of bluefin tuna, their modelled daily energy requirements, their population size, and the abundance of prey species in the area, we calculated the proportion of the prey populations that were consumed by bluefin tuna annually over 2011-2013. To assess whether tuna could alter the size structure of the three small pelagic fish populations (anchovy, sardine, and sprat (Sprattus sprattus)), the size distributions of the consumed prey species were compared with those of the wild populations. We estimated that the annual consumption of small pelagic fish by bluefin tuna is less than 2% of the abundance of these populations. Furthermore, size selectivity patterns were not observed. We thus concluded that tuna predation is unlikely to be the main cause of major changes in the small pelagic fish populations from this area.
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ISSN 0706-652x ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2195
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Auteur Albo-Puigserver, M.; Navarro, J.; Coll, M.; Layman, C.A.; Palomera, I.
Titre Trophic structure of pelagic species in the northwestern Mediterranean Sea Type Article scientifique
Année 2016 Publication Revue Abrégée J. Appl. Dev. Psychol.
Volume 47 Numéro Pages 27-35
Mots-Clés (up) anchovy engraulis-encrasicolus; biscay northeast atlantic; Community structure; diet composition; food-web; Food web; hake merluccius-merluccius; horse mackerel; Isotopic niche; mackerel scomber-japonicus; Pelagic fish; sardine sardina-pilchardus; Seasonal; seasonal-changes; Stable isotopes; stable-isotopes; Trophic segregation
Résumé Ecological knowledge of food web interactions within pelagic marine communities is often limited, impairing our capabilities to manage these ecologically and economically important marine fish species. Here we used stable isotope analyses to investigate trophic interactions in the pelagic ecosystem of the northwestern Mediterranean Sea during 2012 and 2013. Our results suggest that European sardine, Sardina pilchardus, and anchovy, Engraulis encrasicolus, are consumers located at relatively low levels of the pelagic food web. Unexpectedly, the round sardinella, Sardinella aurita, appeared to be located at a higher trophic level than the other small pelagic fish species, although previous studies found similarity in their diets. Isotope data suggested that trophic niches of species within the genera Trachurus spp. and Scomber spp., were distinct. Atlantic bonito Sarda sarda, European hake Merluccius merluccius and European squid Loligo vulgaris, appeared to feed at higher trophic levels than other species. Despite some intraspecific seasonal variability for some species, community trophic structure appeared relatively stable through the year. These data provide an important step for developing models of food web dynamics in the northwestern Mediterranean Sea. (C) 2016 Elsevier B.V. All rights reserved.
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ISSN 0193-3973 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1691
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Auteur Iversen, N.K.; McKenzie, D.J.; Malte, H.; Wang, T.
Titre Reflex bradycardia does not influence oxygen consumption during hypoxia in the European eel (Anguilla anguilla) Type Article scientifique
Année 2010 Publication Revue Abrégée J. Comp. Physiol. B-Biochem. Syst. Environ. Physiol.
Volume 180 Numéro 4 Pages 495-502
Mots-Clés (up) Anguilla anguilla; Cardiac output; Critical oxygen tension; Hypoxic bradycardia; Oxygen; Teleost; atlantic cod; cardiac vagotomy; circulation; consumption; dogfish scyliorhinus-canicula; fish; heart-rate; rainbow-trout; responses; temperature; tolerance
Résumé Most teleost fish reduce heart rate when exposed to acute hypoxia. This hypoxic bradycardia has been characterised for many fish species, but it remains uncertain whether this reflex contributes to the maintenance of oxygen uptake in hypoxia. Here we describe the effects of inhibiting the bradycardia on oxygen consumption (MO(2)), standard metabolic rate (SMR) and the critical oxygen partial pressure for regulation of SMR in hypoxia (Pcrit) in European eels Anguilla anguilla (mean +/- A SEM mass 528 +/- A 36 g; n = 14). Eels were instrumented with a Transonic flow probe around the ventral aorta to measure cardiac output (Q) and heart rate (f (H)). MO(2) was then measured by intermittent closed respirometry during sequential exposure to various levels of increasing hypoxia, to determine Pcrit. Each fish was studied before and after abolition of reflex bradycardia by intraperitoneal injection of the muscarinic antagonist atropine (5 mg kg(-1)). In the untreated eels, f (H) fell from 39.0 +/- A 4.3 min(-1) in normoxia to 14.8 +/- A 5.2 min(-1) at the deepest level of hypoxia (2 kPa), and this was associated with a decline in Q, from 7.5 +/- A 0.8 mL min(-1) kg(-1) to 3.3 +/- A 0.7 mL min(-1) kg(-1) in normoxia versus deepest hypoxia, respectively. Atropine had no effect on SMR, which was 16.0 +/- A 1.8 mu mol O(2) kg(-1) min(-1) in control versus 16.8 +/- A 0.8 mu mol O(2) kg(-1) min(-1) following treatment with atropine. Atropine also had no significant effect on normoxic f (H) or Q in the eel, but completely abolished the bradycardia and associated decline in Q during progressive hypoxia. This pharmacological inhibition of the cardiac responses to hypoxia was, however, without affect on Pcrit, which was 11.7 +/- A 1.3 versus 12.5 +/- A 1.5 kPa in control versus atropinised eels, respectively. These results indicate, therefore, that reflex bradycardia does not contribute to maintenance of MO(2) and regulation of SMR by the European eel in hypoxia.
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ISSN 0174-1578 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 805
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Auteur Puerta, P.; Johnson, C.; Carreiro-Silva, M.; Henry, L.-A.; Kenchington, E.; Morato, T.; Kazanidis, G.; Luis Rueda, J.; Urra, J.; Ross, S.; Wei, C.-L.; Manuel Gonzalez-Irusta, J.; Arnaud-Haond, S.; Orejas, C.
Titre Influence of Water Masses on the Biodiversity and Biogeography of Deep-Sea Benthic Ecosystems in the North Atlantic Type Article scientifique
Année 2020 Publication Revue Abrégée Front. Mar. Sci.
Volume 7 Numéro Pages 239
Mots-Clés (up) antarctic intermediate water; biodiversity; biogeography; climate-change impacts; coral lophelia-pertusa; deep-sea; food-supply mechanisms; global habitat suitability; meridional overturning circulation; ne atlantic; North Atlantic; ocean acidification; porcupine seabight; rockall trough margin; vulnerable marine ecosystems; water masses
Résumé Circulation patterns in the North Atlantic Ocean have changed and re-organized multiple times over millions of years, influencing the biodiversity, distribution, and connectivity patterns of deep-sea species and ecosystems. In this study, we review the effects of the water mass properties (temperature, salinity, food supply, carbonate chemistry, and oxygen) on deep-sea benthic megafauna (from species to community level) and discussed in future scenarios of climate change. We focus on the key oceanic controls on deep-sea megafauna biodiversity and biogeography patterns. We place particular attention on cold-water corals and sponges, as these are ecosystem-engineering organisms that constitute vulnerable marine ecosystems (VME) with high associated biodiversity. Besides documenting the current state of the knowledge on this topic, a future scenario for water mass properties in the deep North Atlantic basin was predicted. The pace and severity of climate change in the deep-sea will vary across regions. However, predicted water mass properties showed that all regions in the North Atlantic will be exposed to multiple stressors by 2100, experiencing at least one critical change in water temperature (+2 degrees C), organic carbon fluxes (reduced up to 50%), ocean acidification (pH reduced up to 0.3), aragonite saturation horizon (shoaling above 1000 m) and/or reduction in dissolved oxygen (> 5%). The northernmost regions of the North Atlantic will suffer the greatest impacts. Warmer and more acidic oceans will drastically reduce the suitable habitat for ecosystem-engineers, with severe consequences such as declines in population densities, even compromising their long-term survival, loss of biodiversity and reduced biogeographic distribution that might compromise connectivity at large scales. These effects can be aggravated by reductions in carbon fluxes, particularly in areas where food availability is already limited. Declines in benthic biomass and biodiversity will diminish ecosystem services such as habitat provision, nutrient cycling, etc. This study shows that the deep-sea VME affected by contemporary anthropogenic impacts and with the ongoing climate change impacts are unlikely to withstand additional pressures from more intrusive human activities. This study serves also as a warning to protect these ecosystems through regulations and by tempering the ongoing socio-political drivers for increasing exploitation of marine resources.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2767
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Auteur Dueri, S.; Bopp, L.; Maury, O.
Titre Projecting the impacts of climate change on skipjack tuna abundance and spatial distribution Type Article scientifique
Année 2014 Publication Revue Abrégée Global Change Biology
Volume 20 Numéro 3 Pages 742-753
Mots-Clés (up) Apecosm-E; Atlantic Ocean; global warming; Indian Ocean; Katsuwonus pelamis; Pacific Ocean; scenario; Tropical tuna
Résumé Climate-induced changes in the physical, chemical, and biological environment are expected to increasingly stress marine ecosystems, with important consequences for fisheries exploitation. Here, we use the APECOSM-E numerical model (Apex Predator ECOSystem Model – Estimation) to evaluate the future impacts of climate change on the physiology, spatial distribution, and abundance of skipjack tuna, the worldwide most fished species of tropical tuna. The main novelties of our approach lie in the mechanistic link between environmental factors, metabolic rates, and behavioral responses and in the fully three dimensional representation of habitat and population abundance. Physical and biogeochemical fields used to force the model are provided by the last generation of the IPSL-CM5 Earth System Model run from 1990 to 2100 under a &8216;business-as-usual&8217; scenario (RCP8.5). Our simulations show significant changes in the spatial distribution of skipjack tuna suitable habitat, as well as in their population abundance. The model projects deterioration of skipjack habitat in most tropical waters and an improvement of habitat at higher latitudes. The primary driver of habitat changes is ocean warming, followed by food density changes. Our projections show an increase of global skipjack biomass between 2010 and 2050 followed by a marked decrease between 2050 and 2095. Spawning rates are consistent with population trends, showing that spawning depends primarily on the adult biomass. On the other hand, growth rates display very smooth temporal changes, suggesting that the ability of skipjack to keep high metabolic rates in the changing environment is generally effective. Uncertainties related to our model spatial resolution, to the lack or simplification of key processes and to the climate forcings are discussed.
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ISSN 1354-1013 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 327
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