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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 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 Lorin-Nebel, C.; Felten, V.; Blondeau-Bidet, E.; Grousset, E.; Amilhat, E.; Simon, G.; Biagianti, S.; Charmantier, G.
Titre Individual and combined effects of copper and parasitism on osmoregulation in the European eel Anguilla anguilla Type Article scientifique
Année 2013 Publication Revue Abrégée Aquatic toxicology
Volume 130–131 Numéro Pages 41-50
Mots-Clés Anguilla anguilla; Anguillicoloides crassus; Copper; Gills; Ionic concentrations; Na+/K+-ATPase activity; osmolality
Résumé The European eel (Anguilla anguilla), a catadromous species, breeds in the sea and migrates to estuarine, lagoon or freshwater habitats for growth and development. Yellow eels, exposed to low or fluctuating salinities, are also exposed to multiple other stressors as pollution, over-fishing and parasitism, which contribute to the dramatic decrease of eel populations in several European countries. The objective of this study was to evaluate the single and combined effects of waterborne copper and experimental infestation of eels with the nematode Anguillicoloides crassus after a salinity challenge from nearly isotonic (18ppt) to hypo- (5ppt) and hypertonic (29ppt) conditions, in order to investigate the osmoregulatory capacity of eels exposed to these stressors. In a nearly isotonic condition (18ppt), blood osmolality remained constant over the 6 weeks contamination to Cu(2+) and Anguillicoloides crassus. In fish exposed to a salinity challenge of 29ppt for 2 weeks, no significant effect was recorded in blood osmolality, Na(+)/K(+)-ATPase (NKA) activity, Na(+) and Cl(-) concentrations. After 2 weeks at 5ppt however, a significant blood osmolality decrease was detected in fish exposed to Anguillicoloides crassus infestation with or without Cu(2+) addition. This decrease may originate from lower Cl(-) levels measured in eels exposed to both stressors. Blood Na(+) levels remained relatively stable in all tested animals, but gill NKA activities were lower in eels exposed to combined stress. No apparent branchial lesions were detected following the different treatments and immunolocalization of NKA revealed well-differentiated ionocytes. Thus, the 5ppt challenge in eels exposed to copper and Anguillicoloides crassus seems to clearly enhance iono/osmoregulatory disturbances. Funded by ANR CES/CIEL 2008-12.
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ISSN 0166-445x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 686
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Auteur Panfili, J.; Darnaude, A.M.; Lin, Y.J.; Chevalley, M.; Iizuka, Y.; Tzeng, W.N.; Crivelli, A.J.
Titre Habitat residence during continental life of the European eel Anguilla anguilla investigated using linear discriminant analysis applied to otolith Sr:Ca ratios Type Article scientifique
Année 2012 Publication Revue Abrégée Aquat. Biol.
Volume 15 Numéro 2 Pages 175-185
Mots-Clés Anguilla anguilla; Epma; European eel; La-Icpms; Mediterranean area; Otolith; Strontium:calcium ratio; coastal; elemental fingerprints; estuarine; fish otoliths; fresh-water environments; history; japonica; mass; microchemistry; rostrata; spectrometry; sr-ca ratios
Résumé European eel Anguilla anguilla migratory behaviour during continental life is still unclear due to the multiplicity of aquatic environments colonised by the species. In the Camargue area (NW Mediterranean), eel colonisation of the Fumemorte canal, a freshwater habitat that communicates only with a vast brackish ecosystem (the Vaccares lagoon), offers a rare opportunity to test for freshwater habitat residence during continental life. To this end, both laser ablation inductively coupled plasma mass spectrometry and electron probe micro-analysis were used to measure chronological variations of strontium concentrations (Sr:Ca) in the otoliths of 58 silver eels captured in the canal between 1997 and 2007. Comparing mean Sr: Ca ratios measured on otolith edges with the 2 analytical methods indicated that they provide comparable measurement accuracies. Linear discriminant analysis (LDA), based on the otolith Sr: Ca values corresponding to the initial entrance of the fish into the brackish ecosystem and their final capture in the freshwater canal, allowed successful discrimination of the 2 habitats and reconstruction of migratory history for all individuals. Six different migratory behaviours were identified. Eels that entered the freshwater canal did so either directly (67%) or after 1 to 2 yr spent in the lagoon (33%), with a subsequent majority of freshwater residents (55%) until their silvering. These results indicate the value of LDA for reconstructing habitat use during continental life using Sr: Ca ratios. They confirm the occurrence of freshwater residence during continental life in European eels, even in Mediterranean continental areas where brackish environments are predominant. This observed sedentary behaviour has implications for eel population management and conservation.
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ISSN 1864-7790 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 626
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