title: Trophic transfer of radioisotopes in Mediterranean sponges through bacteria consumption.
abstract: Numerous field studies highlighted the capacities of marine sponges to bioaccumulate trace elements and assessed their potential as biomonitors of the marine environment. Experimental works demonstrated that dissolved metals and radionuclides can be taken up directly by sponge tissues but, to the best of our knowledge, little is known on the contribution of the dietary pathway through the consumption of contaminated bacteria considered as one of the trophic source in sponge diet. Objectives of this work are to study trophic transfer of radiotracers (110m)Ag, (241)Am, (109)Cd, (57)Co, (134)Cs, (54)Mn and (65)Zn from the marine bacteria Pseudomonas stutzeri to the Mediterranean sponges Aplysina cavernicola and Ircinia oros. P. stutzeri efficiently bioaccumulated trace elements in our culture experimental conditions with CF comprised between 10(5) and 10(7) after 48 h of growth in radiolabeled medium. When fed with these radiolabelled bacteria, A. cavernicola took up around 60% of radiotracers accumulated in trophic source except (134)Cs for which only 8% has been transferred from bacteria to sponge. Contrasting to this, I. oros retained only 7% of (110m)Ag, (109)Cd and (65)Zn counted in bacteria, but retained 2-fold longer accumulated metals in its tissues. The sponge inter-specific differences of accumulation and depuration following a trophic exposure are discussed with respect to the structure and the clearance capacities of each species.
authors.affiliation: International Atomic Energy Agency - Environment Laboratories, 4 Quai Antoine Ier, MC 98000 Monaco, Monaco; Littoral Environnement et Sociétés, UMR 7266 CNRS - Université de La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France. Electronic address: tlacouel@univ-lr.fr.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lacoue-Labarthe
authors.affiliation: International Atomic Energy Agency - Environment Laboratories, 4 Quai Antoine Ier, MC 98000 Monaco, Monaco.
authors.forename: Michel
authors.initials: M
authors.lastname: Warnau
authors.affiliation: Littoral Environnement et Sociétés, UMR 7266 CNRS - Université de La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France.
authors.forename: Laureen
authors.initials: L
authors.lastname: Beaugeard
authors.affiliation: Département de Biologie, Université des Antilles et de la Guyane, UMR 7138 UPMC-CNRS-MNHN-IRD, Equipe 'biologie de la mangrove', UFR des Sciences Exactes et Naturelles, BP 592, 97159 Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Pascal
mesh_terms: D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D004784:Environmental Monitoring; D020387:Food Chain; D008522:Mediterranean Sea; D011161:Porifera / Q000378:metabolism*; D011868:Radioisotopes / Q000378:metabolism*; D014131:Trace Elements / Q000378:metabolism; D014873:Water Pollutants / Q000378:metabolism*
chemical_list: D011868:Radioisotopes; D014131:Trace Elements; D014873:Water Pollutants
keywords: Bacteria; Biomonitor; Metal bioaccumulation; Radiotracers; Sponges; Trophic route