Bioaccumulation of 65 Zn and 109 Cd by the cuttlefish Sepia officinalis L. was studied at different stages of its life cycle, i.e. in embryos, juveniles and adults, following exposures via sea water, sediments and food. Cuttlefish eggs efficiently accumulated both elements from seawater with bioconcentration factors of 79 for 65 Zn and 46 for 109 Cd after 11 d exposure. Most of the radiotracers were found in the capsule membrane of the eggs, demonstrating that the capsule acts as a shield to protect embryos against metals. Juveniles and adults efficiently bioconcentrated both radiotracers from seawater, with the muscular tissues containing 84% of the total 65 Zn and 62% of the total 109Cd. Loss kinetics followed a single exponential function for 65 Zn, while for 109 Cd loss was best described by a double exponential model. Biological half-lives for elimination were ca. 2 mo for both elements. After 29 d depuration in uncontaminated seawater, 76 to 87% of the radiotracers were found in the digestive gland. For both elements, the dissolved phase can be considered as a significant source of accumulation. In an experiment with radiolabelled sediments, transfer factors were very low, even after 29 d exposure. Food-chain transfer experiments demonstrated that both juveniles and adults assimilated
Uptake and loss kinetics of Zn, Ag, Cd, '=CS, and 241Am by the echinoid Paracentrotus lividus contaminated through either water or food were determined in controlled laboratory radiotracer experiments using low contaminant concentrations. The echinoid efficiently accumulated most of the elements from water. The only exception was '"CS (concentration factor at steady state = 2.71. With respect to relative metal bioavailability, concentrations in the different body compartments of P lividus were generally ranked in the order: digestive wall > gonads 2 body wall >Aristotle's lantern > coelomlc fluid. However, for2''~rn, body wall uptake was as efficient as that of the digestive wall. The loss kinetics for Zn, Ag, and 1 3 4~s were described by a 2-component model whereas loss of Cd and '"'Am was linear during the time course of the experiment. Loss of the different elements was relatively slow, except for 134Cs, whose long-lived loss component was characterized by a biological half-life of 6 d. Loss of the different elements ingested wlth food was described by a single-component model for Cd, '34Cs, and &;'.Am and by a 2-component model for Zn and Ag. Parameters of the kinetics ~n d~c a t e that all (for Cd, I3Ts, and 'j1.4m) or most (for Zn and Ag) of the ingested amount of element is readily lost from the organism with the faeces. However, estimation of the assimilated fraction of elements ingested by the echlnoids suggests that food could contr~bute significantly to the total body burden of Ag in f? lividus.
Three pathways of exposure (sediment, seawater and food) were examined to determine transfer of 110m Ag and 57 Co in juvenile cuttlefish Sepia officinalis. Additional experiments were conducted on adult cuttlefish and their eggs/embryos in order to assess bioaccumulation patterns at different stages of the organism's life cycle. Eggs, juveniles and adults readily accumulated both Ag and Co from seawater. In eggs, both metals were predominantly adsorbed onto the capsule membrane (≥ 60% for Ag and ≥ 99% for Co), indicating that the latter may act as an effective shield to limit exposure of embryos to soluble metals. Adult cuttlefish incorporated waterborne radiotracers mainly in their muscular tissues (≥ 60% of the whole-body burden); subsequent metal retention was greater for Co (biological half-life, T b ! = 34 d) than for Ag (T b ! = 7 d). Turnover of Co ingested with food was much more rapid in juveniles (T b ! = 5 d) than in adults (T b ! = 990 d), suggesting that the functional maturation of the digestive gland was not complete in the juveniles. With ingested Ag, retention was roughly similar for juveniles and adults (T b ! = 13 and 9 d, respectively). Transfer from sediments was negligible for Co and Ag. Regardless of the exposure pathway, the digestive gland of juveniles and adults contained the major fraction of incorporated metal either following uptake or after depuration. This observation demonstrates that substantial metal transfer takes place from several organs to the digestive gland, and further highlights the major role this organ plays in metal storage and detoxification processes in these cephalopods.
KEY WORDS: Metal · Radiotracer · Bioaccumulation · Digestive gland · CephalopodsResale or republication not permitted without written consent of the publisher
The concentrations of nine elements (Ag, As, Cd, Co, Cr, Cu, Mn, Ni and Zn) were measured in the oyster Isognomon isognomon and the edible clam Gafrarium tumidum from different sites along the SW New Caledonian coast which is subjected to important chemical inputs due to intense land-based mining activities (New Caledonia is the third world producer of nickel). Results indicate that concentrations in the two organisms mirrored the geographical differences in contamination levels as established through element analyses in sediment. On the basis of organism analyses, two out of the seven investigated stations can be considered as relative "reference" sites, except for As, for which very high levels were detected in clam and oyster tissues (up to 441 microg g(-1) dry wt for clams). Overall, our results indicate that both tropical organisms investigated could be used as valuable bioindicator species for surveying metal contamination in the coastal waters of New Caledonia with reasonable perspectives of wider application to other coral reef environments.
Uptake of waterborne Cd, Co, Mn and Zn was determined in laboratory experiments using radiotracer techniques (109Cd, 57Co, 54Mn and 65Zn). Labelled Zn was mainly accumulated in the digestive gland (65%) and Co in kidneys (81%); Cd and Mn were similarly distributed in digestive gland and gills. In a complementary field study, Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, and Zn were analysed in scallops collected at two stations showing different contamination levels. Digestive gland and kidneys displayed the highest concentrations. Ag, As, Cd, and Fe differed in soft tissues from the two stations, suggesting that Comptopallium radula could be a valuable local biomonitor species for these elements. Low Mn and Zn concentrations found in kidneys suggest that their content in calcium-phosphate concretions differs from the other pectinids. Preliminary risk considerations suggest that As would be the only element potentially leading to exposure of concern for seafood consumers.
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