Variation of 210-polonium in the cephalopod community from the Bay of Biscay, North-East Atlantic.

Among natural radionuclides, Po is the major contributor to the radiation dose received by marine organisms. In cephalopods, Po is concentrated in the digestive gland, which contains over 90% of the whole-body burden of the nuclide. Although previous studies showed that Po was taken up independently of Pb, its parent nuclide, very little is known about the factors influencing its levels in cephalopods.

Diet variably affects the trophic transfer of trace elements in the oyster Crassostrea gigas.

Although it has been shown that trophic transfer of trace elements in oysters can be influenced by the diet, most of the studies investigating the ability of oysters to bioaccumulate trace elements from their diet are based on experiments using phytoplankton alone. Wild oysters feed also on large bacteria, ciliates or detritic organic matter. The present study aimed at examining the influence of food quality on the assimilation efficiency (AE) of trace elements in the Pacific cupped oyster Crassostrea gigas.

Influence of food (ciliate and phytoplankton) on the trophic transfer of inorganic and methyl-mercury in the Pacific cupped oyster Crassostrea gigas.

Diet is an important route of mercury (Hg) uptake in marine organisms. Trophic transfer of Hg throughout the food webs may be influenced by various factors, including diet and Hg speciation. Bivalves such as oysters are widely used as bioindicators of trace element pollution such as Hg.

Biokinetics of the anionic surfactant linear alkylbenzene sulfonate (LAS) in the marine fish Sparus aurata: Investigation via seawater and food exposure pathways.

Uptake and depuration kinetics of [C]C-6-linear alkylbenzene sulfonate (LAS) in the fish Sparus aurata were determined during experimental exposure via seawater or food separately under laboratory conditions. The fish concentrated LAS from seawater (using realistic contaminant concentrations) with a mean BCF value of 20 ± 2 L kg reached within 3 days and following a one-compartment exponential model. High differences in BCF were noted among organs, with values ranking in the order gall bladder (1400 ± 600 L kg) >>  digestive tract (52 ± 9 L kg) > liver (38 ± 4 L kg) > gills (16 ± 3 L kg) > skin (13 ± 2 L kg) > head (9 ± 1 L kg) > muscles (4 ± 1 L kg).

Allometric relationship in the bioaccumulation of radionuclides (Cs &Am) and delineation of contamination pathways (food and seawater) in bloody cockle Anadara senilis using radiotracer techniques.

The uptake and depuration kinetics of Cs and Am were investigated in the bloody cockle Anadara senilis exposed via seawater and food in controlled conditions, using animals of different weight groups in order to assess how their bioaccumulation is affected by allometry and, hence, the individual's age. This study is one of the few experiments investigating bioaccumulation capacities of radionuclides in a West-African bivalve. Results showed that allometric relationships were mainly dependent on the exposure pathway considered.

Interspecific comparison of radiocesium trophic transfer in two tropical fish species.

The trophic transfer of radiocesium (Cs) was investigated in two tropical fish, the silver moony Monodactylus argenteus and the spotted scat Scatophagus argus. Juveniles of both species were exposed to dietary Cs using the pulse-chase feeding methodology. The food was brine shrimp (Artemia salina) previously exposed to the dissolved radiotracer.

High contribution of the particulate uptake pathway to metal bioaccumulation in the tropical marine clam Gafrarium pectinatum.

The clam Gafrarium pectinatum was investigated to assess its usefulness as a bioindicator species of metal mining contamination in the New Caledonia lagoon. The uptake and depuration kinetics of Ag, Cd, Co, Cr, and Zn were determined following exposures via seawater, sediment, and food using highly sensitive radiotracer techniques (Ag, Cd, Cr, Co, and Zn). When the clams were exposed to dissolved metals, Co, Zn, and Ag were readily incorporated in their tissues (concentration factors (CF) ranging from 181 to 4982 after 28 days of exposure) and all metals were strongly retained (biological half-lives always >2 months).

Comparing single-feeding and multi-feeding approaches for experimentally assessing trophic transfer of metals in fish.

Diet is an important pathway for metal uptake in marine organisms, and assimilation efficiency is one of the most relevant parameters to quantify trophic transfer of metals along aquatic food webs. The most commonly used method to estimate this parameter is pulse-chase feeding using radiolabeled food. This approach is, however, based on several assumptions that are not always tested in an experimental context.

Bioconcentration of Ag, Cd, Co, Mn and Zn in the Mangrove Oyster (Crassostrea gasar) and Preliminary Human Health Risk Assessment: A Radiotracer Study.

Bioaccumulation kinetics of five dissolved metals were determined in the mangrove oyster Crassostrea gasar, using corresponding radiotracers ((54)Mn, (57)Co, (65)Zn, (109)Cd and (110m)Ag). Additionally, their bioaccessibility to human consumers was estimated. Results indicated that over a 14-day exposure (54)Mn and (57)Co were linearly concentrated in oysters whereas (109)Cd, (65)Zn and (110m)Ag were starting to saturate (steady-state not reached).

Bioaccumulation of (63)Ni in the scleractinian coral Stylophora pistillata and isolated Symbiodinium using radiotracer techniques.

Development of nickel mining activities along the New Caledonia coasts threatens the biodiversity of coral reefs. Although the validation of tropical marine organisms as bioindicators of metal mining contamination has received much attention in the literature over the last decade, few studies have examined the potential of corals, the fundamental organisms of coral reefs, to monitor nickel (Ni) contamination in tropical marine ecosystems. In an effort to bridge this gap, the present work investigated the bioaccumulation of (63)Ni in the scleractinian coral Stylophora pistillata and in its isolated zooxanthellae Symbiodinium, using radiotracer techniques.

Differential bioaccumulation of (134)Cs in tropical marine organisms and the relative importance of exposure pathways.

Bioaccumulation of (134)Cs was determined in 5 tropical marine species: three bivalves (the oysters Isognomon isognomum and Malleus regula, and the clam Gafrarium pectinatum), one decapod (shrimp Penaeus stylirostris) and one alga (Lobophora variegata). Marine organisms were exposed to the radionuclides via different pathways: seawater (all of them), food (shrimp and bivalves) and sediment (bivalves). Our results indicate that the studied tropical species accumulate Cs similarly than species from temperate regions whereas retention capacities seems to be greater in the tropical species.

Trophic transfer of radioisotopes in Mediterranean sponges through bacteria consumption.

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.

Trophic transfer of (110m)Ag in the turbot Scophthalmus maximus through natural prey and compounded feed.

Industrial incidents can result in radionuclide release in the environment, among which (110m)Ag. Indeed, under particular circumstances, non-negligible amounts of (110m)Ag have been measured in the marine environment (as observed in Fukushima Dai-ichi incident). This element can therefore be accumulated by aquatic organisms through different pathways including the trophic transfer.

Delineation of ¹³⁴Cs uptake pathways (seawater and food) in the variegated scallop Mimachlamys varia.

Among bivalves, scallops have been shown to be good bioindicator species for radionuclide monitoring. The present paper looked at the Cs bioaccumulation capacities of the variegated scallop Mimachlamys varia exposed separately via seawater and food under laboratory conditions. Results were compared with data previously obtained for the king scallop Pecten maximus, the only Pectinid species for which Cs accumulation has been studied in laboratory.

Metal bioconcentration in the scleractinian coral Stylophora pistillata: investigating the role of different components of the holobiont using radiotracers.

Bioconcentration kinetics of five metals (Ag, Cd, Co, Mn, and Zn) were determined in the scleractinian coral Stylophora pistillata (entire symbiotic association vs. cultured symbionts), using radiotracer techniques. Among contrasting element behaviors observed in S.

Bioconcentration of the anionic surfactant linear alkylbenzene sulfonate (LAS) in the marine shrimp Palaemonetes varians: a radiotracer study.

Uptake and depuration kinetics of dissolved [(14)C]C₁₂-6-linear alkylbenzene sulfonate (LAS) were determined in the shrimp Palaemonetes varians using environmentally relevant exposure concentration. The shrimp concentrated LAS from seawater with a mean BCF value of 120 L kg(-1) after a 7-day exposure. Uptake biokinetics were best described by a saturation model, with an estimated BCFss, of 159 ± 34 L kg(-1), reached after 11.

Further insights into brevetoxin metabolism by de novo radiolabeling.

The toxic dinoflagellate Karenia brevis, responsible for early harmful algal blooms in the Gulf of Mexico, produces many secondary metabolites, including potent neurotoxins called brevetoxins (PbTx). These compounds have been identified as toxic agents for humans, and they are also responsible for the deaths of several marine organisms. The overall biosynthesis of these highly complex metabolites has not been fully ascertained, even if there is little doubt on a polyketide origin.

Trace element bioaccumulation in reef fish from New Caledonia: influence of trophic groups and risk assessment for consumers.

Fourteen trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn) were analyzed in livers and muscles from 22 fish species from the New Caledonia lagoon, which is subjected to important chemical inputs due to intense land-based mining activities (New Caledonia is the third largest world producer of Ni). The results of this baseline research indicated that livers generally concentrated trace elements to a greater extent than muscles. Nevertheless, the overall trace element concentrations in both tissues were barely above the levels reported in fish and thus contamination at the local scale was poorly discriminated.

Sorption-desorption kinetics and toxic cell concentration in marine phytoplankton microalgae exposed to Linear Alkylbenzene Sulfonate.

Linear Alkylbenzene Sulfonates (LAS) are ubiquitous surfactants. Traces can be found in coastal environments. Sorption and toxicity of C(12)-LAS congeners were studied in controlled conditions (2-3500 μg C(12)LAS/L) in five marine phytoplanktonic species, using standardized methods.

Characterization of ²⁴¹ Am and ¹³⁴Cs bioaccumulation in the king scallop Pecten maximus: investigation via three exposure pathways.

In order to understand the bioaccumulation of (241)Am and (134)Cs in scallops living in sediments, the uptake and depuration kinetics of these two elements were investigated in the king scallop Pecten maximus exposed via seawater, food, or sediment under laboratory conditions. Generally, (241)Am accumulation was higher and its retention was stronger than (134)Cs. This was especially obvious when considering whole animals exposed through seawater with whole-body concentration factors (CF(7d)) of 62 vs.

Validation of two tropical marine bivalves as bioindicators of mining contamination in the New Caledonia lagoon: field transplantation experiments.

The bioaccumulation and retention capacities of some key local contaminants of the New Caledonia lagoon (Ag, As, Cd, Co, Cr, Cu, Mn, Ni and Zn) have been determined in the oyster Isognomon isognomon and the edible clam Gafrarium tumidum during transplantation experiments. In a first set of experiments, oysters and clams from a clean site were transplanted into contaminated sites. Uptake kinetics determined in the field indicated that for Cr and Cu in oysters and Co, Ni, and Zn in clams, concentrations in transplanted bivalves reached those of resident organisms after 100d, whereas for the other elements, it would require a longer time for transplanted bivalves to reach the same levels as in the resident populations (e.

Cytogenetic and developmental toxicity of cerium and lanthanum to sea urchin embryos.

The aim of this study was to evaluate the toxicity of two rare earth elements (REE), cerium and lanthanum on sea urchin embryos and sperm. Sea urchin (Paracentrotus lividus) embryos were reared for 72 h in Ce(IV)- or La(III)-contaminated seawater at concentrations ranging from 10(-8) to 10(-5) M. Cleaving embryos (5h post-fertilization) were submitted to cytogenetic analysis, scoring mitotic activity and a set of mitotic aberrations.

Influence of food on the assimilation of selected metals in tropical bivalves from the New Caledonia lagoon: qualitative and quantitative aspects.

The present study aimed at examining the influence of food quality and quantity on the assimilation efficiency (AE) of metals in two abundant bivalves in the New Caledonia lagoon, the oyster Isognomon isognomon and the clam Gafrarium tumidum. Bivalves were exposed via their food to the radiotracers of three metals of concern in New Caledonia ((54)Mn, (57)Co and (65)Zn) under different feeding conditions (phytoplankton species, cell density, and cell-associated metal concentration). When bivalves were fed Heterocapsa triquetra, Emiliania huxleyi and Isochrysis galbana, AE of Mn, Co and Zn was strongly influenced by the phytoplankton species and by the metal considered.

Metal and metalloid bioconcentration capacity of two tropical bivalves for monitoring the impact of land-based mining activities in the New Caledonia lagoon.

The clam Gafrarium tumidum and the oyster Isognomon isognomon have been proposed as potential biomonitor species of metal contamination in the New Caledonia lagoon. The influence of dissolved concentrations of As, Cd, Co, Cr, Mn, and Zn on uptake and depuration kinetics, tissue and subcellular distribution of these elements was investigated in both species. Results indicate that both bivalves take up elements proportionally to the dissolved concentration for Cd, Cr and Mn in the surrounding water over the entire range of concentrations tested (three orders of magnitude), and up to the second and third highest added metal concentration tested for Co (23 ng l(-1)) and Zn (700 ng l(-1)), respectively.

Delineation of heavy metal contamination pathways (seawater, food and sediment) in tropical oysters from New Caledonia using radiotracer techniques.

Bioaccumulation of Ag, Cd, Co, Cr and Zn was studied in the oysters Isognomon isognomon and Malleus regula, using highly sensitive radiotracer techniques. Metals were readily bioconcentrated from the dissolved phase. Sediment exposures indicated a low bioavailability of sediment-bound metals (3-5 orders of magnitude lower than dissolved metals).