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. IC(50) values ranged from 0.5 to 2 mg LAS/L. Sorption of (14)C(12)-6 LAS isomer was measured at environmentally relevant trace levels (4µg/L) using liquid scintillation counting. Steady-state sorption on algae was reached within 5h in the order dinoflagellate>diatoms>green algae. The sorption data, fitted a L-type Freundlich isotherm, indicating saturation. Desorption was rapid but a low LAS fraction was still sorbed after 24h. Toxic cell concentration was 0.38±0.09 mg/g for the studied species. LAS toxicity results from sorption on biological membranes leading to non-specific disturbance of algal growth. Results indicate that LAS concentrations in coastal environments do not represent a risk for these organisms.

Impact of chronic cadmium exposure at environmental dose on escape behaviour in sea bass (Dicentrarchus labrax L.; Teleostei, Moronidae).

The effect of chronic exposure to a low concentration (0.5 microg l(-1)) of cadmium ions was investigated on escape behaviour of sea bass, Dicentrarchus labrax, using video analysis. Observations were also performed on the microanatomy of lateral system neuromasts. When fish were exposed for 4h per day over 8 days to the cadmium ions, most of both types of neuromasts observed remained intact. However, some of them presented damaged sensory maculae. Whereas before cadmium exposure, fish responded positively to nearly all the lateral system stimulations, after exposure they decreased by about 10% their positive responses to stimulations. From the 15th day after the beginning of cadmium exposure, neuromasts presented progressively less damage, cadmium accumulation in gills and scales decreased significantly and fish escape behaviour had recovered. This study presents a new concept in ecotoxicology: using behavioural change to reveal the effects of pollution levels, scarcely detectable by currently used techniques (physiological responses).

Effects of cadmium on aneuploidy and hemocyte parameters in the Pacific oyster, Crassostrea gigas.

Pacific oysters, Crassostrea gigas, are commonly reared in estuaries where they are exposed to anthropogenic pollution. Much research has been made on the toxicity of cadmium to aquatic organisms because the compound recurrently contaminates their environment. Our study examined the influence of cadmium on aneuploidy level (lowered chromosome number in a percentage of somatic cells) and hemocyte parameters in C. gigas at different stages of life. Adults and juveniles were exposed to two different concentrations of cadmium. The first concentration applied was equivalent to a peak value found in Marennes-Oléron bay (Charente-Maritime, France; 50 ngL(-1)) and the second was 10 times higher (500 ngL(-1)). Exposure to 50 ngL(-1) cadmium caused a significant decrease in the survival time of C. gigas, but exposure to 500 ngL(-1) surprisingly affected the survival time positively. Significant differences in aneuploidy level were observed between the cadmium treatments and the control in adults but not in juveniles or the offspring of the adult groups. The effects of cadmium on hemocyte parameters were analyzed by flow cytometry. Several hemocyte parameters increased significantly after 21 days of cadmium exposure and subsequently decreased. Phenoloxidase-like activity, evaluated by spectrophotometry, varied over the time of the experiment and increased after 66 days of contact with 500 ngL(-1) cadmium. Taken together, cadmium at environmentally relevant concentrations seems to have only moderate effects on aneuploidy and hemocyte parameters.

Variation of heavy metal concentrations (Ag, Cd, Co, Cu, Fe, Pb, V, and Zn) during the life cycle of the common cuttlefish Sepia officinalis.

The developmental changes in the concentration of 8 essential and non-essential heavy metals (Ag, Cd, Cu, Co, Fe, Pb, V, Zn) in the tissues (digestive gland, cuttlebone and whole animal) of the common cuttlefish Sepia officinalis collected in the bay of the river Seine were monitored from the end of the embryogenesis until the adult reproductive stage. Compared to embryos, juveniles after hatching displayed much higher concentrations of Ag, Cu, Fe and Zn, suggesting an efficient incorporation from seawater. Conversely, the amounts of Cd, Pb and V in hatchlings remained constant suggesting that these metals are barely bioavailable for juveniles. Once the juveniles start to feed, the digestive gland appears to play a major role in the storage of all metals. After only one month of benthic life, the digestive gland already contains up to 90% of the total metal body burden, indicating that it plays a major role in the storage and presumed detoxification of the selected metals. Metal concentrations in the digestive gland increase in a logarithmic fashion with age during the entire life of cuttlefish, except for Ag, which decreases as soon as cuttlefish migrate to open sea. This strongly suggests that (1) Ag is excreted from the digestive gland in relation to presumably lower exposure in less contaminated environments compared to coastal waters and (2) the digestive gland of cephalopods could be a very good indicator of Ag contamination in the marine environment.

Impact of acute cadmium exposure on the trunk lateral line neuromasts and consequences on the "C-start" response behaviour of the sea bass (Dicentrarchus labrax L.; Teleostei, Moronidae).

Behavioural responses of sea bass Dicentrarchus labrax were investigated after exposure to cadmium ions in laboratory-controlled conditions. The aim of this study was to discover whether environmental exposure to cadmium ions inactivates fish lateral line system neuromasts, and to determine the behavioural consequences of such a sensory blockage. For this, fish escape behaviour in response to an artificial water jet was recorded using a 25-frames s(-1) analog video camera before and after cadmium exposure. Experimental set up was tested with fish whose lateral line system was artificially inactivated by antibiotics (gentamicin and streptomycin). Histological analyses with scanning electron microscopy showed antibiotic treatment destroyed lateral line system neuromasts. In addition, these fish did not respond to stimulations provoked by the water jet after antibiotic treatment. Fish escape behaviour was then recorded before and after cadmium exposure at two different concentrations. When fish were exposed to the first concentration of cadmium tested (0.5 microg l(-1), which represents the maximal cadmium concentration encountered in contaminated estuaries), no alteration in neuromast tissue was observed. In addition, before cadmium exposure, fish responded positively in 98.41 +/- 4.95% of lateral line system stimulations (escape behaviour in response to the water jet). After cadmium exposure, no behavioural modification could be detected: the fish responded positively in 95.16 +/- 9.79% of stimulations (chi(2) = 2.464, p = 0.116). In contrast, the high cadmium concentration used (5 microg l(-1), which represents 10 times the concentration occurring in highly polluted estuarine areas) involved severe neuromast tissue damage. Just after such cadmium exposure, fish showed only 41.67 +/- 35.36% of positive responses to their lateral line system stimulations, while they responded positively in 95.93 +/- 9.10% of stimulations under control conditions (chi(2) = 24.562, p < 0.0001). Their lateral line system neuromasts seemed to regenerate about 1 month after cadmium exposure. Associated with this regeneration, from the 21st day after cadmium exposure, their escape behaviour had recovered and was not significantly different from that recorded under control conditions (86.74 +/- 20.82%, chi(2) = 2.876, p = 0.090). This study shows that although 5 microg l(-1) cadmium is able to damage lateral line system neuromasts and causes fish behavioural alterations, fish exposed to 0.5 microg l(-1) cadmium displayed neither tissue neuromast nor behavioural modification.

Evaluation of the variegated scallop Chlamys varia as a biomonitor of temporal trends of Cd, Cu, and Zn in the field.

This study assesses the potential of the scallop Chlamys varia as a biomonitor of metal contamination in the field. Cd, Cu, and Zn concentrations were determined in the soft tissues and organs of individuals from the French Atlantic coast sampled over a 1 year period and covering a wide range of size. All metals were selectively distributed among the different body compartments considered, and their concentrations were influenced by the size of the specimens or the sampling-season. The present work shows the importance of considering the body compartment, the sampling period and the size in studies aiming at using this scallop as a biomonitor species. Among tissues, the digestive gland and kidneys exhibited the highest metal concentrations whatever the season or the size. The digestive gland contained 65 and 48% of the whole Cd and Cu body burdens, respectively, and kidneys accounted for 85% of the Zn load. Those tissues are therefore particularly recommended for use in biomonitoring programs.

Subcellular and body distributions of 17 trace elements in the variegated scallop Chlamys varia from the French coast of the Bay of Biscay.

Seventeen elements were analysed in the organs and tissues of the variegated scallop Chlamys varia, from the Atlantic coast of France. Concentration levels were determined in scallops of different sizes sampled in contaminated (La Rochelle Bay) and clean (Re Island) sites. Greater concentrations of Ag, Al, Ce, Cr, La, Mo, Nd, Ti, and V were found in the digestive gland while As, Cd, Co, Cu, Mn, Ni, Pb, and Zn were the highest in the kidneys. In the digestive gland, most of the metals were found in the insoluble fraction while As, Co, Cd, Mo, Ni, and V appeared to be mostly bound to soluble compounds. Among tissues, the adductor muscle always displayed the lowest trace element concentrations. According to size, Ag and Cd showed significantly higher concentrations in larger individuals, while Co and Zn were higher in the smallest ones. According to the sampling area, most of the metals, Ag, Al, Ce, Co, Cu, La, Mn, Nd, Pb, and Zn, showed significantly higher concentrations in La Rochelle Bay compared to the Re Island, reflecting differing inputs from industrial, domestic and harbour activities. However, Cr, Mo, Ni, Ti, and V concentrations did not display significant differences between sites and As and Cd were significantly higher at the Re Island. This study highlighted the ability of the variegated scallop C. varia to concentrate numerous trace elements to high levels, even those reported as poorly bioavailable for marine biota, such as rare earth elements.

Interspecific and geographical variations of trace element concentrations in Pectinidae from European waters.

Cd, Cu and Zn were analysed in the organs and tissues of the three scallop species from the Bay of Biscay, the variegated Chlamys varia L., the queen scallop Aequipecten opercularis L. and the common scallop Pecten maximus L. for interspecific comparisons. In P. maximus the greatest concentrations of Cd and Cu were found in the digestive gland, whereas the two other species showed similar levels of Cd between digestive gland and kidneys and higher renal Cu concentrations. However, the digestive gland of all Pectinidae species contained from 75% to 93% and 52% to 74% of the total body burdens of Cd and Cu, respectively. Whatever the species, kidneys displayed the highest Zn concentrations, which therefore contained from 53% to 97% of the total body burden of this metal. Also using reported results, ratios between the concentrations in the digestive gland and that in the kidneys discriminated two groups of Pectinidae: (1) the Pecten group (P. maximus, P. jacobeus and Adamussium colbecki) with a Cd ratio > or = 4, a Cu ratio > or = 1 and a Zn ratio > 20x10(-3); (2) the Chlamys group with a Cd ratio < or = 1, a Cu ratio < or = 1 and a Zn ratio < or = 6x10(-3). However, no differences in the detoxification processes in the digestive gland were found between groups in this study. 72-80% of the total Cd was found to be soluble, probably bound to metalloproteins such as metallothioneins, while Cu and Zn were mainly found associated to the insoluble fraction of the digestive gland cells whatever the species. Queen scallops from the Faroe Islands were also considered to examine variations of the metal concentrations due to the geographical origin. In this northern area, queen scallops displayed Cd concentrations 2, 4 and 6 times higher in kidneys, muscle and digestive gland, respectively, compared to those from the Bay of Biscay. Consequently, the Cd concentrations in the whole soft parts of the queen scallops were more than 6 times higher in the Faroe Islands than in the Bay of Biscay. In contrast to Cd, both Cu and Zn concentrations in the whole soft parts were 2 times lower in the Faroe Islands, suggesting lower bioavailability of these essential elements.