Effect of chronic exposure to zinc in young spats of the Pacific oyster (Crassostrea gigas)

Abstract

The marine coastal environment is exposed to a mixture of environmental pollutants of anthropogenic origin, resulting in chronic low concentrations of contaminants. As a consequence, most coastal marine species are exposed to low doses of such pollutants during their entire life. Many marine species live for years in their natural environment, whereas they do not under laboratory exposure conditions. Using early stages of development in laboratory work allows animals to be chronically exposed from an early age over a reasonable experiment period. In the present study, the authors investigated the effect of chronic exposure to zinc in spats of the Pacific oyster (Crassostrea gigas), from metamorphosis up to 10 weeks. The authors investigated integrated biological endpoints that would account for the apparent general health of the animals as well as molecular markers showing more subtle effects that could potentially go unnoticed at a biologically integrated level. The authors measured in parallel both growth and the transcriptional level of target stress genes. Growth was monitored by image analysis of large samples to avoid high variability and ensure statistical robustness. A dose-response relationship was derived from growth data, yielding a median effective concentration (EC50) of 7.55 µM. Stress genes selected on the basis of available RNA sequences in C. gigas included genes involved in chaperone proteins, oxidative stress, detoxification, and cell cycle regulation. Out of nine stress target genes, only metallothionein displayed overexpression in response to high levels of zinc.

Physiological perturbations in juvenile cuttlefish Sepia officinalis induced by subchronic exposure to dissolved zinc

“…This result further supports the high sensitivity of juvenile cuttlefish in comparison to the fresh water crustacean Daphnia magna (3-week LC 50 = 840 lg l À1 ; Enserink et al, 1991), and to adult and juvenile stages of C. gigas which 7-week exposure at concentrations above 500 lg l À1 did not induce mortality (Devos et al, 2012;Mottin et al, 2012). Our data suggest the existence of a Zn lethality threshold in juvenile cuttlefish.…”

“…Recently, Devos et al (2012) measured a 50% effect concentration for growth (i.e. concentration that induced 50% reduction of parameter studied, EC 50 ) on oyster spat, C. gigas, after 1-week exposure to 497 lg l À1 Zn, whereas Dorgelo et al (1995) reported an EC 50 value of 103 lg l À1 after more than 10-weeks Zn exposure to freshwater snail Potamopyrgus jenkinsi.…”

Gills are an initial target of zinc oxide nanoparticles in oysters Crassostrea gigas, leading to mitochondrial disruption and oxidative stress

“…These data are corroborated by an increase in lipid peroxidation and metallothionein levels in freshwater mussels (Gagné et al, 2013) or behavioral disturbances and increased catalase activity in marine clams (Buffet et al, 2012). In contrast, soluble zinc toxicity to bivalves is well documented, with accumulation occurring mainly in epithelial tissues (George and Pirie et al, 1980) impaired development (Fathallah et al, 2010) and physiology (Hietanen et al, 1988), oxidative and cellular stress (Devos et al, 2012;Franco et al, 2006;Trevisan et al, 2013) and immunologic disturbance (Taylor et al, 2013).…”

Trace metal concentrations in post-hatching cuttlefish Sepia officinalis and consequences of dissolved zinc exposure

“…For all 3 batches (control and the 2 exposure conditions), 20 ml of seawater was sampled daily, immediately acidifed with 1% nitric acid (HNO 3 69.5%, Normapur grade), and stored at 4°C until analyses. Zn concentrations in the seawater were determined as previously described in Devos et al (2012). Triplicate analyses were done on each sample and the mean values were used for evaluation.…”