Pharmacokinetics and distribution of dietary tributyltin compared to those of methylmercury in the American plaice Hippoglossoides platessoides

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111

We experimentally determined the assimilation efficiency (AE) of ingested prey, the uptake-rate constant from the aqueous phase, and elimination-rate constant of both inorganic Hg (Hg [II]) and methylmercury (MeHg) in a marine predatory fish, the sweetlips Plectorhinchus gibbosus, using radiotracer techniques. The AE of Hg(II) and MeHg ranged between 10 and 27% and between 56 and 95%, respectively, for 3 different prey (copepods, silverside, and brine shrimp). The ingestion rate of the fish did not significantly affect the AE of Hg(II). Uptake of both species of Hg proceeded in a linear pattern, and the calculated uptake-rate constant was 0.195 and 4.515 l g -1 d -1 for Hg(II) and MeHg, respectively. Most of the accumulated Hg(II) was distributed in muscle tissues, whereas the accumulated MeHg was distributed evenly between gills and muscle tissues. The calculated elimination-rate constants for MeHg were 0.0103 and 0.0129 d -1 following dietary and aqueous uptake, respectively, whereas the elimination-rate constant of Hg(II) following dietary uptake (0.0547 d -1 ) was 1.9 times higher than the elimination following aqueous uptake (0.0287 d -1 ). These experimentally determined values were incorporated into a kinetic model to predict the exposure pathways and the relative contribution of Hg(II) and MeHg to the sweetlips. At the high end of the bioconcentration factor for both species of Hg in the prey, dietary ingestion is likely to be the main channel for their accumulation in the fish. The relative contribution of Hg(II) vs MeHg to the overall Hg bioaccumulation is largely controlled by the relative concentration of MeHg dissolved in seawater. Similar to the results of numerous field studies, the kinetic model predicted a potential trophic transfer factor of < 0.6 for Hg(II) and >1 for MeHg under conditions likely to be experienced by the fish in its natural environment. KEY WORDS: Mercury · Methylmercury · Exposure · Fish · Kinetic modeling Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 261: [257][258][259][260][261][262][263][264][265][266][267][268] 2003 bioavailability of these Hg species in marine fishes are less well studied (Pentreath 1976a,b, Honda et al. 1978, Barkay et al. 1997, Rouleau et al. 1998.Most previous studies measured the concentration of different Hg species in different tissues of fishes (Leah et al. 1991, Monteiro et al. 1996, Joiris et al. 2000. The routes of Hg accumulation, including the relative importance of different Hg species (inorganic and organic) and exposure pathways (aqueous vs dietary),are not yet well understood. Whereas it has generally been assumed that fishes accumulate MeHg mainly from dietary sources through very efficient assimilation of this compound (Mason 2002), it is quite possible that, because of its highly efficient absorption properties, they accumulate it from the aqueous phase also. Experimental studies on the routes of methylmercury exposure in fishes are indeed rather controversial (Honda et...

Section: Introductionmentioning

confidence: 99%

“…Mar Ecol Prog Ser 261: [257][258][259][260][261][262][263][264][265][266][267][268] 2003 bioavailability of these Hg species in marine fishes are less well studied (Pentreath 1976a,b, Honda et al 1978, Barkay et al 1997, Rouleau et al 1998.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Bioaccumulation kinetics and exposure pathways of inorganic mercury and methylmercury in a marine fish, the sweetlips Plectorhinchus gibbosus

Wang¹,

Wong²

2003

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111

“…Radioactivity in all water samples was below the detection limit of 0.05 Bq ml -1 . Whole-body 109 Cd activity was repeatedly monitored over 154 d, using an in vivo gamma counting system consisting in a 3 inch (ca 76 mm) NaI(Tl) gamma detector (Canberra-Packard, Meriden, CT) fitted into a 2 cm thick cylindrical Pb shield with a 0.6 cm thick copper-brass inside lining (Rouleau et al 1998, Rouleau et al 2000. The detector-shield assembly was fixed onto a specially designed stand and placed at 40 ± 0.5 mm above the crabs, which were placed upside down, motionless, and positioned on a target drawn on plastic plate cut to the exact size of the base of the stand.…”

Section: Methodsmentioning

confidence: 99%

Cadmium accumulation in the snow crab Chionoecetes opilio

Rouleau¹,

Gobeil²,

Tjälve³

2001

Self Cite

The aim of this work is to evaluate the significance of Cd uptake via food in the snow crab Chionoecetes opilio. We used in vivo gamma counting to measure the retention efficiency of a single dietary dose of 109 Cd(II) and follow elimination kinetics of the metal retained over a 5 mo period. Whole-body autoradiography was used to determine the fine-scale tissue distribution. The biological half-life of Cd retained in the body after the first 15 d, which represented 26 to 52% of the ingested dose, ranged from 141 to 346 d. Whole-body autoradiography showed that 109 Cd was distributed to all the tissues, highest concentrations being found in the hepatopancreas and gut, followed in decreasing order by antennal glands ≥ hemolymph > gonads > gills ≈ hypodermis ≈ muscle > eye. We used these data and a reasonable estimate of Cd levels in benthic organisms of lower trophic levels living in the Estuary and Gulf of St. Lawrence to model the long-term dietary uptake of Cd in snow crab. Predicted concentrations in hepatopancreas and muscle agreed quite well with field data (predicted range 13.0 to 39.2 nmol Cd g -1 and field range 3.5 to 24.1 nmol Cd g -1 for hepatopancreas; predicted range 0.20 to 1.33 nmol Cd g -1 and field range 0.52 to 2.03 nmol Cd g -1 in muscle). The similarity between experimentally based predictions and field data strongly suggests that diet is a major transfer route of Cd towards snow crab in the St. Lawrence.

“…Cd activity was repeatedly monitored over 42 d in the viscera and caudal muscle with an in vivo gamma counting system described elsewhere (Rouleau et al 1998). Fish were anesthetized prior to radioactivity measurements and the 88 keV γ-ray emission of 109 Cd was monitored for 1 to 3 min, daily during the first 7 d and then every 2 to 4 d thereafter.…”

mentioning

confidence: 99%

“…50 g, were each given 0.5 g of the 109 Cd-contaminated food (2.5 μg Cd or ca. 50 μg Cd kg -1 body weight) and sampled 7 d after feeding to be used for whole-body autoradiography, as described previously (Ullberg et al 1982, Rouleau et al 1998.…”

mentioning

confidence: 99%

Cadmium accumulation in coastal demersal fish

Rouleau¹,

Gobeil²,

Tjälve³

2006

Self Cite

The hepatic Cd burden, measured on 291 individuals of 4 species of demersal fish (Gadus morhua, Reinhardtius hippoglossoides, Hippoglossoides platessoides, and Raja radiata), is 2 to 5 times higher in fish from the open Gulf of St. Lawrence than in fish from the St. Lawrence Estuary, 600 km landward. The higher Cd burden in the open Gulf is not related to the input of anthropogenic Cd, nor can it be attributed to differences in size, sex, sampling season, or state of health. Rather, the Cd burden in demersal fish may be related to sediment diagenesis, since the concentration of authigenic Cd (i.e. Cd minerals formed in the sediments) is higher in the Gulf than in the Estuary, which may lead in turn to Cd-enrichment in sediment-dwelling organisms. Measured Cd burdens in the liver agree with predictions made with a simple biokinetic model that uses realistic estimates of the Cd content of benthic invertebrates in combination with kinetic parameters determined in H. platessoides with in vivo gamma counting. These results strongly suggest that the Cd content of the diet, rather than of the water phase, determines the hepatic Cd burden in these demersal fish species.