Influence of physiological condition on cadmium transport from haemolymph to hepatopancreas inCarcinus maenas

Effects of salinity on the accumulation of Zn and Cd in the haemolymph (relative indices of Zn and Cd uptake rates) of 2 populations of shore crab Carcinus maenas (L.) were investigated. Zn accumulation rates in the haemolymph of the Scottish (high salinity) crabs were higher than those of the Danish (low salinity) crabs. Decreases in salinity significantly decreased the Zn accumulation rate in the Scottish crabs but increases in salinity did not change the Zn accumulation rates in the Danish crabs significantly. Scottish crabs also showed a higher Cd accumulation rate, as well as elimination rate, than those of the Danish crabs. The highest Cd accumulation rate in Scottish crabs was found at 33 ppt salinity. In contrast the Cd accumulation rate of Danish crabs was highest at 15 ppt. It is proposed that exposure of the crabs to low salinity probably involves changes to crab permeability (e.g. apparent water permeability), thereby off-setting physico-chemical changes promoting the availabilities of free zinc and cadmium ions in solution which would otherwise increase metal uptake rates.

Section: Discussionmentioning

confidence: 99%

Uptake of zinc and cadmium by two different populations of shore crabs Carcinus maenus at different salinities

Chan¹,

Bjerregaard²,

Rainbow³

et al. 1992

“…Inorganic and organic mercury were determined accordmg to RiisgArd & Hansen (1990) and selenium and total mercury (in carapace) were analysed as described by Sarensen & Bjerregaard (1991). Tissue homogenisation and gel filtration procedures used in the determination of the subcellular distribution of mercury and selenium were described in Bjerregaard (1990) …”

Section: Methodsmentioning

confidence: 99%

Accumulation of organic and inorganic mercury from food in the tissues of Carcinus maenas: effect of waterborne selenium

Bjerregaard¹,

Christensen²

1993

Accumulation of organic and inorganic mercury from contaminated food into the tissues of selenium-and non-selenium-exposed shore crabs Carcinus maenas were investigated in the laboratory. Crabs fed homogenates of Cardiurn edule collected in the mercury-contaminated Nissum Bredning, Jutland, Denmark, assimilated 50 to 60 % of ingested inorganic and organic mercury. Muscle and midgut gland contained approxin~ately 50 to 60 % and 40 % respectively of both asslmilated mercury species. Simultaneous exposure to selenite augmented accumulation of organic mercury in muscle and increased assimilation of organic mercury from the food. Accumulation of inorganic mercury was not affected by exposure to selenite. When the mercury concentration of the food was increased 10-fold (by the addition of HgClz and CH3HgCl directly to the cockle homogenate), a higher percentage of the ingested inorganic mercury was assimilated by the crabs, 95 % of the inorganic mercury being accumulated in the rnidgut gland. Percent assimilation and tissue distribution of organic mercury was less affected by increasing the concentration in the diet. The subcellular distribution of the 2 mercury species was almost identical. In the soluble fraction both mercury species were bound predominantly to proteins with a molecular weight (MW) of ca 12 000 Da. In the soluble fraction, exposure to selenite diverted mercury from the 12 000 Da region to high (MW > 70 000 Da) or very low (MW c 4000 Da) molecular weight proteins. Injected organic mercury was cleared from the haemolymph more rapidly than inorganic mercury, and clearance of both mercury species from the haemolymph proceeded faster in selenite-exposed crabs.

“…Fluctuations of haemolymph copper and protein concentrations are linked with crustacean blood volume changes, the haemolymph volume decreasing in Penaeus spp. (Smith & Dall 1982) and in Carcinus rnaenas (Bjerregaard 1990) as haemolymph protein concentrations increase. Changes in haemolymph volume and protein concentrations are consequently related to the moulting cycle and food supplies (Smith & Dall 1982).…”

Section: Introductionmentioning

confidence: 99%

Seasonal changes of the copper level in shore crabs Carcinus mediterraneus

Devescovi¹,

Lucu²

1995

Seasonal changes in copper content of the shore crab Carcinus mediterraneus Csrn. (whole crab, haemolymph, hepatopancreas and exoskeleton) were studied to establish patterns and to examine fluctuations in the population. A significant decrease in copper content in the haernolymph and hepatopancreas and an increase in the copper space (taken as an estimation of the haelnolymph volume) occurred in winter. These changes are closely related to the drops in the protein and copper haemolyrnph concentrations of the winter crab populations when their activities and food intake are significantly decreased The copper space strongly correlates with the haemolymph copper content and with the haernolymph copper concentration. On the basis of the haernolymph copper deterrninatlons a model of the copper space is described