The effects of copper exposure on the shore crab Carcinus maenas (L.) were investigated at constant and changing salinities. Crabs were acclimated to 20 ppt artificial seawater (SW)
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.
Nephrops norvegicus exposed to starvation and hypoxia in the field as well as in the laboratory exhibited marked differences in glycogen reserves, haemolymph haemocyanin concentrations, and tissue copper and manganese contents. Muscle glycogen concentration was reduced by ca 50% in lobsters collected from hypoxic field conhtions. Glycogen concentrations were reduced to ca 3 "/o of initial values in muscle and 10% in midgut gland following 7 mo starvation in the laboratory. Haemolymph haemocyanin concentration was markedly reduced in N. nowegicusexposed to severely hypoxic conditions although haemolymph copper concentration remained virtually unchanged. Starvation resulted in a slower reduction of haemocyanin concentration than was associated with hypoxia. Starvation resulted in a net loss of copper after 7 mo. Experimental exposures to moderate or severe hypoxia were not associated with net losses of copper, although in long-term moderate hypoxia the whole body copper load was redistributed, especially to the midgut gland increasing the concentration there 4 times. Redistribution of copper to the midgut gland did not occur in N. norvegicus exposed to severe hypoxia in the field. Threeto four-fold lower copper concentrations were found in the midgut glands of hypoxic lobsters (compared to controls from normoxic areas). As well as low copper concentrations, these lobsters had 2 to 4 times higher manganese concentrations in internal tissues. In the absence of sediment, manganese concentrations and contents were not influenced by laboratory exposure to hypoxia.
The spindle shell Hem~fusus ternatanus (Gmehn) may accumulate large quanhbes of arsemc m its bssues, exhib~ting on occaslon concentrations of total arsenic exceeding 100 pg g-' wet weight Investigation of the distribution of total and inorganic arsenic In tissues of this species has revealed that the majonty of the body load arsenic is present in the soft parts, as opposed to the operculum and shell The g111 In particular exh~bits very high concentrations of arsenic, much of which is present in the inorganic form It is probable that arsenlc is taken up by H ternatanus both from seawater and food, biotransformation of accumulated inorganic arsenic may occur in the g111 and possibly other hssues also The foot -that porbon of the ammal most commonly eaten by Mangenerally conta~ns only moderate concentrations of total arsenic and low levels of inorganic forms of the element Ingestion of tissues other than the foot may represent a toxicological hazard particularly in the case of the gill
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