GLYCOGEN DEPLETION AND ALTERED COPPER AND MANGANESE HANDLING IN NEPHROPS-NORVEGICUS FOLLOWING STARVATION AND EXPOSURE TO HYPOXIA

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 conditions. Glycogen concentrations were reduced to ca 3 % 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. norvegicus exposed 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. Three- to 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.