Manganese in the haemolymph and tissues of the Norway lobster, Nephrops norvegicus (L.), along the Swedish west coast, 1993-1995

Spatial and temporal differences in manganese levels in Norway lobsters, Nephrops norvegicus, were compared with the concentrations of manganese in their environment. Animals were collected twice yearly (spring and autumn) from seven stations along the Swedish west coast and from one site in the Faroe Islands, during 1993-94, and analysed for manganese tissue concentration and content. Animals were also collected from the Swedish stations in the autumn of 1995 and compared with animals from a stressful environment, frequently exposed to hypoxia. There were large spatial differences and the animals collected in the Faroe Islands contained (in most tissues) one order of magnitude less manganese than the animals collected along the Swedish west coast. The manganese level of the haemolymph correlated most closely with the manganese concentration the animal was exposed to in the field. The manganese concentration of the female gonad tissue did however not differ with space nor time and remained stable around 5.1 mu g Mn g(-1) dw tissue throughout the investigation. Animals taken from an area with known repeated hypoxia in the bottom water, had high levels of manganese in especially the gills. Their mean manganese concentration was over 20 times higher (1560 mu g Mn g(-1) dw tissue) than the manganese concentration in animals from the other Swedish stations. They also had more than threefold the amount of manganese in the brain, giving a mean concentration of 193 mu g Mn g(-1) dw tissue.