THE TRACE-METAL ECOLOGY OF ICHTHYOFAUNA IN THE ROCKALL TROUGH, NORTH-EASTERN ATLANTIC

The concentrations of Cu, Mn, and Ni in tissue samples from 230 fish f rom the Rockall Trough were determined by atomic absorption spectropho tometry. Concentrations of Cu, Mn and Ni were 0.02-23 mu g g(-1) 0.02- 6.5 mu g g(-1) and 0.02-10 mu g g(-1) respectively. Cu appeared to sel ectively accumulate in liver tissues while Mn accumulated in gill tiss ues. Ni was evenly distributed throughout all tissues examined. Concen trations of all three metals generally decreased with length. Inter-sp ecific differences between teleosts were found to be related to differ ences in feeding behaviour. There was no apparent concentration of met als through the food chain from prey to sharks. Low concentrations of Cu, Mn and Ni were detected in the water column (Cu 86-103 ng l(-1), M n <75 ng l(-1), Ni 210-224 ng l(-1)), suggesting that for sharks in th e Rockall Trough, the uptake of metals from diet is of more importance than that from the water column. Metallothionein-like proteins were d etected in liver samples from nine species of deep-water shark. Concen trations were similar in all species (8-10 mu g g(-1)) and were indepe ndent of hepatic Cu and Cd. It is suggested that these proteins are in volved in the homeostasis of essential trace metals.