Experimental design with different temperature, food and oxygen levels. a. Basins (coloured rectangles) with three replicate tanks (open black circles) containing five suspended nets (solid black circles) with ten individuals per species and origin (Dutch Mytilus edulis, Danish Mytilus edulis, Portugese Mytilus galloprovincialis, Dutch Crassostrea gigas and Dutch Ostrea edulis). b. Replicate tanks (black circles) containing 41 individually marked mussels Mytilus edulis from Dutch and Danish origin (black and grey ellipses). Main supply of water with aeration or N₂ providing three different O₂ saturation levels to the different replicates.