SHORE-LEVEL RELATED MORPHOLOGICAL AND PHYSIOLOGICAL VARIATIONS IN THE MUSSEL MYTILUS GALLOPROVINCIALIS (LAMARCK, 1819) (MOLLUSCA BIVALVIA) IN THE NORTH ADRIATIC SEA

SUMMARY A Mytilus galloprovincialis (Lamarck, 1819) (Mollusca Bivalvia) population on a rocky shore with a small vertical distribution (1 m) and subject to small tides (1 m) in the North Adriatic Sea was investigated. Biometrical and metabolic differences were found between the exposed high shore level and the more sheltered low shore level mussels. Low shore level M. galloprovincialis possess higher and narrower shells, and a higher dry weight/wet weight ratio. High shore subpopulations consume oxygen at a rate up to 45% higher than low level mussels.