p. 7 - 24 THE ROLE OF Mya arenaria L. POPULATIONS IN COASTAL SEDIMENTARY PROCESSES M-T Gomoiu Institut Roumain de Recherches Marines Constanta Abstract The observations and measurements carried out at Mamaia (the Romanian black Sea coast) between 1977-1981 led to the conclusion that every year the storms transport and deposit on a 1 metre beach lengh an average quantity of nearly 7 tons of Mya arenaria (out of them 2.4 tons of calcarous shells) which accumulate on the shore and modify the chemical and granulometric composition of sediments. So far as the supply of mineral sediemnts carried by the danube mainly, has diminuished, the role of mya arenaria populations in sedimentary processes has become predominant on the beaches North of Constanta.