Mussels were then individually fed on 14C-labeled diets in 1-l beakers containing 800 ml of water (natural seston with 14C-labeled particle) for the first 2 h of a 6-h period of submergence (i.e., ApulseB period.) After 2 h, mussels were transferred to clean 1-l beakers having 800 ml of nonlabeled-25 mm filtered marsh water in which they were permitted to feed normally