Ja. Nott et A. Nicolaidou, KINETICS OF METALS IN MOLLUSCAN FECAL PELLETS AND MINERALIZED GRANULES, INCUBATED IN MARINE-SEDIMENTS, Journal of experimental marine biology and ecology, 197(2), 1996, pp. 203-218
Marine snails excrete metals via the gut. The sediment-feeding, tower
shell Cerithium vulgatum, from a polluted environment, accumulates Cr
and Ni to 3500 ppm dry weight in the faecal pellets. Pellets from C. v
ulgatum acid the grazing, top shell Monodonta mutabilis were incubated
in surface and deeper anoxic layers of clean and metal-polluted sedim
ent. Pellets retained the original load of metals and in some cases ga
ined Ti, Cr, Mn, Fe and Ni. Effects were modified by sediment properti
es. Pellets of C. vulgatum are durable, membrane-bound structures and
they reduce metal bioavailability to food chains by compartmentalizati
on. Intracellular, phosphate granules bind metals in digestive glands
of snails and they are excreted via the gut and faecal pellets. These
granules were extracted from digestive glands of both species of snail
and incubated in the same sediments. Magnesium phosphate granules fro
m M. mutabilis dissolved but calcium/metal phosphate granules from C.
vulgatum remained; they had differentially retained or lost Mn, Fe, Co
, Ni acid Zn according to the type of sediment.