INTRODUCTION
Because of their high productivity and allochthonous
organic-matter input, estuarine systems are hospitable for
feeding and reproduction of many species of fish and
invertebrates, in at least one stage of life (Day et al. 1989).
The benthos includes a set of animals belonging to a variety
of invertebrate groups including polychaetes, molluscs,
crustaceans, and nemertine worms, and which have direct