Polychaetes are well represented in most marine and estuarine environments,
both in terms of number of individuals and species, and they typically con
tribute a significant percentage of the total macrofaunal diversity. They e
xhibit considerable variations in recruitment in both time and space, which
is then often reflected in adult distributions. Whilst families and genera
of polychaetes have wide distributions, normally species have discrete dis
tributions. Polychaetes are often classified according to their diverse fee
ding guilds. They play a major role in the functioning of benthic communiti
es, in terms of recycling and reworking of benthic sediments, bioturbating
sediments and in the burial of organic matter. Some species form dense tubi
culous colonies which can radically change recruitment patterns of other in
faunal organisms. Polychaetes, by their burrowing and feeding activity, may
considerably enhance various sedimentary processes. However, much remains
to be learnt as to how benthic communities function, and how they may chang
e in function as they are increasingly being impacted especially in coastal
waters adjacent to centres of population.