Download (20MB) - Repository@Napier

larvae (Santos and Simon, 1980a; Levin, 1984a; Strathmann, 1986), experiments have
shown that small-scale patches of disturbed sediments are often initially dominated by
species with benthic dispersal (Levin, 1984a; Savidge and Taghon, 1988; Frid, 1989;
Smith and Brumsickle, 1989). However, the role of post-larval colonisation of
disturbed sediments has also been shown to be important at both large and small
scales (Dauer and Simon, 1976a; Thistle, 1981; Zajac and Whitlatch, 1982a; Levin,
1984a; Frid, 1989; Smith and Brumsickle, 1989; Gunther, 1992; Thrush et al., 1992;
Turner et al., 1997). Santos and Simon (1980b) suggested however that it is possible
to incorrectly infer adult colonisation when sampling intervals are too long and/or
sieve mesh sizes are too large to detect larval colonisation.
Connell and Slatyer (1977) proposed four generalised models for community
assembly during succession. These were the facilitation, inhibition, tolerance and the
random colonisation models. Many studies have been performed to elucidate which
of these predominate within marine soft-bottom environments (e.g., Woodin 1981;
Gallagher et al., 1983; Whitlatch and Zajac, 1985; Trueblood, 1991) and in general,
succession proceeds via a mixture of different kinds of interactions rather than one
single model prevailing. Whitlatch and Zajac (1985), however, concluded that
although biotic interactions between opportunistic organisms were important in
controlling successional dynamics, the type of interaction ultimately depended upon
the species present, their density and the habitat conditions. Dense aggregations of
polychaetes' tubes have been shown to stabilise sediments by altering the
characteristics of near-bed flow (Eckman et al., 1981) and have been shown to be
particularly important in affecting the early stages of faunal succession (Levin, 1981,
1982; Gallagher et al., 1983; Whitlatch and Zajac, 1985; Noji and Noji, 1991).
Therefore, colonisation following disturbances within polychaete tube-beds are likely
to have different successional dynamics compared with those outside tube-beds.
Most studies investigating community establishment have followed species and
community responses to disturbances which have occurred at only one point during
the year and/or within only one type of habitat. However, since the colonisation
potential of most species is predominantly governed by their larval availability at any
one time (Bonsdorff and Osterman, 1984; Levin, 1984a; Ragnarsson, 1996), the
132