Recovery Dynamics in Benthic Communities: Balancing Detail with Simplification
303
opportunistic «boom and bust" abundance could be influenced by demographics. Some species that do achieve high densities in disturbed patches are
highly mobile and quite effective at utilising patchy/ephemeral resources
(e.g., Van Blaricom 1982; Oliver and Slattery 1985). These types of species
operate over broader scales than individual patches and their demographics
are more influenced by the landscape of patches rather than tied to events
within a single patch. This type of response is often associated with subtidal
pits created by feeding predators. A number of studies of recolonisation of
intertidal pits have failed to indicate any resource exploitation; rather
recolonisation occurred through the passive movement of animals from the
surrounding sediments (Levin 1984; Savidge and Taghon 1988; Thrush et al.
1991). This intertidal pattern is probably due to tidal currents and wind-waves
mobilising surficial sediments and quickly transporting sediment and organisms into pits. Demonstration of opportunistic responses requires opportunists that are present in the ambient species pool, as well as a high level of
resources within the disturbed area that are not overwhelmed by fluxes across
the patch boundary.
14.3.5 Biotic Interactions
The role of early colonists ameliorating sediment biogeochemical conditions
for subsequent species is important in the classic succession model for marine
benthos (Rhoads 1974). Connell and Slatyer (1977) categorised the interactions between species that influence the successional process as facilitation
(i. e. positive effect), tolerance (i. e. no effect), and inhibition (i. e. negative
effect). Gallagher et al. (1983) concluded that tube-builders usually facilitate
recruitment (see also Noji and Noji 1991). However, manipulative experiments conducted by Whitlatch and Zajac (1985) contrasted with those of
Gallagher et al. (1983) and failed to demonstrate a consistent role for a variety
of opportunistic species, including tube-builders. Whitlatch and Zajac (1985)
concluded that the difference in the outcome of their experiment relative to
Gallagher et al. (1983) was a result of the initial densities used in the two
experiments, thus indicating that facilitation, tolerance and inhibition in
biotic interactions are likely to be density dependent. Other experiments have
demonstrated density- and location-dependent variation in the strength and
direction of effects of one species on another during the recovery processes
(Thrush et al. 1992, 1996b, 1997b). Connell et al. (1987) recognised that the
strengths and directions of interactions between colonists may vary over the
successional processes. In the multi-species context, identifying the importance of facilitation, tolerance, or inhibition during the successional process
will be complicated. But, given that in studying succession we are interested in
the patterns that emerge through time from one location, should we simply
303
opportunistic «boom and bust" abundance could be influenced by demographics. Some species that do achieve high densities in disturbed patches are
highly mobile and quite effective at utilising patchy/ephemeral resources
(e.g., Van Blaricom 1982; Oliver and Slattery 1985). These types of species
operate over broader scales than individual patches and their demographics
are more influenced by the landscape of patches rather than tied to events
within a single patch. This type of response is often associated with subtidal
pits created by feeding predators. A number of studies of recolonisation of
intertidal pits have failed to indicate any resource exploitation; rather
recolonisation occurred through the passive movement of animals from the
surrounding sediments (Levin 1984; Savidge and Taghon 1988; Thrush et al.
1991). This intertidal pattern is probably due to tidal currents and wind-waves
mobilising surficial sediments and quickly transporting sediment and organisms into pits. Demonstration of opportunistic responses requires opportunists that are present in the ambient species pool, as well as a high level of
resources within the disturbed area that are not overwhelmed by fluxes across
the patch boundary.
14.3.5 Biotic Interactions
The role of early colonists ameliorating sediment biogeochemical conditions
for subsequent species is important in the classic succession model for marine
benthos (Rhoads 1974). Connell and Slatyer (1977) categorised the interactions between species that influence the successional process as facilitation
(i. e. positive effect), tolerance (i. e. no effect), and inhibition (i. e. negative
effect). Gallagher et al. (1983) concluded that tube-builders usually facilitate
recruitment (see also Noji and Noji 1991). However, manipulative experiments conducted by Whitlatch and Zajac (1985) contrasted with those of
Gallagher et al. (1983) and failed to demonstrate a consistent role for a variety
of opportunistic species, including tube-builders. Whitlatch and Zajac (1985)
concluded that the difference in the outcome of their experiment relative to
Gallagher et al. (1983) was a result of the initial densities used in the two
experiments, thus indicating that facilitation, tolerance and inhibition in
biotic interactions are likely to be density dependent. Other experiments have
demonstrated density- and location-dependent variation in the strength and
direction of effects of one species on another during the recovery processes
(Thrush et al. 1992, 1996b, 1997b). Connell et al. (1987) recognised that the
strengths and directions of interactions between colonists may vary over the
successional processes. In the multi-species context, identifying the importance of facilitation, tolerance, or inhibition during the successional process
will be complicated. But, given that in studying succession we are interested in
the patterns that emerge through time from one location, should we simply