Recovery Dynamics in Benthic Communities: Balancing Detail with Simplification
301
14.3 Some General Mechanisms Influencing Recovery
14.3.1 Seasonality
Many environmental factors potentially important to the recovery process
vary with season. For example, water temperature may influence the seasonal
availability of larval and juvenile recruits. The strength of temperature effects
may be expected to vary with latitude and climate (stronger seasonal
variation in air and coastal water temperatures are found on continental land
masses rather than islands). In the wet tropics, strong seasonal effects can be
generated by seasonal changes in freshwater inputs (Alongi 1990). Zajac and
Whitlatch (1982a,b) demonstrated that rates of recovery increased in experiments conducted in spring and summer compared to those conducted at
other times of the year. Similarly, Ford et al. (1999) demonstrated rates of
recolonisation were slow in winter compared to summer and that seasonal
differences in recovery rate were linked to the density of the dominant taxa
that were typically more abundant in the summer. For long-lived species,
Zajac and Whitlatch (1989) demonstrated that the demographic state of the
population at the time of disturbance had an important influence on its
recovery. Other factors, such as benthic primary production or wave climate,
may also influence recovery dynamics and vary with season or other longterm cyclical atmospheric/oceanographic processes (e.g., El Nino Southern
Oscillation).
14.3.2 Hydrodynamics
Hydrodynamic conditions can have a profound influence on benthic recovery
processes (e.g., Eckman 1983; Jumars and Nowell 1984; Butman 1987; Hall
1994; Paterson and Black 1999). Water depth and flow characteristics
influence benthic food quality and quantity and the supply of colonists to
disturbed patches. Water depth will also influence the type of waves that
expend energy on the seabed. On sand flats, small wind-waves that generate
1-2 cm high sand ripples can be particularly important in resuspending
animals and sediments so that tidal currents can transport them (Bell et al.
1997). Hydrodynamic processes associated with the mobility of macrofauna
have a major influence on the scale of disturbance needed to detect differences in the relative importance of adult, juvenile and larval colonists. Even in
quiescent mudflat environments tidal flows may be sufficient to transport
post-settlement macrofauna to defaunated plots (Thrush and Roper 1988).
Whitlatch et al. (in press) reviewed shallow-water experimental defaunation
experiments and found no clear evidence for differences in the rate of
301
14.3 Some General Mechanisms Influencing Recovery
14.3.1 Seasonality
Many environmental factors potentially important to the recovery process
vary with season. For example, water temperature may influence the seasonal
availability of larval and juvenile recruits. The strength of temperature effects
may be expected to vary with latitude and climate (stronger seasonal
variation in air and coastal water temperatures are found on continental land
masses rather than islands). In the wet tropics, strong seasonal effects can be
generated by seasonal changes in freshwater inputs (Alongi 1990). Zajac and
Whitlatch (1982a,b) demonstrated that rates of recovery increased in experiments conducted in spring and summer compared to those conducted at
other times of the year. Similarly, Ford et al. (1999) demonstrated rates of
recolonisation were slow in winter compared to summer and that seasonal
differences in recovery rate were linked to the density of the dominant taxa
that were typically more abundant in the summer. For long-lived species,
Zajac and Whitlatch (1989) demonstrated that the demographic state of the
population at the time of disturbance had an important influence on its
recovery. Other factors, such as benthic primary production or wave climate,
may also influence recovery dynamics and vary with season or other longterm cyclical atmospheric/oceanographic processes (e.g., El Nino Southern
Oscillation).
14.3.2 Hydrodynamics
Hydrodynamic conditions can have a profound influence on benthic recovery
processes (e.g., Eckman 1983; Jumars and Nowell 1984; Butman 1987; Hall
1994; Paterson and Black 1999). Water depth and flow characteristics
influence benthic food quality and quantity and the supply of colonists to
disturbed patches. Water depth will also influence the type of waves that
expend energy on the seabed. On sand flats, small wind-waves that generate
1-2 cm high sand ripples can be particularly important in resuspending
animals and sediments so that tidal currents can transport them (Bell et al.
1997). Hydrodynamic processes associated with the mobility of macrofauna
have a major influence on the scale of disturbance needed to detect differences in the relative importance of adult, juvenile and larval colonists. Even in
quiescent mudflat environments tidal flows may be sufficient to transport
post-settlement macrofauna to defaunated plots (Thrush and Roper 1988).
Whitlatch et al. (in press) reviewed shallow-water experimental defaunation
experiments and found no clear evidence for differences in the rate of