202
10. Life-Stage-Based Recovery Dynamics of M arine Invertebrates
by increasing advec tion of the other life stage. Figure 10.9 shows the recovery time of Nepbtys incisa (wee ks) as a function of adult and juvenile
advection in patches of differing size (A = small patch, radius = 2; B =
medium patch, r = 20; C = large patch, r = 200). Similarly, Figure 10.10
shows recovery times of Polydora corn uta (wee ks) as a function of adult
and juvenile advection in patches of differing size (A = small patch, radius
= 2; B = medium patch, r = 20; C = large patch, r = 200). Particularly pronou nced results are present in large-sized disturbed patches, and when the
juven ile advection is held constant at low levels « .25). This signals the relatively wea k effect of adult life-stage immigration in large patches compared with that of juvenile life-stages.
Immigration of post-settlers, regardless of life-stage, reduced recovery
times in small patches much more than in large patches. Selected results are
shown in Table 10.2 for juvenile and adult advection set equal to each
other at (a) 0.25 and (b) 0.75. Patch recovery times of Polydora, for example, were not influenced by advection of juveniles and adults to large
patches (Fig. 2C), since settled larvae of this species can mature before immigrant densities accumulate. In the smallest patches, both Nepbtys and
Polydo ra showed rapid recovery when juvenile advection >0.25 a nd adult
advec tion >0.5. Recovery was almost immediate (I wk) in small patches
when adult advec tion exceeded 0.95 (partly as an artifact of how recovery
was defined).
In the absence of either juvenile or adult immigration, Nepbtys require 83
weeks to recover (compared with 6 weeks in Polydora) . A priori, Nepb tys
stand to benefit more from post-settler immigration than Polydora due to the
difference in larva-to-adult maturation times. With post-settler immigration,
recovery times of Nepb tys are reduced more than those of Polydora in
patches of all sizes. Figure 10.11 shows average improvements in recovery
time due to post-settler immigration (%; data are split by species and patch
size). Improvement percentages are calculated by comparing recovery time
with (W) and without (WO) colonization by adult and juvenile stages (i.e.
W-WO/W) . Bar height represents the average improvement of all juvenile
and adult advection combinations for which juvenile+adult advection>O (n =
48). In small patch es and und er conditions favoring high rates of immigration , Nepbtys recovery is similar to that of the more opportunistic species,
Polydora . Recovery in Polydora appea rs driven predominantly by its great
larval produ ction and extremely rapid growth and maturation rates. Immigration-enhancing morphologies and behaviors would be much more useful
for slow-growing, rep roductively constrained species such as Nepbtys.
10.4. Conclusions
There is some evidence that small-scale disturbances in soft-sediment hab itats recove r more quickly than large ones (Smith and Brumsickle 1989;
10. Life-Stage-Based Recovery Dynamics of M arine Invertebrates
by increasing advec tion of the other life stage. Figure 10.9 shows the recovery time of Nepbtys incisa (wee ks) as a function of adult and juvenile
advection in patches of differing size (A = small patch, radius = 2; B =
medium patch, r = 20; C = large patch, r = 200). Similarly, Figure 10.10
shows recovery times of Polydora corn uta (wee ks) as a function of adult
and juvenile advection in patches of differing size (A = small patch, radius
= 2; B = medium patch, r = 20; C = large patch, r = 200). Particularly pronou nced results are present in large-sized disturbed patches, and when the
juven ile advection is held constant at low levels « .25). This signals the relatively wea k effect of adult life-stage immigration in large patches compared with that of juvenile life-stages.
Immigration of post-settlers, regardless of life-stage, reduced recovery
times in small patches much more than in large patches. Selected results are
shown in Table 10.2 for juvenile and adult advection set equal to each
other at (a) 0.25 and (b) 0.75. Patch recovery times of Polydora, for example, were not influenced by advection of juveniles and adults to large
patches (Fig. 2C), since settled larvae of this species can mature before immigrant densities accumulate. In the smallest patches, both Nepbtys and
Polydo ra showed rapid recovery when juvenile advection >0.25 a nd adult
advec tion >0.5. Recovery was almost immediate (I wk) in small patches
when adult advec tion exceeded 0.95 (partly as an artifact of how recovery
was defined).
In the absence of either juvenile or adult immigration, Nepbtys require 83
weeks to recover (compared with 6 weeks in Polydora) . A priori, Nepb tys
stand to benefit more from post-settler immigration than Polydora due to the
difference in larva-to-adult maturation times. With post-settler immigration,
recovery times of Nepb tys are reduced more than those of Polydora in
patches of all sizes. Figure 10.11 shows average improvements in recovery
time due to post-settler immigration (%; data are split by species and patch
size). Improvement percentages are calculated by comparing recovery time
with (W) and without (WO) colonization by adult and juvenile stages (i.e.
W-WO/W) . Bar height represents the average improvement of all juvenile
and adult advection combinations for which juvenile+adult advection>O (n =
48). In small patch es and und er conditions favoring high rates of immigration , Nepbtys recovery is similar to that of the more opportunistic species,
Polydora . Recovery in Polydora appea rs driven predominantly by its great
larval produ ction and extremely rapid growth and maturation rates. Immigration-enhancing morphologies and behaviors would be much more useful
for slow-growing, rep roductively constrained species such as Nepbtys.
10.4. Conclusions
There is some evidence that small-scale disturbances in soft-sediment hab itats recove r more quickly than large ones (Smith and Brumsickle 1989;