Benthic Suspension Feeders in Shallow Coastal Water
23
many of the studies used unrealistically high concentrations of suspended
particles that probably saturated the digestive system of the worms. This idea
is further supported by Riisgard and Ivarsson (1990) who determined that an
average Sabella penicillus filtered an estimated 3541 of water per ml of oxygen
consumed and that the worms are very efficient, only expending about 3.10/0
of the worm's metabolized energy for water processing.
Sabellid associations are physical structures that influence water flow and,
in the case of Phargmatopoma lapidos systems, have been touted as erosioncontrol devices for Florida beaches (Kirtley and Tanner 1968). The structure
of these systems also provides a special habitat in the high-energy flow zones
of temperate and subtropical environments. We have found no published
evidence of the influence of sabellid aggregations on the biogeochemical
character of their ecosystems.
1.2.4 Serpulids (Polychaeta)
Serpulids are benthic suspension-feeding segmented worms that secrete their
own calcareous tube. Serpulids have planktonic larvae that exhibit gregarious
behavior by preferring settlement on or near adult worms of the same species
at densities of 1 mm- 2 or higher (ten Hove and van den Hurk 1993). In a few
genera, asexual reproduction may enhance aggregation (ten Hove 1979). This
intense aggregation results in the formation of reefs in intertidal and shallow
subtidal environments from the arctic to the tropics. The largest serpulid reefs
are several meters in height and kilometers long and are typically found in
sheltered bays (ten Hove and van den Hurk 1993).
Like the sabellid worms described earlier, serpulids utilize a funnel-shaped
fan or crown-filament pump (Riisgard and Ivarsson 1990) to move water and
filter particles. Particles between 2 and 12 11m are removed efficiently (Davies
et al. 1989). Dales (1957), Kl6ckner (1976), Davies et al. (1989) and Riisgard
and Ivarsson (1990) reported serpulid filtration rates of 4.7 to 10.21 g-l h-l that
are slightly higher than those values reported for sabellids (Table 1.1). These
differences may be explained by allometry, as the sizes of the observed
individual serpulids were smaller than those of the sabellids. Weight-specific
rates typically decline with increasing size. It should also be noted that Davies
et al. (1989) reported rates for a reef-building serpulid, Ficopomatus enigmaticus (=Mercierella enigmatica), and found no evidence of the food
saturation effects that concerned Riisgard and Ivarsson (1990).
There are at least two published studies (Keene 1980; Davies et al. 1989)
that examine the role of serpulid reefs in shallow coastal ecosystems. In both
studies, the species of interest is F. enigmaticus. In the earlier study, Keene
(1980) investigated the importance of the reefs of this species on the Lac de
Tunis, a shallow hypereutrophic lagoon on the north coast of Tunisia. The
23
many of the studies used unrealistically high concentrations of suspended
particles that probably saturated the digestive system of the worms. This idea
is further supported by Riisgard and Ivarsson (1990) who determined that an
average Sabella penicillus filtered an estimated 3541 of water per ml of oxygen
consumed and that the worms are very efficient, only expending about 3.10/0
of the worm's metabolized energy for water processing.
Sabellid associations are physical structures that influence water flow and,
in the case of Phargmatopoma lapidos systems, have been touted as erosioncontrol devices for Florida beaches (Kirtley and Tanner 1968). The structure
of these systems also provides a special habitat in the high-energy flow zones
of temperate and subtropical environments. We have found no published
evidence of the influence of sabellid aggregations on the biogeochemical
character of their ecosystems.
1.2.4 Serpulids (Polychaeta)
Serpulids are benthic suspension-feeding segmented worms that secrete their
own calcareous tube. Serpulids have planktonic larvae that exhibit gregarious
behavior by preferring settlement on or near adult worms of the same species
at densities of 1 mm- 2 or higher (ten Hove and van den Hurk 1993). In a few
genera, asexual reproduction may enhance aggregation (ten Hove 1979). This
intense aggregation results in the formation of reefs in intertidal and shallow
subtidal environments from the arctic to the tropics. The largest serpulid reefs
are several meters in height and kilometers long and are typically found in
sheltered bays (ten Hove and van den Hurk 1993).
Like the sabellid worms described earlier, serpulids utilize a funnel-shaped
fan or crown-filament pump (Riisgard and Ivarsson 1990) to move water and
filter particles. Particles between 2 and 12 11m are removed efficiently (Davies
et al. 1989). Dales (1957), Kl6ckner (1976), Davies et al. (1989) and Riisgard
and Ivarsson (1990) reported serpulid filtration rates of 4.7 to 10.21 g-l h-l that
are slightly higher than those values reported for sabellids (Table 1.1). These
differences may be explained by allometry, as the sizes of the observed
individual serpulids were smaller than those of the sabellids. Weight-specific
rates typically decline with increasing size. It should also be noted that Davies
et al. (1989) reported rates for a reef-building serpulid, Ficopomatus enigmaticus (=Mercierella enigmatica), and found no evidence of the food
saturation effects that concerned Riisgard and Ivarsson (1990).
There are at least two published studies (Keene 1980; Davies et al. 1989)
that examine the role of serpulid reefs in shallow coastal ecosystems. In both
studies, the species of interest is F. enigmaticus. In the earlier study, Keene
(1980) investigated the importance of the reefs of this species on the Lac de
Tunis, a shallow hypereutrophic lagoon on the north coast of Tunisia. The