Site by Bennett Web & Design Co.
2007 SOUTHEASTERN NATURALIST 6(2):351–358
Deposit Feeding During Tidal Emersion by the
Suspension-feeding Polychaete, Mesochaetopterus taylori
Thomas O. Busby1 and Craig J. Plante2,*
Abstract - Observations on tidal flats in North Inlet, SC suggested facultative
suspension- and deposit-feeding in the chaetopterid polychaete, Mesochaetopterus
taylori. Fecal coils consisted of two disparate sections, the first composed of small,
brown fecal pellets wrapped together by mucus into long strands, which abruptly
transitioned into a second gray, ropy section. We also made direct observations of
exposed palps and probing of the sediment surface intermittently following tidal
emersion. Granulometric analyses of gray and brown fecal material, surficial sediments,
subsurface sediments, and materials in suspenson above the worm at high
tide, corroborate our field observations that M. taylori is a facultative feeder, switching
from suspension- to deposit-feeding with tidal emersion. Typically, this shift in
feeding mode is not thought to effect a fundamental change in diet, i.e., the same
materials are ingested, suspended or deposited depending on hydrodynamic regime.
In contrast, M. taylori ingests finer particulates during tidal immersion, with concomitant
differences in granulometric characteristics. The distinct provenance and
composition of the dietary components of M. taylori likely supplies a relatively broad
range of essential nutrients. The geophysical effects of M. taylori feeding are likely
profound, in that it both translocates subsurface sediment to the surface during
deposit feeding and deposits fine, suspended materials following filter-feeding.
Many of the most important feeding guilds of aquatic animals are uncommon
to terrestrial habitats, and are therefore unfamiliar to many casual
observers. These include deposit- and suspension-feeders, those animals that
feed on particulates deposited on the bed or suspended in water, respectively.
Facultative suspension-feeding refers to an ability to switch between
these two modes, often associated with changes in water flow velocity
(Taghon et al. 1980). A clear-cut distinction between these two feeding
modes is probably unrealistic, however, because suspended and settled
particulates comprising these diets often are qualitatively similar (Snelgrove
and Butman 1994, Taghon et al. 1980). The ability to shift feeding modes
may be an adaptation to their variable environment (Miller and Sternberg
1988, Taghon et al. 1980), as it could be advantageous for an animal to
adjust its feeding behavior to utilize food in suspension or deposited on the
bottom, depending on the dominant source of food at a particular time.
Switching feeding behavior may also reduce intraspecific competition in
dense assemblages (Levin 1981).
1Biology Department, College of Charleston, Charleston, SC 29401. 2Grice Marine
Laboratory, 205 Fort Johnson, Charleston, SC 29412. *Corresponding author -
352 Southeastern Naturalist Vol. 6, No. 2
Numerous benthic organisms, including representatives of the spionid,
nereid, sabellid, and oweniid polychaetes, tellinid bivalves, and amphipod
crustaceans, are known to be capable of both suspension- and depositfeeding
(Taghon et al. 1980). Chaetopterid polychaetes are generally
suspension-feeders, employing a mucous net apparatus to filter organic
particles from seawater pumped into their straight, vertically oriented tubes
(Fauchald and Jumars 1979, Sendall et al. 1995). Fecal matter is carried
anteriorly along a mid-dorsal ciliated groove. The principal function of
chaetopterid palps is thought to be for the ejection of fecal pellets and debris
(Barnes 1965). In nearshore South Carolina habitats, common chaetopterids
include Chaetopterus variopedatus (Renier), Spiochaetopterus oculatus
(Webster), and Mesochaetopterus taylori (Potts), with only S.
oculatus known to employ both deposit- and suspension-feeding (Fauchald
and Jumars 1979, Turner and Miller 1991).
The present study reports on the feeding behavior of the chaetopterid,
Mesochaetopterus taylori. This polychaete can reach high densities (up to 70
m-2) in intertidal areas (Sendall et al. 1995), but is patchy in distribution
along the southeast US coast (Fox and Ruppert 1985). Like other
chaetopterids, this species resides beneath the sediment surface and so is
rarely seen; evidence of its presence is provided by a sandy, cylindrical tube,
which projects vertically above the sediment-water interface. It is generally
considered to be less common than other chaetopterids on southeastern
coasts (e.g., Chaetopterus and Spiochaetopterus; Ruppert and Fox 1988).
However, its tube resembles that of the common onuphid polychaete,
Kinbergonuphis jenneri (Gardiner); thus, its abundance might be greatly
underestimated due to this similarity.
Observations on the Debidue River tidal flats in North Inlet, SC
(33°21'0"N, 79°11'27"W) suggested facultative feeding in this species in
that we noted that its fecal coils seemed to consist of two disparate sections.
One section was brown and was composed of small, distinct fecal pellets
wrapped together by mucus into long coils. These coils abruptly changed
into gray, ropy coils, more reminiscent of the egesta of arenicolid polychaetes
and hemichordates (Fig. 1). The spatial orientation of these coil sections
suggested that the brown pellets, probably processed suspended matter, were
egested first. Gray material was egested later, typically after > 60 minutes of
tidal exposure, and likely represented materials that were ingested via deposit
feeding just after emersion. This speculation was supported by direct
observation of exposed palps, apparent probing of the sediment surface, and
movement of collected sediment toward the mouth (Fig. 2) intermittently
following tidal emersion.
Most documented facultative feeding has been shown in flume experiments;
however, in some instances, switching in feeding modes may have
been artifactual due to use of unrealistic flow velocities (Barnes 1964, Turner
and Miller 1991). In addition, M. taylori lives in deep burrows, and it has
proven exceedingly difficult to collect intact specimens for experimentation
2007 T.O. Busby and C.J. Plante 353
(Barnes 1965, Petersen 1966). Instead, we tested for facultative feeding in M.
taylori by comparing geological and biological characteristics of the two
dissimilar fecal sections, in addition to those of surrounding surface sediment,
subsurface sediments, and suspended particulate materials in waters overlying
the worms at high tide.
All samples were collected during a 4-hour period surrounding low tide
while the sandflat was emersed. The first step in the sampling process was to
identify and flag specimens of M. taylori that showed signs of recent feeding
(i.e., tube apertures surrounded by small, packaged, brown pellets). All
egesta samples and surface sediment samples were collected from one small
area ( 20 m non-vegetated zone between creek and Spartina alterniflora
Figure 1. Fecal coils
two distinct sections,
differing in color and
Figure 2. Deposit
feeding at sediment
surface by M. taylori
at low tide.
354 Southeastern Naturalist Vol. 6, No. 2
marsh, along < 100 m of shoreline) using clean spatulas and pipettes. Fecal
or sediment samples were pooled to obtain individual replicates, each of at
least 1 ml of material. Number of replicates ranged between 5 and 7 for the
various sample types. Deeper sediment samples ( 5 cm) were collected
using a corer (30-ml plastic pipette with dispensing end cut off). Several
liters of the nepheloid layer also were collected using a sterile 1-L filtering
flask (with tubulation) with 1 m of sterile tubing attached. The intake end
of tubing was held 0.5–1 cm above the sediment surface (approximate height
of M. taylori tube), with tube opening facing directly upward into the highly
turbid water column. Suction was applied, and water flowed into the flask.
Samples were placed on ice for transport to the laboratory where material
that was suspended in water was separated using centrifugation (10 min at
4000 x g).
Using copious amounts (> 3 L) of distilled water, samples were washed
through a series of eight small ( 50-mm diameter) sieves of mesh sizes of
1000, 500, 355, 250, 180, 125, 90, and 63 mm. Fractions collected on each
sieve were then washed under pressure onto pre-dried (> 2 h at 60 ºC) and
pre-weighed glass fiber filters (Millipore, Bedford, MA). Material passing
through the 63-mm sieve was also collected. Filters with sample were then
dried at 60 ºC (at least overnight) and re-weighed.
Measures of median grain diameter were obtained from graphical analysis
of cumulative frequency curves. In addition, the degree of scatter (or
quartile deviation) and data asymmetry around the median (i.e., skewness)
were obtained according to Buchanan and Kain (1971). Percent silt/clay was
calculated as the percent of total mass comprised of material passing through
the smallest (63-mm) sieve. One-way ANOVA was used to compare
granulometric attributes among sample types. When significant ( = 0.05)
global differences were noted, pairwise comparisons were conducted using
Fisher’s LSD correction.
Grain-size analysis revealed significant global differences in median
grain diameter (Md; F4,24 = 231.26, P < 0.001), quartile deviation (QD;
F4,24 = 4.32, P < 0.009), and skewness (Skq; F4,24 = 6.90, P < 0.001). Median
grain size in all sample types was significantly larger than in the nepheloid
layer (P < 0.001 for all such comparisons, Fisher’s LSD; Table 1). Otherwise,
only the surface and subsurface sediments differed, with deeper
sediments significantly coarser (P = 0.022), whereas all other pairwise
grain-size comparisons were not significant, P > 0.107). Surface sediment
and brown fecal casts were more poorly sorted (i.e., larger spread between
25 and 75% points on the cumulative frequency curve, QD) than the other
three sample types (Table 1; P values ranged between 0.002 and 0.089 for all
pairwise comparisons), and did not differ from one another in this regard (P
= 0.606). The nepheloid layer showed the lowest QD (Table 1), but was not
significantly different than either subsurface sediment (P = 0.405) or the
2007 T.O. Busby and C.J. Plante 355
gray fecal casts (P = 0.292). The nepheloid samples also deviated from all
other sample types in that the only negative Skq values were from these
samples. Subsurface sediments and gray fecal casts again resembled one
another in this aspect (P = 0.859), and differed from surface sediment and
brown fecal casts (P < 0.041 for all four cross-comparisons), whereas surface
sediment and brown casts were not significantly different (P = 0.823).
The % silt/clay fraction (< 63 mm grain size) differed globally (F4,24 =
147.69, P < 0.001) and among various sample types (Table 1). While gray
fecal coils differed from both brown fecal material (P = 0.028) and surface
sediments (P = 0.010), % silt/clay was not significantly different than the
deeper sediment samples (P = 0.663). Brown feces differed in this regard
from subsurface sediments (P = 0.008), but were not significantly different
than surface sediments (P = 0.725). Again, the nepheloid layer differed from
all other sample types, with a much higher fraction of fine grains (P < 0.001
for all pairwise comparisons; Table 1).
In sum, the material ingested during suspension-feeding most closely
matched the brown, fine materials collected as surface deposit at low tide.
This material shared some qualities with the nepheloid layer, but it appears
that the finest fraction of this seston is not deposited during the
tidal ebb, so is not sampled as surface deposit at low tide. After emersion,
M. taylori deposit feeds on coarser material. Observation of feeding activity
suggests that these deposits lie just below this surficial fluff layer.
However, we cannot rule out the possibility that M. taylori also feeds
from the opposite end of its tube during this interval, on much deeper
sediments. Analogous comparisons of chlorophyll concentrations, and
bacterial community structure (C.J. Plante and T.O. Busby, unpubl. data)
similarly matches brown fecal coils with seston, and subsurface sediments
to that ingested at low tide.
Table 1. Mean (± SD) of granulometric properties of various sample types (FC = fecal casts).
Md, QD, and Skq refer to median grain size, quartile deviation, and skewness, respectively.
Sample type Md QD Skq % silt/clay
Brown FC 2.91 (0.13) 0.43 (0.23) 0.13 (0.12) 15.6 (11.0)
Gray FC 2.88 (0.01) 0.25 (0.03) 0.03 (0.02) 4.8 (1.2)
Surface sediments 2.95 (0.19) 0.39 (0.20) 0.12 (0.10) 17.2 (10.1)
Subsurface sediments 2.80 (0.05) 0.23 (0.02) 0.02 (0.01) 2.8 (1.4)
Nepheloid layer 4.31 (0.02) 0.16 (0.04) -0.05 (0.03) 86.3 (6.8)
AMedian grain sizes were converted from units to diameter (in m) using the equation: d =
356 Southeastern Naturalist Vol. 6, No. 2
Sedimentological analyses corroborate our field observations that M.
taylori is a facultative feeder, switching from suspension- to deposit-feeding
with tidal emersion. This capacity to both suspension- and deposit-feed is
not novel, having previously been noted in at least one species,
Spiochaetopterus oculatus, of the same polychaete family (Chaetopteridae),
and is even more familiar among spionid polychaetes, tellinid bivalves, and
varied crustaceans. However, unlike these other invertebrates that primarily
deposit-feed, but may switch to suspension-feeding at high flow velocity, M.
taylori is typically classified as a suspension-feeder. This switching behavior
is also unusual in that the switch is not due to change in water velocity,
but rather to fluctuations in tidal height (i.e., emersion). In addition, switching
in most facultative feeders is not thought to represent a fundamental
switch in diet, i.e., the same materials are thought to be ingested, simply
suspended or deposited depending on flow (e.g., Taghon 1980). With M.
taylori, on the other hand, finer particulates are ingested during tidal immersion,
with concomitant differences in granulometric characteristics.
Large-scale spatial distributions of benthic fauna have largely been explained
by the notion that the suspension-feeding guild dominates where
water velocity is relatively high and the flux of suspended matter is adequate,
whereas deposit-feeders should be more abundant where flow is
reduced and organic particulates are deposited on the sea bed. Facultative
feeders defy this simple scheme and illustrate that flow is variable to greater
or lesser degrees, so the dominant mode of feeding in a given habitat can
vary temporally. Earlier work has demonstrated facultative deposit-feeding,
which has lead to predictions that “switching” between feeding modes
should occur in dynamically variable benthic habitats (Taghon 1980, Turner
and Miller 1991), for instance, when flow is oscillatory or when the average
rate of flow varies significantly through time. During periods of reduced
flow, deposit-feeding is predicted. Mesochaetopterus taylori provides an
extreme example of this situation, as there is obviously no flow of seawater
to carry suspended matter to them at low tide. The ability to continue
deposit-feeding after emersion is an adaptation to intertidal life and potentially
provides a competitive advantage to M. taylori in this habitat, as most
supension feeders cease feeding during aerial exposure (Newell 1972). Perhaps
even more important, the disparate dietary components (with respect to
both provenance and composition) of M. taylori should supply a relatively
broad range of essential nutrients and remedy the nutritional deficiencies of
specific detrital components (Phillips 1984).
Deposit feeding has been shown to alter sedimentary microbial communities,
both through translocation of sediments (Plante and Wilde 2004) and
digestive removal (Dobbs and Guckert 1988, Plante and Wilde 2004). It has
not yet been established if the quantitative or qualitative effects of various
deposit-feeding species are unique or are generally similar (Plante and
Shriver 1998, Plante and Wilde 2004). The compositional effects on the
microbiota of bulk sediment of M. taylori are likely unique and particularly
2007 T.O. Busby and C.J. Plante 357
great, in that it both translocates subsurface sediment to the surface during
deposit feeding and deposits fine, suspended materials following filter
feeding. Geophysical effects may even be more significant, for similar
reasons. On one hand, the worm brings subsurface sediments to the surface,
defecating this material in coils that project into the benthic boundary
layer, enhancing their resuspension when the tide returns. On the other hand,
fine, suspended particles are removed from the nepheloid layer and packaged
into mucus-bound pellets, and deposited in relatively large coils.
Field assistance was provided by Jeremiah Easley and Jason Curry. Primary
funding was provided through the National Science Foundation grant DEB 0108615.
Additional support was provided to T.O. Busby by the College of Charleston Biology
Department’s fund for undergraduate research.
Barnes, R.D. 1964. Tube-building and feeding in the chaetopterid polychaete,
Spiochaetopterus oculatus. Biological Bulletin 127:397–412.
Barnes, R.D. 1965. Tube-building and feeding in the chaetopterid polychaetes.
Biological Bulletin 129:217–233.
Buchanan, J.B., and J.M. Kain. 1971. Measurement of the physical and chemical
environment. Pp. 30–58, In N.A. Holme and A.D. McIntyre (Eds.). Methods for
the Study of Marine Benthos. Blackwell Scientific Publications, Oxford, UK.
Dobbs, F.C., and J.B. Guckert. 1988. Microbial food resources of the macrofaunaldeposit
feeder Ptychodera bahamensis (Hemichordata: Enteropneusta). Marine
Ecology Progress Series 45:127–136.
Fauchald, K., and P.A. Jumars. 1979. The diet of worms: A study of polychaete
feeding guilds. Oceanography and Marine Biology: An Annual Review
Fox, R.S., and E.E. Ruppert. 1985. Shallow-water Marine Benthic
Macroinvertebrates of South Carolina. University of South Carolina Press, Columbia,
SC. 330 pp.
Levin, L.A. 1981. Interference interactions among tube-dwelling polychaetes in a
dense infaunal assemblage. Journal of Experimental Marine Biology and Ecology
Miller, D.C., and R.W. Sternberg. 1988. The fluid and sediment-dynamic environment
of a benthic deposit-feeder. Journal of Marine Research 46:771–796.
Newell, R.C. 1972. Biology of Intertidal Animals. Paul Elek Limited, London, UK.
Petersen, J.A. 1966. Sobre a fisiologia e ecologia de Mesochaetopterus taylori.
Ciencia e Cultura (Sao Paulo) 18:247–248.
Phillips, N.W. 1984. Role of different microbes and substrates as potential suppliers
of specific, essential nutrients to marine detritivores. Bulletin of Marine Science
Plante, C.J., and A. Shriver. 1998. Patterns of differential digestion of bacteria in
deposit feeders: A test of resource partitioning. Marine Ecology Progress Series
358 Southeastern Naturalist Vol. 6, No. 2
Plante, C.J., and S.B. Wilde. 2004. Biotic disturbance, recolonization, and early
succession of bacterial assemblages in intertidal sediments. Microbial Ecology
Ruppert, E.E., and R.S. Fox. 1988. Seashore Animals of the Southeast. University of
South Carolina Press, Columbia, SC. 429 pp.
Sendall, K.A., A.R. Fontaine, and D. O’Foighil. 1995. Tube morphology, and activity
patterns related to feeding and tube-building in the polychaete
Mesochaetopterus taylori Potts. Canadian Journal of Zoology 73:509–517.
Snelgrove, P.V.R., and C.A. Butman. 1994. Animal-sediment relationships revisited:
Cause versus effect. Oceanography and Marine Biology: An Annual Review
Taghon, G.L., A.R.M. Nowell, and P.A. Jumars. 1980. Induction of suspension
feeding in spionid polychaetes by high particulate fluxes. Science 210:562–564.
Turner, E.J., and D.C. Miller. 1991. Behavior of a passive suspension-feeder
(Spiochaetopterus oculatus (Webster)) under oscillatory flow. Journal of Experimental
Marine Biology and Ecology 149:123–137.