(DRAFT) - Taxonomy
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
TAXONOMY
NAME - worm, reef-building tube
OTHER COMMON NAMES - sand-tube worm, honeycomb worm, reef-building polychaete and tube-building marine polychaete
ELEMENT CODE -
CATEGORY - Other Aquatic Invertebrate Taxa
PHYLUM AND SUBPHYLUM - Annelida,
CLASS AND SUBCLASS - Polychaeta,
ORDER AND SUBORDER - Terebellida,
FAMILY AND SUBFAMILY - Sabellariidae,
GENUS AND SUBGENUS - Phragmatopoma,
SPECIES AND SSP - lapidosa,
SCIENTIFIC NAME - Phragmatopoma lapidosa
AUTHORITY - Kinberg (1867)
TAXONOMY REFERENCES - 256
COMMENTS ON TAXONOMY -
Reciprocal crosses of P.lapidosa gametes with gametes of the northeast
Pacific congener, P.californica, suggest the two taxa are conspecific
subspecies.*256*
Taxonomy - 1 (DRAFT) - Status
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
STATUS
Coded Status
Biological Indicator
REFERENCES FOR STATUS - 256
COMMENTS ON STATUS -
The reefs constructed by reef-building tube worms along the southeast coast
of Florida are significant both geologically and biologically. Reefs of the
sand tubes of reef-building tube worms extend within their geographic range
for hundreds of kilometers of coastline. The ability of the worms to thrive
under high energy breaker conditions and to extend their colonial tube
masses upward and seaward by extraction and agglutination of littoral drift
materials makes them important vectors in coastline development. Beachrock,
converted from the reefs, and sand impounded on their landward sides provide
for actual progradation of beaches. By sorting out flat shell fragments and
the heavier suspended particles in littoral drift, tube construction by the
worms results in the retention of beach sediment. The cracks and crevices
of the reefs act as traps for sediment and shell fragments, thereby further
contributing to sediment retention. Being wave resistant, the reefs protect
the shore against wave attach and retard erosion. It appears likely that
reef-building tube worms are at least in part responsible for the formation
and maintenance of beaches and barrier islands in southeast Florida.
The reefs are the primary basis for an elaborate and stable marine
community. They provide hard and stable substrate, shelter, and food, and
thereby allow many species to inhabit the surf zone, an area where most
would normally by unable to survive.*256*
A total of 40 fishes of commercial or sport value were "frequent", "common"
or "abundant" in the worm reef habitat, compared with 35 in the adjacent
open surf zone; 27 of these species were found exclusively (at these
frequencies) in the reef habitat and 22 in open habitats. Although the
species richness of fishes of the worm and reef habitat is not remarkably
higher than that of the adjacent open surf zone, the large number of
habitat-specific species indicates that the presence of worm reefs
substantially enhances the overall diversity of commercially and
recreationally important fishes in the beach zone.*256*
Status - 1 (DRAFT) - Distribution
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - MARINE
REFERENCES FOR HABITAT - 256
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Estuarine, intertidal RF3 N 2
REFERENCES FOR NWI - 256
COMMENTS ON HABITAT ASSOCIATIONS -
Stable settlement substate is a critical environmental requirement of
reef-building tube worms. Beaches composed entirely on shifting sands
afford larval worms no opportunity for settlement. Unstable objects
subject to rolling or burial by sands are unsatisfactory. However, a wide
variety of natural and artificial substrates can be colonized, including
living and dead shells of mollusks and horseshoe crabs (Limulus
polyphemus), coquina rock, sea walls, piers, jetties, peat, and beach
debris. Existing "living" and "dead" worm reefs are common attachment
sites. Complete removal of a reef or reef sand will probably delay
recolonization considerably because the larvae usually require, for
metamorphosis, a chemical stimulus produced by conspecific worms. In
addition to providing stable settlement, substrates surrounding the
colonization site must be composed of sand and similar sized particles
suitable for tube construction. Habitats such as exposed rocky shorelines
that have adequate wave action and stable substrates are unsuitable
environments for reef-building tube worms because they lack the amounts of
suspended particles needed for tube building.*256*
ANIMAL/PLANT SPECIES ASSOCIATIONS -
Predators: Reef-building tube worms are eaten by crustaceans (including the
grapsid crab Pachygrapsus transversus and the xanthid crabs Mennipe
nodifrons, Pilumus dasypodus, and Panopeus bermudensis), gastropods, and
fishes. The worms appear to be the primary forage of a number of species of
crabs that live on or within the reefs.
Competitors: Barnacles (Tetraclita squamosa) colonizing worm reefs compete
with reef-building tube worms for space. The crab Pachycheles monilifer,
which is an abundant inhabitant of worm reefs in southeastern Florida, feeds
on suspended material and plankton and may compete with reef-building tube
worms for food.*256*
REFERENCES FOR SPECIES ASSOCIATIONS - 256
Habitat Associations - 1 (DRAFT) - Food Habits
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
FILTERER
REFERENCES FOR TROPHIC LEVEL - 256
LIFESTAGE FOOD FOOD PART
General Plankton Not Specified
General Algae Not Specified
General Bacillariophyceae Not Specified
REFERENCES FOR GENERAL FOOD - 256
COMMENTS ON FOOD -
The organism lies on its dorsum, partly extended into the "hood" of its
tube. The operculum is turned backward and downward, and the ciliated
prostomial tentacles are extended upward and outward. Water currents
produced by the cilia convey small suspended particulate matter toward a
rapidly revolving bolus of mucus just above the mouth. The bolus is
periodically ingested. The worms also feed on algae and other organisms
encrusting sand and shell fragments. The fragments are grasped with the
opercular paleae and then directed with the aid of the prostomial tentacles
to the mouth where the organic materials are removed. If the fragment is
suitable for tube construction, it may then be passed along to the building
organ. The prostomial feeding tentacles may also be used to seize small
sand particles and transport them toward the building organ for tube
building. Feeding and tube-building are highly integrated and complementary
functions.
Food: The food of reef-building tube worms consists primarily of planktonic
microorganisms, including diatoms, foraminiferans, and algae; encrusting
organisms adhering to sand and silt are also eaten.*256*
Food Habits - 1 (DRAFT) - Environment Associations
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Water temperatures for reef-building colonies in southeastern Florida
ranged from 18 to 27 degrees C. Water temperatures studied at other reefs
ranged from 11 to 32 degrees C over a 2 year period. However, these
extremes are probably exceeded within tubes of reefs exposed at low tide
during exceptionally hot or cold weather. Extreme air temperatures may
stress reef-building tube worms in intertidal reefs. Massive die-offs of
Sabellaria alveolata were reported after severe frosts in southwestern
England; also, S. vulgaris has suffered heavy winter mortality in Delaware
Bay. It is believed that elevated summer temperatures may have resulted in
the death of a reef-building tube worm colony in Florida. The tropical and
subtropical distribution of the reef-building tube worm suggests that it is
intolerant of temperate climates. Cape Canaveral, the northern extreme of
the range of the species, marks the approximate center of a transition zone
between the warm-temperate Carolinian and tropical Caribbean faunal
regions.
Salinity: Water salinities measured at reef-building tube worm reefs ranged
from 28 to 39 ppt. In the laboratory, the worms survived at salinities as
low as about 10 ppt for several days. This tolerance is probably adaptive
in southeastern Florida, where heavy rains and freshwater runoff may
appreciably dilute salinities within worm tubes between high tides.*256*
Depth: Habitats occupied by reef-building tube worms are primarily
intertidal and nearshore. Optimal habitat extends from mid-tide level to a
depth of about 2 meters. Reefs occasionally occur above mid-tide, but only
if suitable substrate and strong wave action are present. At depths
greater than 2 m, wave action is generally insufficient to maintain the
required turbulent conditions. However, colonies have been reported to
occur to depths of 100 m, perhaps at sites with strong submarine
currents.*256*
Current: Reef-building tube worms require constant high-energy wave action
to supply food, remove metabolic waters, and maintain the suspension of
sand grains and other particles for tube building. Average breaker heights
along the east coast of Florida where worm reefs are well developed are
50-75 cm. Worm reefs may also form at the mouths of inlets where tidal
currents are strong enough. South of Dade County, the turbulent, silt and
sand laden conditions required by the worms do not exist; such habitats
foster the formation of coral reefs.
Suspended Solids: Reef building tube worms showed no indication of a
negative reponse to experimental suspended-solid levels as high as two
orders of magnitude greater than maximum levels reported from surf zones in
Florida. Habitats having the intense turbulence and shifting sand
(surrounding) substrate required by reef-building tube worms are high in
suspended solids. However, high suspended solid loads alone may not
provide habitat suitable for reef building tube worms if particle size of
the suspended materials is too small. Habitats having high silt loadings
only are unsuitable; sand-sized particles must be present.*256*
Environment Associations - 1 (DRAFT) - Life History
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
LIFE HISTORY
Spawning: Florida populations of reef-building tube worms may spawn
semicontinuously (without a seasonal trend) throughout most of the year.
This semicontinuous spawning periodicity differs markedly from the polytelic
spawning (with a seasonal trend) of all other sabellariids.
Fertilization occurs in the water. Males release sperm into their sand
tubes through a series of bilaterally arranged nephridia throughout the
gamete-bearing abdominal segments; sperm are expelled into the water column
in short bursts by rapid withdrawl of the head region into the tube.
Initiation of sperm release by one male generally stimulates releases by
adjacent males; females release eggs in response to the presence of sperm in
the water. Mature sperm have distintive long, tapering, curved acrosomes
and laterally displaced flagella. Total length of sperm is about 42
micrometers; the head, including the acrosome, is about 6 micrometers long.
Females expel eggs from their tubes as males expel sperm. Diameters of
spawned oocytes are 97 to 103 micrometers. The eggs are sticky and adhere
to sand grains upon expulsion; this property may be an adaptation to
restrict transport in the turbulent surf zone.
Larvae: Larvae of the reef-building tube worm are common in the nearshore
plankton along the east coast of Florida and may be an ecologically
significant component of the planktonic community. Freshly shed ova are
irregular in shape and have a clear, conspicuous geminal vessicle. Within
minutes, the eggs become round and develop a wrinkled vitelline membrane.
The germinal vesicle breaks down 10 to 15 minutes after fertilization. The
first and second polar bodies appear in about 50 to 55 minutes after
fertilization and the first and second cleavages occur within 75 to 85 min
of fertilization, the embryo loses its sticky coat and hatches as a simple
top-shaped trocophore that possesses a prototroch (ciliated girdle) and an
apical tuft consisting of short, fine cilia. At 17 to 20 h, a single
reddish eyespot is formed and a stiff cilium appears posteriorly. At 20 to
21 h, the larva develops a pair of small barbed provisional setae that begin
to protrude through the body wall on each side. At this stage, the larvae
is opaque and granular in appearance; groups of irregular, yellow-green
pigment specks are scattered over its surface. At 22 to 24 h, 3 paris of
privisional seate are present, distinct chromatophores have formed, and a
mouth and digestive system have developed; active feeding begins at this
stage. At 40 to 42 h, the larva is more elongate and shows faint
indications of segmentation. It has 4 to 7 provisional setae on each side
and two eyespots; a second ciliated girdle, the telotroch, circles its anus.
At about 6 days, the larva is clearly elongate and has 4 eyespots and as
many as 20 provisional setae. Between 7 and 10 days, the larva develops a
pair of dorsal tentacle buds and abdominal uncini. Three clearly defined
parathoracic segments and 3 less clearly defined abdominal segments are
present. At 12 days, the tentacles have lengthened and dorsal parapodial
lobes of the parathoracic segments are clearly defined; each as 4 setae.
One to three primary paleae and two pairs of opercular spines appear. At
about 19 days, the tentacles are about half the length of the body and have
ciliated food grooves; segmentation of the robust larva is distinct. At
this stage, the larvae alternately crawl over or swim close to the surface
of the substrate. During crawling, they are oriented head-downward and
frequently contact the substrate with the mouth and tentacles.
Juveniles: Metamorphosis and settlement occur 14 to 30 days after
Life History - 1 (DRAFT) - Life History
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
fertilization in circulating or aerated cultures at 21 to 23 degrees C.;
length ranges from 0.6 to 1.0 mm at settlement. Metamorphosis usually
requires the presence of conspecific tubes or sand and is triggered by the
presence of free fatty acids, a requirement which accounts for the
gregariousness of the species. It was found that when larvae were cultured
with sand that came from conspecific tubes, frequency of metamorphosis was
50% at 15 degrees C about 28 hours after hatching and also 50% at 20 degrees
C about 17 hours after hatching.
Metamorphosis involves an elongation of the body and dramatic changes in the
head region; the tentacles rotate anteriorly until they project forward, the
provisional setae are replaced by 6-10 pairs of primary paleae, the entire
head shrinks in relative size, the building organ appears around the mouth,
and various appendages develop on a number of segments. The telotroch is
still present at this stage but the prototroch has disappeared. After
settlement, development continues rapidly; within one month, the juvenile
closely resembles the adult worm. Upon settling, the larva actively moves
over the substrate, presumably evaluating possible attachment sites. A wide
variety of natural and artificial settlement sites are used. Existing worm
reefs, both "dead" and "living", are perhaps the most common attachment
sites. Established reefs are therefore essentially permanent. Settlement
occurs over the entire surface of dead, wave-eroded worm mounds, but only
between the openings of existing and occupied adult tubes of sparsely
populated reefs. No recruitment occurs on the surfaces of mounds consisting
of closely packed tubes of adults; successful settlement on such mounds is
limited to their periphery. Adult and juvenile worms use their operculum to
scrape away algal growths, fouling organisms, and debris located around the
openings of their tubes; this activity probably serves to preclude the
settlement of new larvae.
Upon selection of a site, the metamorphosing larva secretes and attaches a
cylindrical, muco-proteinaceous tube to which it begins cementing small
fragments; the initial fragments often consist largely of small, dark grains
of heavy minerals. Tubes of juveniles can therefore be readily
distinguished from those of adults by their color from a considerable
distance; adults use larger, lighter-colored sand grains and shell
fragments. It was demonstrated that the median size of particles
incorporated in the tubes increases with worm size. Other materials used by
young worms include small quartz grains, foraminiferal tests, sponge
spicules, and silt. Larger worms use correspondingly larger materials
including ostracod carapaces, small mollusk shells, fragmented pieces of
larger mollusk shells, large quartz grains, large foraminiferans, and
echinoid spines. Generally, worms prefer sediments of 250 to 500
micrometers in diameter or 125 to 500 micrometers for tube construction;
depending on the diameters of available materials, they therefore
preferentially concentrate finer or coarser grains than they would if
selection were random. Significant amounts of sediment finer than 62
micrometers in diameter (silt) are incorporated into tubes, probably serving
as "mortar" to fill cracks between larger grains. Flat mollusk-shell
fragments are typically used to line the inner wall of the tube; more
rounded grains are incorportated in the outer layers. Platy shll fragments
are incorporated much more frequently than quartz sand grains, perhaps
because the shell fragments are less dense and less spherical in form and
hence more easily suspended in the water column. Construction materials are
grasped from the water column by the oral tentacles or oopercular paleae,
Life History - 2 (DRAFT) - Life History
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
passed to the building organ, coated with proteinaceous cement, and
implanted into the tube with the opercular paleae.
The size, shape, and orientation of the tube are influenced by hydrodynamic
and sedimentary conditions prevailing at the site and the presence or
absence or other organisms or obstructions. Damaged tubes are quickly
repaired; human footprints on reefs are not detectable after 24 hours.
Adults: Reef-building tube worms are dioecious. Populations are composed
of equal proportions of males and females. Sex products first develop in
both sexes about 6 to 8 weeks after larval settlement and the worms are
fully mature after 4 months. Sexes are easily distinguished; the
gamete-containing abdominal segments of mature males and females are creamy
white and steel blue, respectively, corresponding to coloration of sex
products. The sexes are otherwise morphologically identical. The testes
and ovaries are bilaterally arranged organs in the abdominal segments.
Removal of sexually mature worms from their tubes induces expulsion of
gametes and thus facilitates artificial fertilization in the laboratory.
Age and Growth: No information is available on the longevity of
reef-building tube worms in Florida, but is was suggested that these
organisms would not survive for longer than one or two years. However, a
similar species, Sabellaria alveolata, in southwestern England, lives from 5
to 10 years. The mean daily growth increment of worm tubes was 1.45 mm at
Punta Moron, Venezuela. Accretion rates of tubes of worms from this
population in the laboratory were 2.03, 3.18, and 0.97 mm per day at 22,26,
and 30 degrees C, respectively. It was reported that 6 months after
settlement in March, new reefs were indistinguishable from older colonies
that had been established in previous years. A newly settled reef attained
a thickness of about 25 cm within 6 weeks.
Maximum total length is about 40 mm. Body length varies annually and by
locality, perhaps depending on food availability or physical conditions;
tube diameters and body lengths are highly correlated.*256*
REFERENCES FOR LIFE HISTORY- 256
Life History - 3 (DRAFT) - Management Practices
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Constructing/maintaining jetties, groins, and breakwaters
Adverse Dredging
Beneficial Controlling sedimentation
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 256
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 256
COMMENTS ON MANAGEMENT PRACTICES -
Strong currents and high sediment loadings characteristic of coastal inlets
provide excellent habitat for reef-building tube worms. Accordingly, worm
reefs grow well on bulkheads, jetties, and along the bottoms of channels at
some inlets, eventually making them navigable only by shallow-draft
watercraft. The narrowed channels also increase the velocity of tidal
currents, thereby making passage dangerous. Dredging of worm reefs required
to keep such inlets navigable is deleterious to reef-building tube worms and
associated fauna directly affected by dredging.*256*
Beach Nourishment: Burial, siltation, and exposure to sulfides are all
factors which may be present due to beach nourishment or disposal of dredged
sediments. It was reported that total mortality of reef-building tube worms
occurred at reefs adjacent to beaches nourished by spoil dredged from
nearby Sebastian Inlet, Florida. The presence of large quantities of
drifting sand over the reefs suggested that mortality was the direct result
of overwash with sand and consequent smothering of worms.*256*
Management Practices - 1 (DRAFT) - References
Species worm, reef-building tube
Species Id M090004
Date 26 AUG 96
References
References - 1