Distribution of Sipuncula in the Coral Reef Community, Carrie Bow Cay, Belize Mary E. Rice and lan G. Macintyre throughout the world. They occupy a variety of ABSTRACT habitats within the community: sand burrowing A survey of sipunculan fauna associated with species occur in sand flats of lagoons and in coral rock and rubble along a transect across the sediments surrounding the bases of coral growths; coral reef at Carrie Bow Cay, Belize, revealed other species inhabit crevices in rubble or live eight species, six of which inhabited burrows within algal mats on surfaces of coral boulders; within rock samples and two of which occurred in crevices and crannies. Comprising 95 percent still others dwell in burrows that they excavate in of the collection, the four most abundant species coral rubble and in coral-rock framework. These were, in order of abundance: Lithacrosiphon alt- rock-boring species, often occurring in great den- conus ‘Yen Broeke; Aspidostphon brocki Augener; sities, contribute to the erosion of reefs by weak- Phascolosoma perlucens Baird; and Paraspidosiphon ening the supporting structures of the corals and steenstrupi (Diesing). The greatest concentration of thus increasing their susceptibility to breakage sipunculans, measured as number per square me- ter of surface area of rock, occurred in reef-crest and destruction by physical stresses related to material. Sipunculans were least abundant in currents and wave action. Numerous papers have material from the patch-reef zone of the back reef referred to the boring activities of sipunculans in and from the fore-reef slope. The four most abun- coral limestone and to their possible role in reef dant species showed a distinct distributional pat- destruction (Gardiner, 1903; Otter, 1937; Rice, tern along the transect. Generally, sipunculans from the same reef habitat were densest in fresh, NIGMS 7aa, LOO: Nice andiMacimntyres 1972): relatively unaltered coral rock having little sec- This study is a preliminary survey of the sipun- ondary infill of calcite cement and a rather uni- culan fauna associated with the reef at Carrie form skeletal framework characteristic of species Bow Cay, Belize. From the distributions of sipun- of Porites and Acropora. Samples of more highly culans in different zones of this coral reef com- eroded, commonly well-cemented, and presum- ably older rocks contained few, if any sipuncu- munity and in different types of coral rock, hab- lans. Aspects of sipunculan distribution suggested itat preferences of the rock-boring species are for further study include reproductive strategy suggested. Reproductive patterns that may have and variations in substrate characteristics. a bearing on distribution are also noted. ACKNOWLEDGMENTS.—We express our appreci- ation to D. S. Putnam for his technical contri- Introduction butions to this project and to J. Piraino for pho- Marine worms of the phylum Sipuncula are tographic assistance. common inhabitants of coral reef communities Materials and Methods Mary E .Rice ,Departmen to fInvertebrate Zoology ,and Ian G. Macintyr eD,epartme n oPtfaleobiolog yN,ation aMl useu m oNfatural Observations and collections were made during Fiistor yS,mithsonia nInstitution W, ashington D, .C 2.0560. three 10-day trips to Carrie Bow Cay in 1972, 311 al SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES | Ba Rcekef Re|ef Inn eFro rReeef Out eFro rReeef T|ha |l-San |ad assiaRu |bble Pa Rt Zcehoenf e R uPba &bvelem Zeonnt e Crest H Li goShwp G &urroo S vZpeounre & Groove Zone RIneneefrSandTroughROiudtgeer FRoSerefSlope lope ]100 '200 1300 1400 1500 l600 Mete | S(ae y2)04| e© |eo=)O 5 ° N C O+oOeO)o sup ‘jonzNouui/ndic $505Y0s) SeterteleteteceG!LyOr QOD Br5e5ss Seectetesecerese, oO b ™é 50 40 i eOsO4 30 NO A AXX ?RKmIAXrAoZrerererererotoretare: sup jBn “YoO/4u2N0dyis10 - POCO R RqRoReSRSG OS 1 Station No. Ficure 138.—Density of sipunculans in coral rock along the transect of the reef, Carrie Bow Gjay |, 973, 1974. Density is expressed as numbers of sipunculans per kilogram of rock (1973, L97Z47), and as numbers of sipunculans per square meter of rock surface (1974), for each of six stations. NUMBE R12 ols) 1973, and 1974. Species of sipunculans on the IDENTIFICATION OF CorAL Rock.—Component reef were surveyed in 1972, and types of coral coral species of each rock fragment were identi- rock inhabited as well as numbers of sipunculans fied. Other factors examined included the char- per kilogram of rock were determined in 1973. acter and distribution of encrusting biota, the These observations were repeated in 1974 and, in destruction of coral skeleton by bioerosion, and addition, numbers of: sipunculans per unit of secondary infilling by submarine lithification. surface area of rock were determined. The extent of secondary infilling by magnesium COLLECTING SITES.—Sipunculans were col- calcite cement is said to be directly related to lected at numerous sites along a transect across both the length of time and degree of water different zones of the reef to the north of Carrie agitation to which the substrata have been ex- Bow Cay (Figure 138). The transect extends from posed (Macintyre, 1977). Borings of known spe- the Thalassia beds of the lagoon across the back cles were saved for a separate study on boring reef, reef crest, inner fore reef and outer fore reef mechanisms of rock-dwelling sipunculans (Rice, to a depth of 35 m on the fore-reef slope. This 1976). transect, which has been the site of many other studies, is described in detail by Rutzler and Results Macintyre (herein: 9). Density of sipunculan spe- cles was examined at six stations ranging in depth AEREAL DistrisuTion.—Of the eight species of from intertidal waters at the reef crest to 35 m on sipunculans collected from coral rock and rubble the fore-reef slope (Figure 138). at Carrie Bow Cay (Table 22), six species were COLLECTION OF Rock.—On average, four rocks found in burrows within the rocks and two in were collected at each station but this number crevices or crannies. The four most abundant varied from two to 10, depending on their avail- species, which comprised 95 percent of the speci- ability and size; the greatest number was col- mens collected over the three-year period, were lected at station 6 on the outer fore-reef slope. rock-boring species. In order of abundance, they These were usually free boulders of coral rock were: Lithacrosiphon alticonus Ten Broeke, Aspido- found on the surface of the sediment. Samples of siphon brockt Augener, Phascolosoma perlucens Baird, limited size (0.4 to 4.6 kg, averaging | to 2 kg) and Paraspidosiphon steenstrupi (Diesing). were selected at random at each site. The most common species (47 percent of spec- DescripTION OF Rock Sampres.—Length, imens collected) was Lithacrosiphon alticonus, which width, thickness, and general shape of each rock is also referred to in the literature by its synonym, were recorded along with associated flora and L. gurjanovae. It was found at all depths along the fauna. Rocks were weighed to the nearest gram, transect, including intertidal sites, but was most and surface area was calculated by covering the common in depths of 3 to 35 m. This small rocks with aluminum foil and converting the species, which averages about 10 mm in retracted weight of the foil to square meters, after the length, possesses an anterior calcareous cone, typ- method of Marsh (1970). ical of the genus, that functions to close the EXTRACTION OF SIPUNCULANS.—Except for opening of the boring when the anterior retract- small fragments saved for petrographic analysis, able portion of the body—the introvert—is with- each rock was completely fractured with a rock drawn (Figure 139a). Endemic to the Caribbean, pick and chisel and all sipunculans were ex- L. alticonus has been reported from beachrock, tracted. Species were identified, counted and, in recent unaltered coral rock, and highly eroded most cases, preserved in 70 percent ethyl] alcohol. coral rock (Ten Broeke, 1925; Murina, 1967; A few specimens were kept alive for laboratory Riecew Saal): observations on spawning and developmental Twenty-three percent of the specimens were patterns. Aspidosiphon brocki, found in small numbers at Oi SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES TABLE 22.—Sipunculans collected from coral rock at Carrie Bow Cay, 1972, 1973, 1974 Numb ecrollected Percen otf Sipunculan species (3-year total) tot aslample Habitats Aspidosiphon brocki 261 23.0 Borings in recent cora llimestone ;commonly inter- tidal to 1 m depth; rubble of Porites porites, P. astreoid Aecsr, op opraalmata Golfingia sp. 6 0.5 Crevices and holes of cora lrock ;scattered through- ou tcora lree fcommunity Lithacrosiphon alticonus 531 47.0 Borings in all types of coral rock from fresh, dense cora lto extensively bored and eroded limestone; most common in deeper water, 3-35 m Paraspidosiphon fischeri 9 0.8 Borings in all types of coral rock; most common in rubble o fPorites porites in shallow water P. speciosus 8 0.7 Borings usually in eroded cora lrock ,with secondary infill ;most frequent in deeper waters of outer reef slope P. steenstrupi 107 oH Borings in all types of coral rock throughout reef; at all depths, most common at reef crest; Porites astreoid Aecsr, op opraalmata Phascolosoma perlucens 171 15.1 Borings in recent coral limestone; shallow waters, intertidal to 3 m; abundant in rocks of Acropora palmat a n dAgarici asp. P. varians 40 3:9 Crevices and holes of cora lrock ;alga lmats covering rocks; most abundant in intertidal and shallow waters various depths along the transect and in great terior end and at the base of the introvert. The densities at the reef crest. The smallest species introvert is marked dorsally by bands of reddish- collected, it ranges from 3 to 10 mm in length of brown pigment (Figure 139d). Frequently re- the trunk. The thickened anterior and posterior ferred to in the literature by its junior synonym, shields of the trunk are characteristic of the genus Phascolosoma dentigerum, this circumtropical species (Figure 1396), although: the posterior shield may has been reported as the most common rock- be weakly developed in specimens that are regen- boring species in the Caribbean (Rice, 1975a). erating after undergoing asexual reproduction. Paraspidosiphon steenstrupi made up only 9 per- Unlike species that reproduce sexually, A. brocki cent of the collection. Although found in small reproduces asexually (Figure 139c) by constricting numbers, it occurred along most of the transect. the posterior end to form a juvenile individual; This species, which has characteristic anterior thereafter, the posterior end of the adult regen- and posterior shields, averages 20 mm in length erates (Rice, 1970). This species was first de- when the introvert is retracted (Figure 139e). scribed from the Philippines and has been re- Circumtropical in distribution, it is especially ported since from calcareous rock throughout the common throughout the Indo-Pacific and is re- Caribbean (Murina, 1967; Rice, 1970, 1975a). ported from a number of localities in the Carib- Phascolosoma perlucens, which comprised 15 per- bean (Shipley, 1903; Fischer, 1922angl 922195) Mer cent of the sipunculans collected, was found only Broeke, 1925; Murina, 1967; Rice, 1975a). in shallow waters of the reef crest and the high- The size and shape of the borings of sipuncu- relief spur and groove zone. Averaging 30 to 40 lans in coral rock reflect the size, shape, and mm in extended length, this long, slender species activity of the inhabiting species (Rice, 1969, has concentrations of conical papillae at the pos- 1975a). Borings of Lithacrosiphon alticonus, a rela- NUMBE R12 eS, tively inactive species, are generally straight and comparison of densities of the indwelling sipun- cylindrical, and the closed end of the passage is culan fauna is most meaningful when numbers of distinctly rounded. The small species, Aspzdosiphon sipunculans are related to surface area. In the brocki, has a short, narrow boring, usually straight 1974 data considered below, densities of species and always near the surface, extending at any at the six transect stations are calculated as num- angle from the surface into the rock. The borings bers per square meter of rock surface (Figure 138). of Phascolosoma perlucens, a larger, more active The greatest concentration of sipunculans was species capable of considerable extension and con- found on the reef crest (station 2). The substratum traction, are long and winding, sometimes ex- of this zone, partially exposed at low tide and tending deep into the interior of the rock. The subject to strong wave action, consists of in-place unpredictable course of these borings makes it scattered live coral heads on a coral rock pave- difficult to extract specimens without injury. The ment, coral boulders, and coral rubble. The coral borings of Paraspidosiphon steenstrupi are also long rock, predominantly Porites astreoides Lamarck and and penetrate far into the rock, but they are Acropora palmata(Lamarck), contains traces of sub- usually less sinuous than those of P. perlucens. microsucrosic magnesium calcite (Macintyre, DisTRIBUTION ALONG THE TRANSECT.—Avail- 1977) and consists of a relatively unaltered ara- able surface area of substrate rock is an important gonite coral skeleton. All four rocks (totaling 4 limiting factor for sipunculan habitation; among kg) from this station consisted of dead Porttes rocks of different thickness, shape, and size, a astreoides. Growths of coralline and filamentous Figure 139.—Common sipunculans from Carrie Bow Cay: a, Lithacrosiphon alticonus; 6, ¢, Aspidosiphon brock i(specimen in ¢c undergoing asexua lreproduction ,division wil loccur a tthe point of the constriction ,the posterior portion forming a juvenile individual) ;¢ ,Phascolosoma perlucen s eP;,araspidosipho nsteenstrup r(.Sca l‘=e mm.) 316 SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES algae, some encrusting sponges and foraminifers dosiphon brocki; its upper surface was covered with (Homotrema sp.) were scattered on the rock sur- red boring sponges and encrusting and filamen- faces. Other than sipunculans, the few living tous algae, whereas the lower surface was almost ~ organisms within the rocks consisted of a few barren, with a lesser amount of crustose coralline polychaetes and boring barnacles (Lithotrypa sp.), algae and red sponges. This second rock con- and some vermetids and boring sponges near the tained only a few polychaetes and one specimen surface. of L. alticonus; around its edges were several All four common rock-boring sipunculan spe- patches of live coral, also encrusting byrozoans, cies at Carrie Bow Cay occurred at the reef crest; crustose coralline algae, and a white sponge. Its the dominant species, here accounting for 71 internal composition was similar to that of the percent of the individuals, was Aspidosiphon brocka. first rock, except that one surface contained more The order of abundance of the other three species submicrosucrosic magnesium calcite infill. was Paraspidosiphon steenstrupi, and equal numbers Next in abundance of sipunculans was station of Lithacrosiphon alticonus and Phascolosoma perlucens. 4 located in 23 m of water at the base of the inner Other species associated with the rocks, either in reef slope; here the substratum is mainly sandy old cavities or in crevices but showing no evidence sediment with small amounts of scattered rubble of forming their own burrows, were Phascolosoma and a few heads of live Montastrea annularis (Ellis varians and an unidentified species of Golfingza. and Solander), dominated by flattened growth The second largest concentration of sipuncu- forms. Of the three rock samples (6.7 kg) col- lans was found in depths of 2 to 3 m in an area lected, two were M. annularis and one Manicina of large coral buttresses seaward of the reef crest areolata (L.). One Montastrea annularis rock had (station 3). Known as the high-relief spur and considerable crustose coralline algal cover and groove zone, it is dominated by a substratum of extensive borings at the surface and contained living corals, coral rubble, and boulders inter- numerous sipunculans of the genus Lithacrosiphon. spersed with sand patches and loose coral that The other M. annularts rock had very little cover- cover a smooth rock pavement. Whereas the reef ing growth and was nearly devoid of sipunculans. crest 1s in part intertidal, the high-relief spur and The third rock had an open porous meandroid groove zone is entirely subtidal. Of the four rocks skeleton and large masses of boring sponges near examined (totaling 5.6 kg), one was fresh Portes the surface. It contained many sipunculans, astreoides with no infill. It was difficult to break mainly Lithacrosiphon, but they were less concen- and contained only one sipunculan. Two rocks trated than in the first rock. The sipunculan were fresh Acropora palmata and the fourth fresh burrows commonly ran parallel to the dissepi- Agaricia sp. One had a trace of submicrosucrosic ments of the coral skeleton. magnesium calcite infill. The remaining two stations at either end of the The most abundant species at this station were transect had the fewest sipunculans. Station | in Phascolosoma perlucens and Lithacrosiphon alticonus. the patch-reef zone of the back reef (depth about Only small numbers of Phascolosoma varians, Par- 1 m) had substrata of scattered rubble and boul- aspidosiphon steenstrupr, and Asprdosiphon brockt were ders in a sand matrix between live coral patches present. (dominantly Montastrea annularis). The four rocks Next in abundance of sipunculans was station from this station were composed of M. annularis 5 on the outer ridge in 15 m of water, where the (total weight, 3.5 kg). Surfaces adjacent to the bottom is primarily living coral with patches of sand were almost bare, with scattered foramini- _ sand and coral rubble. Two rocks totaling more fers (Homotrema sp.) and some crustose coralline than 5 kg from this area consisted of fresh Porttes algae. On the upper surfaces, crustose coralline astreoides having little or no infill. One contained algae and red and brown filamentous algae were numerous Lithacrosiphon alticonus and a few Aspi- common. The degree of infiltration and erosion NUMBE R12 Bl] and the amount of freshly preserved coral skeleton number per kilogram of rock, the distribution of varied from a highly eroded skeleton with exten- species and relative densities were almost the sive sediment-rich submicrosucrosic magnesium same as when measured as number per square calcite to an almost freshly preserved skeleton. meter of surface area. Data from 1973 and 1974 The highest density of sipunculans was found in are compared in Figure 138. the rock having the most intact skeleton and the DIsTRIBUTION IN DiFFERING Rock Types.—Of least calcite infill. Species of sipunculans at sta- the nine types of coral rock in the 1974 collections, tion 1 were Luthacrosiphon alticonus, Aspidosiphon Porites, Agaricia, and Acropora specimens contained brockt, Paraspidosiphon steenstrupi, and Phascolosoma the greatest density (Table 23) and diversity of vartans. sipunculans. These rocks were not distributed Station 6 was located on the fore-reef slope in equally along the transect; only Porites astreoides depths of 25 to 35 m. The substratum exposed and Agaricia sp. were collected at more than one between the rich cover of octocorals and domi- station. Porites rock, the most common, was found nantly platy coral colonies was in-place coral at four stations: reef crest, high-relief spur and framework with a thin cover of Halimeda-rich sand groove, outer ridge, and fore-reef slope. Porites and scattered rubble. The coral rock from this rock at the reef crest contained, in order of abun- zone was highly eroded and infiltrated with dance, Aspidosiphon brocki, Paraspidosiphon steen- sponge growth. The 10 rocks collected (total strupi, and equal numbers of Lithacrosiphon alticonus weight, 14 kg) were covered with numerous and Phascolosoma perlucens. The sipunculan fauna sponges, some compound tunicates, tunicates, in Porites rocks from other stations consisted al- coralline algae, “leafy” brown and green algae, most entirely of Luthacrosiphon alticonus (Figure bryozoans, and small serpulid worm tubes. These 140). All Porites samples were recent, unaltered rocks were lying on, or were partially embedded coral rock having little secondary calcite infill. in the sediment. Three were so extensively bored, The density of sipunculans varied considerably, infilled, and lithified with dense microcrystalline even among rocks of the same composition at the and porous submicrosucrosic magnesium calcite same locality (Figure 140). that the coral skeleton could not be recognized. OBSERVATIONS ON REPRODUCTIVE ACTIVITY.— Five corals were identified in the other seven After removal from coral rock, specimens of Phas- rocks: Porites astreoides, Meandrina sp. Stephanocoenia colosoma perlucens ,Phascolosoma varians ,Paraspidosi- sp., Agaricia sp., and Siderastrea siderea (Ellis and phon steenstrupi, and Lithacrosiphon alticonus were Solander). Two rocks were fresh coral with their skeletal structure intact and with little secondary TABLE 23.— Density o fsipunculans in different types o fcoral infill. The others were water worn and extensively rocks bored and they contained some submarine lithi- fication. Boring sponges had infiltrated the rocks. Rocks Sipunculans Empty borings and other large holes within the rocks were filled with sand and mud and patches Coral species Number Weight Total Number/(kg) num-_ kg rock of submicrosucrosic magnesium calcite. Few si- ber punculans were found in any of these rocks, the Acropora palmata 4 10.78 75 6.96 most occurring in a sample of fresh Porites astreowdes Agaricia sp. 2 3:34 27 8.08 that contained five Lithacrosiphon alticonus and one Manicina sp. - - - Paraspidosiphon steenstrupi .Paraspidosiphon speciosus Meandrina sp. - - - ~Montastrea annularis 7 8.09 0 6.18 was found only in highly eroded samples. A few Porites astreoides 6 11.10 72 6.49 polychaetes, alphaeid shrimp, and an echiuran Porites sp. 4 a3 22 +.10 occurred within the sand-filled holes in the rock. Szderastrea siderea 7 10.84 61 5.63 When density of sipunculans was measured as Stephanocoenia sp. - 318 SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES LBiathacrosiph oalnticonus community, the greatest diversity occurring at 1200 1974 Aspidosip bhroncki the reef crest where six species (of which four were common rock borers) were found. The four rock nOGO Phascolosoma perlucens borers, found together only in the reef crest and = Paraspidosiphon steenstrupi i) high-relief spur and groove zones, each had dis-29£ 800 | be BS L OI thers tinctive distribution on the transect. Lithacrosiphon 5 Ons alticonus was found all along the transect in both a Fore - Reef = Inner Outer deep and shallow waters but it was most abun- 5 600 - | dant from the high-relief spur and groove zone to Ss Outer Ridge = High Spur the outer ridge. Aspidosiphon brockt was dominant at the reef crest but occurred only sporadically 5 400 Groove Zone 3 and in small numbers in other areas. Paraspidosi- =a phon steenstrupi was most abundant at the reef crest 2o00 Fore =Reef but occurred in small numbers along most of theZz Slepe transect. Phascolosoma perlucens was limited to the reef crest and to the shallow waters of the fore- reef zone. In being related to reef zonation, the N oR.oc kesxamined overall distribution of these four sipunculan spe- Ficure 140.—Density of sipunculans along the transect in cies must also be related directly or indirectly to Porites astreoides rock ,Carrie Bow Cay ,1974. physical parameters that control this zonation, the most important of which are water agitation and light intensity, both depth-dependent factors. kept alive in the laboratory for one to two months The substratum most densely inhabited by si- for observations on spawning. The first two spe- punculans was generally fresh coral rock with cies were observed to spawn in April and Paras- almost uniform skeletal framework, as is charac- pidosiphon steenstrupi in June. Lithacrosiphon alticonus teristic of Porites and Acropora species, and with did not spawn even though oocytes in the body relatively little secondary calcite cement infill. cavity were visible through the body wall of many The more highly eroded, water-worn, older rocks specimens. A planktotrophic larval stage occurs on the transect generally contained few, if any, in the development of Phascolosoma perlucens and sipunculans. Internally, such rocks showed con- P. varians. Although development of Paraspidosi- siderable infilling of calcite cement and were phon steenstrupi has not been observed, the small heavily infiltrated by boring sponges. The pres- size of the egg and the relatively sparse yolk ence of numerous tunnels and cavities suggested indicate that development of this species is also previous habitation by boring organisms such as planktotrophic. sipunculans. The absence of extant sipunculans Specimens of Aspidosiphon brockt, known to re- might be explained by natural death of specimens produce asexually by constricting the posterior that had formed the borings, by natural succes- end to form a new individual (Rice, 1970), were sion of boring organisms, or by death due to a examined for evidence of reproductive activity. catastrophic event (for example, rocks having Nineteen percent of the April 1974 collections been buried in sediment). The lack of new boring had posterior constrictions. An additional eight by sipunculans might be due to unavailability of percent had juveniles in their burrows. sufficient solid substratum in rocks that are heav- ily bored and infiltrated with sponges. Discussion and Conclusions Typically, the rocks containing sipunculans were covered by sponges and algal growths (fila- The rock-boring sipunculans at Carrie Bow mentous, leafy and crustose coralline). Encrusting Cay showed specific distribution within the reef organisms such as bryozoans and the foramini- NUMBE R12 519 feran Homotrema sp. occurred most commonly but ther studies should compare the relative signifi- not exclusively on the underside of the rock sam- cance to rock-boring sipunculans of the type of ples. Sponges, along with a host of other inverte- coral skeleton and degree of secondary infilling. brates such as crabs, stomatopods, alpheid Tests of habitat preference could be made by shrimp, isopods, barnacles, certain polychaetes, transplanting rocks of known composition to dif- and bivalves, were found within the rocks—either ferent parts of the reef community and by ex- in interstices and cavities or in burrows that they amining these rocks over a period of years. had formed in the rocks. Organisms in burrows Many other questions concerning colonization included the boring sponges, polychaetes of the of coral rock by boring sipunculans remain to be families Spionidae, Sabellidae, and Serpulidae as explored. Factors. affecting larval settlement are well as certain boring bivalves (Lithophaga sp. and unknown, yet they undoubtedly play an impor- Gastrochaena sp.) and boring barnacles (Lithotrya tant role in determining distribution of those sp.). Sipunculans were rarely found in rocks with species having planktotrophic larvae, such as barren surfaces and were not observed in live Phascolosoma perlucens (Rice, 1975b). Distribution portions of coral colonies. Sipunculan borings of species lacking planktotrophic larvae would be open most commonly on the upper surfaces and regulated by different factors. For example, an sides of rocks, but also on the lower surface lying explanation for the localized concentrations of on the sand. Boring sipunculans are known to Aspidosiphon brockt might be found in the pattern feed on the surfaces of rocks they inhabit, ingest- of asexual reproduction of this species. Young, ing bits of debris and sand entrapped in the crawling juveniles, unable to traverse great dis- surface cover and possibly pieces of algae (Rice, tances, probably would colonize either the same 1969, 1975a); thus the epibiota are probably im- rock as the parent or other rocks in the vicinity. portant to the survival of the animals within the Recent studies on infaunal communities of rock, although details of this association remain coral rock have suggested that surface area, po- to be investigated. rosity of rock, percentage of live coral and epibi- The present study points out pertinent factors ota may influence infaunal distribution and col- for future evaluation of the relative influence of onization (Hutchings, 1978). Therefore, reliable various physical and biotic factors on distribution quantitative data and improved methods of ap- of rock-dwelling sipunculans in the coral com- proach are obviously necessary. Brock and Brock munity. The greater density of animals in recent (1977) proposed the use of acid dissolution of rock unaltered coral rock from Carrie Bow Cay than for quantitative removal of specimens previously in highly eroded rock indicates the probable im- preserved in formalin. Hutchings (1977) mea- portance of internal structure of the rock to infil- sured exposed surface area of substrata by coating tration by boring sipunculans. On the other hand, surfaces with Playtex rubber which, after drying, the observation that different species may inhabit can be peeled off, traced and measured with a the same type of coral rock in different areas of polar planimeter. Various other techniques for the reef community suggests that physical factors measurements and sampling have been listed in associated with locality—such as agitation and a recent review of research methods for studies of depth of water—may be even more significant coral reef cryptofauna (Hutchings, 1978). To than coral skeleton in determining specific distri- date, most research efforts on specific groups of bution. These data, however, must be considered rock-dwelling fauna in coral reefs have focussed preliminary because the same rock types could on polychaetes, although sipunculans have been not be collected in each reef locality. Moreover, recognized as a significant component of the the variation in density of sipunculans in similar coral-rock infauna (Kohn and Lloyd, 1973; Pey- rocks from the same locality indicates the com- rot-Clausade, 1974; Hutchings, 1974, 1977). It is plexity of the problem and the necessity for more hoped that future studies will apply the more rigidly controlled quantitative procedures. Fur- refined current techniques to the rock-boring si- 320 SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES punculans and thus may provide a better under- nity and of their significance to the total reef standing of their distribution in the reef commu- ecosystem. Literature Cited Brock, R. E., and J. H. Brock Zoologicheski tZhurna l4, 6:35-47 [.In Russian.] 1977. A Method for Quantitatively Assessing the In- Otter, G. W. faunal Community in Coral Rock. Limnology and 1937. Rock-destroying Organisms in Relation to Coral Oceanogra p22h:y9,48-951. Reefs .In Britesh Museum (Natura lHistory) Great Fische rW, . Barrie rRee fExpedition 1928-29 1, :323-352. 1922a W. estindisch eGephyreen Z. oologische rAnzeiger 5, 5: Peyrot-Clausad eM, . 10-18. 1974. Ecological Study of Coral Reef Cryptobiotic Com- 1922b .Gephyreen des Reichmuseums zu Stockholm .Arkiv munities: An Analysis of the Polychaete Crypto- for Zoologt, 15:1-39. fauna. Jn A. M. Cameron, B. M. Campbell, A. B. Gardiner, J. S. Cribb, R. Endean, 3 )h:Ss Jel @Oxeaejoness 1903. The Maldive and Laccadive Groups, with Notes Mather, and F. H. Talbot, editors, Proceedings of on Other Coral Formations in the Indian Ocean. th eSecon dInternationa Cl ora Rl ee Sfymposium 1,:269- In J. S. Gardiner ,editor ,The Fauna and Geography 283. Brisbane, Australia: The Great Barrier Reef o tfh eMaldiv ean dLaccadw eArchipelagoes 1,:333-341. Committee. Cambridge :Cambridge University Press. Rice MEE: Hutchings ,P .A. 1969 .Possible Boring Structures o fSipunculids .American 1974. A Preliminary Report on the Density and Distri- Zoolog i9st:8, 03-812. bution of Invertebrates Living on Coral Reefs. Jn 1970. Asexual Reproduction in a Sipunculan Worm. A. M. Cameron, B. M. Campbell, A. B. Cribb, R. Sci e1n6c7e:1, 618—-1620. Endean, J. S. Jell, O. A. Jones, P. Mather, and F. 1975a. Survey of the Sipuncula of the Coral and Beach- H T. albot e, ditors P, roceeding so fthe Second Interna- rock Communities of the Caribbean Sea. Jn M. E. tiona lCora lRee fSymposium ,1:285-296 .Brisbane, Rice and M .Todorovic ,editors ,Proceedings of the Australia: The Great Barrier Reef Committee. Internationa Slymposium o nth eBiolog yo tfh eSipuncula Distribution and Abundance of Cryptofauna from and Echiura 1, :35—49 .Belgrade :Naucno Delo Press. Lizard Island ,Great Barrier Reef .Marine Research 1975b. Observations on the Development of Six Species Iindones 1ia9,:99—-112. of Caribbean Sipuncula with a Review of Devel- 1978. Non-Colonial Cryptofauna. Jn D. R. Stoddart and opment in the Phylum. Jn M. E. Rice and M. R. E. Johannes, editors, Coral Reefs: Research Todorovic e, ditors P, roceeding so fthe International Method Ms.onograp h oOsnceanograph Micethodology, Symposium on th eBrolog yo fSipuncul aand Echiura 1, : 9:251-262. Paris: UNESCO. 141-160 .Belgrade :Naucno Delo Press. nohn ,A. J., and M. C. Lloyd 1976. Sipunculans Associated with Cora lCommunities. 1973. Polychaetes of Truncated Reef Limestone Sub- Micrones i1c2a:,119-132. strates on Eastern Indian Ocean Coral Reefs: Rice, M. E., and I. G. Macintyre Diversity A, bundance a, nd Taxonomy I.nternation- 1972. A Preliminary Study of Sipunculan Burrows in a lReevu de egresamte Hnydrobiolog iuen Hdydrographie, Roc kThin-Sections C. aribbean Journa ol fScience 1, 2: 58:369-399. 41-44. Macintyre ,I .G. Shipley, A. E. 1977. Distribution of Submarine Cements in a Modern 1903. Report on the Gephyrea Collected by Professor Caribbean Fringing Reef. Journa lof Sedimentary Herdman at Ceylon in 1902. Jn W. A. Herdman, Petrolo 4g7y:,503-516. Repor to the Governmen to fCeylon on the Pear Ol yster Marsh, J. A., Jr. Fisheries o fthe Gul fo fManaar ,par t1 ,supplemen t3, 1970. Primary Productivity of Reef-building Calcareous pag e1s69-176. Red Algae .Ecology ,51:255-263. Ten Broeke ,A. Murina, V. V. 1925. Westindische Sipunculiden und Echiuriden. Bzdr- 1967. [On the Sipunculid Fauna of the Littoral of Cuba.] age nto dt De ierkund e2,4:81—96. ‘| Rice, Mary Esther and Macintyre, Ian G. 1982. "Distribution of Sipuncula in the Coral Reef Community, Carrie Bow Cay, Belize." The Atlantic Barrier Reef Ecosystem at Carrie Bow Cay, Belize 12, 311–320. View This Item Online: https://www.biodiversitylibrary.org/item/131277 Permalink: https://www.biodiversitylibrary.org/partpdf/387325 Holding Institution Smithsonian Libraries and Archives Sponsored by Biodiversity Heritage Library Copyright & Reuse Copyright Status: In Copyright. 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