Boring sponges living into precious corals from the Pacific Ocean

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Boring sponges living into precious corals from the Pacific Ocean a

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Barbara Calcinai , Giorgio Bavestrello , Carlo Cerrano & Michele Sara

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Istituto di Scienze Del Mare , Università di Ancona , via Brecce Bianche, I‐60131, Ancona, Italy b

Dip. Te. Ris. , Università di Genova , corso Europa 26, I‐16132, Genova, Italy Published online: 28 Jan 2009.

To cite this article: Barbara Calcinai , Giorgio Bavestrello , Carlo Cerrano & Michele Sara (2001) Boring sponges living into precious corals from the Pacific Ocean, Italian Journal of Zoology, 68:2, 153-160, DOI: 10.1080/11250000109356400 To link to this article: http://dx.doi.org/10.1080/11250000109356400

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Ital. J. Zool., 68: 153-160 (2001)

Boring sponges living into precious corals from the Pacific Ocean BARBARA CALCINAI GIORGIO BAVESTRELLO Istituto di Scienze Del Mare, Università di Ancona, via Brecce Bianche, I-60131 Ancona (Italy)

CARLO CERRANO MICHELE SARA

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Dip. Te. Ris., Università di Genova, corso Europa 26, I-16132 Genova (Italy)

INTRODUCTION A group of sponges living in several excavated specimens of the precious corals Corallium elatius from Taiwan and Corallium sp. from Midway has been studied. This material comes from commercial stocks and has been collected from fisheries. Until now, twenty species of Corallium have been described, but only six of them are of commercial value (Wells, 1983): one species (C rubrum) lives in the Mediterranean and in some Atlantic Islands, while the others are spread throughout the Pacific area. Both Mediterranean and Pacific corals are strongly affected by sponge bioerosion that may reduce their commercial value (Liverino, 1984). Fishery activities conducted on the precious coral banks make a large quantity of specimens available for the study of boring sponges. In spite of the important role played by these sponges and the possibility to easily find materials for investigations, there are not many studies on precious corals boring sponges. Some works have been focused on the endolithic community of the Mediterranean Corallium rubrum (Melone, 1965; Barletta & Vighi, 1968; Corriero etal, 1988, 1997; Bavestrello et al, 1999; Calcinai et al, 2000b). Assemblages of boring species, associated with colonies of precious Pacific corals, have been previously investigated only by Bavestrello et al. (1995, 1998) on material coming from the Japan Sea and Taiwan. In these latter works, six species (Cliona desimoni, Scantiletta acus and Alectona triradiata, A. wallichii, A. sorrentini, Alectona sp.) were found. With this work, five more boring species, two of which new, have been recorded, leading to a total of eleven species known to attack the precious Indo-Pacific coral.

MATERIAL AND METHODS

ABSTRACT Some new or little known sponge species living in the scleraxis of colonies of Corallium elatius from the Japan Sea and Corallium sp. from Midway Islands (Pacific Ocean) have been studied. The assemblage is composed of five species: two of them are new (Holoxea excavans, Scantiletta macroxeata), Thoosa amphiasterina is recorded for the first time since its description, the very rare T. bulbosa and Dotona pulchella have been collected for the first time in the Pacific Ocean. The boring capacity of the genus Holoxea is assessed for the first time. KEY WORDS: Boring sponges - Corallium elatius - Pacific Ocean. (Received 3 July 2000 - Accepted 20 December 2000)

Studied material consists of preserved dry portions of C. elatius scleraxis, coming from Taiwan and provided to us by courtesy of the coral manufacturer Sorrentino of Torre del Greco (Naples). Other samples from Midway Islands (Pacific Ocean) were kindly given by Dr. Sadao Kosuge (Institute of Malacology, Tokyo). Corallium elatius, forming large, pink to dark pink colonies (more than 1 m high and 25 Kg weight), lives in the Western Pacific between the Northern Philippines and Japan on rocky bottom at 250-400 m depth (Wells, 1983). The specimens of Corallium sp. from Midway were dead, without coenenchyme; it was thus impossible to identify the species. In the Midway area, different species of the genus Corallium, with a wide bathymetric distribution (from 100 to 1500 m depth) were collected (Wells, 1983; Liverino, 1984). Their taxonomic positions are not completely clear. Sponges were studied by opening the cavities of numerous portions of the coral scleraxis with a scalpel. The sponge tissue, filling the chambers, has been dehydrated and mounted in toto on slides. Moreover, spicular dissociations have been carried out dissolving the sponge fragments in boiling nitric acid in order to study the specimens under optical microscope as well as for scanning electron microscopy (SEM) analysis. SEM micrographs of the spicules and of coral portions were taken by a PHILIPS SEM 515. The type material of the new species is kept at the Natural History Museum of Genoa (NHMG).

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B. CALCINAI, G. BAVESTRELLO, C. CERRANO, M. SARA

Holotype SOR 45, a. fragment of C. elatius, kept at the MSNG 50531; paratypes, SOR 33, SOR 37, SOR 52, portions of C. elatius belong to Authors' collection.

the typical pitted pattern of sponge bioerosion (Fig. 1A). In the interior chamber, the large oxeas are irregularly arranged but, in the canals connecting two chambers, and in some cases around the chamber walls, they tend to form regular tracts (Fig. 1A). The chamber wall is lined with a palisade of thin oxeas reinforced by a crust of sanidasters (Fig. IB, C). Spiculation: a) Large, curved oxeas, (Fig. 1A; 8091055x37-40 pm) often with rounded tips, b) Thin and almost straight oxeas (Fig. IB, C; 103-122x3-4 um). c) Straight sanidasters (Fig. 1C-E; 7-11x2 pm) with spined outgrowths arranged along the shaft, in some cases producing a central swelling (Fig. 1C -arrow-, D).

Description

Remarks

This white sponge, rich in spongin, was found inside small circular chambers (0.5-2 mm) with walls showing

This species looks like Cliona pruvoti Topsent, 1900 from which it differs for the greater oxeas and the

TAXONOMIC ACCOUNT Family ANCORINIDAE Genus Holoxea Topsent, 1892

Holoxea excavansn. sp.

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Material

f 'Mr

Fig. 1 - Holoxea excavans n. sp. A, regular tract of larger oxeas. B, groups of short oxeas inside a boring chamber; numerous chips are present (arrows). C, short oxeas organized in palisade, reinforced by a crust of sanidasters; some of them show a characteristic central swelling (arrow). D, E, sanidasters. Scale bars: A, B, 100 pm; C, 40 pm; D, E, 2 pm.

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PRECIOUS PACIFIC CORAL BORING SPONGES

shape of microscleres. The presence of two categories of oxeas (see Topsent, 1900), and sanidasters together with some elements of the skeleton organization, suggest that this species belongs to the genus Holoxea, although no raphides were found in our specimens. However, according to Topsent (1900), the presence of raphides is optional. All the other species of this genus differ from H. excavans in having only one, generally larger, kind of oxeas. Holoxea furtiva (Topsent, 1900) is the most similar species to H. excavans, described as insinuating into cavities and crevices. Nevertheless, we have recorded H. furtiva inside boring chambers of C. rubrum scleraxis from Capo Verde Islands (unpubl. data). Holoxea furtiva differs from our species also for the larger size of oxeas, and for the shape and larger size of sanidasters. The presence in the sponge tissue of numerous, typical fragments (chips, maximum 40-50 pm in diameter) derived from bioerosion (Fig. IB), and the corresponding pitted pattern of the chambers in which the sponge lives confirm the boring ability of this species. Etymology For its boring ability. Family CLIONIDAE Genus Dotona Carter, 1880

Dotona pulchella Carter, 1880 Material SOR 48, fragment of C. elatius belonging to Authors' collection.

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Genus Thoosa Hancock, 1849

Thoosa amphiasterina Topsent, 1920 Material KO 1, KO 2, KO 3, fragments of scleraxis of Corallium sp. belonging to Authors' collection. Description Presence of this species in the dead coral is not evident, being papilla holes very small (400 pm in diameter). The boring activity produces small, superficial chambers. They are irregularly ovoid and 2-3 mm large. Boring chambers are connected by circular foramina (600 pm in diameter). Spiculation: a) Amphiasters (48-62 pm) with a straight, cone-shaped axis and two verticils of 3-4 conical rays (18.5-26x3-4 pm) spined at the tips (Fig. 3A, B). b) Nodular amphiasters characteristic of Thoosa; some of them are regular (Fig. 3C) with two terminal knobs and two verticils made of six short, spiny, spherical swellings (26-50x8 pm); spines and tubercles are often smaller in size (Fig. 3D). From this kind of spicules, other amphiasters originate: they may have a longer central axis and knobs and be totally covered with spines. In other cases, they may present short axis and rays. Remarks Thoosa amphiasterina was described by Topsent (1920) boring a shell of Tridacna sp. from Marutea (Gambier Island), Polynesia. This is the first record for this species since its description.

Thoosa bulbosa Hancock, 1849

Description Only small fragments were present in small chambers of coral. Spare spicules were often found mixed to those of other species. Spiculation: a) Curved microstrongyles, with spirally arranged tubercles (Fig. 2A, B; 46-64x6-7 pm). These spicules line the chamber walls; in the foramina connecting two adjacent chambers, they are arranged in a sort of rosetta (Fig. 2F). b) Slender, thin, straight or gently curved styles (Fig. 2C; 88-150x2 um). c) Rare, small amphiasters with numerous conical rays, microspined particularly at their tips (Fig. 2D, E; 10-12x4 um). Remarks Dotona pulchella described for the Indian Ocean (Gulf of Mannar) was later recorded in the Atlantic Ocean (Azores) by Topsent (1898, 1904) and in the Mediterranean (Rosell, 1996). This is the first record for the Pacific area. Macroscleres reported by Rosell and Uriz (1997) in their new diagnosis of the genus have not been found in this specimen.

Material SOR 12, a big portion of scleraxis of C. elatius belonging to Authors' collection. Description The boring activity of this sponge, very abundant in our material, produces large cavities (2.5-13x2.5-5 mm) in the coral scleraxis, which is completely filled by a yellow brownish tissue. Chambers are spherical, subspherical, or ovoid when two chambers merge. They are contiguous and separated by walls (0.5-2.5 mm thick) perforated by some foramina 0.5-1 mm in diameter. Boring chamber walls show the typical pits of sponge bioerosion. Spiculation: a) Amphiasters (Fig. 3E, F) with 12 microspined nodules arranged in two central verticils, and with two terminal spiny knobs (20-25.5x10-11 pm). b) Oxyasters with three to five microspined rays (1023x2.9 pm) ending with spined tips and with a basal swelling (Fig. 3H). c) Multiradiate amphiasters (Fig. 3D,

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B. CALCINAI, G. BAVESTRELLO, C. CERRANO, M. SARA

Fi Fig. 2 - Dotona pulchella. A, curved microstrongyle with spirally arranged tubercles. B, microstrongyle magnification. C, slender style. D, E, spiny amphiasters. F, microstrongyles arranged in rosetta. Scale bars: A, 6 pm; B, 4 pm; C, 20 um; D, E, 6 pm; F, 50 pm.

with seven-eight or more microspined rays (14-18x1.5 um). d) Smooth oxyasters (Fig. 3L) generally biradiate ('bird wings') but sometimes triradiate; these spicules are characterized by a central swelling, bent axis (6374x4 pm) and lanceolate tips; monoradiate forms (79103x3-5 pm) composed of a single straight ray ending in a swelling (Fig. 3M) are also common, e) Amphiasters with thin and short axis (18.2x6 pm on average; Fig. 3G) and very short amphiasters (10-14x1.5 pm) are probably forms of reduction of the typical amphiasters.

Remarks This species is characterized by the extreme variability of its nodular amphiasters present in the preparations in different shapes and sizes. Amphiasters with thin and short axis (18.2x6 pm on average; Fig. 3G) are probably reduction forms of the typical amphiasters (Fig. 3E, F); very short amphiasters are present in significant numbers in the preparation (10-14x1.6 pm); they are probably a more stressed form of reduc-

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Fig. 3 - Thoosa amphiasterina (A-D) and T. bulbosa (E-M). A, B, amphiasters with cone-shaped axis, microspined at the tips. C, regular, nodular amphiaster. D, amphiaster with reduced spines and tubercles. E, F, nodular amphiasters. G, reduced amphiaster with thin and short axis. H, oxyaster. I, multiradiate amphiaster. L, biradiate, smooth oxyaster. M, oxyaster in monoradiate form. Scale bars: A-D, 10 um; E, F, 4 pm; G, 5 um; H-M, 10 um; L, 30 um.

Genus Scantiletta de Loubenfels, 1936 tion of the typical amphiasters or other particular amphiasters. This is the most common and destructive Scantiletta macroxeata n. sp. species present in this collection. Thoosa bulbosa was recorded only twice (Hancok, 1849; Topsent 1888) always in bivalve shells from shallow waters, whereas Material our specimens are recorded at more than 150 m depth. Holotype SOR 25, a fragment of C. elatius, kept at the This is the first record of this species in the Pacific MSNG 50532; paratype SOR 29, a fragment of C. elatius Ocean. belonging to Authors' collection.

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Fig. 4 - Scantiletta macroxeata n. sp. A, boring chamber showing the skeleton organization. B, tract of new bioerosion. C, chamber wall showing irregular and small pits. D, large oxea. E, F, modifications of main oxeas. G, thin anisoxea. H, microspined, vermiform spirasters. I, irregularly curved spiraster. L, magnification of a spiraster showing the spiny surface. Scale bars: A, 1 mm; B, D, 100 um; C, G, 50 um; E, 170 um; F, 160 um; H, 8 pm; I, 20 um; L, 2 um.

PRECIOUS PACIFIC CORAL BORING SPONGES

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TABLE I - Boring sponges recorded into Pacific red coral.

Species

Distribution

Substratum

Depth (m)

Principal References

Allectona millari Carter, 1879

Mediterranean, North Atlantic

Calcareous rock, coral, Pacific red coral

450-1188

Topsent, 1900

A. triradiata Levi & Levi, 1983

New Caledonia

Calcareous conglomerate, C. elatius

150-350

Bavestrello et al, 1998

A. wallichii (Carter), 1874

Japan Sea, Seychelles

Arenaceous deposit, C. elatius

100-200

Topsent, 1900, Bavestrello et al, 1998

A. verticillata (Johnson), 1899

Madeira

C. johnsoni

150-200

Topsen, 1904

A. sorrentini Bavestrello et al, 1998

Japan Sea

C. elatius

150-200

Bavestrello et al, 1998

Alectona sp.

Japan Sea

C. elatius

150-200

Bavestrello et al, 1998

Scantiletta acus (Bavestrello et al., 1995)

Western Pacific Ocean

C. elatius

150-200

Bavestrello et al, 1995

S. macroxeata Calcinai et al., present work

Pacific Ocean

C. elatius

150-400

Calcinai et al, present work

Cliona desimoni (Bavestrello et al., 1995)

Western Pacific Ocean

C. elatius

150-200

Bavestrello et al, 1995

Thoosa amphiasterina Topsent, 1920

Polynesia

Tridacna sp., C. elatius

150-400

Calcinai et al, present work

T. bulbosa Hancock, 1849

Pacific Ocean

Bivalve shells, C. elatius

150-400

Topsent, 1888; Rutzler & Stone, 1986

Dotona pulchella Carter, 1880

Indian Ocean, Atlantic Ocean, Mediterranean, Pacific Ocean

Coralline algae, C. elatius

150-400

Topsent, 1898, 1904; Rosell, 1996

Holoxea excavans Calcinai et al, present work

Pacific Ocean

C. elatius

150-400

Calcinai et al, present work

Description

Remarks

This white-yellowish sponge creates small, circular boring chambers (1-3 mm) in the coral scleraxis. Larger oxeas produce a pack of parallel spicules in the cylindrical channel connecting two contiguous chambers (Fig. 4A, B). In the new bioerosion tract, only microscleres (spirasters) and slender anisoxeas are present (Fig. 4B). Spirasters are also dispersed within the chamber walls which show irregular and small pits (Fig. 4C). Spiculation-. a) Large, slightly curved oxeas (Fig. 4A, D; 900-1500x46-56 um) often with hastate, sometimes biforcate tips; numerous styles and strongyles, probably deriving from oxeas are present (Fig. 4E, F; 8371113x56 um). b) Straight, small, thin anisoxeas (Fig. 4G; 126-155 um) with different extremities, c) Microspined, curved, vermiform spirasters (Fig. 4H; 2292x2-4 um). Some almost straight, or irregularly curved spirasters, with spiny surface, are common (Fig. 41, L).

The genus Scantiletta comprises five species (S. spiralis (Johnson, 1899), S. levispira (Topsent, 1898), S. sarai (Melone 1965), S. acus (Bavestrello et al., 1995), and S. macroxeata) that are very similar to each other, and all characterized by large oxeas, sometimes transformed into styles and strongyles, small oxeas or styles and vermiform, smooth or slightly spiny, spirasters. In the Indo-Pacific area S. levispira and S. acus have been recorded (Bavestrello et al., 1995, Calcinai et al, 2000a). Especially S. macroxeata differs from the other species of the genus for the very large size and shape of the megascleres and for the presence of thin anisoxeas. Etymology The specific name is related to the very large oxeas.

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DISCUSSION In spite of the paucity of works devoted to the study of endolithic sponges associated to the scleraxis of the species of the genus Corallium, this substratum shows extraordinarily high biodiversity. Remarkably, a high number of species has been recorded both in the Mediterranean C. rubrum (14 species) (Barletta & Vighi, 1968; Corriero et al, 1988; Bavestrello et al., 1999; Calcinai et al., 2000b) and in the Pacific species (11 species, Tab. I) (Bavestrello et al., 1995, 1998; Calcinai et al., 2000a). These data agree with the suggestion that boring sponges preferentially etch compact carbonatic structures (Highsmith, 1981; Perry, 1998). The scleraxis of the precious coral (genus Corallium) is indeed one of the most compact carbonatic biodeposition (Cortesogno et al, 1999). Biodiversity of this habitat is widely enhanced by a conspicuous complex of cryptobiotic sponges able to live inside the cavity produced by boring sponges (Bavestrello et al, 1995; Corriero et al., 1997). These cryptobiotic species are particularly abundant in the Pacific coral due to the large diameter of the scleraxis and the wide size of the boring chambers produced by some species. In the Indo-Pacific area, boring species have generally been recorded to penetrate shells and madreporic structures in shallow water (e.g. Calcinai et al., 2000a). Investigations on the boring assemblage of Corallium scleraxis are important because they expand our knowledge to a deeper (100 and 1500 m) boring species assemblage. Recorded evidence of three species, previously collected in shallow waters (D. pulchella, T. amphiasterina and T. bulbosa), indicates a high eurybaty and a wide range of suitable substrata for these boring species. REFERENCES Barletta G., Vighi M, 1968 - Ricerche sul corallo rosso: V - poriferi perforanti lo sclerasse di Corallium rubrum Lamarck. Rend. Ist. Lomb. Sci. Lett. B Milano, 102: 145-159. Bavestrello G., Calcinai B., Sarà M., 1995 - Two new species of Cliona (Porifera, Demospongiae) boring the scleraxis of Corallium elatius from the Western Pacific. Ital. J. Zool., 62: 375-381. Bavestrello G., Calcinai B., Cerrano C, Sara M., 1998 - Alectona species from North-Western Pacific (Demospongiae: Clionidae). J. mar. biol. Assoc. U.K., 78: 59-73. Bavestrello G., Calcinai B., Cattaneo-Vietti R., Cerrano C., Pansini M., 1999 - Distribuzione e modalità di erosione di alcune specie

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di clionidi (Porifera, Demospongiae) associati a Corallium rubrum (Cnidaria, Anthozoa). In: F. Cicogna & R. Cattaneo-Vietti (eds), Seconda ricerca sul corallo rosso nelle acque italiane. CLEM, Ministero per le Risorse Agricole, Alimentari e Forestali, Roma, pp. 113-122. Calcinai B., Cerrano C., Bavestrello G., Sara M., 2000a - Boring sponges (Porifera, Demospongiae) from the Indian Ocean. Ital. J. Zool., 67: 203-219. Calcinai B., Cerrano C, Milanese M., Bavestrello G., 2000b - Il popolamento di spugne perforatrici di Corallium rubrum e di alcuni madreporarai del promontorio di Portofino. Boll. Mus. Ist. Biol. Univ. Genova, 64-65: 53-59. Corriero G., Abbiati M., Santangelo G., 1997 - Sponges inhabiting a Mediterranean red coral population. P.S.Z.N. Mar. Ecol., 18: 147-155. Corriero G., Pansini M., Sara M., 1988 - Boring sponges (Demospongiae, Clionidae) perforating Corallium rubrum in the Mediterranean Sea. FAO Fish. Rep., 413: 73-77. Cortesogno L., Gaggero L., Bavestrello G., Cerrano C, CattaneoVietti R., 1999 - Struttura, mineralogia, minerochimica e chimismo del corallo rosso. In: F. Cicogna, G. Bavestrello & R. Cattaneo-Vietti (eds), Biologia e tutela del corallo rosso e di altri ottocoralli del Mediterraneo. Ministero delle Politiche Agricole, Roma, pp. 83-97. Hancock A., 1849 - On the excavating power of certain sponges to the genus Cliona. Ann. Mag. Nat. Hist., 3: 321-348. Highsmith R., 1981 - Coral bioerosion: damage relative to skeletal density. Notes and comments. Am. Nat., 117: 193-198. Johnson J. Y., 1899 - Notes of some Sponges belonging to the Clionidae obtained at Madera. J. R. microsc. Soc, 5: 461-463. Liverino B., 1984 - Il corallo. Ed. Analisi, Bologna, 229 pp. Melone N., 1965 - I poriferi associati a Corallium rubrum (L.) della Sardegna. Ann. Mus. civ. Stor. nat. 'Giacomo Doria', 75: 343-358. Perry C. T., 1998 - Grain susceptibility to the effects of microboring: implications for the preservation of skeletal carbonates. Sedimentology, 45: 39-51. Rosell D., 1996 - A new diagnosis of the genus Delectona (Porifera, Hadromerida), whit a description of a new species from the Alboran Sea (western Mediterranean). Helgol. Meeresunters., 50: 425-432. Rosell D., Uriz M., 1997 - Phylogenetic relationships within the excavating Hadromerida (Porifera), whit a systematic revision. Cladistic, 13: 349-366. Rützler K., Stone S. M., 1986 - Discovery and significance of Albany Hancock's microscope preparations of excavating sponges (Porifera: Hadromerida: Clionidae). Proc. biol. Soc. Wash., 99: 658-675. Topsent E., 1888 - Contribution a l'étude des clionides. Arch. Zool. exp. gén., 5: 1-165. Topsent E., 1898 - Eponge nouvelle des Açores. Première série. Mem. Soc. zool. Fr., 11: 225-255. Topsent E., 1900 - Etude monographique des spongiaires de France. III, Monaxonida (Hadromerina). Arch. Zool. exp. gén., 3: 1-331. Topsent E., 1904 - Spongiaires des Açores. Result, des Camp. Sci. Prince Albert I Monaco, 25: 1-280. Topsent E., 1920 - Caractères et affinités des Thoosa Hancock et des Alectona Carter. Considerations sur leurs germes à armure. Bull. Soc. Zool. de France, 45: 88-97. Wells S., 1983 - Precious coral commercially threatened. In: The IUCN invertebrate red data book. Publ. IUCN, Gland, pp. 35-42.