THE RAFFLES BULLETIN OF ZOOLOGY 2007 THE RAFFLES BULLETIN OF ZOOLOGY 2007 55(2): 371-380 Date of Publication: 31 Aug.2007 © National University of Singapore ASSOCIATION BETWEEN THE SCALLOP, PEDUM SPONDYLOIDEUM, (BIVALVIA: PTERIOMORPHIA: PECTINIDAE) AND SCLERACTINIAN CORALS FROM THE WAKATOBI MARINE NATIONAL PARK (SOUTHEASTERN SULAWESI, INDONESIA) Patrick Scaps Laboratoire de Biologie animale, Université des Sciences et Technologies de Lille, 59 655 Villeneuve d’Ascq Cédex, France Email: [email protected] (Corresponding author) Vianney Denis Laboratoire de Biologie animale, Université des Sciences et Technologies de Lille, 59 655 Villeneuve d’Ascq Cédex, France Email: [email protected] ABSTRACT. – The associations between the nestling and facultative boring pectinid bivalve Pedum spondyloideum and scleractinian host corals were studied at the Wakatobi Marine National Park (MNP), part of the Tukang Besi Archipelago in the Banda Sea, Indonesia. There, Pedum uses fi fteen hosts including the previously unrecorded species Montipora capricornis, M. danae, M. informis, M. mactanensis, Pavona clavus, Pav. duerdeni and Turbinaria irregularis. Massive Porites lobata and Por. lutea are the favourites. The depth range of Pedum extends from 3.5–18 m. There is no correlation between the number of Pedum and depth, and between the number of Pedum per colony and depth. Local distribution indicates that associations are more diversifi ed and Pedum occur in greater numbers on fringing reefs off Kaledupa Island or on sites located further off Hoga Island. Sites located near the Hoga Marine Research Station and the training platforms had only a few Pedum and associations. A site with a particularly heavy sedimentation rate and elevated nutrient concentration in the water contained many individuals associated only with massive Porites. Competitors of Pedum (nestling and boring bivalves, vermetid gastropods, serpulid annelids, hermit crabs, cryptochirid and cirriped crustaceans) were mainly observed in massive Porites. KEY WORDS. – Pedum, bivalvia, corals, Indonesia. INTRODUCTION skeleton; it is usually completely surrounded by live tissue on the coral surface, but not inside the dwelling (Yonge, Living scleractinian corals provide microhabitats for a large 1967; Waller, 1972; DeVantier & Endean, 1988; Kleemann, number of parasitic and commensal associates, which use 1990; Savazzi, 1999). The coral-bivalve relationship may be the tissue and skeletons of the colonies as substrata (Frank mutualistic, with the coral providing the bivalve with support et al.,1995; Floros et al., 2005). Coral associates are defi ned and protection, and the bivalve enhancing water circulation as sessile invertebrates that live on or within the coral for coral feeding. Furthermore, DeVantier & Endean (1988) skeleton (Risk et al., 2001) and apertures of the latter open showed that Pedum reduced the effects of heavy levels of through the living coral tissue (Scott, 1987). Many taxa are predation by the starfi sh Acanthaster planci on their coral involved, including sponges, polychaetes, bivalves, tunicates hosts on the Great Barrier Reef by repelling foraging starfi sh and hydroids (reviewed in Scott, 1987). Most of these coral on contact by repeated expulsion of jets of water. On the associates stress the coral to some degree, and some of them, other hand, Ped. spondyloideum may cause some structural particularly some sponges, polychaetes and bivalves can do weakness to its coral host, since its impact, both alive and considerable harm, at least to the skeleton (Sammarco & Risk, dead, result in a cavity within the coral structure. 1990; Smith & Harriott, 1988; Floros et al., 2005). To date, little attention has been paid to the associates of The pectinid bivalve Pedum spondyloideum (Gmelin, 1791) is living corals in Indonesia although this country lies within an obligate associate of living coral that occurs in the Indo- the triangle of biodiversity harbouring the most biologically Pacifi c (Kleemann, 1990, 1995, 2001; Scaps et al., 2005). diverse coral reefs in the world. Only recently, Scaps et al., It is byssally attached and it lives embedded in the coral (2005) studied coral associations and competitors for space 371 1144__SSccaappss((PPgg337711--338800))..iinndddd 337711 88//2299//0077 66::2299::4499 PPMM Scaps & Denis: Scallop-coral association of Ped. spondyloideum from the northeast coast of Sulawesi. the Banda Sea, in Indonesia (Elliot et al., 2001). Wakatobi It was found that Pedum was associated with 11 host coral MNP was established in 1996 and contains approximately species (eight genera) but mainly with massive corals of the 50,000 ha (500 km2) of coral reefs. The area selected for this genus Porites (Por. lobata and Por. lutea). On the contrary, fi eld study lies near the centre of global marine biodiversity data from the Red Sea showed that Pedum occupied at least or “Coral Triangle” composed of Indonesia, Philippines, 25 species (14 genera) and was associated more frequently Malaysia and Papua New Guinea. This region harbours the and in higher densities with encrusting to semi-massive most biologically diverse coral reefs in the world. and even branching Montipora species (Kleemann, 1990). Scaps et al., (2005) suggested that the associations may Observations were carried out in the fi eld by SCUBA-diving differ regionally. in the summer of 2005 (between the 2 and 6 July). Ten sites were surveyed for Pedum-coral associations. For sampling The aim of the study was to enhance the understanding of the locations and dates see Table 1. The maximal tidal range nature of associations between Pedum and its scleractinian on Hoga is 2 meters but is typically 1.5 meters. During this host corals within the distribution range of the species and study, the seawater temperature varied between 27 and 28°C. more specifi cally in the world’s most diverse coral reefs, i.e The salinity ranged from 32 to 33 ppm . No difference was where one can expect to fi nd the most varied associations. noticed between the surface and the bottom temperature and salinity. The transparency of the water, measured with a Secchi disk, was comprised between 7 m (Site 8) and 14 MATERIALS AND METHODS m (Site 4). Most of the sites were fringing reefs, with a developped reef crest and a fairly steep reef slope after which The study sites were located around the islands of Hoga and a fl at gentle slope of sandy habitat dominates. Maximum Kaledupa (Figs. 1, 2). They are close (less than one hour) depth (18 m) and maximum dive times (45 minutes) were to a Marine Research Station run by Operation Wallacea in compliance with the standards of Operation Wallacea. on the small island of Hoga (approximately 6 km2). Both Dives consisted of a slow ascent along the reef in a zigzag islands are situated in the Wakatobi MNP, part of the Tukang path to the shallowest points. The occurence percentages of Besi Archipelago, a remote island group of about 200,000 Pedum in the different scleractinian corals was defi nied as the ha (2,000 km2) off the southeastern coast of Sulawesi in ratio of the number of colonies of a given species infested by Pedum on the whole of the coral colonies colonized by Pedum. The distribution and population density of Pedum was estimated from notes in the fi eld and from in situ underwater photography. In order to study the population structure, the width of each Pedum was measured with a caliper to the nearest mm. Because of our aim to document the range of host corals, genera and species, photographs were taken of new or rarely observed associations. Additional pictures were taken of known associations when the Pedum density was high for either the particular host or the locality. Due to diffi culties in identifying massive corals of the genus Porites (Por. lutea and Por. lobata) and due to the fact that these two species represent the most common host corals of Ped. spondyloideum (Scaps et al., 2005), they were all grouped as “massive Porites”. For the other corals, many Fig. 1. Location map of the study area. The white arrow points to Fig. 2. Location of the study sites around Hoga and Kaledupa Hoga and Kaledupa Islands. The entire Tukang Besi Archipelago Islands. Thin black border represents the reef wall and the symbol lies within the Wakatobi Marine National Park. (■) represents Sampela village. 372 1144__SSccaappss((PPgg337711--338800))..iinndddd 337722 88//2299//0077 66::2299::5500 PPMM THE RAFFLES BULLETIN OF ZOOLOGY 2007 Table 1. Locations and details of the study sites on Hoga and Kaledupa islands. Date (2005) Site Island Name Latitude Longitude South (S) East (E) 02/07 AM Hoga Buoy 2 5°28'545'' 123°45'545'' 02/07 PM Hoga Buoy 5 5°28'02'' 123°45'33'' 03/07 AM Hoga Buoy 4 5°28'29'' 123°45'40 03/07 PM Hoga Pat Kasim 5°27'569'' 123°45'179'' 04/07 AM Kaledupa Kaledupa 5°28'22'' 123°43'47'' 04/07 PM Hoga Ridge 5°26'565'' 123°45'38'' 05/07 AM Hoga Inner Pinnacle 5°27'22'' 123°45'43'' 05/07 PM Kaledupa Sampela 5°29'01'' 123°45'08'' 06/07 AM Hoga Outer Pinnacle 5°27'19'' 123°45'25'' 06/07 PM Hoga Coral Gardens 5°26'83'' 123°45'21'' Table 2. Pedum spondyloideum hosts at Wakatobi Marine National Park. Species % N M SD Montipora capricornis 1.6 1 1 - Montipora confusa 3.2 2 2 - Montipora danae 1.6 1 1 - Montipora informis 1.6 1 1 - Montipora mactanensis 4.8 3 4.66 5.50 Montipora sp. 6.4 4 1 0 Gardineroseris planulata 4.8 3 1.66 1.15 Pavona clavus 1.6 1 1 - Pavona duerdini 1.6 1 1 - Pavona maldiviensis 1.6 1 1 - Cyphastrea microphthalma 1.6 1 3 - Favia stelligera 1.6 1 2 - Massive Porites (Porites lobata + Porites lutea) 64.8 39 1.89 1.42 Porites rus 1.6 1 1 - Turbinaria irregularis 1.6 1 1 - %, percentage of occurrence; N, number of infested colonies; M, mean number of Pedum per colony; SD, standard deviation. species can be positively identifi ed underwater down to Fungiina, Agaricidae (Gardineroseris, Pavona); 3) Faviina, species level, but several species cannot be recognized with Faviidae (Cyphastrea); 4) Poritiina, Poritidae (Porites); and certainty without knowing skeletal details. In the latter case, 5) Dendrophylliina, Dendrophylliidae (Turbinaria). representative samples were collected to enable a positive identifi cation in the laboratory. Corals were bleached for Some of these associations have been reported before from 24–48 h to remove living tissue. They were then rinsed in other localities in the Indo-Pacifi c (Table 3) but four species freshwater, dried and identifi ed following Veron (2000), Veron of Montipora (M. capricornis, M. danae, M. informis and & Pichon (1976, 1980, 1982), Veron & Wallace (1984) and M. mactanensis), two species of Pavona (Pav. clavus and Veron et al., (1977). Pav. duerdeni) and a species of Turbinaria (T. irregularis) are new records. A colony of M. capricornis from Site 6, hosted a single Pedum. Also, only a single Pedum was found RESULTS in M. informis (Fig. 3A) from Site 2. The association between Pedum and M. mactanensis was observed from Sites 5 and Associations with live scleractinian corals 9. We found one Pedum in a colony of M. danae (Fig. 3B) from Site 9. Other colonies of unidentifi ed Montipora species In the Wakatobi MNP, 15 associations of Pedum with host hosted a single Pedum from Sites 5, 6, 9 and 10. Only a single corals were recorded (Table 2). Pedum was observed in six Pedum was found in Pav. clavus (Fig. 3C) from Site 4 and genera of host corals (Table 3) belonging to fi ve families from in Pav. duerdeni (Fig. 3D) from Site 10. Also, a colony of fi ve suborders: 1) Astrocoeniina, Acroporidae (Montipora); 2) Turbinaria irregularis hosted a single Pedum from Site 5. 373 1144__SSccaappss((PPgg337711--338800))..iinndddd 337733 88//2299//0077 66::2299::5522 PPMM Scaps & Denis: Scallop-coral association wesi wesi wesi wesi wesi Locality Northeastern Sula Northern Red Sea Northern Red Sea Northern Red Sea Northern Red Sea Northern Red Sea Northern Red Se Northern Red Sea Northern Red Sea Northeastern Sula Wakatobi MNP Wakatobi MNP Wakatobi MNP WakatobiMNP Wakatobi MNP Aqaba, Red Sea Northeastern Sula Northern Red Sea Northeastern Sula Wakatobi MNP Northern Red Se NorthEastern Sula Northern Red Sea Wakatobi MNP Northern Red Sea Northern Red Sea Wakatobi MNP Wakatobi MNP Torres Strait, GBR Northern Red Sea Reference Scaps et al., (2005) Kleemann (1990) Kleemann (1990) Kleemann (1990) Kleemann (1990) Kleemann (2001) Kleemann (2001) Kleemann (2001) Kleemann (2001) Scaps et al., (2005) new record new record new record new record new record Kleemann (2001) Scaps et al. (2005) Kleemann (1990) Scaps et al. (2005) new record Kleemann (1990) Scaps et al. (2005) Kleemann (1990) new record Kleemann (2001) Kleemann (2001) new record new record Kleemann (1990) Kleemann (1990) (2005). Species A. robusta M. meandrina M. stilosa M. fl oweri M. tertia M. hoffmeisteri M. monasteriata M. tuberculosa M. venosa M. confusa M. confusa M. capricornis M danae M. informis M. mactanensis A. myriophthalma C. mayeri G. planulata G. planulata G. planulata Pac. speciosa Pac. speciosa Pav. maldivensis Pav. maldivensis Pav. cactus Pav. varians Pav. clavus Pav. duerdeni L. mycetoseroides C. monile al., et s p a c 1), an update of S Genus Acropora Montipora Astreopora Coeloseris Gardineroseris Pachyseris Pavona Leptoseris Coscinarea 9 7 1 n, eli m G ( m y eu mil dum spondyloid Family, Subfa Acroporidae Agaricidae Siderastreidae e P of s al or st c na Table 3. Ho Suborder Astrocoenii Fungiina 374 1144__SSccaappss((PPgg337711--338800))..iinndddd 337744 88//2299//0077 66::2299::5522 PPMM THE RAFFLES BULLETIN OF ZOOLOGY 2007 si fi c si si si si si Locality Northern Red Sea Northern Red Sea Wakatobi MNP Northern Red Sea Northern Red Sea Northeastern Sulawe Northern Red Sea Eniwetok Atoll, Paci Northern Red Sea Wakatobi MNP Northern Red Sea Northern Red Sea Northern Red Sea Northeastern Sulawe Port Sudan, Red Sea Phuket, Thailand Northern Red Sea Northeastern Sulawe Wakatobi MNP Mellish Reef, GBR Northeastern Sulawe Wakatobi MNP Northeastern Sulawe Northeastern Sulawe Raboul, New Britain Northern Red Sea Lizard Island, GBR Wakatobi MNP Northern Red Sea Wakatobi MNP 0) 0 0 2 ( w a h s d a Br 7) n & 9 fi Reference Kleemann (1990) Zuschin & Piller (19 new record Kleemann (1990) Kleemann (2001) Scaps et al. (2005) Kleemann (2001) Waller (1972) Kleemann (1990) new record Kleemann (1990) Kleemann (2001) Kleemann (2001) Scaps et al. (2005) Mastaller (1978) Nielsen (1986); Scof Kleemann (1990) Scaps et al. (2005) new record Kleemann (1990) Scaps et al. (2005) new record Scaps et al. (2005) Scaps et al. (2005) Yonge (1967) Kleemann (1990) Kleemann (1995) new record Kleemann (1990) new record a) x e v n o Species C. microphthalma C. microphthalma C. microphthalma E. gemmacea L. purpurea L. purpurea F. helianthoides F. stelligera F. stelligera F. stelligera G. retiformis G. edwardsi H. microconos H. microconos Por. lutea Por. lutea Por. lutea Por. lutea Por. lutea Por. lobata Por. lobata Por. lobata Por. evermanni Por. monticulosa Por. rus (as Por. c Por. rus Por. rus Por. rus T. mesenterina T. irregularis Genus Cyphastrea Echinopora Leptastrea Favia Goniastrea Hydnophora Porites Turbinaria nal Park. o ati N e n ae Mari Family, Subfamily Faviidae, Montastrein Faviidae, Faviinae Merulinidae Poritidae Dendrophylliidae at Barrier Reef; MNP, e Gr ed). BR, 3. (continu der a na ophylliina viations: G Table Subor Faviin Poritii Dendr Abbre 375 1144__SSccaappss((PPgg337711--338800))..iinndddd 337755 88//2299//0077 66::2299::5522 PPMM Scaps & Denis: Scallop-coral association Fig. 3. Associations with Pedum spondyloideum: A, Montipora informis inhabited by Pedum; B, Pedum imbedded in M. danae; C, Pavona clavus with Pedum; D, Pedum in Pav. duerdeni; E, Porites rus inhabited by Pedum; F, Pedum aggregation in Cyphastrea microphthalma; G, Favia stelligera with Pedum. A–D are new associations; E, G are new records for Indonesia; Scale bars = 1 cm. 376 1144__SSccaappss((PPgg337711--338800))..iinndddd 337766 88//2299//0077 66::2299::5522 PPMM THE RAFFLES BULLETIN OF ZOOLOGY 2007 Some of the associations are new records from Indonesia. A various host corals were 12.5 m in M. capricornis, 15 m in colony of Por. rus from Site 6, hosted a single Pedum (Fig. M. confusa, 9 m in M. danae, 8 m in M. informis, 13–15 3E). Also a single Pedum was found in Pav. maldivensis from m (14.33 ± 1.15 m) in M. mactanensis, 3.5–15.5 m (10.66 Site 7. We found three Pedum in a colony of Cyphastrea ± 6.33 m) in Gardineroseris planulata, 7 m in Pav. clavus, microphthalma (Fig. 3F) from Site 7 and two Pedum in a 14.5 m in Pav. duerdeni, 7 m in Pav. maldivensis, 5 m in colony of Favia stelligera (Fig. 3G) from Site 9. Pedum Cyphastrea microphthalma, 3.5–18 m (8.86 ± 6.64 m) in also occured commonly in Por. lutea and Por. lobata and massive corals of the genus Porites, 17 m in Por. rus and 8 occasionally in M. confusa (Sites 6 and 7) and Gardineroseris m in T. irregularis. planulata (Sites 2 and 7). Local distribution of Pedum Abundance and depth distribution of Pedum All the sites surveyed contained several individuals of Pedum (Table 4). The sites located on the fringing reefs near the The number of Pedum per infested colony varied from one Marine Research Station and near the training platforms to eleven. A colony of M. mactanensis from Site 5 hosted a on Hoga Island (Sites 1–4; Fig. 2) contained only a few very high number of Pedum (11 individuals) at 15 m. Several individuals and Pedum was associated with a few coral specimens of Pedum were also found in M. confusa (maximum species. On the contrary, the sites located further off Hoga three individuals), Gardineroseris planulata (maximum three Island (Sites 6, 7, 9 and 10) contained more individuals and individuals), Cyphastrea microphthalma (maximum three the associations were more diversifi ed, particularly at Site 7. individuals) and Favia stelligera (maximum two individuals). Pedum from Sites 6 and 9 were recorded from fi ve different Up to six Pedum were found on massive Porites (Fig. 4) but coral species. The sites located on the fringing reefs on in most cases Pedum occured only once (60%). The highest Kaledupa Island (Sites 5 and 8) contained many individuals; Pedum density (six individuals) was found between six to nevertheless, Pedum was recorded from four different coral thirteen metres. For all other associations only one Pedum species from Site 5 whereas it was only associated with was found. The mean number of Pedum per infested colony massive corals of the genus Porites from Site 8. is maximum for M. mactanensis (Table 2). No relationship was found between the number of Pedum associated with host corals and the depth (correlation coeffi cient r = 0.2123, Competitors P = 0.3688; considered not signifi cant) and between the number of Pedum per association and the depth (correlation Apart from intraspecifi c competition for food and space, coeffi cient r = 0.0371, P = 0.8371; considered not signifi cant). Pedum often has to cope with several competitors associated The population of Pedum was composed mainly of one–two with the same host colony, dwelling in crevices or settling cm wide individuals (Fig. 5), a width which corresponds to on dead parts of the coral (Kleemann, 2001; Scaps et al., young adults. 2005). Competitors were mainly observed in massive corals of the genus Porites (Por. lutea and Por. lobata). Pedum The depth range of Pedum in the Wakatobi MNP extended occured with other bivalves byssally attached to corals or from 3.5 to 18 m. The depth records of Pedum in the within corals (Tridacna spp.), byssally attached in crevices of Fig. 4. The number of Pedum spondyloideum occuring in Porites Fig. 5. Size distribution of Pedum spondyloideum in the Wakatobi lobata and Por. lutea. MNP. 377 1144__SSccaappss((PPgg337711--338800))..iinndddd 337777 88//2299//0077 66::2299::5522 PPMM Scaps & Denis: Scallop-coral association Table 4. Associations of Pedum spondyloideum according to sites. Site N Nd N Depth (m) Size (cm) ass ass ped 1 1 1 3 7 1.2-2.8 2 4 3 8 3.5-15.5 1.4-3.7 3 1 1 2 8.5 1.6-2.4 4 2 2 2 7-7.5 2.4-3.2 5 7 4 21 5-14 1.4-4.8 6 7 5 11 5.5-17 1.8-4.6 7 12 6 23 5-15 0.6-5.8 8 11 1 22 4-7.5 0.7-5.6 9 11 5 14 5-18 1.2-4.4 10 4 3 9 6-14.5 1.4-3.8 Total 49 15 115 3.5-18 0.6-5.8 N , number of associations; Nd , number of different associations; N , number of Pedum. ass ass ped living corals (Arca ventricosa, Barbatia foliata and Modiolus Pulisan area while it was observed associated with massive philippinarum) or boring in living corals (Lithophaga spp.). (Gardineroseris planulata, Pav. maldivensis, Pav. clavus, Pav. It also occured with vermetid gastropods (Dendropoma duerdeni, Cyphastrea microphthalma, Favia stelligera) or maxima and Serpulorbis grandis) encrusted to living corals, encrusting to semi-massive to even laminar species mainly serpulid annelids (Spirobranchus giganteus), hermit crabs of the genus Montipora (M. capricornis, M. confusa, M. of the genus Paguritta living in self-created boreholes in danae, M. informis, M. mactanensis, Por. rus, T. irregularis) living corals (Lewinsohn, 1978; Patton & Roberston, 1980) in the Wakatobi region. Data from the Red Sea showed that and cryptochirid and cirriped crustaceans. Massive corals Pedum has so far been recorded from 14 host genera (Table carried also sometimes some individuals of the corallivorous 5) and is associated more frequently and in higher densities gastropod Coralliophila neritoidea. with Montipora species; however, Pedum do not infest the same Montipora species (such as M. meandrina, M. stilosa, M. fl oweri, M. tertia, M. hoffmeisteri, M. monasteriata, DISCUSSION M. tuberculosa and M. venosa) as in the Wakatobi MNP. Although some species of Montipora are endemic to the Red Fifteen coral species are occupied to some degree by the Sea (M. meandrina and M. stilosa) the others have a large scallop Pedum spondyloideum in the Wakatobi region; Indo-Pacifi c distribution and can be found on the coasts of nevertheless, Pedum shows a strong preference for massive Sulawesi. In consequence, the differences observed between species of Porites (65%) with few records of other hosts. the different regions of the biogeographic distribution of the Previous reports from other localities in the western Indo- species suggest that the associations may differ regionally. Pacifi c also showed that Pedum is mostly restricted to massive As yet, it is unclear what type of association exists between species of Porites (Table 3). Pedum was found associated Ped. spondyloideum and its host coral. It is certain, however, with Por. lutea and Por. lobata at Phuket in Thailand and that the distribution of Ped. spondyloideum on different coral at Mellish Reef (Great Barrier Reef) in Australia (Nielsen, species is not random, and there is a distinct habitat preference 1986; Kleemann, 1990; Scoffi n & Bradshaw, 2000). At Lizard for certain corals over others. Island (Great Barrier Reef) Pedum was only found in Por. rus (Kleemann, 1995). More recently, Scaps et al., (2005) The depth distribution of Pedum in the Wakatobi MNP found that in the Pulisan region, located on the northeast ranges from 3.5 to 18 m, which is within the range for other coast of Sulawesi, Pedum was also mainly associated localities: 0.5–25 m in the northern Red Sea (Kleemann, (87.5%) with massive Porites species (Por. lobata and Por. 1990); below seven metres in Eniwetok Atoll (Waller, 1972); lutea). However, the associations are more diversifi ed in the four metres on the northeast coast of Redika Island, south Wakatobi region compared to the Pulisan region. Thus, 15 of Noumea, New Caledonia (Waller, 1972); two–ten metres different associations were found in the Wakatobi region below the reef crest on Holbourne Island Reef and Keeper for 10 surveyed sites compared to 11 associations for 21 Reef, central Great Barrier Reef (DeVantier & Endean, 1988) surveyed sites in the Pulisan region. Moreover, although and two–sixteen metres in the north-east coast of Sulawesi the same coral host species for Pedum are present in the (Scaps et al., 2005). two areas, some associations observed on the northeast coast of Sulawesi were not recorded in the Wakatobi region High population densities within single coral heads from and vice-versa (Table 3). Thus, apart from massive species Raboul, New Britain (Yonge, 1967) and from the Red Sea of Porites, Pedum was found associated with massive (Kleemann, 1990, 2001; Zuschin & Piller, 1997) are less (Coeloseris mayeri, Gardineroseris planulata, Hydnophora frequent in Wakatobi MNP. Densities are more important in microconos, Por. evermanni and Por. monticulosa) or the Wakatobi region (49 associations observed and 115 Pedum encrusting (Acropora robusta, Montipora confusa, Pachyseris counted during 7.5 hours of diving) than in the Pulisan area speciosa and Leptastrea purpurea) species of corals in the (112 associations observed and 212 Pedum counted during 378 1144__SSccaappss((PPgg337711--338800))..iinndddd 337788 88//2299//0077 66::2299::5533 PPMM THE RAFFLES BULLETIN OF ZOOLOGY 2007 24 hours of diving). At the Great Barrier Reef, low densities This is based on the theory that coral associate numbers will in Porites were also noted, the highest values being 10 per increase with organic loading: stressed corals will be less 0.46 m coral diameter and 24 per 1.06 m across (DeVantier able to protect themselves from settlement and overgrowth & Endean, 1988). From the Philippines, Savazzi (1999) (Risk et al. 1993). In that sense our results are particularly reported even lower densities, rarely more than two–three interesting since we have found that Pedum is more common Pedum per Porites one metre across. on a reef severely impacted by sedimentation and with a low coral cover. In the Wakatobi region, Pedum was present at all the sites surveyed. Nevertheless, Pedum was rarer on the sites located on the fringing reefs near the Marine Research Station and ACKNOWLEDGEMENTS near the training platforms on Hoga Island (Sites 1–4). On the contrary, Pedum was more common on the sites located This research was sponsored by Operation Wallacea and was around Hoga Island but further away from the Marine in compliance with the laws of Indonesia. We are grateful Research Station (Sites 6, 7, 9 and 10) and around Kaledupa to the Indonesian Institute of Sciences (Lembaga Ilmu Island (Sites 5 and 8). Therefore, it seems that Pedum is Pengetahuan Indonesia, LIPI). We would like to thank all sensitive to the disturbance induced by SCUBA-divers or the volunteer SCUBA divers who assisted with diving and to chemical factors or marine currents which are likely to Professor Michel Pichon of the University of Perpignan, differ between the sites close or further away from the Marine France, who assisted in identifying scleractinian species. Research Station. Pedum is particularly common in Site 8 (Sampela) but is only LITERATURE CITED associated with massive corals of the genus Porites. This Site is on the reef surrounding the Baujo village of Sampela Crabbe, M. J. C. & D. J. Smith, 2002. Comparison of two reef sites on Kaledupa Island and sedimentation rates are particularly in the Wakatobi marine national park (SE Sulawesi, Indonesia) important (four times higher at Sampela than at Kaledupa; using digital image analysis. Coral Reefs, 21: 242–244. Crabbe & Smith, 2002). Sediment being deposited on the DeVantier, L. M. & R. Endean, 1988. The scallop Pedum Sampela reef consists of fi ne sublittoral sands (Crabbe & spondyloideum mitigates the effects of Acanthaster planci predation on the host coral Porites: host defence facilitated by Smith, 2002). The coral reef cover at Sampela is particularly exaptation? Marine Ecology Progress Series, 47: 293–301. low due to the fact that the scleractinian coral community is Elliott, G., B. Mitchell., B. Wiltshire., I. R. Abdum Manan & S. severely impacted by sedimentation. The coral community Wisman, 2001. Community participation in marine protected at this site is less diversifi ed and dominated by species that area management: Wakatobi national park, Sulawesi, Indonesia. can survive in a turbid environment such as massive Porites Coastal Management, 29: 295–316. species. Nevertheless, although the coral cover is much less Floros, C. D., M. J. Samways & B. Armstrong, 2005. Polychaete important at Sampela compared to the other sites, the number (Spirobranchus giganteus) loading on South African corals. of Pedum specimen associated with scleractinian host corals is Aquatic Conservation: Marine and Freshwater Ecosystems, comparable or even higher than that of other sites indicating 15: 289–298. that the massive colonies of Porites are heavily infested by Frank, U., I. Brickner., B. Rinkevich., Y. Loya., R. P. M. Bak., Y. Pedum. These data are in concordance with previous studies Achituv & M. Ilan, 1995. Allogeneic and xenogeneic interactions indicating that Pedum is mainly found in sheltered areas in reef-building corals may indice tissue growth without with high sedimentation rates and high nutrient content calcifi cation. Marine Ecology Progress Series, 124: 181–188. (Kleemann, 1990; Scaps et al., 2005) and is rare at exposed Kleemann, K., 1990. Coral associations, biocorrosion, and space sites (Kleemann, 1995; Waller, 1972). competition in Pedum spondyloideum (Gmelin) (Pectinacea, Bivalvia). P.S.Z.N.: Marine Ecology, 11: 77–94. As has been observed by Kleemann (1990, 2001) from the Kleemann, K., 1995. Associations of coral and boring bivalves: northern Red Sea and by Scaps et al., (2005) from the Pulisan Lizard Island (Great Barrier Reef, Australia) versus Safaga (N region, we also found in the Wakatobi MNP that Pedum Red Sea). Beiträge zur Paläontologie, 20: 31–39. occurring on massive coral colonies occurred alone or together Kleemann, K., 2001. The pectinid bivalve Pedum spondyloideum with other nestling (Tridacna spp., Arca ventricosa, Barbatia (Gmelin, 1791): amount of surface and volume occupied in foliata, Modiolus philippinarum, vermetid gastropods) host corals from the Red Sea. 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