Free-living mushroom corals strike back by overtopping a coral-killing sponge
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OCEANARIUM Free-living mushroom corals strike back by overtopping a coral-killing sponge Bert W. Hoeksema & Friso Dekker & Nicole J. de Voogd Received: 12 September 2013 /Revised: 28 September 2013 /Accepted: 30 September 2013 /Published online: 25 October 2013 # Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2013 In competitive interactions for space, some encrusting sponge species are able to overgrow and smother living corals to death, which usually is a species-specific process regarding both the coral and the sponge (Aerts and van Soest 1997). Records of such aggressive behaviour usually concern phototrophic sponge species with symbiotic zooxanthellae or cyanobacteria, which may help their hosts to expand rapidly (Wulff 2006; de Voogd et al. 2013). During a survey (August 2012) on the northwestern reef flat of Pajenekang Island (04°58′16′′S; 119°19′19′′E) in the Spermonde Archipelago (South Sulawesi, Indonesia), two free-living mushroom corals of Lithophyllon repanda (Dana, 1846) were observed on top of an encrusting sponge, Chalinula milnei (de Laubenfels, 1954), at 3 m depth (Fig. 1). This sponge contains phototrophic cyanobacterial symbionts (Dekker unpubl.). When one of the corals was moved aside, the sponge appeared to be absent from the area below, as well as any other organisms, while the overtopping coral itself seemed unharmed (Fig. 1b). This observation suggests that light deprivation caused by the coral may have damaged the sponge or prevented its growth underneath, since no direct observations of submissive reactions by sponges in competition with corals have ever been reported in which the latter used bioactive compounds (Wulff 2006). While mobility of mushroom corals may help them to escape from competition with sponges (Hoeksema and de Voogd 2012, references herein), the present case suggests that they can outcompete coral-killing sponges when they drop on top of them. Acknowledgments Research Permits were issued by the Indonesian State Ministry for Research and Technology (RISTEK) and the Indonesian Institute of Sciences (PPO-LIPI). Hasanuddin University at Makassar provided local support. Fig. 1 Free-living Lithophyllon repanda corals on top of an encrusting killer sponge, Chalinula milnei . a Two corals in original position. b Lifting the left one (diameter, 8 cm) exposed a void in the sponge cover after its removal. c Close-up of a C. milnei overgrowing a colony of Montipora sp. B. W. Hoeksema (*) : F. Dekker : N. J. de Voogd Department of Marine Zoology, Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands e-mail: [email protected] F. Dekker Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands Mar Biodiv (2014) 44:3–4 DOI 10.1007/s12526-013-0188-x
Transcript of Free-living mushroom corals strike back by overtopping a coral-killing sponge
OCEANARIUM
Free-living mushroom corals strike back by overtoppinga coral-killing sponge
Bert W. Hoeksema & Friso Dekker & Nicole J. de Voogd
Received: 12 September 2013 /Revised: 28 September 2013 /Accepted: 30 September 2013 /Published online: 25 October 2013# Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2013
In competitive interactions for space, some encrusting spongespecies are able to overgrow and smother living corals todeath, which usually is a species-specific process regardingboth the coral and the sponge (Aerts and van Soest 1997).Records of such aggressive behaviour usually concernphototrophic sponge species with symbiotic zooxanthellae orcyanobacteria, which may help their hosts to expand rapidly(Wulff 2006; de Voogd et al. 2013).
During a survey (August 2012) on the northwestern reefflat of Pajenekang Island (04°58′16′′S; 119°19′19′′E) in theSpermonde Archipelago (South Sulawesi, Indonesia), twofree-living mushroom corals of Lithophyllon repanda (Dana,1846) were observed on top of an encrusting sponge,Chalinula milnei (de Laubenfels, 1954), at 3 m depth(Fig. 1). This sponge contains phototrophic cyanobacterialsymbionts (Dekker unpubl.). When one of the corals wasmoved aside, the sponge appeared to be absent from the areabelow, as well as any other organisms, while the overtoppingcoral itself seemed unharmed (Fig. 1b).
This observation suggests that light deprivation causedby the coral may have damaged the sponge or preventedits growth underneath, since no direct observations ofsubmissive reactions by sponges in competition withcorals have ever been reported in which the latter usedbioactive compounds (Wulff 2006). While mobility ofmushroom corals may help them to escape fromcompetition with sponges (Hoeksema and de Voogd2012, references herein), the present case suggests thatthey can outcompete coral-killing sponges when they dropon top of them.
Acknowledgments Research Permits were issued by the IndonesianState Ministry for Research and Technology (RISTEK) and theIndonesian Institute of Sciences (PPO-LIPI). Hasanuddin University atMakassar provided local support.
Fig. 1 Free-living Lithophyllon repanda corals on top of an encrustingkiller sponge,Chalinula milnei. a Two corals in original position. b Liftingthe left one (diameter, 8 cm) exposed a void in the sponge cover after itsremoval. c Close-up of a C. milnei overgrowing a colony ofMontipora sp.
B. W. Hoeksema (*) : F. Dekker :N. J. de VoogdDepartment of Marine Zoology, Naturalis Biodiversity Center,P.O. Box 9517, 2300 RA Leiden, The Netherlandse-mail: [email protected]
F. DekkerInstitute for Biodiversity and Ecosystem Dynamics,University of Amsterdam, 1090 GE Amsterdam, The Netherlands
Mar Biodiv (2014) 44:3–4DOI 10.1007/s12526-013-0188-x
References
Aerts LAM, van Soest RWM (1997) Quantification of sponge/coralinteractions in a physically stressed reef community, NEColombia. Mar Ecol Prog Ser 148:125–134
de Voogd NJ, Cleary DFR, Dekker F (2013) The coral-killing spongeTerpios hoshinota invades Indonesia. Coral Reefs 32:755
Hoeksema BW, de Voogd NJ (2012) On the run: free-living mushroomcorals avoiding interaction with sponges. Coral Reefs 31:455–459
Wulff JL (2006) Ecological interactions of marine sponges. Can J Zool84:146–166
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