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Vol. 51 No. 3, 2012
A Coral-Killing Sponge, Terpios hoshinota, Releases Larvae Harboring Cyanobacterial Symbionts: An Implication of Dispersal
Jih-Terng Wang1,*, Euichi Hirose2, Chia-Min Hsu3, Yi-Yun Chen1, Pei-Jie Meng4,5, and Chaolun Allen Chen3,6,7
1Graduate Institute of Biotechnology, Tajen University, Pingtung 907, Taiwan
2Faculty of Science, University of the Ryukyus, Okinawa 903-0213, Japan
3Institute of Oceanography, National Taiwan University, Taipei 108, Taiwan
4National Museum of Marine Biology and Aquarium, Checheng, Pingtung 944, Taiwan
5Institute of Marine Biodiversity and Evolution, National Dong Hwa University, Checheng, Pingtung 944, Taiwan
6Biodiversity Research Center, Academia Sinica, Nangung, Taipei 115, Taiwan
7Taiwan International Graduate Program (TIGP)-Biodiversity, Academia Sinica, Nangang, Taipei 115, Taiwan
A.
Terpios hoshinota, an encrusting sponge, overgrows hard corals on a
relatively large scale, raising concerns for coral survival in the
Indo-West Pacific region. However, mechanisms of dispersal of this
sponge remain unknown. This study examined the ultrastructure of
parenchymella larvae collected from T. hoshinota
to infer potential mechanisms of dispersal and outbreaks of this
threatening sponge. The ovum-shaped parenchymella larva has negative
buoyancy and a limited swimming capability even though cilia cover its
entire surface. Furthermore, larvae settled within 1 d in an aquarium,
indicating a larval stage of short duration. These characteristics
suggest that dispersion distances of Terpios
larvae are short. An ultrastructural examination also indicated that
larvae are filled with cyanobacteria, and lack spicules and a mesophyl
structure as found in other sponge larvae. Most cyanobacteria in the
larvae appeared intact and dividing as are found in adult Terpios, but
some found within sponge cells had disintegrated. Cyanobacteria being
engulfed in Terpios cells implies a trophic function of the microbes during larval development.
Key words: Porifera, Coral, Symbiotic cyanobacteria, Dispersal, Parenchymella larva.
*Correspondence: Tel: 886-8-7624002. Fax: 886-8-7621645. E-mail:jtw@mail.tajen.edu.tw; euichi@sci.u-ryukyu.ac.jp
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