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Journal of the Marine Biological Association of the United Kingdom Journal of the Marine Biological Association of the United Kingdom http://journals.cambridge.org/MBI Additional services for Journal of the Marine Biological Association of the United Kingdom: Email alerts: Click here Subscriptions: Click here Commercial reprints: Click here Terms of use : Click here Habitat correlation of Symbiodinium diversity in two reef­building coral species in an upwelling region, eastern Hainan Island, China G. Zhou, H. Huang, J. Lian, C. Zhang and X. Li Journal of the Marine Biological Association of the United Kingdom / Volume 92 / Issue 06 / September 2012, pp 1309 ­ 1316 DOI: 10.1017/S0025315411001548, Published online: 21 October 2011 Link to this article: http://journals.cambridge.org/abstract_S0025315411001548 How to cite this article: G. Zhou, H. Huang, J. Lian, C. Zhang and X. Li (2012). Habitat correlation of Symbiodinium diversity in two reef­building coral species in an upwelling region, eastern Hainan Island, China. Journal of the Marine Biological Association of the United Kingdom, 92, pp 1309­1316 doi:10.1017/S0025315411001548 Request Permissions : Click here Downloaded from http://journals.cambridge.org/MBI, IP address: 202.40.139.167 on 02 Nov 2012 Journal of the Marine Biological Association of the United Kingdom, 2012, 92(6), 1309–1316. # Marine Biological Association of the United Kingdom, 2011 doi:10.1017/S0025315411001548 Habitat correlation of Symbiodinium diversity in two reef-building coral species in an upwelling region, eastern Hainan Island, China g. zhou1,2, h. huang1,2, j. lian1, c. zhang1 and x. li1 1Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China, 2National Experiment Station of Tropical Marine Biology, Sanya 572000, China Reef-building corals are fundamental to the most diverse marine ecosystems, and the coral–dinoflagellate (zooxanthellae) associations on fine scale remains largely unknown. Spatial variation in the diversity of symbiotic dinoflagellates of two scler- actinian coral species was studied in an upwelling region near Qinlan Harbor in eastern Hainan Island, China. Results showed that stress-tolerant Symbiodinium trenchi in individual colonies of Galaxea fascicularis occurred more frequently in shallow back-reef than in deep fore-reef. The higher symbiont diversity was found in colonies of G. fascicularis in shallow and close to the harbour mouth whereas the coral Pocillipora damicornis always harboured Symbiodinium internal transcribed spacer 2 (ITS2) types C1c or C42a. Furthermore, both corals were found to simultaneously contain Symbiodinium ITS2 types belonging to two distinct phylogenetic clades (C and D). This indicates that the distribution of genetically distinct Symbiodinium may correlate with light regime and possibly temperature in some (but not all) colonies at particular locations, which we interpret as holobiont acclimation to the local environmental conditions. Therefore, we conclude that reef-building corals can adapt to the local environment by harbouring genetically distinct symbionts but depend on their respective sym- biont transmission modes. Keywords: scleractinian coral, Symbiodinium, symbiosis, South China Sea Submitted 6 January 2011; accepted 8 August 2011; first published online 21 October 2011 INTRODUCTION Consequently, investigating the patterns of diversity in coral– algal symbioses on a variety of spatial scales with specific habi- The success of coral reefs largely depends on the symbiotic tats is important for understanding the tolerance and adapta- relationships between reef invertebrates and dinoflagellates of bility of coral species to natural and anthropogenic the genus Symbiodinium (Freudenthal, 1962). Disruption of perturbations. these interactions produces coral bleaching, which is widely The patterns of coral–Symbiodinium associations depend considered to be one of the biggest threats to the health of largely on the specificity of the symbioses (Baker, 2003; coral reefs today (Hoegh-Guldberg et al., 2007). Currently, LaJeunesse et al., 2004, 2008; Garren et al., 2006). Although a nine clades (A–I) of Symbiodinium have been identified as dis- much debated issue, studies have suggested symbiont trans- tinct lineages based on nuclear ribosomal DNA (rDNA) and mission mode have effect on symbiont diversity and specificity, chloroplast 23S rDNA (LaJeunesse, 2002; Santos et al., 2002; especially apparent in corals with a vertical symbiont trans- Pochon & Gates, 2010), with each clade containing numerous mission strategy, in which symbionts are passed directly from Symbiodinium types often resolved using the internal tran- the maternal colony to the offspring (Baker, 2003; Barneah scribed spacer (ITS) regions (ITS1 and ITS2: e.g. LaJeunesse et al., 2004; van Oppen, 2004; Stat et al., 2008). Specificity of et al., 2003, 2004; van Oppen, 2004). Previous investigations host–symbiont associations also depends largely on the host have shown that distinct symbiont types exhibit physiologically (Baker, 2003; Weis, 2008). Additionally, the host–symbiont diverse as well as distinct ecological functions (Sampayo et al., partnerships differ not only between coral taxa but also 2007, 2008; Frade et al., 2008; LaJeunesse et al., 2010). Recent between conspecific populations at both large (Loh et al., 2001; studies have highlighted the high genetic diversity within the Rodriguez-Lanetty et al., 2001) and small scales (Oliver & genus Symbiodinium, which raised the possibility that reef Palumbi, 2009), as well as showing clear patterns of depth zona- corals’ tolerance to bleaching and environmental stress may tion (Sampayo et al.,2007;Fradeet al., 2008). For example, a lati- vary according to their symbiotic associations (Baker, 2003). tudinal pattern was observed in the coral Plesiastrea versipora along the eastern Australian coast, with a transition of Symbiodinium types occurring from clade C to clade B in the cooler, high latitude communities (Rodriguez-Lanetty et al., Corresponding author: H. Huang 2001). The symbiotic dinoflagellates of reef-building corals are Email: [email protected] sensitive to changes such as temperature, irradiance and 1309 1310 g. zhou et al. turbidity. The combinations of corals and their symbionts may MATERIALS AND METHODS be environmentally determined (Toller et al., 2001; Garren et al., 2006). It has also been shown that some symbiont types Study site and sampling were better suited to withstand environmental pressure than others (Baker, 2003). For instance, Berkelmans & van Oppen Gaolong Bay is located on the north-eastern coast of Hainan (2006) found that Symbiodinium type D displaced symbiont Island, the second largest island in China and in the northern type C in corals transplanted from a clear water habitat in the part of the South China Sea (Figure 1). Wind-induced southern Great Barrier Reef (GBR) to a more turbid and Qiongdong Upwelling in northern Hainan Island during the warmer inshore reef in the centre of the GBR. summer (June to September: Jing et al., 2009) exposes corals However, little is known concerning the fine-scale diversity to cool and nutrient-rich waters and in addition, locations for Symbiodinium spp. populations inhabiting coral species near Qinlan Harbor and estuarine zones of the Wenchang with different symbiont transmission mode (Stat et al., River and the Wenjiao River. The water quality here is par- 2008), particularly in an extreme environment. Given the pro- ticularly affected by several external physical factors, the jected global changes expected to affect the coral reefs most important of which are coastal development and (Hoegh-Guldberg et al., 2008), there is a critical need to by-passing of vessels to Qinlan Harbor contributing to turbid- conduct more research on patterns of host–symbiont associ- ity. Therefore, such extreme environmental conditions can ations from different habitats, as differences in symbiosis may potentially affect the coral and symbiont. partially explain and help predict how coral communities Corals were sampled at five sites with increasing distance respond to environmental change. away from Qinlan Harbor by SCUBA diving (Figure 1). At Herein, we examined the diversity of Symbiodinium associ- each site, approximately 5 cm2 fragments of coral Galaxea fas- ated with two scleractinian corals, Galaxea fascicularis cicularis were sampled at two depths (shallow back-reef: 3 m (Linnaeus, 1767) and Pocillopora damicornis (Linnaeus, 1758), and deep fore-reef: 8 m) and Pocillipora damicornis was using denaturing gradient gel electrophoresis (DGGE) analysis sampled at the shallow depth due to limited distribution. In of polymerase chain reaction (PCR) amplified fragments of all cases, coral colonies were collected at least separated by ITS2 rDNA. Galaxea fascicularis and P. damicornis are two eco- 5 m to avoid sampling possible clones formed by fragmenta- logically dominant reef-building corals in the Pacific as well as in tion. The samples were preserved in 100% ethyl alcohol the tropical regions of the South China Sea. Galaxea fascicularis (EtOH) at room temperature. is a bleaching resistant species which acquires Symbiodinium from the external environment each generation (horizontal DNA extraction, PCR and DGGE transmission); Pocillopora damicornis is a bleaching sensitive species with a vertical symbiont transmission strategy Total DNA was extracted using the modification of protocol (Richmond & Hunter, 1990). We attempted to characterize described in
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