Diversity of Zooxanthellae from
Scleractinian Corals of One Tree
Island (The Great Barrier Reef)
William Loh 1,2, Deirdre Carter 1 and Ove HoeghGuldberg2
1
2
The Department of Microbiology, The University of Sydney, NSW 2006
The School of Biological Sciences, The University of Sydney, NSW 2006
ABSTRACT
The small subunit ribosomal gene (18S rDNA) of zooxanthellae from 19 species of Australian Pacific
scleractinian corals was amplified using algae-specific PCR primers. Preliminary results of the restriction
fragment length polymorphism (RFLP) profiles obtained by digestion of these PCR products by a single
restriction enzyme, indicate that three recognised clades of zooxanthellae (A, B and C) are present.
Clade C was detected in 18 species of corals but in two of these species, Acropora longicyathus and
Pavona decussata, other clades were also found. Acropora longicyathus has either clade A or C depending
on the colony. Pavona decussata produced an unusual RFLP profile indicating that it had a mixture of
clade B and C. Plesiastrea versipora, which was the only coral species taken from a temperate region in
our study, appears to host clade B zooxanthellae exclusively. Results from this preliminary study suggest
that clade C is the predominant zooxanthella group in corals of One Tree Island.
INTRODUCTION
Scleractinian corals, and invertebrates from at least five other phyla, play host to dinoflagellate
symbionts belonging to the genus Symbiodinium (Fruedenthal, 1962). These protists, which
are known as zooxanthellae, live intracellularly (except in tridacnid clams) and provide for a
major portion of the energy needs of the host (Trench, 1979; Muscatine et al., 1984; HoeghGuldberg et al., 1986). Until the early 1980s, most zooxanthellae were considered to belong to
the species Symbiodinium microadriaticum. Detailed work by Schoenberg & Trench (1980a;
b; c) and Trench & Blank (1987), however, provided strong morphological and biochemical
(isozyme analysis) evidence for the existence of different zooxanthella taxa associated with
specific coral hosts. These initial observations have recently been supported by molecular
analysis of the small subunit ribosomal RNA gene, which revealed three major groupings or
clades of Symbiodinium designated A, B and C (Rowan & Powers, 1991a).
Although many coral species studied are specific for one of these clades, combinations of A
and C, B and C or all three clades have been detected in some Caribbean coral species (Rowan
& Powers, 1991a; Rowan & Knowlton, 1995; Baker & Rowan, 1997; Rowan et al., 1997).
Variation in host specificity for these zooxanthellar clades may be an adaptation by the corals
to different environmental conditions, such as levels of ambient light (Buddemeier & Fautin,
1993). Two species, Montastrea annularis and M. faveolata, have been shown to contain
combinations of A, B and C at varying ratios depending on the colony (Rowan & Knowlton,
1995; Rowan et al., 1997). Clades A and B are detected mostly from colonies or parts of
colonies at depths of 0-6 m whereas clade C is present at all depths and is often the only clade
detected at depths greater than 6 m (Rowan & Knowlton, 1995; Rowan et al., 1997). This
distribution appears to be directly related to sunlight levels, as large columns of M. annularis
colonies present at intermediate depths, have clade A and B predominantly in their topmost
In: Greenwood, J.G. & Hall, N.J., eds (1998)
Proceedings of the Australian Coral Reef Society 75th Anniversary Conference, Heron Island October 1997.
School of Marine Science, The University of Queensland, Brisbane. pp. 87-??.
Loh, Carter & Hoegh-Guldberg
areas but relatively more of clade C on the relatively less sunlit flanks. When these coral
columns were experimentally oriented by 90°, a subsequent redistribution of the various clades
to their original distribution occurred after six months (Rowan et al., 1997).
Another Caribbean species, Acropora cervicornis has colonies that contain either clade A or C
(Baker et al., 1997). This species also shows a depth /ambient light relationship with their
zooxanthellae, with clade A detected exclusively in colonies at 0-9m, and clade C in the lower
light conditions at 15 m (Baker et al., 1997).
A greater understanding of the diversity of zooxanthellae and their inherent physiological
diversity may help to explain why some coral-zooxanthellae associations are more susceptible
to bleaching stress than others (Hoegh-Guldberg & Salvat, 1995; Rowan et al., 1997). Clade C,
to date, is the most common symbiont detected in corals sampled from the Caribbean, and
hitherto the only clade found in corals of the Central and Eastern Pacific (Hawaiian and
Panamanian coasts respectively) (Rowan & Powers, 1991a; Baker & Rowan, 1997). Many
more studies on coral biogeography of zooxanthellae clade-specificity are needed to develop
theories for coral-algae ecology and evolution (Baker & Rowan, 1997). This study represents
a survey from the western Pacific, of 18 species from The Great Barrier Reef and a single
temperate water species from Sydney Harbour.
MATERIALS AND METHODS
Zooxanthellae cultures
Zooxanthellae strains CS-153, CS-156 and CS-164 were purchased from the CSIRO microalgae
culture collection (CSIRO Marine Laboratories, Australia). These strains originate from
Cassiopeia xamachana (class Scyphozoa), Montipora verrucosa (order Scleractinia) and
Aiptasia tagetes (order Actininaria) respectively.
Batches (10 ml) of culture were grown in f/2 medium (Guillard & Ryther, 1962) at 26°C with
a 12:12 h dark-light cycle (50-100 mEm-²s-¹). Two weeks after inoculation, the cells were
harvested by centrifugation at 12g and processed for DNA extraction.
Collection of corals
Samples of scleractinian corals were collected at depths ranging from 0-5m, at One Tree Island
(latitude 23°30’S, longitude 152°06’E) on the southern Great Barrier Reef, Australia, in July
1996 and March 1997. The exception was Plesiastrea versipora, which was collected from
Sydney Harbour, Australia, from a depth of 5m.
The species and number of replicate colonies (n) collected were from Pocilloporidae
(Pocillopora damicornis Linnaeus n = 20, Stylophora pistillata Schweigger n=20, Seriatopora
hystrix Dana n=6), Acroporidae (Acropora pulchra Brook n=2, A. humilis Dana n=1,
A. bushyensis Veron & Wallace n=3, A. divaricata Dana n=9, A. valida Dana n=3, A. nasuta
Dana n=1, A. longicyathus Edwards & Haime n=5), Poritidae (Goniopora tenuidens Quelch
n=9, Porites lobata Dana n=3), Agariciidae (Pavona decussata Dana n=10), Fungiidae
(Heliofungia actiniformis Quoy & Gammard n=10), Oculinidae (Acrhelia horrescens Edwards
& Haime n=3), Mussidae (Lobophyllia hemrichii Ehrenberg n=2), Faviidae (Plesiastrea
versipora Lamarck n=5, Leptastrea purpurea Dana n=3, Echinopora hirsutissima Edwards &
Haime n=1).
Where possible, pieces were removed from tips and stems of branching corals, or in massive
and encrusting corals, the top, mid and base parts of the colony. Coral samples were placed in
88
ACRS Proceedings - 75th Anniversary Conference
Diversity of zooxanthellae from scleractinian corals
buffer (DNAB- 0.4M NaCl, 50 mM EDTA, pH 8.0) (Rowan & Powers, 1991b) and frozen at
-20°C until processed for DNA extraction.
Extraction of DNA
The harvested zooxanthellae cultures were resuspended in 500 ml of DNAB with 1 % sodium
dodecyl sulphate (SDS). Pieces of coral from each colony were pulverized with separate sterile
mortars and pestles. The ensuing slurries were collected and SDS was added at a final
concentration of 1%. All cells (cultures and slurries) were lysed by incubation at 65°C for one
hour, followed by the addition of Proteinase K (Sigma, U.S.A.) to a final concentration of
0.5 mgml-¹ and further overnight incubation at 37°C.
Lysates were then extracted with equal volumes of phenol, followed by phenol-chloroform
(25:24) and chloroform-isoamyl alcohol (25:1). DNA was precipitated with equal volumes of
4M lithium chloride (pH 9.0) and double volumes of cold isopropanol. The precipitate was
cleaned with 70% ethanol, dried, resuspended in 50 ml of sterile MQ water, and stored at
-70°C.
PCR amplification and characterisation of zooxanthella DNA
Zooxanthellae 18SrDNA was amplified using the algae-specific primers ss5z (an equimolar
mixture of 5'-GCAGTTATAATTTATTTGATGGTCACTGCTAC-3' and 5'-GCAGTT
ATAATTTATTTGATGGTTGCTGCTAC-3') and the complimentary primer ss3z
(5'-AGCACTGCGTCAGTCCGAATAATTCACCGG-3') (Rowan & Powers, 1991a; b). We
use, the term ‘algae-specific primers’ instead of ‘zooxanthellae-specific primers’, following
the misgivings of its use by McNally et al. (1994).
All PCR reactions contained 0.4 mg of template DNA, 10mM total dNTP, 40 mg DNAasefree Bovine serum albumin (Pharmacia), 30 pmol of each primer and 0.5 ml of Taq polymerase
(Ampli-Taq, Perkin Elmer) in a total volume of 100 ml. Amplifications were performed using
a Perkin Elmer-Cetus 480 Thermal cycler with the following thermal profile: 35 cycles of
1 min at 94°C, 2min at 55°C, 3 min at 72°C. The PCR product was analysed by electrophoresis
in 1% agarose gels (10 V.cm-¹; 40 mA). The DNA was stained with ethidium bromide and
visualized with UV transillumination.
RFLP analysis was performed on the amplified products by digestion with Taq 1 restriction
enzyme (Progen Industries, Australia) for 30 min at 65°C. Digests were analysed by
electrophoresis as described above.
RESULTS
PCR amplification of each of the cultures using the ss5z/ss3z primer pair, produced a DNA
fragment of approximately 1 600 bp (Figure 1), in accordance with the size of zooxanthellae
DNA amplified by Rowan & Powers (1991a; b) using the same primers. Digestion of the
amplified DNA with Taq 1 yielded fragments of approximately 710 and 600 base pairs from
zooxanthella CS-153, 890 and 500 base pairs from zooxanthella CS-164 and 890 and 710
base pairs from zooxanthella CS-156 (Figure 2). These RFLP profiles were consistent with
fragment sizes reported by (Rowan & Powers, 1991a) of zooxanthellae belonging to clades A,
B and C respectively, following digestion by the same enzyme. The RFLP profiles produced
by Taq 1 digestion were always reproducible and consistent and provided the study with control
profiles for the three clades.
ACRS Proceedings - 75th Anniversary Conference
89
Loh, Carter & Hoegh-Guldberg
1 600 bp
M
1
2
3
Figure 1. Agarose gel electrophoresis showing a DNA fragment of approximately 1 600 bp produced
following PCR amplification of zooxanthellae DNA, using primers ss5z and ss3z. DNA
amplified from cultured zooxanthellae CS-153 of C. xamachana (lane 1), CS-164 of A.
tagetes (lane 2) and CS-156 of Montipora verrucosa (lane 3). The molecular size marker
was Spp1/EcoR1 digest (lane M).
890 bp
710 bp
600 bp
500 bp
1
2
3
Figure 2. Agarose gel electrophoresis showing RFLP profiles produced from the amplified 1 600 bp
fragments following digestion with Taq 1. The fragment sizes are indicated on the gel. Digested
DNA amplified from zooxanthella CS-153 (lane 1): 710 and 600 bp (clade A); zooxanthella
CS-164 (lane 2): 890 and 500 bp (clade B); zooxanthella CS-156 (lane 3): 890 and 710 bp
(clade C).
90
ACRS Proceedings - 75th Anniversary Conference
Diversity of zooxanthellae from scleractinian corals
L. hemrichii
P. versipora
L. purpurea
E. hirsutissima
A. horescens
P. decussata
A. nasuta
A. longicyathus
G. tenuidens
P. lobata
H. actiniformis
A. valida
P. damicornis
S. pistillata
S. hystrix
A. pulchra
A. humilis
A. bushyensis
A. divaricata
DNA extracted from all corals was amplified with the algae-specific primers producing the
expected 1 600 bp fragment (Figure 3). The consistency of this result indicated that DNA
amplified was from Symbiodinium of symbiotic origin in the corals. However, a non-specific
PCR product of approximately 1 160 bp was also consistently amplified from some colonies
of P. decussata and L. purpurea (Figure 3).
1 600
bp
M 1
2
3
4
5
6
7
8
9 10 11 12 13
14 15 16 17 18 19
Figure 3. Agarose gel electrophoresis showing the 1 600 bp fragment produced, using algae specific
primers ss5z and ss3z. Each numbered lane (1-19) contains the PCR product from a
representative coral colony belonging to the species marked above. Non-specific amplification
fragment of approximately 1 160 bp present in lanes 14 and 18. The molecular size marker
was Spp1/EcoR1 digest (lane M).
Amplified zooxanthellae DNA from 16 out of 19 coral species produced a RFLP profile
consistent with clade C ( 890 and 710 bp fragments) (Figure 4, lanes 1-16). Of these, atypical
clade C RFLP profiles were observed in P. damicornis (additional 550 and 350 bp fragments)
(Figure 4, lane 1); A. bushyensis and A. divaricata (additional 350 bp fragment) (Figure 4,
lanes 6 & 7); L. purpurea (additional 680 & 480 bp fragments) (Figure 4, lane 15). The
P. damicornis RFLP profile appears identical to those from the same species obtained from
the mid-Pacific (Rowan & Powers, 1991a; b). Using sequencing data, Rowan & Powers (1991a)
established that this RFLP profile probably comes from clade C zooxanthellae containing
DNA with an extra Taq 1 site. The larger 980 bp fragment observed in lanes 2 and 11 of
Figure 4 were not consistent, and probably represent partial digestion fragments.
Of the remaining coral species analysed, both A. longicyathus and P. decussata appeared to
contain clade C and/or non-C clade zooxanthellae. The RFLP profiles derived from amplified
fragments from five colonies of A. longicyathus suggest that either clade A or C zooxanthella
are present in mutual exclusion (three colonies with 710 and 600 bp fragments- clade A; two
colonies with 890 and 710 bp fragments- clade C) (Figure 5, lanes 2-6). RFLP profiles from
P. decussata indicate a superimposition of clade B and C profiles and may be interpreted as a
mixture of clades B and C in each coral sample (ten colonies with the 890,710 and 500 bp
fragments) (Figure 5, lanes 10-12). Arguably, this unusual RFLP profile could be derived from
the digestion of the non-specific 1 160 bp PCR product (Figure 3, lane 14). Further analysis
involving the cloning and sequencing of the DNA is needed to confirm this result.
ACRS Proceedings - 75th Anniversary Conference
91
L. hemrichii
L. purpurea
E. hirsutissima
A. horescens
A. nasuta
G. tenuidens
P. lobata
H. actiniformis
A. valida
A. divaricata
S. pistillata
S. hystrix
A. pulchra
A. humilis
A. bushyensis
P. damicornis
Loh, Carter & Hoegh-Guldberg
890 bp
710 bp
550 bp
350 bp
M
1 2
3
4
5
6 7
8
9 10 11 12 13 14 15 16 C
Figure 4. Agarose gel electrophoresis showing clade C RFLP profiles produced by digestion with Taq
1. Each numbered lane (1-16) contains the RFLP profile produced from a representative
coral colony belonging to the species marked above. Clade C RFLP profile control (lane C)
was produced from cultured zooxanthella CS-156 of Montipora verrucosa. The molecular
size marker was Spp1/EcoR1 digest (lane M).
A. longicyathus
P. versipora
P. decussata
890 bp
710 bp
600 bp
500 bp
M
1
2
3
4
5
A
B
C 6
7
8
9
10 11 12 13
Figure 5. Agarose gel electrophoresis showing the comparison of RFLP profiles produced by digestion
with Taq 1 restriction enzyme. Each numbered lane contains digested DNA from one coral
colony. Clade A or C RFLP profiles in Acropora longicyathus (lanes 1-5); Clade B and C
(superimposed RFLP profiles) in Pavona decussata (lanes 6-8); Clade B RFLP profile in
Plesiastrea versipora (lanes 9-13). Clade A, B and C control RFLP profiles (lanes A, B and
C). The molecular size marker was Spp1/EcoR1 digest (lane M).
Plesiastrea versipora was the only host species where the clade C RFLP profile was not detected.
RFLP profiles derived from this host suggest that a pure population of clade B zooxanthellae
was present (five colonies with 890 and 500 bp fragments) (Figure 5, lanes 9-13). A summary
of all coral species surveyed and their clades is presented in Table 1.
92
ACRS Proceedings - 75th Anniversary Conference
Diversity of zooxanthellae from scleractinian corals
Table 1.
Summary of coral species and associated zooxanthella clades. Figures in parenthesis indicate
the number of replicate colonies.
Coral species
Pocillopora damicornis (20)
Stylophora pistillata (20)
Seriatopora hystrix (6)
Acropora pulchra (2)
Acropora humilis (1)
Acropora bushyensis (3)
Acropora divaricata (9)
Acropora valida (3)
Acropora nasuta (1)
Acropora longicyathus (5)
Goniopora tenuidens (9)
Porites lobata (3)
Heliofungia actiniformis (10)
Pavona decussata (3)
Achrelia horescens (3)
Lobophyllia hemrichii (2)
Plesiastrea versipora (5)
Leptastrea purpurea (3)
Echinopora hirsutissima (1)
Zooxanthella Clade
RFLP detected
C
C
C
C
C
C
C
C
C
A or C
C
C
C
B and C
C
C
B
C
C
DISCUSSION
The predominance of clade C in corals of One Tree Island is consistent with previous studies
undertaken of several different eastern Pacific coral species (Rowan & Powers, 1991a; Baker
& Rowan, 1997). However, clades A and B detected in colonies of A. longicyathus, P. decussata
and P. versipora demonstrate that non-C symbioses can also occur in the Pacific.
The mutually exclusive host-clade specificity in A. longicyathus is similar to the species
A. cervicornis (Baker et al., 1997). However, unlike the latter species, both clades A or C
were detected in shallow water colonies (from 0-2 m) and a depth/light based distribution of
clades is not readily apparent in this coral species.
Conceivably, the clade B and C zooxanthellae of P. decussata may have a sunlight-related
distribution similar to M. annularis (Rowan et al., 1997). Colonies of P. decussata often consist
of numerous closely spaced, bifacial and upright laminae. As a result, much of the colony
surface is self-shading and it is conceivable that the distribution of clade B and C may vary
with amount of exposure to light. Initial studies have revealed light distributions within colonies
that range from 10-20 to 2000 µE m-2 s-1 within the same colony (Hoegh-Guldberg et al.,
unpubl. data).
Plesiastrea versipora is unusual because its distribution extends from the tropics to temperate
habitats off southeastern Australia (Squires, 1966). It is interesting to note that the zooxanthellae
of the only other temperate scleractinian to be sampled so far, Astrangia dane, also contains
clade B zooxanthellae exclusively (Rowan & Powers, 1991a; b). Although clade B is also
found in many tropical corals of the Caribbean (Rowan & Powers, 1991a; b; Baker & Rowan,
1997), this clade may be more able to form symbioses with temperate water hosts.
ACRS Proceedings - 75th Anniversary Conference
93
Loh, Carter & Hoegh-Guldberg
Unpublished results of an ongoing survey conducted at the northern Great Barrier Reef (Lizard
Island) showed that A. longicyathus, P. decussata and P. versipora contained clade C
zooxanthellae exclusively (Baker, pers. comm.). These differences suggests that biogeography
of the hosts may also determine the specificity and distribution of the zooxanthellae clades.
Conversely, P. damicornis colonies from One Tree Island show similar RFLP profiles to those
from the mid Pacific, which suggests that clade specificity can also be constant over long
distances.
The distribution of clades among corals of One Tree Island is not fully explicable at present,
but differences in the range and types of habitats penetrated by zooxanthellae and their hosts
probably relate to the physiological abilities of the symbiont. Studies of the photobiology of
hermatypic corals and clams and their symbionts suggest distinct light-adaptive zooxanthellabased abilities (Chang et al., 1983; Iglesias-Prieto & Trench, 1994). Analysing how the different
clades respond to different physiological challenges may reveal why clade C is generalist, and
why the distribution of clades like B extends to temperate environments.
The results of this study on zooxanthellae diversity are preliminary. They are based on RFLP
profiles produced from only one restriction enzyme digestion. Moreover, several species such
as A. pulchra, A. humilis, L. hemrichii and E. hirsutissima were replicated only once or not at
all, and different clades may be present in other colonies. This paper, however, foreshadows
work that is currently being undertaken to provide firmer conclusions based on digestion with
at least one other restriction enzyme (e.g. Sau 3A l, Rowan & Powers, 1991a), direct sequencing,
and subsequent phylogenetic analyses. Early sequencing results of our 18SrDNA PCR products
from P. damicornis, H. actiniformis, S. pistillata, S. hystrix, G. tenuidens and A. longicyathus
confirm the clade identity shown by respective RFLP profiles. Preliminary evidence suggests
a strong trend for clade C predomination in the few scleractinian corals surveyed along the
Australian Pacific coast.
REFERENCES
Baker, A.C. & Rowan, R. (1997) Diversity of symbiotic dinoflagellates (zooxanthellae) in scleractinian
corals of the Caribbean and Eastern Pacific. In: Proceedings of the 8th International Coral Reef
Symposium, Vol. 2. (eds Lessios, H.A. & Macintyre, I.G.) pp. 1301-1306. Smithsonian Tropical
Research Institute, Balboa, Panama.
Baker, A.C., Rowan, R. & Knowlton, N. (1997) Symbiosis ecology of two Caribbean acroporid corals.
In: Proceedings of the 8th International Coral Reef Symposium, Vol. 2. (eds Lessios, H.A. &
Macintyre, I.G.) pp. 1295-1300. Smithsonian Tropical Research Institute, Balboa, Panama.
Buddemeier, R.W. & Fautin, D.G. (1993) Coral bleaching as an adaptive mechanism. Bioscience 43:
320-326.
Chang, S.S., Prézelin, B.B. & Trench, R.K. (1983) Mechanisms of photoadaptation in three strains of
the symbiotic dinoflagellate Symbiodinium microadriaticum. Marine Biology 76: 219-229.
Freudenthal, H.D. (1962) Symbiodinium gen. nov. and Symbiodinium microadriaticum sp. nov., a
zooxanthella: Taxonomy, life cycle and morphology. Journal of Protozoology 9: 45-52.
Guillard, R.R.L. & Ryther, J.H. (1962) Studies of marine plankton diatoms. I Cyclotella nana Hustedt
and Detonula confervacea (Cleve) Gran. Canadian Journal of Microbiology 8: 229-239.
Hoegh-Guldberg, O., Hinde, R. & Muscatine, L. (1986) Studies on a nudibranch that contains
zooxanthellae. II. Contribution of zooxanthellae to animal respiration (CZAR) in Pteraeolidia
ianthina with high and low densities of zooxanthellae. Proceedings of the Royal Society of London B
228: 511-521.
94
ACRS Proceedings - 75th Anniversary Conference
Diversity of zooxanthellae from scleractinian corals
Hoegh-Guldberg, O. & Salvat, B. (1995) Periodic mass bleaching of reef corals along the outer reef
slope in Moorea, French Polynesia. Marine Ecology Progress Series 121: 181-190.
Iglesias-Prieto, R. & Trench, R.K. (1994) Acclimation and adaptation to irradiance in symbiotic
dinoflagellates. I. Responses in photosynthetic unit to changes in photon flux density. Marine Ecology
Progress Series 113: 163-175.
McNally, K.L., Govind, N.S., Thomé, P.E. & Trench, R.K. (1994) Small subunit ribosomal DNA sequence
analyses and a reconstruction of inferred phylogeny among symbiotic dinoflagellates (Pyrrophyta).
Journal of Phycology 30: 316-329.
Muscatine, L., Falkowski, P.G., Porter, J.W. & Dubinsky, Z. (1984) Fate of photosynthetic fixed carbon
in light- and shade-adapted colonies of the symbiotic coral Stylophora pistillata. Proceedings of
the Royal Society of London B 222: 181-202.
Rowan, R. & Powers, D.A. (1991a) A molecular genetic classification of zooxanthellae and the evolution
of animal-algal symbioses. Science 251: 1348-1351.
Rowan, R. & Powers, D.A. (1991b) Molecular genetic identification of symbiotic dinoflagellates
(zooxanthellae). Marine Ecology Progress Series 71: 65-73.
Rowan. R. & Knowlton, N. (1995) Intraspecific diversity and ecological zonation in coral-algal symbiosis.
Proceedings of the National Academy of Science USA 92: 2850-2853.
Rowan, R., Knowlton, N., Baker, A. & Jara, J. (1997) Landscape ecology of algal symbionts creates
variation in episodes of bleaching. Nature 388: 265-269.
Schoenberg, D.A. & Trench, R.K. (1980a) Genetic variation in Symbiodinium (=Gymnodinium)
microadriaticum Freudenthal, and specificity in its symbiosis with marine invertebrates. I. Isoenzyme
and soluble protein patterns of axenic cultures of Symbiodinium microadriaticum. Proceedings of
the Royal Society of London B 207: 405-427.
Schoenberg, D.A. & Trench, R.K. (1980b) Genetic variation in Symbiodinium (=Gymnodinium)
microadriaticum Freudenthal, and specificity in its symbiosis with marine invertebrates. II.
Morphological variation in Symbiodinium microadriaticum. Proceedings of the Royal Society of
London B 207: 429-444.
Schoenberg, D.A. & Trench, R.K. (1980c) Genetic variation in Symbiodinium (=Gymnodinium)
microadriaticum Freudenthal, and specificity in its symbiosis with marine invertebrates. III.
Specificity and infectivity of Symbiodinium microadriaticum. Proceedings of the Royal Society of
London B 207: 445-460.
Squires, D.F. (1966) Sclerectinia. Port Philip Survey, 1957-1963. Memoirs of the National Museum of
Victoria 27: 167-174.
Trench, R.K. (1979) The cell biology of plant-animal symbiosis. Annual Review of Plant Physiology 30:
485-532.
Trench, R.K. & Blank, R.J. (1987) Symbiodinium microadriaticum Freudenthal, S. goreauii, sp. nov.,
S. kawagutii, sp. nov., and S. pilosum: gymnodinioid dinoflagellate symbionts of marine invertebrates.
Journal of Phycology 23: 469-481.
ACRS Proceedings - 75th Anniversary Conference
95