Dr. Doug Fenner studies corals on the Undersea Explorer

Dr. Doug Fenner, a visitor at the Australian Institute of Marine Science (AIMS), joined two Undersea Explorer expeditions in late October. Doug is a coral taxonomist, who studies the species and biodiversity of hard corals on reefs.

He was eager to compare the corals on the Great Barrier Reef and Osprey Reef in the Coral Sea with corals he has studied in Southeast Asia. He recorded the species of corals he saw, and took photos and collected a few samples of species of particular interest. He found the diversity higher than he expected, close to the very high diversity found on Southeast Asian coral reefs. Osprey Reef had a high diversity, well deserving of protected status.

Dr. Fenner found 11 species of coral which were known from other countries but had never been reported from Australia before. In addition, he found one species of coral which may prove to be
a new species.

Hard Coral Species Diversity on Great Barrier Reef and Osprey Reef Sites
Visited by the Undersea Explorer

Douglas Fenner, Ph.D.                November, 2003


Abstract

Hard coral species diversity was recorded at 11 outer reef sites on the Cairns Section of the Great Barrier Reef, and 9 sites on Osprey and Shark Reefs, Coral Sea visited by the Undersea Explorer in October, 2003, in a total of 31 dives. A total of 257 species were found. An average of 71 species were found per dive. At sites on the Great Barrier Reef an average of 82 species were found per dive, and at Osprey and Shark reefs, 66 species per dive, which was a significant difference. Osprey and Shark reefs had an average of 76% of the number of species as the GBR sites for the same number of dives. The number of coral species found in this study for the equal number of dives is less than that found in "Coral Triangle" area of highest diversity (Philippines, Indonesia, and PNG), but not much less, averaging 92% for GBR outer reefs, and the whole data set average 87% of that of the Coral Triangle. Thus, Eastern Australian reefs have very high coral diversity, higher than the present total number of species known suggests. This is consistent with the finding of 11 species not previously reported from Australia before. Further, Osprey Reef has a high coral diversity, nearly that of the outer GBR reefs, and likely higher than inner GBR reefs and perhaps middle GBR reefs as well. The total coral diversity at Osprey Reef is certainly higher than the counts in this study, as the lagoon was not investigated, and because of the very different conditions there will have corals that are not found on the outer reef front. The high diversity of corals found on Osprey Reef, plus their healthy state, supports the view that Osprey Reef deserves protected status.


The coral species of Australia have been the subject of major studies by leading taxonomists (e.g., Wallace 1978; Veron and Pichon 1976; 1980; 1982; Veron, Pichon and Wijsman-Best 1977; Veron and Wallace 1984; Veron 1985; Veron 1986). There have been studies of coral diversity on the Great Barrier Reef as well (e.g., Done, 1982). However, few if any taxonomic studies of Australian reef corals have been published since 1986, and there is little data on the coral diversity of the reefs of the Coral Sea. The present study aimed to make a rapid assessment of coral diversity on outer barrier reef sites visited by the Undersea Explorer in the Cairns Section of the Great Barrier Reef, and an atoll in the Coral Sea, Osprey Reef. The method used was the same the author has used on a variety of Southeast Asia sites, and thus allows a comparison of the coral diversity with those sites, in the area generally agreed to be the most diverse area for coral reefs.

Methods

Coral presence or absence was recorded during dives of approximately one hour at 11 outer barrier reef sites in the Cairn Section of the Great Barrier Reef, and 8 reef front sites at Osprey Reef in the Coral Sea and one site on nearby Shark Reef. Dives began at about 25 m depth and involved a haphazard search toward shallower water over the course of about one hour, and ended in water as shallow as possible. Photographs were taken of some species, and samples of a few species, with an attempt to photograph and/or collect any species not previously reported from Australia. Dive sites are given in Tables 1 and 2. All dives were on coral reefs, except dive 22 at Lizard Island, which was on a sandy bottom. Dives 13a and 13b were on the same reef (Steve's Bommie), and while all corals were recorded on 13a, only corals that appeared to be additional were recorded on 13b, so the total number on 13b is not comparable with other dives. On dive 28, Rapid Horn, corals were only recorded for about 30 minutes, with the second half of the dive spent observing fish spawning, thus the total for this dive is not comparable with other dives.
There is a very strong effect in data sets of the effect of amount of search effort, time, or area searched. The more time, effort or area searched, the more species found. Because it is a very strong effect, sites can only be compared based on the same amount of search effort, such as after one dive, or five dives, etc.

Results

A total of 247 species of hard corals were recorded, including 234 zooxanthellate scleractinia, 5 azooxanthellate scleractinia (genera Tubastraea, Dendrophyllia and Rhizopsammia), and 8 non-scleractinian hard corals (genera Millepora, Stylaster, Distichopora, Tubipora, and Heliopora). These proportions are typical of Indo-Pacific reefs.
The number of coral species found at each dive site are shown in Tables 1 and 2. The average number of species found per dive site is comparable between sites, but the total number of species found per site is not, since the number of dives at a site varied from 1 to 4, and will strongly affect the result.
Table 3 shows average numbers of corals for 1, 5, 10, and 15 dives for the outer Great Barrier Reef sites, Osprey Reef sites, all Eastern Australia sites (the outer GBR sites plus Osprey sites), and 7 sites in the Coral Triangle area of highest diversity (3 in the Philippines (Veron and Fenner, 2000), 2 in Indonesia (Fenner, 2001, 2002), 1 in Papua New Guinea (Fenner, 2003), and 1 in Sabah (Malaysia). Osprey Reef sites had an average of 76% as many species as the outer GBR sites. The difference was significant (t test, p < .003). Both Osprey and GBR sites were less than the average Coral Triangle sites, but the GBR sites in particular were quite close to those in the Coral Triangle, averaging 92% of the Coral Triangle numbers. East Australia as a whole averaged 87% of the Coral Triangle numbers. Osprey Reef averaged 76% of the number of corals at GBR sites for the same number of dives.
Table 4 presents the 11 species found for the first time in Australia. All of these species are known from elsewhere in the Indo-Pacific, but had not been reported from Australia (Veron, 1993; Wallace, 1999; Veron, 2000). Each was photographed and/or a sample collected. One of these species, Pavona bipartita, is quite common, and even is the most common coral on one of the reefs (Steve's Bommie). In addition, a coral that may represent an undescribed species of Anacropora, was collected at Osprey Reef. Considerable additional study will be required to determine if it is in fact a new species.

Conclusions

This study represents the first study of the biodiversity of corals on Osprey Reef, and the first study of Australian corals which controls for the amount of search effort, time, or area. The amount of search time is a powerful variable, with the number of species found increasing with additional effort. The present method is a rapid method that can compare the biodiversity of corals in different areas without having to find all species in that area.
No study finds all the species of coral in an area, including this study. The amount of search time and effort to find nearly all species is very large and requires a major expenditure of time and money. The present method is far more cost effective. The present results suggest that the reefs of Eastern Australia have a good number of coral species left to find, because the total known (about 391) is less than the number predicted by considering the number known from the Coral Triangle (a total of about 600, or 581 in Indonesia, and 512 in the Philippines). The fact that 11 species were found that had not been previously reported from Australia, and that taxonomic studies of Australian hard corals have not been published since 1985. In the time since 1985, many additional species have been recognized by leading coral taxonomists outside Australia (Wallace, 1999; Veron, 2000), and some of them are likely to be eventually found in Australia. The 11 additional species found it this study raise the number of corals known from eastern Australia from 391 to 402, and the number for all of Australia from 416 to 427 (Veron, 2000).

Osprey Reef has healthy abundant coral (with few or no dead corals, Crown-of-Thorns starfish or coral diseases sighted), and a high species diversity. Although the diversity is less than on outer Great Barrier Reef sites, the diversity is likely to be greater than that on inner barrier reefs, and perhaps middle reefs as well. In addition, only sites on the outer reef slopes of Osprey Reef were visited. Osprey is an atoll, with a large lagoon and having just one entrance. The lagoon is large and deep, and has coral communities that are likely to be quite different from those on the outer slopes of the atoll. This is because the water enclosed in the lagoon is quite different from that on the outside of the reef due to its almost complete enclosure. It is likely that there are fewer species inside the lagoon, but many species inside the lagoon are likely to be different and not found on the outside slopes. Thus, the total coral diversity of Osprey is almost certainly higher than that found in this study.

For perspective, the entire Caribbean has only about 55 species of coral (Fenner, 1999), fewer than found on almost every single dive in this study, and all of Hawaii has only 65 (Fenner, in press). Diversity is only one of several different desirable attributes for reefs that can be evaluated for considering desirability for protection. Health and abundance of corals may also be considered. The pristine nature of the area is an important. The abundance of large fish (sharks, grouper) on Osprey indicates that it has had little or no fishing pressure, as these large fish are usually the first to be removed. At a time when some shark species in Australia are endangered, this is one of the few places left in Eastern Australia where abundant natural populations of reef sharks remain. There is a unique opportunity at Osprey Reef to protect a pristine coral reef, and maintain its strong attraction for dive tourism.

The high diversity and good health of the corals on the outer slopes of Osprey Reef and its likely higher total diversity support the effort to protect this reef. Further, the finding of species not previously found in Australia at this site, and the finding of what may prove to be a new species, all support the need to protect this reef.

Acknowledgements
This study was supported by a grant in kind by the Undersea Explorer. I wish to thank all the staff and crew of the Undersea Explorer for all there assistance in making this study possible.

References

Done, TJ. 1982. Patterns in the distribution of coral communities across the central Great Barrier Reef. Coral Reefs 1: 95-107.

Fenner, D. 1999. New Observations on the Stony Coral Species (Scleractinia, Milliporidae, Stylaseridae) of Belize (Central America) and Cozumel (Mexico). Bulletin of Marine Science 64: 143-154.

Fenner, D. 2001. Reef corals of the Togian and Banggai Islands, Sulawesi, Indonesia. P. 18-25 and 63-71 in Allen, G. R. and S. A. McKenna (Eds.), A marine rapid assessment of the Togean and Banggai Islands, Sulawesi, Indonesia. RAP Bulletin of Biological Assessment 20, Conservation International, Washington, D.C.

Fenner, D. 2002 Reef corals of the Raja Ampat Islands, Papua Province, Indonesia. Part II. Comparison of individual survey sites. Appendix 2. Coral species recorded at individual sites in the Raja Ampat Islands. In McKenna, S. A., G. A. Allen, and S. Suryadi S. (eds) A marine rapid assessment of the Raja Ampat Islands, Papua Province, Indonesia. RAP Bulletin of Biological Assessment 22. Conservation International, Wash, DC, pp 29-36, 104-112.

Fenner, D. 2003. Corals of Milne Bay Province, Papua New Guinea. In Allen, G. R., J. P. Kinch, S. A. McKenna, and P. Seeto. Eeds.). A rapid marine biodiversity assessment of Milne Bay Province, Papua New Guinea - Survey II (2000). RAP Bulletin of Biological Assessment 29. Conservation International, Washington, DC, USA, pp 20-26.

Fenner, D in press. Corals of Hawai'i, Field Guide to the Hard, Soft, and Black Corals of Hawai'i and the Northwest Hawaiian Islands, including Midway. Mutual Publishing, Honolulu.

Veron, JEN 1985. New scleractinia from Australian coral reefs. Rec Western Australian Mus 12: 147-183.

Veron, JEN 1986. Corals of Australia and the Indo-Pacific. Angus and Robertson, Sydney. 644pp.

Veron, JEN 2000. Corals of the World. Vol 1-3. Australian Institute of Marine Science.

Veron, J. E. N. and D. Fenner. 2000. Corals (zooxanthellate Scleractinia) of the Calamianes Islands, Palawan Province, Philippines. Pages 24-26 in Werner, T. B. and G. R. Allen (eds.), A rapid marine biodiversity assessment of the Calamianes Islands, Palawan Province, Philippines. RAP Bulletin of Biological Assessment 17. Washington, D.C.: Conservation International.


Veron JEN and Pichon M 1976. Scleractinia of Eastern Australia. Part 1. Families Thamnasteriidae, Astrocoeniidae, Pocilloporidae. Australian Inst Mar Sci Monogr Ser I: 86 pp.

Veron JEN and Pichon M. 1980. Scleractinia of Eastern Australia. Part 3. Families Agaraciidae, Siderastreidae, Fungiidae, Oculinidae, Merulinidae, Mussidae, Pectiniidae, Caryophyllidae, Dendrophyllidae. Australian Inst. Mar. Sci Monogr. Ser IV: 471 pp.

Veron JEN and Pichon M. 1982. Scleractinia of Eastern Australia. Part 4, Family Poritidae. Australian Inst. Mar Sci Monogr. Ser V: 210 pp.

Veron JEN, Pichon M and Wijsman-Best M 1977. Scleractinia of Eastern Australia. Part 2, Families Faviidae, Trachyphyllidae. Australian Inst. Mar Sci Monogr Ser III: 233 pp.

Wallace, CC. 1978. The coral genus Acropora (Scleractinia: Astrocoenia: Acroporidae) in the central and southern Great Barrier Reef Province. Mem Queensland Mus 18: 273-319.

Wallace, CC. 1999. Staghorn Corals of the World CSIRO Publ, Melbourne. 422 pp.

Table 1             Great Barrier Reef sites

Table 2 Osprey and Shark Reef sites

Table 3 Comparison of East Australian Reefs with the Coral Triangle

Table 4 Corals found which were not previously reported from Australia

                                      Photo   Sample

1. Acanthastrea brevis            x          x
2. Acropora brevis                  x          x
3. Acropora globiceps             x          x
4. Acropora insignis                x         
5. Echinomorpha nishihirai       x
6. Goniastrea minuta              x          x
7. Leptoseris striata               x
8. Montipora verruculosus       x
9. Pavona bipartita                 x          x
10. Pocillopora ligulata            x          x
11. Seriatopora aculeata         x          x