Choat and Russell, 2008: 

"Some 1625 species, including trawl fishes, are recorded from the GBR, of which 1468 are coral reef species. This is a relatively high value and may be explained by two critical influences.

First, there is the geographical location of the reef and its setting in terms of the hydrodynamic environment. The position of the GBR relative to the Indonesian and Philippine archipelagoes to the north and the close proximity to the western Pacific reefs has resulted in a diverse fauna of reef fishes. Colonisation by larval reef fish from sources to the north and west are reflected in the strong bio geographical affinities of the GBR fish fauna with widespread tropical Indo-West Pacific elements.

Second, there is the size, configuration and habitat structure of the reef. The GBR is exceptional in terms of its size (350 000 km2), extending along the east Australian coastline from 10°S to 24°S, a distance of 1200 km (Fig. 28.1). The main structure of the reef terminates just south of the tropic of Capricorn. Beyond this there are a number of isolated coral reefs (Elizabeth and Middleton Reefs and Lord Howe Island) extending as far south as 31°30’S. These support faunas of coral reef fishes and also representatives of subtropical and temperate fish groups. A recent survey of Elizabeth and Middleton identified 322 species of reef associated fishes including 26 groupers, 25 butterfly fishes, 21 benthic feeding damselfishes, 22 parrotfishes and 21 surgeonfishes. Some species are endemic to these southern regions. Similar data from the northern end of the reef (Lizard Island) identifies a major shift in diversity, with approximately 900 species of reef associated fishes recorded. For the same groups the diversities were: groupers 41, butterfly fishes 38, benthic feeding damselfishes 48, parrotfishes 25 and surgeonfishes 31. However, the southern reefs also harbour species with warm temperate water affinities including morwongs (Cheilodactylidae), ludericks or sea chubs (Kyphosus, Girella), large pomacentrids (Parma), wrasses (Pseudolabrus) and surgeonfishes (Prionurus). These species contribute to the overall diversity of the reef, providing a small but distinctive southern element to the reef fauna (Fig. 28.2).

There are also strong longitudinal trends in reef fish diversity. Comparison of equivalent habitats from inner coastal reefs and mid-shelf and outer barrier reefs at the central region of the GBR revealed the following differences in species diversities: butterfly fishes: inner 7, outer 15; damselfishes: inner 10, outer 26; parrot-fishes: inner 8, outer 20; surgeonfishes: inner 4, outer 15. An important aspect of this distribution is that some inshore species have restricted distributions that reflect some of the unusual habitat features of inshore reefs (Fig. 28.3). An important summary point is that the GBR maintains a very high diversity of fishes for two reasons. The first is its sheer size, comprising 2000 reefs spread over 350 000 km². This provides a massive target with a high probability of suitable habitats for larval fishes that may disperse from other regions to the north and east. The second is the variety of habitats, including inshore coastal reefs extending out to reefs exposed to fully oceanic conditions.

The continuous nature of the reef, its latitudinal distribution from tropical to subtropical environments and the strong longitudinal gradient of habitat structure from the coasts to the Coral Sea are factors that underlie the notable diversity of reef fish species. In addition, the unique evolutionary history of the Australian coastal fauna has made an important contribution to the diversity of the present day GBR fish assemblage."

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Citation and/or URL

Choat, J.H, and Russell, B.C. 2008, The fish assemblages of the Great Barrier Reef: their diversity and origin, In: The Great Barrier Reef: biology, environment and management, eds P.A. Hutchings, M.J. Kingsford and O. Hoegh-Guldberg, CSIRO Publishing, p.327-342. © ACRS 2008. http://www.publish.csiro.au/pid/5921.htm.

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Spatial Coverage

A synthesis of information covering the entire Reef

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Temporal Coverage

Not applicable

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Update Frequency

Not applicable

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Other Information

None