Box 202 Families And Genera Of Scleractinia Hard Corals On The Great Barrier Reef

Families 1 to 6 are dominant in the ecology of the GBR. Genera and families in bold are suggested as a first learning tool for the beginner. Genera in bold here are illustrated in this chapter. Asterisked genera are azooxanthellate.

Table 20.1

(1) Family Acroporidae

(5) Family Fungiidae

(10) Family Pectiniidae

Acropora

Fungia

Pectinia

Isopora

Cycloseris

Echinophyllia

Montipora

Heliofungia

Oxypora

Astreopora

Ctenactis

Mycedium

Halomitra

(11) Family Euphyllidae

(2) Family Faviidae

Podobacia

Euphyllia

Favia

Catalophyllia

Favites

(6) Family Mussidae

Physogyra

Goniastrea

Lobophyllia

Montastrea

Symphyllia Acanthastrea

(12) Family Oculinidae

Leptastrea

Micromussa

Galaxea

Leptoria

Blastomussa

(13) F. Dendrophyllidae

Oulophyllia

Cynarina

Turbinaria

Plesiastrea

Scolymia

Duncanopsammia

Echinopora

Caulastrea Cyphastrea

(7) Family Astrocoeniidae Stylocoeniella

Tubastrea *Heteropsammia

Diploastrea

Palauastrea

(14) Family Merulinidae

Moseleya

(8) Family Siderastreidae

Merulina

Barabattoia

Siderastrea

Hydnophora

(3) Family Poritidae

Psammocora

Scapophyllia

Porites

Coscinaria

(15) F. Trachyphyllidae

Goniopora

(9) Family Agaricidae

Trachyphyllia

Alveopora

Pavona

(16) F. Caryophyllidae

(4) Family Pocilloporidae Pocillopora

Leptoseris Gardenoseris

*Heterocyathus

Stylophora

Pachyseris

Seriatopora

Australia, and exhibit a number of different strategies in the way they release their gametes; for example, gametes may be negatively rather than positively buoyant in some species. The genera Goniastrea and Leptastrea appear to be among the most tolerant of all corals to heat stress and exposure to silty conditions. On reef flats, Platygyra and Goniastrea commonly develop into 'microatolls', with living coral surface confined to the vertical sides of the colony, surrounding a dead top, which sometimes gets colonised by algae or other corals. This morphology comes about when the top of the colony gets regularly exposed to the air and/or sunlight on low tide.

Scleractinian Coral Colony Structure

Figure 20.5 Examples of genera and species from the major coral families Acroporidae (A-F) and Faviidae (G-L). Species: A, Acropora echinata; B, Acropora muricata; C, Acropora hyacinthus; D, Isopora palifera; E, Montipora incrasata; F, Astreopora gracilis; G, Favia maritima; H, Favites halicora; I, Goniastrea aspera; J, Platygyra sinensis; K, Echinopora gemmifera; L, Diploastrea heliopora. (Photos: P. Muir.)

Figure 20.5 Examples of genera and species from the major coral families Acroporidae (A-F) and Faviidae (G-L). Species: A, Acropora echinata; B, Acropora muricata; C, Acropora hyacinthus; D, Isopora palifera; E, Montipora incrasata; F, Astreopora gracilis; G, Favia maritima; H, Favites halicora; I, Goniastrea aspera; J, Platygyra sinensis; K, Echinopora gemmifera; L, Diploastrea heliopora. (Photos: P. Muir.)

(3) Family Poritidae ('golf ball' corals, 'bommie' corals) (Fig. 20.6A-C)

Colonies in this family are massive, encrusting, plating or branching. In all cases, corallite walls are formed by upward growth of fine trabecular elements. This family contains one of the most remarkable zooxanthellate genera, Porites. Although species of Porites can exist in branching and plating forms, it is the massive species that provide examples of the longest-lived and largest solid coral forms. Growth in these massive colonies is in usually in increments of 1-2 centimetres per year, with two growth seasons being recorded by a 'dark' and a 'light' (dense and less dense) band. By counting and measuring these bands, it is possible to calculate the age of the colony and witness the history of environmental conditions that the colony has encountered. Colonies of over 700 years old have been identified and these sometimes form the basis of the huge 'bommies' found within lagoons and just outside the reef slope on reefs of the GBR. Not surprisingly, species of Porites form the subject of numerous studies of coral growth, vulnerability to environmental conditions, effects of coastal runoff and many other research topics.

Some situations favour the development of Porites-dominated coral assemblages, for example, calm, shallow offshore shoals or fringing reefs. Goniopora may also be present in these habitats. This genus is most notable for its long-columned polyps that are extended during the day. It is a popular aquarium subject and is apparently tolerant of high turbidity and low-light situations. Another genus, Alveopora, looks superficially like Goniastrea because its polyps are also extended during the day, but genetic studies indicate it may belong in the Acroporidae.

(4) Family Pocilloporidae ('brown stem corals') (Fig. 20.6D-G)

This is a family of genera with relatively small colonies, a branching mode of growth, simple, small coral-lites with reduced walls, only two septal cycles and always separated by coenosteum. All genera are brooders, and in some species of Pocillopora, planulae can be produced asexually by budding. Pocillopora is regarded as a 'weedy' genus, its species recruiting soon after catastrophic events and living short lives, with relatively regular monthly release of larvae throughout the year. Early observations of the breeding patterns of genera in this family led to the misconception that all corals release brooded larvae throughout the year, making larvae available for settlement on the reef at all times. This misconception influenced ecological thinking about reef corals until the 1980s, when mass broadcast spawning in corals was discovered (see Box 20.1). The best-known species are Stylophora pistillata and Pocillopora damicornis, which have been used for much published experimentation on the effects of water chemistry, light, temperature and other factors on corals.

(5) Family Fungiidae ('mushroom corals') (Fig. 20.6H-K)

Most species in this family occur as individual polyps that grow very large instead of multiplying, and that remain free living (unattached to the reef) during adult life. These corals contain zooxanthellae, are mostly regarded as non reef-building, or 'ahermatypic', because they generally do not contribute much to the reef structure (though there are notable exceptions when they and their dead predecessors occur in large mounds of thousands of individuals). Sexual reproduction often involves gonochoric gamete development (individuals of separate sexes), followed by simultaneous release of eggs or sperm by many individuals of the same species. Polyps settle on the reef to form an attached juvenile coral that may bud to form a 'stack' of cloned individuals: as these grow, they break off the stack and lie free on the reef floor. Generally found in the subtidal parts of reefs, fungiids may occur in great abundance and diversity.

(6) Family Mussidae ('spiky brain corals') (Fig. 20.7A-C)

Genera in this family have massive or encrusting colonies, with pronounced teeth on the septa and corallite walls formed by complex trabecular growth, which leads to very sturdy corallites, including some of the largest corallites to be seen in colonial corals. Polyp tissues are very fleshy and sometimes very colourful. These corals contribute great bulk to the reef structure.

Porites Lutea

Figure 20.6 Examples of genera and species from the major coral families: Poritidae (A-C), Pocilloporidae (D-G); Fungiidae (H-K) and minor family Oculinidae (L). Species: A, Porites lutea; B, Porites cylindrical; C, Goniopora fruticosa; D, Pocillopora damicornis; E, Pocillopora eydouxi; F, Stylophora pistillata; G, Seriatopora hystrix; H, Fungia valida; I, Heliofungia actiniformis; J, Ctenactis echinata; K, Herpolitha webberi; L, Galaxea astreata. (Photos: P. Muir except G, GBRMPA.)

Figure 20.6 Examples of genera and species from the major coral families: Poritidae (A-C), Pocilloporidae (D-G); Fungiidae (H-K) and minor family Oculinidae (L). Species: A, Porites lutea; B, Porites cylindrical; C, Goniopora fruticosa; D, Pocillopora damicornis; E, Pocillopora eydouxi; F, Stylophora pistillata; G, Seriatopora hystrix; H, Fungia valida; I, Heliofungia actiniformis; J, Ctenactis echinata; K, Herpolitha webberi; L, Galaxea astreata. (Photos: P. Muir except G, GBRMPA.)

Coscinaria

Figure 20.7 Examples of genera and species from the major coral family Mussidae (A-C) and minor families Siderastre-idae (D, E); Agaricidae (F); Pectiniidae (G, H); Euphyllidae (/); Dendrophyllidae (J) and Merulinidae (K, L). Species: A, Lobophyllia hemprichi; B, Symphyllia recta; C, Acanthastrea echinata; D, Psammocora haimeana; E, Coscinarea exesa; F, Pavona maldivensis; G, Echinophyllia aspera; H, Mycedium elephantotus; /, Euphyllia ancora; J, Turbinaria mesenterina; K, Merulina ampliata; L, Hydnophora exesa. (Photos: P. Muir.)

Figure 20.7 Examples of genera and species from the major coral family Mussidae (A-C) and minor families Siderastre-idae (D, E); Agaricidae (F); Pectiniidae (G, H); Euphyllidae (/); Dendrophyllidae (J) and Merulinidae (K, L). Species: A, Lobophyllia hemprichi; B, Symphyllia recta; C, Acanthastrea echinata; D, Psammocora haimeana; E, Coscinarea exesa; F, Pavona maldivensis; G, Echinophyllia aspera; H, Mycedium elephantotus; /, Euphyllia ancora; J, Turbinaria mesenterina; K, Merulina ampliata; L, Hydnophora exesa. (Photos: P. Muir.)

One genus, Acanthastrea, is common in high latitude reefs, such as Moreton Bay.

Some of the minor coral families are shown in Fig. 20.6L and Fig. 20.7D-I.

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