The laterophysic connection and swim bladder of butterflyfishes in the genus Chaetodon (Perciformes: Chaetodontidae)

The laterophysic connection (LC) is an association between bilaterally paired, anterior swim bladder extensions (horns) and medial openings in the supracleithral lateral line canals that diagnoses butterflyfishes in the genus Chaetodon. It has been hypothesized that the LC makes the lateral line system sensitive to sound pressure stimuli that are transmitted by the swim bladder horns and converted to fluid flow into the lateral line system via a laterophysic tympanum. The purpose of this study was to define variation in the morphology of the LC, swim bladder and swim bladder horns among 41 Chaetodon species from all 11 Chaetodon subgenera and a species from each of four non-Chaetodon genera using gross dissection, histological analysis as well as 2D or 3D CT (computed tomographic) imaging of live, anesthetized fishes. Our results demonstrate that the lateral line system appears rather unspecialized with well-ossified narrow canals in all species examined. Two LC types (direct and indirect), defined by whether or not the paired anterior swim bladder horns are in direct contact with a medial opening in the supracleithral lateral line canal, are found among species examined. Two variants on a direct LC and four variants of an indirect LC are defined by combinations of soft tissue anatomy (horn length [long/short] and width [wide/narrow], number of swim bladder chambers [one/two], and presence/absence of mucoid connective tissue in the medial opening in the supracleithrum). The combination of features defining each LC variant is predicted to have functional consequences for the bioacoustics of the system. These findings are consistent with the recent discovery that Chaetodon produce sounds during social interactions. The data presented here provide the comparative morphological context for the functional analysis of this novel swim bladder-lateral line connection.     

The laterophysic connection in chaetodontid butterflyfish: morphological variation and speculations on sensory function

The laterophysic connection is a novel specialization in chaetodontid butterflyfish, in which paired diverticula of the swim-bladder ('horns') extend anteriorly and approach or directly contact a medial fossa in the lateral line canal contained within the supracleithrum. This study examined the morphology of the laterophysic connection in eight ecologically diverse species belonging to five subgenera within Chaetodon. Two types of laterophysic connections, indirect and direct, were found among Chaetodon species. Intraspecific variation (including sexual dimorphism) in the morphology of the laterophysic connection was not found. The type of laterophysic connection is not correlated with ecological characteristics among Chaetodon species, but appears to be correlated with subgeneric affinities of Chaetodon species. The presence of swim-bladder horns probably increases pressure sensitivity to the inner ear. It is suggested that the presence of a direct laterophysic connection, and possibly an indirect laterophysic connection, imparts pressure sensitivity to the lateral line canal system as well.     

The evolution of the laterophysic connection with a revised phylogeny and taxonomy of butterflyfishes (Teleostei: Chaetodontidae)

The higher‐level relationships of butterflyfishes were examined using 37 morphological characters. This analysis combines characters derived from a histological study describing variation in the morphology of the laterophysic connection (an association between the swim bladder and the lateral‐line canals) with previously described morphological characters. The phylogenetic analysis resulted in four equally parsimonious trees that only differed in the placement of two of the 11 chaetodontid genera (Amphichaetodon and Forcipiger). We compare our analysis with previous hypotheses, present a new taxonomy consistent with the proposed cladistic relationships, and diagnose Chaetodon with five unreversed synapomorphies, including the evolution of characters composing the laterophysic connection. A new character‐based diagnosis of Chaetodon is provided and species are allocated accordingly; Chaetodon now includes the former Parachaetodon ocellatus and excludes the former subgenera Prognathodes and Roa. The evolution of the laterophysic connection is examined by optimizing character‐state transformations on the new hypothesis of relationships.     

Morphological development of the swim bladder in hatchery-reared striped trumpeter Latris lineata

This study examined swim bladder morphogenesis in three cohorts of striped trumpeter (Latris lineata), a euphysoclist species with physostomous larvae. The swim bladder was first discernible 1–2 days after hatching as an evagination on the dorsal surface of the incipient digestive tract. It comprised a cluster of mesenchymal cells surrounding an inner primordium of epithelial cells. At mouth opening in larvae of 5.3 mm standard length (SL), the swim bladder was noticeably enlarged. Histologically, the swim bladder lumen was dilated and liquid filled. The pneumatic duct was first seen during the dilation stage and the rete mirabile began forming among the connective tissue surrounding the swim bladder. Initial swim bladder inflation occurred on day 11 post‐hatching in Cohort 1, at 14°C, and day 9 post‐hatching, in Cohorts 2 and 3, at 16°C. Histologically, the lumens of inflated swim bladders were ellipsoid and the epithelium was squamous, except for cuboidal gas gland cells at the anterio‐ventral and anterio‐lateral regions of the swim bladder. During the initial inflation interval the pneumatic duct was dilated in larvae both with and without swim bladder inflation. The pneumatic duct began to regress in some larvae over 7.5 mm SL. The swim bladder of striped trumpeter was similar to larvae of other altricial perciform marine fish in respect to organ derivation, tissue differentiation, luminal dilation and initial gaseous inflation. However, variations, particularly the delay in initial swim bladder inflation until after the start of feeding, were observed that could be fundamental to problems encountered during larval rearing.     

A proposed mechanism for the observed ontogenetic improvement in the hearing ability of hapuka (Polyprion oxygeneios)

Swim bladder extensions and hearing ability were examined in the temperate reef fish Polyprion oxygeneios (hapuka). Using the auditory evoked potential (AEP) technique, hearing thresholds were determined in four age-classes of hapuka, from larvae to juveniles. The youngest age-class had poor hearing abilities, with lowest thresholds of 132 dB re 1 μPa, and a narrow auditory bandwidth (100–800 Hz). Hearing ability improved significantly throughout the remainder of their first year, including decreases in thresholds of up to 27 dB, and an increase in auditory bandwidth (up to 1,000 Hz). Magnetic resonance imaging (MRI) was used to investigate structural mechanisms that may account for this ontogenetic improvement in hearing. These showed rostral extensions of the swim bladder developing early in the juvenile stage, and extending with increasing age closer to the otic capsule. It is suggested that this indirect connection between the swim bladder and the otic capsule could impart pressure sensitivity closer to the inner ear, accounting for the increase in sensitivity seen during development, although further investigation of older fish is required for conclusive evidence. The improvement in hearing ability in hapuka could be potentially related to a unique life history of extended pelagic durations up to 4 years.     

Mismatch between shape changes and ecological shifts during the post-settlement growth of the surgeonfish, Acanthurus triostegus

Background

Many coral reef fishes undergo habitat and diet shifts during ontogeny. However, studies focusing on the physiological and morphological adaptations that may prepare them for these transitions are relatively scarce. Here, we explored the body shape variation related to ontogenetic shifts in the ecology of the surgeonfish Acanthurus triostegus (Acanthuridae) from new settler to adult stages at Moorea Island (French Polynesia). Specifically, we tested the relationship between diet and habitat shifts and changes in overall body shape during the ontogeny of A. triostegus using a combination of geometric morphometric methods, stomach contents and stable isotope analysis.

Results

After reef settlement, stable isotope composition of carbon and nitrogen revealed a change from a zooplanktivorous to a benthic algae diet. The large amount of algae (> 75% of stomach contents) found in the digestive tract of small juveniles (25?C30 mm SL) suggested the diet shift is rapid. The post-settlement growth of A. triostegus is highly allometric. The allometric shape changes mainly concern cephalic and pectoral regions. The head becomes shorter and more ventrally oriented during growth. Morphological changes are directly related to the diet shift given that a small mouth ventrally oriented is particularly suited for grazing activities at the adult stage. The pectoral fin is more anteriorely and vertically positioned and its basis is larger in adults than in juveniles. This shape variation had implications for swimming performance, manoeuvrability, turning ability and is related to habitat shift. Acanthurus triostegus achieves its main transformation of body shape to an adult-like form at size of 35?C40 mm SL.

Conclusion

Most of the shape changes occurred after the reef colonization but before the transition between juvenile habitat (fringing reef) and adult habitat (barrier reef). A large amount of allometric variation was observed after diet shift from zooplankton to benthic algae. Diet shift could act as an environmental factor favouring or inducing morphological changes. On the other hand, the main shape changes have to be achieved before the recruitment to adult populations and start negotiating the biophysical challenges of locomotion and feeding in wave- and current-swept outer reef habitat.     

Effect of habitat characteristics on the distribution and abundance of damselfish within a Red Sea reef

For coral reef fish with an obligate relationship to their habitat, like Pomacentrid damselfish, choosing a suitable home amongst the reef structure is key to survival. A surprisingly small number of studies have examined patterns in adult damselfish distributions compared to other ontogenetic phases. The aim of this study was to determine which reef and coral colony characteristics explained adult damselfish distribution patterns in a Red Sea reef. The characteristics investigated were reef type (continuous or patchy), coral species (seven species of Acropora), and coral morphology (coral size and branching density). The focal damselfish species were Dascyllus aruanus, D. marginatus, Chromis viridis, and C. flavaxilla. Occupancy (presence or absence of resident damselfish), group size and fish species richness were not significantly different between the seven Acropora species. However, within each coral species, damselfish were more likely to occupy larger coral colonies than smaller coral colonies. Occupancy rates were also higher in patchy reef habitats than in continuous sections of the reef, probably because average coral colony size was greater in patchy reef type. Fish group size increased significantly with coral colony volume and with larger branch spacing. Multi-species groups of fish commonly occurred and were increasingly likely with reduced branching density and increased coral size.     

Survival dynamics of reef coral larvae with special consideration of larval size and the genus Acropora

Temporal dynamics of larval survival were examined in vitro in four broadcast-spawning reef coral species, Acropora hyacinthus, A. japonica, A. solitaryensis, and Goniastrea pectinata. Larval size was treated as an important characteristic that may relate to larval lifespan. Two patterns were observed in larval survival dynamics between the three Acropora species (mean initial larval size; 0.05-0.08 mm(3)) and G. pectinata (0.02 mm(3)), based on the timing of a sharp drop in larval survival rates (ca. > 50% reduction over a 1-2 week period). Consequently, the majority of larvae of the three Acropora species had a lifespan of less than 2-3 weeks, whereas those of G. pectinata were extended a further 2-3 weeks despite the smaller larval size. No significant relationship was detected between the initial larval size and larval lifespan in any of the four reef coral species. These results suggest that (1) larval dispersal of spawning Acropora species may be on a more local scale than that of G. pectinata and most other reef coral species previously reported, and (2) larval size is not a good estimator of larval lifespan in reef coral species.     

Ontogenetic shifts in the social behaviour of pairing coral reef rabbitfishes (Siganidae)

Adult rabbitfishes (Siganidae) differ from most other herbivorous coral reef fishes by forming stable pair bonds throughout their adult lives. However, little is known about the early life stages of rabbitfishes, and no quantitative evidence regarding the ontogeny of pairing behaviour exists to date. This study describes the abundance, distribution and ontogeny of social associations in juvenile rabbitfishes on the mid-shelf reefs around Lizard Island, Great Barrier Reef, Australia. Using underwater visual censuses, we surveyed an area of 5728?m² across three distinct habitat types, revealing that the abundance of juveniles varies significantly among species, size class and exposure level. Furthermore, we demonstrate a pronounced ontogenetic shift in the social associations of juveniles of Siganus doliatus and Siganus corallinus, changing from primarily solitary individuals in the smallest size class (<50?mm) to predominantly paired individuals in the larger size classes (50–100?mm and 100–150?mm). In this context, we report the presence of several mixed-species pairs of rabbitfishes, providing the first evidence for this behaviour within the family. This supports previous research, which posits that there are strong ecological drivers, rather than a solely reproductive basis, for pairing behaviour in rabbitfishes. Based on our results, we suggest that further exploration of the ecology of early life stages of herbivorous reef fishes will increase our knowledge about ecological processes on coral reefs.     

The morphology and ultrastructure of the peripheral olfactory organ in newly metamorphosed coral-dwelling gobies, Paragobiodon xanthosomus Bleeker (Gobiidae, Teleostei)

We examined the peripheral olfactory organ in newly metamorphosed coral-dwelling gobies, Paragobiodon xanthosomus (SL=5.8mm+/-0.8mm, N=15), by the aid of electron microscopy (scanning and transmission) and light microscopy. Two bilateral olfactory placodes were present in each fish. They were oval-shaped and located medio-ventrally, one in each of the olfactory chambers. Each placode had a continuous cover of cilia. The placode epithelium contained three different types of olfactory receptor neurons: ciliated, microvillous and crypt cells. The latter type was rare. Following a pelagic larval phase, P. xanthosomus settle to the reef and form an obligate association with one species of coral, Seriatopora hystrix. Their well-developed olfactory organs likely enable larvae of P. xanthosomus to detect chemical cues that assist in navigating towards and selecting appropriate coral habitat at settlement. Our findings support past studies showing that the peripheral olfactory organ develops early in coral reef fishes.     

Larval Settlement: The Role of Surface Topography for Sessile Coral Reef Invertebrates

For sessile marine invertebrates with complex life cycles, habitat choice is directed by the larval phase. Defining which habitat-linked cues are implicated in sessile invertebrate larval settlement has largely concentrated on chemical cues which are thought to signal optimal habitat. There has been less effort establishing physical settlement cues, including the role of surface microtopography. This laboratory based study tested whether surface microtopography alone (without chemical cues) plays an important contributing role in the settlement of larvae of coral reef sessile invertebrates. We measured settlement to tiles, engineered with surface microtopography (holes) that closely matched the sizes (width) of larvae of a range of corals and sponges, in addition to surfaces with holes that were markedly larger than larvae. Larvae from two species of scleractinian corals (Acropora millepora and Ctenactis crassa) and three species of coral reef sponges (Luffariella variabilis, Carteriospongia foliascens and Ircinia sp.,) were used in experiments. L. variabilis, A. millepora and C. crassa showed markedly higher settlement to surface microtopography that closely matched their larval width. C. foliascens and Ircinia sp., showed no specificity to surface microtopography, settling just as often to microtopography as to flat surfaces. The findings of this study question the sole reliance on chemical based larval settlement cues, previously established for some coral and sponge species, and demonstrate that specific physical cues (surface complexity) can also play an important role in larval settlement of coral reef sessile invertebrates.     

The ontogeny of habitat associations in the tropical tiger tail seahorse Hippocampus comes Cantor, 1850

This study examined how habitat associations changed with ontogeny in the tiger tail seahorse Hippocampus comes Cantor, 1850, over four reef zones in a coral reef ecosystem. Hippocampus comes showed ontogenetic differences in their use of habitat at the scale of reef zones (macrohabitat) and holdfasts (microhabitat). Across reef zones, juvenile size classes (25–105 mm standard length, L _S) were most abundant in wild macroalgal beds ( Sargassum spp.) (55·7%), while adults (>105 mm L _S) occupied both coral reefs (39·7%) and macroalgal beds (42·7%). Microhabitat use also varied with ontogeny. Juveniles generally used macroalgal holdfasts, while adults >135 mm L _S used a greater diversity of specialized microhabitats that included branching sponges, branching corals and tall seagrass. Ontogenetic changes in habitat association, as well as size-related shifts in crypsis and aggregation, suggest that H. comes experiences fitness trade-offs that vary with size; juveniles may associate with habitat that reduces predation, while larger individuals may use distinct microhabitat in reef zones to optimize reproductive success. Results are discussed in the context of targeted exploitation, expanding artisanal mariculture, habitat damage from illegal fishing and reserve design.     

Evidence of an original scale development during the settlement phase of a coral reef fish (Acanthurus triostegus)

As the majority of coral reef fishes, the Convict Surgeonfish Acanthurus triostegus (Acanthuridae) has a complex life cycle that involves an ontogenetic change in morphology, physiology and behaviour as its pelagic larval stage colonizes the benthic habitat. Few studies are devoted to the changes in skeleton during the settlement phase of coral reef fishes. In the present study, we highlighted an unexpected scales development in A. trisostegus just after the reef settlement. At settlement (t₀), A. triostegus showed calcified and very thin vertical plates, lying in the dermis on the whole body. During the first 9 days after settlement, thin vertical plates regressed and adult scales began to appear simultaneously. At 12 days post‐settlement, the whole body was covered with small scales. Overall, such a rapid skeletal transformation is an example of morphological changes dealing with ‘metamorphosis’ of coral reef fishes.     

Identifying the ichthyoplankton of a coral reef using DNA barcodes

Marine fishes exhibit spectacular phenotypic changes during their ontogeny, and the identification of their early stages is challenging due to the paucity of diagnostic morphological characters at the species level. Meanwhile, the importance of early life stages in dispersal and connectivity has recently experienced an increasing interest in conservation programmes for coral reef fishes. This study aims at assessing the effectiveness of DNA barcoding for the automated identification of coral reef fish larvae through large‐scale ecosystemic sampling. Fish larvae were mainly collected using bongo nets and light traps around Moorea between September 2008 and August 2010 in 10 sites distributed in open waters. Fish larvae ranged from 2 to 100 mm of total length, with the most abundant individuals being <5 mm. Among the 505 individuals DNA barcoded, 373 larvae (i.e. 75%) were identified to the species level. A total of 106 species were detected, among which 11 corresponded to pelagic and bathypelagic species, while 95 corresponded to species observed at the adult stage on neighbouring reefs. This study highlights the benefits and pitfalls of using standardized molecular systems for species identification and illustrates the new possibilities enabled by DNA barcoding for future work on coral reef fish larval ecology.     

Effects of parasites on larval and juvenile stages of the coral reef fish Pomacentrus moluccensis

The ecological role of parasites in the early life-history stages of coral reef fish is far from clear. Parasitism in larval, recently settled and juvenile stages of a coral reef fish damselfish (Pomacentridae) was therefore investigated by quantifying the ontogenetic change in parasite load and comparing the growth rates of parasitized juvenile fish to those of unparasitized ones. Parasite prevalence in two lunar pulses of Pomacentrus moluccensis was 4 and 0% for larval stage fish, 34 and 56% for recently settled fish and 42 and 49% for juveniles. A significant increase in parasite prevalence with age group was found; the most marked increase occurred immediately after larval fish had settled. Standard length did not model prevalence well; as length is a proxy for age, this indicates that the higher prevalence in recently settled and juvenile fish compared with larvae was not a simple result of parasites accumulating with age. In one of three cohorts, there was some evidence that parasitism affected the growth rate of juveniles, as measured by otolith width. The study suggests that settling on the reef exposes young fish to potentially harmful parasites. This supports the idea that the pelagic phase may have the effect of reducing the exposure of young fish to the debilitating effects of parasites.     

Distribution,food preference,and trophic position of the corallivorous fireworm Hermodice carunculata in a Caribbean coral reef

The fireworm Hermodice carunculata is a facultative corallivore on coral reefs. It can interact with algal overgrowth to cause coral mortality. However, because of its cryptic nature, little is known about its ecology. We used micropredator attracting devices (MADs) and stable isotope analyses to provide insights into the distribution and diet of H. carunculata in a coral reef on Curaçao, southern Caribbean. MADs consisted of algal clumps inside accessible mesh nets which H. carunculata could use as refuge. To obtain indications on its distribution pattern, MADs filled with Halimeda opuntia were deployed in different reef habitats ranging from 0 to 16 m water depth. Fireworms were found inside MADs in all reef habitats, indicating that they have a widespread horizontal and vertical distribution, ranging from the shoreline to the deeper reef slope. On the reef crest, MADs were filled using different algal species and deployed on dead or live scleractinian corals. MADs hosted more fireworms when placed on live corals, regardless of algal species used, suggesting that algal-induced corallivory may be widespread. To test for food preferences, different food sources were added inside the MADs. Fireworms detected potential prey within 6 h and were significantly more attracted by decaying corals and raw fish than by live corals, hydrozoans, or gorgonians. Stable isotope analyses indicated detritus, macroalgae, and scleractinian corals as potential food sources and revealed an ontogenetic dietary shift toward enriched δ ¹³C and δ ¹⁵N values with increasing fireworm size, suggesting that large-sized individuals feed on food sources of higher trophic levels. Our findings highlight H. carunculata as a widespread, and omnivorous scavenger that has the potential to switch feeding toward weakened or stressed corals, thereby likely acting as a harmful corallivore on degraded reefs.     

Effects of alternate reef states on coral reef fish habitat associations

The present study describes ontogenetic shifts in habitat use for 15 species of coral reef fish at Rangiroa Atoll, French Polynesia. The distribution of fish in different habitats at three ontogenetic stages (new settler, juvenile, and adult) was investigated in coral-dominated and algal-dominated sites at two reefs (fringing reef and inner reef of motu). Three main ontogenetic patterns in habitat use were identified: (1) species that did not change habitats between new settler and juvenile life stages (60% of species) or between juvenile and adult stages (55% of species—no ontogenetic shift); (2) species that changed habitats at different ontogenetic stages (for the transition “new settler to juvenile stage”: 15% of species; for the transition “juvenile to adult stage”: 20% of species); and (3) species that increased the number of habitats they used over ontogeny (for the transition “new settler to juvenile stage”: 25% of species; for the transition “juvenile to adult stage”: 25% of species). Moreover, the majority of studied species (53%) showed a spatial variability in their ontogenetic pattern of habitat use according to alternate reef states (coral reef vs algal reef), suggesting that reef state can influence the dynamics of habitat associations in coral reef fish.     

A novel hearing specialization in the New Zealand bigeye,Pempheris adspersa

The New Zealand bigeye, Pempheris adspersa, is a nocturnal planktivore and has recently been found to be an active sound producer. The rostral end of the swim bladder lies adjacent to Baudelot''s ligament which spans between the bulla and the cleithrum bone of the pectoral girdle. The aim of this study was to use the auditory evoked potential technique to physiologically test the possibility that this structure provides an enhanced sensitivity to sound pressure in the bigeye. At 100 Hz, bigeye had hearing sensitivity similar to that of goldfish (species with a mechanical connection between the swim bladder and the inner ear mediated by the Weberian ossicles) and were much more sensitive than other teleosts without ancillary hearing structures. Severing Baudelot''s ligament bilaterally resulted in a marked decrease in hearing sensitivity, as did swim bladder puncture or lateral line blockage. These results show that bigeye have an enhanced sensitivity to sound pressure and provide experimental evidence that the functional basis of this sensitivity represents a novel hearing specialization in fish involving the swim bladder, Baudelot''s ligament and the lateral line.     

Habitat associations of juvenile fish at Ningaloo Reef, Western Australia: the importance of coral and algae

Habitat specificity plays a pivotal role in forming community patterns in coral reef fishes, yet considerable uncertainty remains as to the extent of this selectivity, particularly among newly settled recruits. Here we quantified habitat specificity of juvenile coral reef fish at three ecological levels; algal meadows vs. coral reefs, live vs. dead coral and among different coral morphologies. In total, 6979 individuals from 11 families and 56 species were censused along Ningaloo Reef, Western Australia. Juvenile fishes exhibited divergence in habitat use and specialization among species and at all study scales. Despite the close proximity of coral reef and algal meadows (10's of metres) 25 species were unique to coral reef habitats, and seven to algal meadows. Of the seven unique to algal meadows, several species are known to occupy coral reef habitat as adults, suggesting possible ontogenetic shifts in habitat use. Selectivity between live and dead coral was found to be species-specific. In particular, juvenile scarids were found predominantly on the skeletons of dead coral whereas many damsel and butterfly fishes were closely associated with live coral habitat. Among the coral dependent species, coral morphology played a key role in juvenile distribution. Corymbose corals supported a disproportionate number of coral species and individuals relative to their availability, whereas less complex shapes (i.e. massive & encrusting) were rarely used by juvenile fish. Habitat specialisation by juvenile species of ecological and fisheries importance, for a variety of habitat types, argues strongly for the careful conservation and management of multiple habitat types within marine parks, and indicates that the current emphasis on planning conservation using representative habitat areas is warranted. Furthermore, the close association of many juvenile fish with corals susceptible to climate change related disturbances suggests that identifying and protecting reefs resilient to this should be a conservation priority.     

Importance of live coral habitat for reef fishes

Live corals are the key habitat forming organisms on coral reefs, contributing to both biological and physical structure. Understanding the importance of corals for reef fishes is, however, restricted to a few key families of fishes, whereas it is likely that a vast number of fish species will be adversely affected by the loss of live corals. This study used data from published literature together with independent field based surveys to quantify the range of reef fish species that use live coral habitats. A total of 320 species from 39 families use live coral habitats, accounting for approximately 8 % of all reef fishes. Many of the fishes reported to use live corals are from the families Pomacentridae (68 spp.) and Gobiidae (44 spp.) and most (66 %) are either planktivores or omnivores. 126 species of fish associate with corals as juveniles, although many of these fishes have no apparent affiliation with coral as adults, suggesting an ontogenetic shift in coral reliance. Collectively, reef fishes have been reported to use at least 93 species of coral, mainly from the genus Acropora and Porities and associate predominantly with branching growth forms. Some fish associate with a single coral species, whilst others can be found on more than 20 different species of coral indicating there is considerable variation in habitat specialisation among coral associated fish species. The large number of fishes that rely on coral highlights that habitat degradation and coral loss will have significant consequences for biodiversity and productivity of reef fish assemblages.