Predators reduce abundance and species richness of coral reef fish recruits via non-selective predation

Predators have important effects on coral reef fish populations, but their effects on community structure have only recently been investigated and are not yet well understood. Here, the effect of predation on the diversity and abundance of young coral reef fishes was experimentally examined in Moorea, French Polynesia. Effects of predators were quantified by monitoring recruitment of fishes onto standardized patch reefs in predator-exclosure cages or uncaged reefs. At the end of the 54-day experiment, recruits were 74% less abundant on reefs exposed to predators than on caged ones, and species richness was 42% lower on reefs exposed to predators. Effects of predators varied somewhat among families, however, rarefaction analysis indicated that predators foraged non-selectively among species. These results indicate that predation can alter diversity of reef fish communities by indiscriminately reducing the abundance of fishes soon after settlement, thereby reducing the number of species present on reefs.     

Effects of Habitat Connectivity on the Abundance and Species Richness of Coral Reef Fishes: Comparison of an Experimental Habitat Established at a Rocky Reef Flat and at a Sandy Sea Bottom

Coral reef fish assemblages are widely recognized for the coexistence of numerous species, which are likely governed by both coral diversity and substratum complexity. However, since coral reefs provide diverse habitats due to their physical structure and different spatial arrangements of coral, findings obtained from an isolated habitat cannot necessarily be applied to fish assemblages in other habitats (e.g. continuous habitats). The aim of this study, therefore, was to determine by a field experiment whether habitat connectivity (spatial arrangement of coral colonies) affects abundance and species richness of fishes in an Okinawan coral reef. The experiment consisted of transplanted branching coral colonies at a 4m×8m quadrat at both a rocky reef flat and sandy sea bottom. Generally, the abundance of fishes was greater at the sandy sea bottom, especially for three species of pomacentrids, one species of labrids, one species of chaetodontids and two species of apogonids. Species–area curves showed that the species richness of fishes was significantly greater in the quadrat at the sandy sea bottom at 3, 6 and 9 months after the start of the experiment. The rate of increase in abundance of fishes per area was significantly greater in the quadrat at the sandy sea bottom over the study period. The results of rarefaction analyses showed that the rate of increase in species richness per abundance was significantly higher in the quadrat at the sandy sea bottom in the juvenile settlement period, indicating that the magnitude of dominance by particular species was greater at the sandy sea bottom habitat. Our findings suggest that habitat connectivity affects the abundance and species richness of coral reef fishes, i.e. the isolated habitat was significantly more attractive for fishes than was the continuous habitat. Our findings also suggest that the main ecological factors responsible for organization of fish assemblage at a continuous habitat and at an isolated habitat are different.     

Detachment of Porites cylindrica nubbins by herbivorous fishes

A form of active restoration for coral assemblages involves culturing coral nubbins at nursery sites before transplantation to recipient reefs. Incidental grazing and/or directed predation by local fish assemblages are major sources of dislodgement and mortality for coral nubbins in nurseries. However, the rate of coral nubbin detachment, how this varies across fish taxa, and whether nubbin size affects rates of detachment warrant further investigation. We used field and aquaria experiments to examine the effect of incidental grazing and predation on the detachment of Porites cylindrica nubbins of different sizes (0.5, 1, 2, 3, 4, and 5 cm height). Short‐term (6 hours) exposure of nubbins to local fish assemblages at Lucero Reef, northwestern Philippines, caused higher detachment (1.93% ± 0.53 SE) compared to caged controls (0.16% ± 0.16 SE), with no detectable effect of nubbin size. To identify the impact of individual fish species, nubbins were exposed to one of four locally abundant herbivorous and corallivorous fish species in aquaria for 8 hours. Nubbin detachment was greater when exposed to Chlorurus spilurus (1.20–36.2%) and Siganus fuscescens (0.00–15.0%) than Chaetodon lunulatus (0.00–4.00%) and Chaetodon kleinii (0.00–1.20%), with the smallest nubbins (0.5 cm) being the most vulnerable. Our results suggest that incidental grazing by herbivorous fishes, especially parrotfishes, may potentially be an important source of detachment and likely mortality of nubbins. Optimizing coral nursery protocols should consider potential trade‐offs between excluding grazing fishes and the accumulation of algal material on caging structures to minimize nubbin mortality and improve coral restoration success.     

The contribution of small individuals to density-body size relationships: examination of energetic equivalence in reef fishes

A key relationship in ecology is that between density and body size, with the emphasis placed on energetic rules constraining the abundance of larger organisms below that of smaller organisms. Most studies have focused upon the density-body size relationship at the species level. However, energy is gathered at an individual level. We therefore examined this relationship in a coral reef fish assemblage, focusing on individuals. Using a comprehensive data set, with over 14,000 observations we found that the relationship between local density and adult body size differs from the linear relationship predicted by the energetic equivalence rule. However, excluding the smallest size classes, the relationship between body size and individual abundance for intermediate to larger fish did not depart from the predicted –0.75. Unlike plants and intermediate to large reef fishes, the smallest fishes appear to have constraints that may reflect different patterns of resource acquisition.     

Depth-Variable Settlement Patterns and Predation Influence on Newly Settled Reef Fishes (Haemulon spp., Haemulidae)

During early demersal ontogeny, many marine fishes display complex habitat-use patterns. Grunts of the speciose genus Haemulon are among the most abundant fishes on western North Atlantic coral reefs, with most species settling to shallow habitats (≤12 m). To gain understanding into cross-shelf distributional patterns exhibited by newly settled stages of grunts (<2 cm total length), we examined: 1) depth-specific distributions of congeners at settlement among sites at 8 m, 12 m, and 21 m, and 2) depth-variable predation pressure on newly settled individuals (species pooled). Of the six species identified from collections of newly settled specimens (n = 2125), Haemulon aurolineatum (tomtate), H. flavolineatum (French grunt), and H. striatum (striped grunt) comprised 98% of the total abundance; with the first two species present at all sites. Prevalence of H. aurolineatum and H. flavolineatum decreased substantially from the 8-m site to the two deeper sites. In contrast, H. striatum was absent from the 8-m site and exhibited its highest frequency at the 21-m site. Comparison of newly settled grunt delta density for all species on caged (predator exclusion) and control artificial reefs at the shallowest site (8-m) revealed no difference, while the 12-m and 21-m sites exhibited significantly greater delta densities on the caged treatment. This result, along with significantly higher abundances of co-occurring piscivorous fishes at the deeper sites, indicated lower predation pressure at the 8-m site. This study suggests habitat-use patterns of newly settled stages of some coral reef fishes that undergo ontogenetic shifts are a function of depth-variable predation pressure while, for at least one deeper-water species, proximity to adult habitat appears to be an important factor affecting settlement distribution.     

Brown-band syndrome on feeding scars of the crown-of-thorn starfish Acanthaster?planci

Despite the growing impact of coral diseases on reef ecosystems, little is known about the role of coral predation in disease transmission. An experiment on the coral reefs of Derawan Island, Indonesia, revealed brown-band syndrome on Acropora cytherea coral colonies following predation by the crown-of-thorn starfish Acanthaster planci. To experimentally exclude predation, living coral tissue adjacent to feeding scars was enclosed using cages and monitored for 15 days. Compared with similarly caged but uninjured colonies, which showed no sign of disease or tissue loss, preyed upon colonies showed a higher incidence of the disease, coupled with further tissue mortality. This study provides preliminary evidence that A. planci might promote the transmission of some coral diseases.     

Growth of reef fishes in response to live coral cover

Although the global decline in coral reef health is likely to have profound effects on reef associated fishes, these effects are poorly understood. While declining coral cover can reduce the abundance of reef fishes through direct effects on recruitment and/or mortality, recent evidence suggests that individuals may survive in disturbed habitats, but may experience sublethal reductions in their condition. This study examined the response of 2 coral associated damselfishes (Pomacentridae), Chrysiptera parasema and Dascyllus melanurus, to varying levels of live coral cover. Growth, persistence, and the condition of individuals were quantified on replicate coral colonies in 3 coral treatments: 100% live coral (control), 50% live coral (partial) and 0% live coral (dead). The growth rates of both species were directly related to the percentage live coral cover, with individuals associated with dead corals exhibiting the slowest growth, and highest growth on control corals. Such differences in individual growth between treatments were apparent after 29 d. There was no significant difference in the numbers of fishes persisting or the physiological condition of individuals between different treatments on this time-scale. Slower growth in disturbed habitats will delay the onset of maturity, reduce lifetime fecundity and increase individual's vulnerability to gape-limited predation. Hence, immediate effects on recruitment and survival may underestimate the longer-term impacts of declining coral on the structure and diversity of coral-associated reef fish communities.     

Using passive acoustic telemetry to infer mortality events in adult herbivorous coral reef fishes

Mortality is considered to be an important factor shaping the structure of coral reef fish communities, but data on the rate and nature of mortality of adult coral reef fishes are sparse. Mortality on coral reefs is intrinsically linked with predation, with most evidence suggesting that predation is highest during crepuscular periods. We tested this hypothesis using passive acoustic telemetry data to determine the time of day of potential mortality events (PMEs) of adult herbivorous reef fishes. A total of 94 fishes were tagged with acoustic transmitters, of which 43 exhibited a PME. Furthermore, we identified five categories of PMEs based on the nature of change in acoustic signal detections from tagged fishes. The majority of PMEs were characterised by an abrupt stop in detections, possibly as a result of a large, mobile predator. Overall, mortality rates were estimated to be approximately 59 % per year using passive acoustic telemetry. The time of day of PMEs suggests that predation was highest during the day and crepuscular periods and lowest at night, offering only partial support for the crepuscular predation hypothesis. Visually oriented, diurnal and crepuscular predators appear to be more important than their nocturnal counterparts in terms of predation on adult reef fishes. By timing PMEs, passive acoustic telemetry may offer an important new tool for investigating the nature of predation on coral reefs.     

Coral reef fish assemblages: intra- and interspecific competition for shelter sites

Synopsis Observations were made on intra- and interspecific aggressive interactions among the fishes living in the rubble/sand coral reef habitat in St. Croix, U. S. Virgin Islands. Four species (beaugregory — Stegastes leucostictus; ocean surgeonfish — Acanthurus bahianus; doctor fish — A. chirurgus; common squirrelfish — Holocentrus rufus) which sheltered in holes on the reef all actively defended one to several shelter sites at dusk. Short-term shelter side fidelity was observed in three of these four species. Agonistic interactions over both food and shelter occurred during the daytime but much less frequently than agonistic interactions over shelter at dusk. Dominance in intraspecific aggression was determined almost completely by the relative sizes of the individuals involved, with the larger individuals dominating in 95–98% of all encounters. A similar, but less strong, relationship between size and dominance existed for interactions between closely related species. For aggressive encounters between unrelated species, however, both relative sizes and species identity determined the outcome. Species, both diurnal and nocturnal, which strongly defend several shelter sites may have a strong and disproportionate impact on the sheltering behavior of other fishes. Intraspecific and interspecific defense of shelter sites may determine the patterns of mortality that result from predation, thereby influencing population abundances and assemblage composition.     

The role of herbivorous fishes and urchins in coral reef communities

Synopsis Herbivorous fishes and invertebrates are conspicious elements of coral reef communities where they predominate both in numbers and biomass. Herbivores and the coral reef algae on which they feed represent a co-evolved system of defense and counter-defense. Algal species have developed toxic, structural, spatial and temporal defense or escape mechanisms, while the herbivores employ strategies that involve anatomical, physiological and behavioral adaptations. Current research demonstrates that many reef fishes are highly selective in the algae they consume. Food selection in these fishes may be correlated with their morphological and digestive capabilities to rupture algal cell walls. Sea urchins select more in accordance with relative abundance, although certain algal species are clearly avoided.The determinants of community structure on coral reefs have yet to be established but evidence indicates a strong influence by herbivores. Reef herbivores may reduce the abundance of certain competitively superior algae, thus allowing corals and cementing coralline algae to survive. We discuss how the foraging activities of tropical marine herbivores affect the distribution and abundance of algae and how these activities contribute to the development of coral reef structure and the fish assemblages which are intimately associated with reef structure.This paper forms a part of the proceedings of a mini-symposium convened at Cornell University, Ithaca, N.Y., 18–19 May 1976, entitled Patterns of Community Structure in Fishes (G. S. Helfman, ed.).     

Movements of Fishes Within and Among Fringing Coral Reefs in Barbados

Movement of coral reef fishes across marine reserve boundaries subsequent to their initial settlement from the plankton will affect the ability of no-take reserves to conserve stocks and to benefit adjacent fisheries. However, the mobility of most exploited reef species is poorly known. We tagged 1443 individuals of 35 reef fish species captured in Antillean fish traps in the Barbados Marine Reserve and adjacent non-reserve over a two-month period. Trapping and visual surveys were used to monitor the movements of these fish during the trapping period and the subsequent two months. Estimates of distances moved were corrected for the spatial distribution of sampling effort and for the number of recaptures of individual fish. Recapture rates for individual species ranged from 0–100% (median=38%). Species mobility estimated by recapture and resighting were highly correlated. Most species were strongly site attached, with the majority of recaptures and resightings occurring at the site of tagging. However, only one of 59 tagged jacks (Caranx latus, C. ruber) was ever resighted, suggesting emigration from the study area. All species were occasionally recorded away from the sites where they had been tagged (20–500m), and several species, including surgeonfish, Acanthurus bahianus, A. coeruleus, filefish, Cantherhines pullus, butterflyfish, Chaetodon striatus, angelfish Holocanthus tricolor and parrotfish, Sparisoma viride, ranged widely within reefs. In contrast, few movements were observed between reefs separated by more than 20m of sand and rubble, and no emigration from the Reserve was recorded. Most reef fishes vulnerable to Antillean traps appear sufficiently site-attached to benefit from reserves. However, many species move over a wide enough area to take them out of small reserves on continuous reef. Use of natural home range boundaries could minimize exposure of fishes in reserves to mortality from adjacent fisheries.     

Population Dynamics and Spatial Distribution of Coral Reef Fishes: Comparison Between Continuous and Isolated Habitats

Recent studies have shown that there are high degrees of spatial and temporal stability in coral reef fish assemblage structures in a continuous habitat, in contrast to results of observations in isolated habitats. In order to determine the reason for the difference in temporal stability of fish assemblage structures in a continuous habitat site and an isolated habitat site, population dynamics and spatial distributions of coral reef fishes (six species of pomacentrids and two species of apogonids) in the two habitat site were investigated over a 2-year period in an Okinawan coral reef. The population densities of pomacentrid and apogonid species increased in juvenile settlement periods at both sites, but the magnitude of seasonal fluctuation in population density was significantly greater at the isolated habitat site, indicating that the rate of juvenile settlement and mortality rate in the isolated habitat were greater than those in the continuous habitat. The magnitude of aggregation of fishes, which affects density-dependent biological interactions that modify population density such as competition and predation, was also significantly greater at the isolated habitat site, especially in the juvenile settlement season. Most of the fishes at the isolated habitat site exhibited more generalized patterns of microhabitat selection because of less coral coverage and diversity. The seasonal stability in the species composition of fishes was greater at the continuous habitat site than that at the isolated habitat. Our findings suggest that the relative importance of various ecological factors responsible for regulation of the population density of coral reef fishes (e.g., competition, predation, microhabitat selection and post-settlement movement) in a continuous habitat site and the isolated habitat site are different.     

A field study of fish predation on juvenile crown-of-thorns starfish

To test whether commercially exploited fishes could regulate populations of crown-of-thorns starfish, laboratory reared juvenile Acanthaster planci were planced on small habitat units in an area of a lagoon where a number of species of fish that feed on benthic invertebrates occurred. Predators were excluded from half the units using wire mesh. In 35 days, losses were low and there was no statistically significant difference between caged and uncaged units. A difference in mortality rate of 1% of individuals per day would have been detected with >85% probability.However, the observed mean difference, the maximum estimate of predatory mortality, was 0.13% of starfish per day. It thus seems unlikely that predation by any large fishes was important in the population dynamics of juvenile A. planci at that site at the time of this experiment. Juvenile starfish were presented to lethrinids in the field at two reefs. Thirteen percent of juvenile A. planci presented at one reef were eaten, but in no presentation did lethrinids eat all the available starfish and those that were eaten were often mouthed and rejected by several fish before being swallowed. No juveniles were taken in a smaller number of trials at the second reef. These results do not favour the hypothesis that predation on juveniles by large fish is important in the population dynamics of A. planci but experiments at more sites will be required before this conclusion can be generalized.     

Stock Structure, Mortality and Growth of The Decorated Goby, Istigobius decoratus (Gobiidae), at Lizard Island, Great Barrier Reef

Gobiids are an abundant component of coral reef ichthyofauna, yet little is known of their life histories. I examined population structure, mortality and growth of the decorated goby, Istigobius decoratus, a common gobiid of shallow patch reefs on the Great Barrier Reef. Presumed daily increments in sagittal otoliths were used as a proxy for age. The upper age estimate was 266 days suggesting at most an annual life cycle. Instantaneous natural mortality rate estimates were 5.92 year^–1 and 7.92 year^–1 using two estimators, both corresponding to less than 1% annual survivorship. Specimens ranged from 12 to 84 mm total length. Analysis of size-at-age data indicated linear growth at a rate of 0.33 mm day^–1. The linear relationship between size and age meant the population size structure mirrored the age structure with both skewed toward the smallest and youngest classes. High mortality over a 1-year longevity and linear growth suggest high population turnover and, therefore, that I. decoratus and ecologically similar species serve a potentially important role as prey species. This suite of traits is rarely reported for coral reef fishes, which is probably due to the limited attention paid to small-bodied species rather than the rarity of such a life history in these communities.     

Caging experiment to examine mortality during metamorphosis of coral reef fish larvae

All previous attempts to estimate early postsettlement mortality of coral reef fishes using either caging experiments or disappearance of new recruits have examined fish that had already settled, and therefore did not include the metamorphosis process. Crest nets capture unharmed transparent larvae during their migration from the open ocean to lagoon reefs before metamorphosis. We released these presettlement larvae at night into cages surrounding patch reefs and measured larval survivorship after two nights. This caging experiment involved cages enclosing the natural resident fish fauna, including predators, and others cleared of fish before releasing the larvae. The analyses of variance showed that (1) there was no difference in survivorship between the seven trials, (2) there was a significant difference between cleared and uncleared cages, and (3) there were significant differences between larval species tested. For the seven species that had a significant difference in survivorship between cleared and uncleared cages, average mortality of the larvae was 14% (range 0-26%) in cleared cages and 67% (range 29-76%) in cages with predators. The difference in mortality between species was related to the size of the larvae, as larger species exhibited reduced mortality compared to smaller species. Mortality was related to the abundance of resident fish that could act as predators or competitors. Predation can have a significant impact on the survival of metamorphosing fish larvae on coral reefs.     

Fish Colonization of an Artificial Reef in the Gulf of Elat, Northern Red Sea

A small near shore artificial reef was constructed in the Gulf of Elat, northern Red Sea at a depth of 22–24m. The colonization of fishes was monitored for a period of 728 days and a total of 94 species was recorded. Colonization was initially rapid. The first species to appear were Dascyllus trimaculatus and Chaetodon paucifasciatus (day 2). In the first seven months, a gradual increase in the number of species was observed, after which it leveled off. Subsequently, a reduction in the number of individuals increased diversity of the community, as measured by the Shannon & Weaver index. The low complexity of the major components of the artificial reef, in addition to its location on a muddy, silty substrate, resulted in a constant cover of fine grain particles which presumably discouraged settlement of invertebrates and small cryptic fish species on the artificial reef.     

Fatty acid composition indicating diverse habitat use in coral reef fishes in the Malaysian South China Sea

Background

In order to understand feeding ecology and habitat use of coral reef fish, fatty acid composition was examined in five coral reef fishes, Thalassoma lunare, Lutjanus lutjanus, Abudefduf bengalensis, Scarus rivulatus and Scolopsis affinis collected in the Bidong Island of Malaysian South China Sea.

Results

Proportions of saturated fatty acids (SAFA) ranged 57.2% 74.2%, with the highest proportions in fatty acids, the second highest was monounsaturated fatty acids (MUFA) ranged from 21.4% to 39.0% and the proportion of polyunsaturated fatty acids (PUFA) was the lowest ranged from 2.8% to 14.1%. Each fatty acid composition differed among fishes, suggesting diverse feeding ecology, habitat use and migration during the fishes’ life history in the coral reef habitats.

Conclusions

Diets of the coral fish species might vary among species in spite of that each species are living sympatrically. Differences in fatty acid profiles might not just be considered with respect to the diets, but might be based on the habitat and migration.     

Coral and Fish Biocoenosis: Ecological Cells Gradually Maturing in Complexity, Species Composition and Energy Turnover

Long-term observations on coral units and their coral fishes, as well as observations on the growth of colonies of marked corals in the Gulf of Aqaba (Red Sea), have revealed the relationship between coral dimension and complexity and the ecomorphology and sociobiology of the inhabiting fishes. In this study, coral fishes are identified as species that, following the planktonic interval, settle and remain in a selected coral or its immediate vicinity. Parallel with growth of the refuge, the number of fishes in such a coral–fish association (=ecological cell) increases to a certain asymptote, forming a stable symbiotic entity of fish species, specific in composition and biomass. The initial cell begins with 4–5-year-old branching corals that harbors 3–4 cryptic species of gobies (Paragobiodon and Gobiodon species). This is followed by several stages of coral growth and increase in fish species and biomass, especially of pomacentrids, anthiases, pseudochromids and blennies. The water column or functional space from which the fishes harvest plankton, their main food source, starts at around a 0.2m³ column in the young colonies, and ends with a water column of around 500m³ in the mature ecological cells of large coral knolls. At the mature stage, large cells harbor up to 100 diurnal and nocturnal species of fish, permanently using this refuge and forming an integrated collective. The territorial limits of the piscivorous groupers (Cephalopholis species) generally establish the dimensions of these ecological cells. Preliminary data on standard energy metabolism of the fishes for mature ecological cells reveal that 800kg food is required each year to maintain this biomass. The biological composition and stability of fish populations of such ecological cells will depend on the biological and physical stability of the host coral population.     

Interactive effects of three pervasive marine stressors in a post-disturbance coral reef

Ecosystems are commonly affected by natural, episodic disturbances that can abruptly and drastically alter communities. Although it has been shown that resilient ecosystems can eventually recover to pre-disturbed states, the extent to which communities in early stages of recovery could be affected by multiple anthropogenic stressors is poorly understood. Pervasive and rising anthropogenic stressors in coastal marine systems that could interactively affect the recovery of these systems following natural disturbances include high sedimentation, nutrient enrichment, and overfishing. Using a 6-month field experiment, we examined the effects of all combinations of these three stressors on key functional groups in the benthic community growing on simulated, post-disturbance reef patches within a system recovering from large-scale natural disturbances (corallivorous seastar outbreak and cyclone). Our study revealed that sedimentation, nutrient enrichment, and overfishing (simulated using exclusion cages) interactively affected coral survival and algal growth, with taxon-specific effects at multiple scales. First, our treatments affected corals and algae differently, with sedimentation being more detrimental to macroalgal growth but less detrimental to coral (Porites rus) survival in caged plots, driving significant interactions between sedimentation and caging for both taxa. We also observed distinct responses between coral species and between algal functional groups, with the most extensive responses from algal turf biomass, for which sedimentation suppressed the synergistic (positive) combined effect of nutrient enrichment and caging. Our findings suggest that different combinations of ubiquitous anthropogenic stressors, related to either sea- or land-based activities, interactively influence community recovery from disturbance and may alter species compositions in the resulting community. Our findings further suggest that anthropogenic stressors could promote further degradation of coral reefs following natural disturbances by inhibiting recovery to coral-dominated states that provide vital ecosystem services to coastal populations worldwide.     

Retention of Habitat Complexity Minimizes Disassembly of Reef Fish Communities following Disturbance: A Large-Scale Natural Experiment

High biodiversity ecosystems are commonly associated with complex habitats. Coral reefs are highly diverse ecosystems, but are under increasing pressure from numerous stressors, many of which reduce live coral cover and habitat complexity with concomitant effects on other organisms such as reef fishes. While previous studies have highlighted the importance of habitat complexity in structuring reef fish communities, they employed gradient or meta-analyses which lacked a controlled experimental design over broad spatial scales to explicitly separate the influence of live coral cover from overall habitat complexity. Here a natural experiment using a long term (20 year), spatially extensive (∼115,000 kms²) dataset from the Great Barrier Reef revealed the fundamental importance of overall habitat complexity for reef fishes. Reductions of both live coral cover and habitat complexity had substantial impacts on fish communities compared to relatively minor impacts after major reductions in coral cover but not habitat complexity. Where habitat complexity was substantially reduced, species abundances broadly declined and a far greater number of fish species were locally extirpated, including economically important fishes. This resulted in decreased species richness and a loss of diversity within functional groups. Our results suggest that the retention of habitat complexity following disturbances can ameliorate the impacts of coral declines on reef fishes, so preserving their capacity to perform important functional roles essential to reef resilience. These results add to a growing body of evidence about the importance of habitat complexity for reef fishes, and represent the first large-scale examination of this question on the Great Barrier Reef.