Habitat degradation drives increased gnathiid isopod ectoparasite infection rate on juvenile but not adult fish

Widespread coral mortality is leading to coral reef degradation worldwide. Many juvenile reef fishes settle on live coral, and their predator-avoidance behaviour is disrupted in seawater exposed to dead corals, ultimately increasing predation risk. Gnathiid isopods are micropredatory fish ectoparasites that occur in higher abundances in dead coral. However, the effect of seawater associated with dead coral on the susceptibility of fish to micropredators has never been investigated. We tested whether the infection rate of cultured gnathiid ectoparasites on individual damselfish, Pomacentrus amboinensis Bleeker 1868, from two different ontogenetic stages (juveniles and adults) was influenced by seawater exposed to three different treatments: dead coral, live coral, or no coral. Seawater treatments were presumed to contain different chemical properties and are meant to represent environmental changes associated with habitat degradation on coral reefs. Gnathiid infection of juvenile fish in seawater exposed to dead coral was twice as high as that of fish in live coral or no coral. Infection rates did not significantly differ between live coral and no coral treatments. In contrast to juveniles, the susceptibility of adults to gnathiids was not affected by seawater treatment. During experiments, juvenile fish mortality was relatively low, but was higher for infected fish (9.7%), compared to fish held without exposure to gnathiids (1.7%). No mortality occurred in adult fish that became infected with gnathiids. Our results suggest that chemical cues released from dead corals and/or dead coral colonisers affect the ability of juvenile, but not adult fish to avoid parasite infection. Considering increased habitat degradation on coral reefs and that gnathiids are more abundant in dead coral substrate, it is possible that wild juvenile fish may experience increased susceptibility to parasitic infection and reduced survival rate. This highlights the importance of including parasitism in ecological studies of global environmental change.

     

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.     

Habitat choice,recruitment and the response of coral reef fishes to coral degradation

The global degradation of coral reefs is having profound effects on the structure and species richness of associated reef fish assemblages. Historically, variation in the composition of fish communities has largely been attributed to factors affecting settlement of reef fish larvae. However, the mechanisms that determine how fish settlers respond to different stages of coral stress and the extent of coral loss on fish settlement are poorly understood. Here, we examined the effects of habitat degradation on fish settlement using a two-stage experimental approach. First, we employed laboratory choice experiments to test how settlers responded to early and terminal stages of coral degradation. We then quantified the settlement response of the whole reef fish assemblage in a field perturbation experiment. The laboratory choice experiments tested how juveniles from nine common Indo-Pacific fishes chose among live colonies, partially degraded colonies, and dead colonies with recent algal growth. Many species did not distinguish between live and partially degraded colonies, suggesting settlement patterns are resilient to the early stages of declining coral health. Several species preferred live or degraded corals, and none preferred to associate with dead, algal-covered colonies. In the field experiment, fish recruitment to coral colonies was monitored before and after the introduction of a coral predator (the crown-of-thorns starfish) and compared with undisturbed control colonies. Starfish reduced live coral cover by 95–100%, causing persistent negative effects on the recruitment of coral-associated fishes. Rapid reductions in new recruit abundance, greater numbers of unoccupied colonies and a shift in the recruit community structure from one dominated by coral-associated fishes before degradation to one predominantly composed of algal-associated fish species were observed. Our results suggest that while resistant to coral stress, coral death alters the process of replenishment of coral reef fish communities.     

High macroalgal cover and low coral recruitment undermines the potential resilience of the world's southernmost coral reef assemblages

Coral reefs are under increasing pressure from anthropogenic and climate-induced stressors. The ability of reefs to reassemble and regenerate after disturbances (i.e., resilience) is largely dependent on the capacity of herbivores to prevent macroalgal expansion, and the replenishment of coral populations through larval recruitment. Currently there is a paucity of this information for higher latitude, subtropical reefs. To assess the potential resilience of the benthic reef assemblages of Lord Howe Island (31°32'S, 159°04'E), the worlds' southernmost coral reef, we quantified the benthic composition, densities of juvenile corals (as a proxy for coral recruitment), and herbivorous fish communities. Despite some variation among habitats and sites, benthic communities were dominated by live scleractinian corals (mean cover 37.4%) and fleshy macroalgae (20.9%). Live coral cover was higher than in most other subtropical reefs and directly comparable to lower latitude tropical reefs. Juvenile coral densities (0.8 ind.m(-2)), however, were 5-200 times lower than those reported for tropical reefs. Overall, macroalgal cover was negatively related to the cover of live coral and the density of juvenile corals, but displayed no relationship with herbivorous fish biomass. The biomass of herbivorous fishes was relatively low (204 kg.ha(-1)), and in marked contrast to tropical reefs was dominated by macroalgal browsing species (84.1%) with relatively few grazing species. Despite their extremely low biomass, grazing fishes were positively related to both the density of juvenile corals and the cover of bare substrata, suggesting that they may enhance the recruitment of corals through the provision of suitable settlement sites. Although Lord Howe Islands' reefs are currently coral-dominated, the high macroalgal cover, coupled with limited coral recruitment and low coral growth rates suggest these reefs may be extremely susceptible to future disturbances.     

Interactions between coral restoration and fish assemblages: implications for reef management

Corals create complex reef structures that provide both habitat and food for many fish species. Because of numerous natural and anthropogenic threats, many coral reefs are currently being degraded, endangering the fish assemblages they support. Coral reef restoration, an active ecological management tool, may help reverse some of the current trends in reef degradation through the transplantation of stony corals. Although restoration techniques have been extensively reviewed in relation to coral survival, our understanding of the effects of adding live coral cover and complexity on fishes is in its infancy with a lack of scientifically validated research. This study reviews the limited data on reef restoration and fish assemblages, and complements this with the more extensive understanding of complex interactions between natural reefs and fishes and how this might inform restoration efforts. It also discusses which key fish species or functional groups may promote, facilitate or inhibit restoration efforts and, in turn, how restoration efforts can be optimised to enhance coral fish assemblages. By highlighting critical knowledge gaps in relation to fishes and restoration interactions, the study aims to stimulate research into the role of reef fishes in restoration projects. A greater understanding of the functional roles of reef fishes would also help inform whether restoration projects can return fish assemblages to their natural compositions or whether alternative species compositions develop, and over what timeframe. Although alleviation of local and global reef stressors remains a priority, reef restoration is an important tool; an increased understanding of the interactions between replanted corals and the fishes they support is critical for ensuring its success for people and nature.     

Maintenance of fish diversity on disturbed coral reefs

Habitat perturbations play a major role in shaping community structure; however, the elements of disturbance-related habitat change that affect diversity are not always apparent. This study examined the effects of habitat disturbances on species richness of coral reef fish assemblages using annual surveys of habitat and 210 fish species from 10 reefs on the Great Barrier Reef (GBR). Over a period of 11 years, major disturbances, including localised outbreaks of crown-of-thorns sea star (Acanthaster planci), severe storms or coral bleaching, resulted in coral decline of 46–96% in all the 10 reefs. Despite declines in coral cover, structural complexity of the reef framework was retained on five and species richness of coral reef fishes maintained on nine of the disturbed reefs. Extensive loss of coral resulted in localised declines of highly specialised coral-dependent species, but this loss of diversity was more than compensated for by increases in the number of species that feed on the epilithic algal matrix (EAM). A unimodal relationship between areal coral cover and species richness indicated species richness was greatest at approximately 20% coral cover declining by 3–4 species (6–8% of average richness) at higher and lower coral cover. Results revealed that declines in coral cover on reefs may have limited short-term impact on the diversity of coral reef fishes, though there may be fundamental changes in the community structure of fishes.     

On the evolution of fish–coral interactions

The biodiversity of tropical reefs is typified by the interaction between fishes and corals. Despite the importance of this ecological association, coevolutionary patterns between these two animal groups have yet to be critically evaluated. After compiling a large dataset on the prevalence of fish–coral interactions, we found that only a minority of fish species associate strongly with live corals (~5%). Furthermore, we reveal an evolutionary decoupling between fish and coral lineage trajectories. While fish lineages expanded in the Miocene, the bulk of coral diversification occurred in the Pliocene/Pleistocene. Most importantly, we found that coral association did not drive major differences in fish diversification. These results suggest that the Miocene fish diversification is more likely related to the development of novel, wave-resistant reef structures and their associated ecological opportunities. Macroevolutionary patterns in reef fishes are thus more strongly correlated with the expansion of reefs than with the corals themselves.     

Live coral repels a common reef fish ectoparasite

Coral reefs are undergoing rapid changes as living corals give way to dead coral on which other benthic organisms grow. This decline in live coral could influence habitat availability for fish parasites with benthic life stages. Gnathiid isopod larvae live in the substratum and are common blood-feeding parasites of reef fishes. We examined substrate associations and preferences of a common Caribbean gnathiid, Gnathia marleyi. Emergence traps set over predominantly live coral substrata captured significantly fewer gnathiids than traps set over dead coral substrata. In laboratory experiments, gnathiids preferred dead coral and sponge and tended to avoid contact with live coral. When live gnathiids were added to containers with dead or live coral, significantly fewer were recovered from the latter after 24 h. Our data therefore suggest that live coral is not suitable microhabitat for parasitic gnathiid isopods and that a decrease in live coral cover increases available habitat for gnathiids.     

Species composition,habitat configuration and seasonal changes of coral reef fish assemblages in western Mexico

In spite of their ecological and economic importance, reef fishes from the coast of Oaxaca, Mexico are rarely studied, therefore precluding their management and conservation. In order to identify the set of habitat characteristics/environmental conditions that predict major shifts in fish assemblages in space and time, a stationary census (5′, φ = 5 m) was conducted on a semi‐monthly basis from 2006 to 2009 at patch reefs along the coast. Habitat configuration was gathered using 25 m long point‐intersect transects (data every 25 cm), recording all underlying coral species and substrate characteristics (rocks, sand, algal mats, rubble or dead corals). Recorded were 65 452 fishes grouped in 11 orders, 36 families, 65 genera and 89 species. Labridae (nine species), Pomacentridae (eight species) and Serranidae (seven species) were the most frequent families. Abundance is severely skewed among species; four species Thalassoma lucasanum, Chromis atrilobata, Apogon pacificus and Stegastes acapulcoensis comprise nearly 59% of the fish abundance, 11 species contribute 30%, whereas most of the species (75) can be considered as rare since they contribute <1% each to the total. Species richness and family‐level assemblage composition are similar to those recorded elsewhere in the eastern Pacific. Non‐parametric multivariate analysis of variance demonstrated that changes of diversity metrics might be associated with environmental differences on the scale of hundreds of meters to kilometers, as well as coupled with major changes on oceanographic variables throughout time, exerting meaningful changes on reef‐related fish assemblages.     

Relationships between habitat structure and fish communities on coral

The influence of habitat structure on reef-fish communities at Bar Reef Marine Sanctuary, Sri Lanka, was investigated. The relationship between habitat characteristics and the distribution and abundance of 135 species of fishes was examined on two reef types: coral and sandstone reefs. Results suggested that the reef-fish communities were strongly influenced by various aspects of reef structure. However, relationships between habitat variables and fish communities structure, varied between the two reef types. Fish species diversity was correlated with a number of habitat variables on the sandstone reefs, although structural complexity seemed to play the dominant role. There were no correlations between habitat structure and fish diversity on the coral reefs. Total abundance was not related to any one habitat parameter on either reef type. However, abundances of some species, families and trophic groups were correlated with habitat features. These specific correlations were commonly related to food or shelter availability. For example, coral feeders were correlated with live coral cover, and pomacentrid species, which used branching corals for protection, showed a significant relationship with the density of Acropora colonies. This shows that a summary statistic such as total abundance may hide important information. Effects of habitat structure on the distribution patterns of the fish communities was further investigated using multi-dimensional scaling ordination (MDS) and the RELATE-procedure. With the MDS ordinations for both habitat and fish-community composition it was possible to show that the multivariate pattern between the two ecological components was clearly correlated.     

Community structure and biogeography of shore fishes in the Gulf of Aqaba,Red Sea

Shore fish community structure off the Jordanian Red Sea coast was determined on fringing coral reefs and in a seagrass-dominated bay at 6 m and 12 m depths. A total of 198 fish species belonging to 121 genera and 43 families was recorded. Labridae and Pomacentridae dominated the ichthyofauna in terms of species richness and Pomacentridae were most abundant. Neither diversity nor species richness was correlated to depth. The abundance of fishes was higher at the deep reef slope, due to schooling planktivorous fishes. At 12 m depth abundance of fishes at the seagrass-dominated site was higher than on the coral reefs. Multivariate analysis demonstrated a strong influence on the fish assemblages by depth and benthic habitat. Fish species richness was positively correlated with hard substrate cover and habitat diversity. Abundance of corallivores was positively linked with live hard coral cover. The assemblages of fishes were different on the shallow reef slope, deep reef slope and seagrass meadows. An analysis of the fish fauna showed that the Gulf of Aqaba harbours a higher species richness than previously reported. The comparison with fish communities on other reefs around the Arabian Peninsula and Indian Ocean supported the recognition of an Arabian subprovince within the Indian Ocean. The affinity of the Arabian Gulf ichthyofauna to the Red Sea is not clear. Received in revised form: 2 November 2001 Electronic Publication     

Influence of habitat degradation on fish replenishment

Temperature-induced coral bleaching is a major threat to the biodiversity of coral reef ecosystems. While reductions in species diversity and abundance of fish communities have been documented following coral bleaching, the mechanisms that underlie these changes are poorly understood. The present study examined the impacts of coral bleaching on the early life-history processes of coral reef fishes. Daily monitoring of fish settlement patterns found that ten times as many fish settled to healthy coral than sub-lethally bleached coral. Species diversity of settling fishes was least on bleached coral and greatest on dead coral, with healthy coral having intermediate levels of diversity. Laboratory experiments using light-trap caught juveniles showed that different damselfish species chose among healthy, bleached and dead coral habitats using different combinations of visual and olfactory cues. The live coral specialist, Pomacentrus moluccensis, preferred live coral and avoided bleached and dead coral, using mostly visual cues to inform their habitat choice. The habitat generalist, Pomacentrus amboinensis, also preferred live coral and avoided bleached and dead coral but selected these habitats using both visual and olfactory cues. Trials with another habitat generalist, Dischistodus sp., suggested that vision played a significant role. A 20 days field experiment that manipulated densities of P. moluccensis on healthy and bleached coral heads found an influence of fish density on juvenile weight and growth, but no significant influence of habitat quality. These results suggests that coral bleaching will affect settlement patterns and species distributions by influencing the visual and olfactory cues that reef fish larvae use to make settlement choices. Furthermore, increased fish density within the remaining healthy coral habitats could play an important role in influencing population dynamics.     

Multiscale habitat associations of detrivorous blennies (Blenniidae: Salariini)

The distribution and habitat associations of detrivorous blennies on a tropical coral reef were investigated at several spatial scales and compared with other fish that feed on the epilithic algal matrix to assess density and biomass contributions of small detrivorous fishes to these assemblages. At broad spatial scales total blenny abundance and biomass were highest on the tops of reefs exposed to prevailing winds. On the finer scale of microhabitat use, all species showed a preference for non-living corals, although the type of coral utilised differed between species. The high abundance of blennies on reef tops and non-living corals may be partially related to the quality and availability of detritus in these habitats. Comparisons of total blenny abundance and biomass with other territorial detrivores found that blennies accounted for approximately 60% of this functional group's density and 21% of their biomass on exposed reef tops. Overall, territorial detrivores were found to constitute approximately 37% of the density and 26% of the biomass of the detrivorous/herbivorous fish assemblage on exposed reef tops. Small detrivorous fish therefore represent a substantial proportion of fish assemblages that feed on epilithic algae and associated detritus on coral reefs.     

Otolith growth of Springer's demoiselle, Chrysiptera springeri (Pomacentridae, Allen & Lubbock), on a protected and non-protected coral reef

The structural complexity of coral reefs is important for their function as shelter and feeding habitats for coral reef fishes, but physical disturbance by human activities often reduce complexity of the reefs by selectively destroying fragile and more complex coral species. The damselfish Springer's demoiselle Chrysiptera springeri primarily utilize complex coral heads for shelter and are hence vulnerable to human disturbance. In order to evaluate the potential effect of habitat degradation on juvenile fish growth, coral reef cover, fish age at settling and otolith growth, juvenile Springer's demoiselle was investigated on a protected and non‐protected coral reef in Darvel Bay, Borneo. The protected reef had higher coverage of complex branching corals and exhibited a more complex 3‐dimensional structure than the non‐protected reef. Springer's demoiselle settled at the same age on non‐protected and protected reefs. The growth rates of the otoliths from Springer's demoiselle were similar during the pre‐settlement period on the two reefs (manova , P > 0.05), but from age 20 to 48 days (post‐settlement period) the otolith growth rate of juveniles on the non‐protected reef was reduced compared to those from the protected reef (manova , P = 0.017). However, the differences in the otolith size, and by inference, fish size, after 48 days were small. The small effect of habitat degradation on growth is likely related to the fact that the Springer's demoiselles collected on the non‐protected reef were associated with the few remaining complex coral heads. Increased foraging‐predation tradeoffs on the non‐protected reef may decrease food intake and growth of juvenile Springer's demoiselle, but the main effect of habitat degradation on their abundance is likely to be related to lack of suitable shelter, and consequently reduced carrying capacity, on disturbed reefs.     

Suspended sediment impairs habitat choice and chemosensory discrimination in two coral reef fishes

Increasing sediment onto coral reefs has been identified as a major source of habitat degradation, and yet little is known about how it affects reef fishes. In this study, we tested the hypothesis that sediment-enriched water impairs the ability of larval damselfish to find suitable settlement sites. At three different experimental concentrations of suspended sediment (45, 90, and 180 mg l⁻¹), pre-settlement individuals of two species (Pomacentrus amboinensis and P. moluccensis) were not able to select their preferred habitat. In a clear water environment (no suspended sediment), both species exhibit a strong preference for live coral over partially dead and dead coral, choosing live coral 70 and 80% of the time, respectively. However, when exposed to suspended sediment, no habitat choice was observed, with individuals of both species settling on live coral, partially dead, and dead coral, at the same frequency. To determine a potential mechanism underlying these results, we tested chemosensory discrimination in sediment-enriched water. We demonstrated that sediment disrupts the ability of this species to respond to chemical cues from different substrata. That is, individuals of P. moluccensis prefer live coral to dead coral in clear water, but in sediment-enriched water, chemical cues from live and dead coral were not distinguished. These results suggest that increasing suspended sediment in coral reef environments may reduce settlement success or survival of coral reef fishes. A sediment-induced disruption of habitat choice may compound the effects of habitat loss on coral reefs.     

Spatial structure of coral reef fish communities at Kudaka Island (Ryukyu Archipelago), Japan

The present study aimed to investigate the spatial structure of fish communities at juvenile and adult stages on coral reefs at Kudaka Island (Ryukyu Archipelago, Japan) and to relate spatial patterns in the structure of the fish communities to gradients in environmental variables. Diurnal visual censuses allowed us to record 2,602 juveniles belonging to 60 species and 1,543 adults belonging to 53 species from October to December 2005. The distribution of species highlighted that the juvenile community was organised into three distinct assemblages, rather than exhibiting gradual change in community structure along the cross-reef gradient. Correlations between spatial patterns of juvenile community and environmental variables revealed that the most significant factors explaining variation in community structure were coral rubble and coral slab. In contrast, the adult community was organised into one assemblage, and the most significant variation factors in community structure were depth, live coral in massive form, live coral in branched form, dead coral and sand. Overall, the present study showed that most juvenile and adult coral reef fish at Kudaka Island exhibited striking patterns in their distribution and depth and some biological factors (e.g., abundance of live coral, dead coral and coral rubble) might exert considerable influence on the distribution of fishes.     

Non‐reef habitats in a tropical seascape affect density and biomass of fishes on coral reefs

Nonreef habitats such as mangroves, seagrass, and macroalgal beds are important for foraging, spawning, and as nursery habitat for some coral reef fishes. The spatial configuration of nonreef habitats adjacent to coral reefs can therefore have a substantial influence on the distribution and composition of reef fish. We investigate how different habitats in a tropical seascape in the Philippines influence the presence, density, and biomass of coral reef fishes to understand the relative importance of different habitats across various spatial scales. A detailed seascape map generated from satellite imagery was combined with field surveys of fish and benthic habitat on coral reefs. We then compared the relative importance of local reef (within coral reef) and adjacent habitat (habitats in the surrounding seascape) variables for coral reef fishes. Overall, adjacent habitat variables were as important as local reef variables in explaining reef fish density and biomass, despite being fewer in number in final models. For adult and juvenile wrasses (Labridae), and juveniles of some parrotfish taxa (Chlorurus), adjacent habitat was more important in explaining fish density and biomass. Notably, wrasses were positively influenced by the amount of sand and macroalgae in the adjacent seascape. Adjacent habitat metrics with the highest relative importance were sand (positive), macroalgae (positive), and mangrove habitats (negative), and fish responses to these metrics were consistent across fish groups evaluated. The 500‐m spatial scale was selected most often in models for seascape variables. Local coral reef variables with the greatest importance were percent cover of live coral (positive), sand (negative), and macroalgae (mixed). Incorporating spatial metrics that describe the surrounding seascape will capture more holistic patterns of fish–habitat relationships on reefs. This is important in regions where protection of reef fish habitat is an integral part of fisheries management but where protection of nonreef habitats is often overlooked.     

Do coral-reef fish faunas have a distinctive taxonomic structure?

Do the highly diverse fish faunas that associate with coral reefs have distinguishing taxonomic and ecological characteristics, as proposed by Choat and Bellwood (1991) and Bellwood (1996)? Does a 50?my old (Eocene) fossil fish fauna from Italy represent a coral-reef fish assemblage that provides unique information about the evolution of such assemblages, as claimed by Bellwood (1996)? I compared the structure of the reef fish faunas of adjacent tropical regions rich and poor in coral reefs, in both America and Polynesia, and found that they exhibit no substantive differences in relative species richness among families of typical “coral-reef” fishes. While coral-rich regions have larger reef fish faunas, a variety of factors probably contribute to such differences. Thus coral-reef fish faunas may lack a distinctive taxonomic structure. A similar comparative approach would be useful for assessing whether assemblages of fishes on coral reefs have distinctive ecological characteristics. Based on patterns of habitat use by modern tropical shorefishes, the Italian Eocene fauna includes few definite reef fishes, and may well consist primarily of non-reef fishes preserved in a non-reef habitat. Until we know more about the environment in which those fossils were preserved, that fauna can contribute little to understanding how coral reef fish assemblages have evolved.     

Simple ecological trade-offs give rise to emergent cross-ecosystem distributions of a coral reef fish

Ecosystems are intricately linked by the flow of organisms across their boundaries, and such connectivity can be essential to the structure and function of the linked ecosystems. For example, many coral reef fish populations are maintained by the movement of individuals from spatially segregated juvenile habitats (i.e., nurseries, such as mangroves and seagrass beds) to areas preferred by adults. It is presumed that nursery habitats provide for faster growth (higher food availability) and/or low predation risk for juveniles, but empirical data supporting this hypothesis is surprisingly lacking for coral reef fishes. Here, we investigate potential mechanisms (growth, predation risk, and reproductive investment) that give rise to the distribution patterns of a common Caribbean reef fish species, Haemulon flavolineatum (French grunt). Adults were primarily found on coral reefs, whereas juvenile fish only occurred in non-reef habitats. Contrary to our initial expectations, analysis of length-at-age revealed that growth rates were highest on coral reefs and not within nursery habitats. Survival rates in tethering trials were 0% for small juvenile fish transplanted to coral reefs and 24-47% in the nurseries. As fish grew, survival rates on coral reefs approached those in non-reef habitats (56 vs. 77-100%, respectively). As such, predation seems to be the primary factor driving across-ecosystem distributions of this fish, and thus the primary reason why mangrove and seagrass habitats function as nursery habitat. Identifying the mechanisms that lead to such distributions is critical to develop appropriate conservation initiatives, identify essential fish habitat, and predict impacts associated with environmental change.