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Coral reef communities between 26.8°N and 18.6°N latitude in the Saudi Arabian Red Sea were surveyed to provide baseline data and an assessment of fine-scale biogeography of communities in this region. Forty reefs along 1100 km of coastline were surveyed using depth-stratified visual transects of fish and benthic communities. Fish abundance and benthic cover data were analyzed using multivariate approaches to investigate whether coral reef communities differed with latitude. A total of 215 fish species and 90 benthic categories were recorded on the surveys. There were no significant differences among locations in fish abundance, species richness, or among several diversity indices. Despite known environmental gradients within the Red Sea, the communities remained surprisingly similar. The communities do, however, exhibit subtle changes across this span of reefs that likely reflect the constrained distributions of several species of reef fish and benthic fauna. [ABSTRACT FROM AUTHOR]

Abstract: A number of theories have been advanced to explain the evolution of specialists and generalists and how they coexist. According to trade-off theory, a species can improve performance by specialising on one habitat but does so at a cost of reduced performance in others. Specialists will outperform generalists in their preferred habitats but will be outperformed by generalists in other habitats. This study aimed to examine trade-offs in juvenile coral reef wrasses that vary in their degree to which they are specialised on microhabitats. We predicted that specialists would exhibit highest survival and growth on preferred habitats, and in contrast, generalists would tend to do equally well on all habitats. Furthermore, we predicted that specialists would outperform generalists on their preferred habitat, while generalists would outperform specialists on less preferred habitats. The predictions were tested by transplanting juveniles from four different species (two specialists, and two generalists) to patch reefs constructed from different kinds of microhabitats (live coral, dead coral, and rubble) and measuring growth and survival after 3weeks in Kimbe Bay, Papua New Guinea. Prior to this, the degree of specialisation was assessed using resource selection ratio-based field observations of habitat use and availability. Results provided mixed evidence for the trade-off hypothesis. Specialists conformed to predictions, while generalists did not. Specialist species showed higher survival rate on their preferred habitat than generalist species and the mean growth was significantly higher on the preferred habitat than less preferred habitats for one specialist species. However, generalist species did not survive on all reefs, regardless of microhabitat. Growth rates between habitats could therefore not be compared for generalists and the presence of a trade-off in fitness expressed in growth may have been missed for these species. It is thus premature to reject the trade-off theory, and we encourage examining a greater range of specialist and generalist species, under conditions in which the fate of all individuals can be more accurately determined. [Copyright &y& Elsevier]

A range of different biodiversity-based selection methods for nature reserves has been tested for terrestrial environments, including those based on diversity hotspots, endemicity hotspots and complementarity. In this study, we investigate the utility of these approaches for a coral reef embayment. We compare coral and fish species richness in a random accumulation of reserve sites with (a) hotspots analysis, (b) stratified selection of hotspots, and (c) complementarity. Cumulative species-site curves indicated that complementarity maximized the rate of accumulation of species of both corals and fishes in reserves, while the hotspot approach performed moderately well. An equivalent number of reserve sites supported a greater proportion of the coral biodiversity when compared to fishes, reflecting the broader distribution of corals. Our results indicate that when choosing an indicator group as a proxy for representing overall diversity in a reserve network, the group with the greatest heterogeneity will provide the best results. Our findings also show that although a modest number of protected sites (20%) will incorporate much of the local diversity (>75%), species-specific approaches must be incorporated to target rare species. [Copyright &y& Elsevier]

Abstract Artificial reefs (ARs) have been advocated and implemented as management tools for recreational fisheries, species conservation and habitat replacement. For ARs to function as substitute habitat for degraded natural reefs, they should perform as close as possible to local natural reefs, however this is seldom investigated. Here we evaluated the performance of new custom-designed reef structures (CDARs) as fish habitat. As a benchmark for their success, we compared fish abundance, diversity and community composition on CDARs to another commonly used AR type (Reef Balls (RBs)) and nearby natural reefs. Fish were monitored on all reef types over two recruitment seasons at three locations in Port Phillip Bay, Australia. Overall, there were no consistent differences in fish density among reef types, although densities on both AR designs were markedly lower than natural reefs at some locations. However, fish species richness on the CDARs was, on average, 2× higher than natural or RB reefs. There were large dissimilarities in fish community composition among reef types across all locations and years. These dissimilarities declined over time with the CDARs becoming more similar to natural communities than to RB reefs. Our results suggest that CDARs can play a role in reef fish conservation where natural reefs are under threat, supporting natural community structure and enhancing local biodiversity. Overall, our findings suggest that location of deployment, rather than design, has a more significant influence on fish abundances on ARs, whereas reef design is an important determinant of species diversity and community structure irrespective of location. ARs represent an important management tool for enhancing fisheries productivity and conservation in areas where reef habitat has been degraded or lost. However, failure to incorporate consideration of reef location and design into future AR deployments may lead to poor performance and failure to achieve restoration or conservation goals. Graphical abstract Unlabelled Image Highlights • Location of artificial reef deployment has a significant effect on fish abundance. • Artificial reef design influences fish species richness and community composition. • Community structure converges closer to natural reef with time on more complex reefs. • Trachinops caudimaculatus - major contributor to the similarity between fish communities [ABSTRACT FROM AUTHOR]

Aquatic animals commonly rely on chemical cues to provide information regarding their surroundings. They can respond either by being attracted to (potential mates, preferred habitats) or avoiding (predators, competitors) the source of the stimuli. Coral reef fishes use chemical cues to detect habitats, avoid predators and recognise conspecifics. However, the extent to which chemical cues are used to detect and respond to potential competitors, has received little attention. Here we test olfactory preferences for conspecifics and heterospecifics in newly settled juvenile coral reef fishes. Juveniles of 4 common coral-associated damselfish species: Dascyllus melanurus , Dascyllus reticulatus , Chrysiptera arnazae and Pomacentrus moluccensis, were subjected to olfactory choice tests. Three of the 4 species (excluding P. moluccensis ) demonstrated preferences for waterborne conspecifics odours. All species exhibited an avoidance towards heterospecific odours; this aversion was consistently greatest towards P. moluccensis . A neutral response toward heterospecifics was only evident in two instances (1) between the two congeneric Dascyllus species, with D. melanurus toward D. reticulatus, and (2) with C. arnazae toward D. melanurus . While it is already known that the presence of conspecifics plays a vital role in settlement site selection, we show here that the presence of heterospecifics may also be key in determining the spatial distributions of juveniles across areas of coral reef. [ABSTRACT FROM AUTHOR]

Coral reef fishes are characterised by extreme site fidelity and are often socially monogamous, forming pair bonds within larger social groups. Despite this, the strong link between reproductive behaviour and site fidelity in such social species is poorly understood. We examine these relationships in the cardinalfish Ostorhinchus cyanosoma on the central Great Barrier Reef. We tagged and followed over 100 individuals for 5 weeks to investigate pair fidelity, and behavioural differences between pairs and singles and between sexes, and we experimentally tested the strength of site and mate fidelity. Tagged pairs were typically highly site attached, and lasted throughout the study period. Sex had very little effect on pairing behaviour or habitat use. Paired individuals showed three times higher site fidelity than single ones, with singles frequently relocating. There was a two-fold increase in the movement of individuals that had their partners experimentally removed. Paired individuals exhibited greater homing success, and homed regardless of whether their mate had been displaced with them or was left on the home site. These results suggest that individuals of this species form at least seasonally stable monogamous pair bonds within larger groups, and that pair formation is closely associated with site fidelity. [ABSTRACT FROM AUTHOR]

Abstract: Coral reef fish use olfaction to respond to a variety of chemical cues that allow them to detect predators, the presence of resident conspecifics and the ‘smell’ of reef water. However, whether olfaction is utilised by juvenile reef fish for discerning among the multiple microhabitat types present on the reef is not known. Additionally the relative importance of chemical cues emitted from habitat types versus those from resident individuals to juveniles has not been assessed. The ability to distinguish and use such cues could be critical in determining spatial distributions of juveniles across coral reef areas. Here we test olfactory preferences for conspecifics, coral health and different branching coral species in newly recruited juveniles of coral reef fishes. Newly settled juveniles of three common coral associated species in Kimbe Bay, Papua New Guinea, Dascyllus melanurus, Chrysiptera parasema and Chaetodon octofasciatus, were subjected to a series of pairwise olfactory choice tests using two-channel choice flume. All three species exhibited a significant preference for the scent of conspecifics (60–70%) and live coral (60–70%) over water with no associated reef cues. All species strongly avoided the odour of degraded coral (≥80%). Only one species, D. melanurus showed olfactory discrimination among branching coral species, favouring Pocillopora damicornis over Acropora spp. Our results indicate that olfactory preferences for both conspecifics and live coral may combine to determine juvenile and recruitment distribution patterns in these species and local population declines in response to coral degradation but do not necessarily contribute to specific coral habitat associations. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Many anemone and anemonefish populations have been depleted by environmental disturbance and over-fishing. However, little is known about recovery potential of these populations, limiting the ability of resource managers to optimise recovery strategies. Depleted populations of multiple anemone and anemonefish species were monitored for ten years after commencement of a species-specific fishing moratorium at the Keppel Islands (Australia), which have recently been impacted by several environmental disturbances including flooding, mass bleaching and a cyclone. Although the moratorium was found to have positive effects on populations of Entacmaea quadricolor (anemone) and Amphiprion melanopus (anemonefish), rates of recovery were very slow, potentially due to Allee effects (depensation), reduced habitat quality, and (or) demographic constraints associated with obligate mutualism. Contemporary densities of E. quadricolor and A. melanopus appeared to be much lower than historical densities, suggesting that ten years without fishing was insufficient to facilitate population recovery in an era punctuated by environmental disturbances. Anemone and anemonefish species that were excluded from the moratorium either declined slightly in density (Amphiprion akindynos) or became so rare that they were not seen again during later surveys (Heteractis crispa and Amphiprion clarkii). We conclude that anemone and anemonefish populations can only support relatively light fishing pressure and likely require extended timeframes to recover from over-exploitation and disturbance. Strong precautionary management, including harvest limits with broad safety margins as insurance against future environmental disturbances, is therefore warranted. [ABSTRACT FROM AUTHOR]

The world's coral reefs are rapidly transforming, with decreasing coral cover and new species configurations. These new Anthropocene reefs pose a challenge for conservation; we can no longer rely on established management plans and actions designed to maintain the status quo when coral reef habitats, and the challenges they faced, were very different. The key questions now are: what do we want to conserve on Anthropocene reefs, why, and how? Trends in reef management over recent decades reveal rapid shifts in perceived threats, goals and solutions. Future reefs will be unlike anything previously seen by humans, and while their ability to support tourism or fisheries may be relatively resilient, our capacity to manage them may be constrained by their new species configurations. Furthermore, there is a growing spatial mismatch between the escalating scale of threats and current or planned responses. We present a blueprint for future reef conservation that recognizes the need to better understand the processes that maintain Anthropocene reefs, and the growing imperative to reform conservation efforts to address both specific local issues and larger-scale threats. The future of coral reef conservation is no longer one solely of localized action and stewardship; it requires practices and institutions operating at far larger scales than today. • The key questions are: what do we want to conserve on coral reefs, why and how? • We identify scale mismatches between reef stressors and proposed interventions. • Anthropocene reefs require a re-prioritization of critical functions. • The scale of institutions and governance needs to match the scale of stressors. • Cosmetic conservation will not combat the coral reef crisis. [ABSTRACT FROM AUTHOR]

Roving herbivorous fishes play an important role in coral reef communities by removing turf-algae, which can facilitate the settlement of coral larvae. Territorial damselfishes can influence the foraging patterns of roving herbivores by excluding them from their territories, altering the benthic assemblage. However, the impacts depend on the intensity of aggression and which taxonomic groups of roving herbivores are being excluded. Here we document the foraging activity of roving herbivores (Acanthuridae, Scaridae, Siganidae) and the extent to which they are subject to aggression by Pomacentrus adelus , the most abundant territorial damselfish in Kimbe Bay, Papua New Guinea. We then conducted experimental removals (220 m 2 plots on the reef flat) of P. adelus to examine its impact on roving herbivores and the benthic community structure. We hypothesized that the removal of P. adelus would lead to an increase in roving herbivore abundance and foraging activity and a decline in algal cover. The relative abundance (MaxN) and foraging activity (bite rate) of each taxa were examined pre and post-removal using video quadrats. The overall relative abundance of roving herbivores was not influenced by the removal of P. adelus . No changes in foraging patterns were observed for parrotfish, the family that received the highest rate of agonistic interactions, and rabbitfish. The removal of P. adelus resulted in a significant decrease in surgeonfish feeding, suggesting P. adelus alters foraging patterns indirectly through territorial maintenance and not aggression. The only measurable benthic impact of the P. adelus removal was an increase in sediment, while all other substratum types remained constant. These results indicate that P. adelus does not have a negative impact on all roving herbivores and instead may contribute to surgeonfish foraging indirectly through the removal of sediment. The generalisation that territorial damselfish reduce foraging rates of roving herbivores may not be applicable in all systems or for all species. [ABSTRACT FROM AUTHOR]

Abstract: Coral reef ecosystems are experiencing a global decline in coral cover, with direct effects on reef fishes. A decline in habitat may lead to crowding of live coral specialists into remnant habitat patches, intensifying intraspecific competition. Increased local densities of conspecifics are known to negatively affect key demographic processes, but the magnitude of density effects and the role of crowding in response to habitat loss are poorly understood. In this study we examined habitat use and relationships between habitat availability and population density in a coral-dwelling damselfish — Chrysiptera parasema. First, we conducted habitat use and availability surveys to establish the level of habitat selectivity. We then investigated the evidence for crowding due to habitat loss by comparing densities within juvenile aggregations on natural reefs with high and low cover of the preferred habitat. Finally, we used a manipulative patch-reef experiment to measure the potential effects of crowding on mortality of juvenile C. parasema. Surveys revealed that 97% of juvenile C. parasema were associated with Acropora corals. Furthermore, C. parasema densities were closely related to the cover of bottlebrush Acropora, the preferred growth form. Contrary to predictions, there was no evidence of crowding on natural reefs with low coral cover, but rather, reefs with abundant Acropora cover supported larger aggregations with double the density of juveniles. We hypothesized that low densities of C. parasema on natural reefs with low coral cover could be explained by intense intraspecific competition. Experimental manipulations showed that juvenile mortality was density-dependent, with mortality 20% higher on high-density experimental patch-reefs compared to low-density reefs. Behavioural observations on the patch-reefs revealed that the frequency of agonistic interactions and distance to shelter were both unrelated to conspecific densities, highlighting the need for further research into mechanisms underpinning density dependent mortality. These results suggest that intraspecific competition may play an important role in reducing reef fish abundance as a consequence of habitat loss. Given that coral reef systems are currently under threat, with a global decline in coral cover, this study adds to the growing body of knowledge of how disturbances to habitat may affect reef fish communities. [Copyright &y& Elsevier]

Highlights: [•] Densities of targeted fishes were higher at sites with recruitment hotspots. [•] Population recovery was enhanced in reserves that contained recruitment hotspots. [•] Reserves primarily protected fishes above the minimum legal size. [Copyright &y& Elsevier]

Availability of specific microhabitat exerts a strong influence on recruitment and abundance of coral reef fishes, but the ecological basis for microhabitat selection is not always clear. This study used a combination of field-based sampling and aquarium-based experiments to test microhabitat preferences of juvenile coral trout (mostly, Plectropomus maculatus), and assess whether microhabitat selection is related to prey access. In the field, coral trout use live Acropora corals situated over sand 3 times more than any other microhabitat, even through these specific microhabitats accounted for only 12.8% of habitat area. Field-based surveys revealed that live coral habitats support higher densities of potential prey species (71.73individuals per m2 ±8.4SE for fish; 423.36individuals per m2 ±91.8SE for crustacean) compared to dead corals (21.92individuals per m2 ±3.9SE for fish; 146.67individuals per m2 ±38.1SE for crustacean). Furthermore, structural microhabitats on sand have higher densities of prey (57.61individuals per m2 ±9.6SE for fish; 539.04individuals per m2 ±79.0SE for crustacean) compared to comparable microhabitats on consolidated carbonate substrata (36.05individuals per m2 ±6.7SE for fish; 129.36individuals per m2 ±15.9SE for crustacean). In the absence of prey, juvenile coral trout did not distinguish between live versus dead corals (37.18%±8.2SE and 35.48%±6.1SE), but both of these microhabitats were preferred over rubble (16.21%±3.5SE), macroalgae (11.09%±6.1SE) and sand (0%). In tank-based studies of prey use, juvenile coral trout consumed prey fishes that associate with non-coral habitats (e.g., Eviota zebrina; 33.28%±3.4SE) and mid water species (e.g., Aioliops tetrophthalmus; 47.97%±2.8SE), but did not consume those fishes with an obligate association with live corals (4.7%±1.9SE; 6.03%±2.2SE; 7.9%±2.8SE). Our results suggest that studies of microhabitat preferences should consider both the structure and location of specific microhabitats. It is presumed that structural microhabitats are essential for evading predators, while occupation of live corals positioned over sandy substrata maximizes accessibility to a diverse array of potential prey fishes and crustaceans. [ABSTRACT FROM AUTHOR]

As well as serving valuable biodiversity conservation roles, functioning no-take fishery reserves protect a portion of the fishery stock as insurance against future overfishing. So long as there is adequate compliance by the fishing community, it is likely that they will also sustain and even enhance fishery yields in the surrounding area. However, there are significant gaps in scientific knowledge that must be filled if no-take reserves are to be used effectively as fishery management tools. Unfortunately, these gaps are being glossed over by some uncritical advocacy. Here, we review the science, identify the most crucial gaps, and suggest ways to fill them, so that a promising management tool can help meet the growing challenges faced by coastal marine fisheries. [Copyright &y& Elsevier]