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The concept of dominance is frequently used to describe changes in rapidly reconfiguring ecosystems, but the definition of dominance can vary widely among studies. Using coral reefs as a model, we use extensive benthic composition data to explore how variability in applying dominance concepts can shape perceptions. We reveal that coral dominance is sensitive to the exclusion of key algal groups and the categorization of other benthic groups, with ramifications for detecting an ecosystem phase shift. For example, ignoring algal turf inflates the dominance of hard and soft corals in the benthic habitats underpinning reef ecosystems. We need a consensus on how dominance concepts are applied so that we can build a more comprehensive understanding of ecosystem shifts across a broad range of aquatic and terrestrial settings. For reefs, we highlight the benefits of comprehensive and inclusive surveys for evaluating and managing the altered ecosystem states that are emerging in the Anthropocene.

Translating scientific evidence into practical actions is a primary goal of scientists working to inform evidence‐based policy and decision‐making, but how can authors best facilitate new conservation interventions following publication of their research? This case study used two articles in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) to examine the mechanisms and barriers to translating published aquatic science into social, ecological and policy interventions for the conservation of threatened Murray crayfish (Euastacus armatus). These articles revealed how steep declines in Murray crayfish abundance arose from the loss of in‐stream and riparian habitats preferred by crayfish, and demonstrated the social reasons for conserving Murray crayfish to protect the wellbeing of a diversity of people (e.g. Traditional Owners, landholders, ecotourism operators). Following publication of these articles in AQC the authors used multi‐modal communication (e.g. written briefs, personal discussions, seminars, magazine articles, media broadcasts) to translate their findings to stakeholders and the general public. Analysis of relevant documents (e.g. management plans, public information leaflets) and stakeholder interviews uncovered a range of interventions arising from the two AQC articles. Social interventions (e.g. new public signage, ecotourism briefings) were the quickest to occur after publication (1–2 years). Although some changes in management were apparent (e.g. revised Murray crayfish action plans, monitoring programmes), systemic barriers (e.g. policy/funding timeframes) have prevented some ecological and policy interventions from being realized. Diverse communication strategies can help rapidly translate published science into new conservation actions by giving stakeholders the right evidence in the right way to inform their particular practice. Open‐access summaries that explain findings within readily shareable media (e.g. graphical/video abstracts) can be particularly effective in raising early awareness. Some types of intervention, however, may require a long‐term perspective and assistance from boundary‐spanning knowledge brokers with an aptitude for evidence‐based policy development.

Australian Research Council; Lizard Island Reef Research Foundation, Grant/Award Number: Lizard Island Doctoral Fellowships to RAM and CJF; James Cook Univeristy, Grant/Award Number: James Cook University Postgraduate Research Schola

Tropical seascapes are comprised of a range of patch habitat types, yet we have only a partial understanding of how local patch condition and seascape position may influence patterns of marine biodiversity, particularly for invertebrate taxa. We investigated how the epifaunal abundance and biomass of tropical Sargassum varied with canopy size (volume, total length and dry weight), local patch conditions (macroalgal composition, canopy structure and invertivorous fish biomass) and seascape setting (nearshore, lagoon and back reef) within the Ningaloo fringing reef ecosystem, Australia. A total of 49431 epifauna, dominated by crustaceans and molluscs, were extracted from the thalli of 81 tropical Sargassum polycystum individuals. Epifaunal abundance and biomass were most strongly correlated with host Sargassum canopy volume and dry weight, respectively. Epifaunal abundance and biomass also varied significantly among separate Sargassum meadow patches, with a significant interaction between canopy size and seascape position. Considerable site-level variations in epifaunal biomass density (mg per g Sargassum dry weight) were best predicted by either seascape context or local invertivorous fish biomass. Sargassum within meadows furthest from the back reef tended to have the highest epifaunal biomass (dominated by molluscs), while meadows closest to the back reef were dominated by crustacea. Sargassum within meadows with a high local abundance of invertivorous labrids and serranids tended to have the lowest epifaunal biomass. Strong Sargassum canopy size-epifauna relationships indicate that even small differences in canopy extent have major flow-on effects for the trophic function of tropical marine ecosystems by affecting the epifaunal secondary productivity available to higher-order consumers, such as fishes.

Macroalgal-dominated reefs are a prominent component of tropical seascapes providing food and shelter for many species whilst subsidising secondary productivity in coastal ecosystems. Monitoring and managing macroalgae require an understanding of key processes that alter these assemblages, especially at the local scale. Here we consider how sediment depth/cover and abundance of the urchin Tripneustes gratilla influence variation in community composition and physical structure of macroalgal patches within the World Heritage listed Ningaloo Reef, Western Australia. Our study found high urchin densities in sites with lower sediment cover and depth and that sediments, urchin abundance, and seascape position explained 32% of the spatial variation in macroalgal community composition with a greater occurrence of Sargassopsis, Caulerpa, Sirophysalis and Hormophysa in the lagoon where sediment cover/depth was high. Canopy height and cover of canopy-forming macroalgae were also greater where sediments were high and urchin abundance low. Macroalgal genera with a strong and robust thallus were found in sediment depths up to 6 cm as opposed to those with softer, fragile thalli that were found in sediments

The University of Newcastle and NSW Department of Primary Industries provided funding with research conducted under NSW DPI Animal Care and Ethics Committee permit 10/09

International audience; Few studies assess the effects of recreational fishing in isolation from commercial fishing. We used meta-analysis to synthesise 4444 samples from 30 years (1987–2017) of fish surveys inside and outside a large network of highly protected reserves in the Ningaloo Marine Park, Western Australia, where the major fishing activity is recreational. Data were collected by different agencies, using varied survey designs and sampling methods. We contrasted the relative abundance and biomass of target and non-target fish groups between fished and reserve locations. We considered the influence of, and possible interactions between, seven additional variables: age and size of reserve, one of two reserve network configurations, reef habitat type, recreational fishing activity, shore-based fishing regulations and survey method. Taxa responded differently: the abundance and biomass inside reserves relative to outside was higher for targeted lethrinids, while other targeted (and non-targeted) fish groups were indistinguishable. Reef habitat was important for explaining lethrinid response to protection, and this factor interacted with reserve size, such that larger reserves were demonstrably more effective in the back reef and lagoon habitats. There was little evidence of changes in relative abundance and biomass of fishes with reserve age, or after rezoning and expansion of the reserve network. Our study demonstrates the complexities in quantifying fishing effects, highlighting some of the key factors and interactions that likely underlie the varied results in reserve assessments that should be considered in future reserve design and assessment.

Macroalgal forests are a prominent component of tropical seascapes providing food and shelter for many species whilst subsidising secondary productivity in coastal ecosystems. Monitoring and managing macroalgae requires an understanding of key processes that alter these assemblages, especially at the local scale. Here we consider how sediment depth/cover and abundance of the macroalgal grazing urchin Tripneustes gratilla (Linnaeus, 1758), influence variation in community composition and physical structure of macroalgal patches within the World Heritage listed Ningaloo Reef, Western Australia. Our study found high urchin densities in sites with lower sediment loads and that sediments, urchin abundance and seascape position combined, explained 32% of the spatial variation in macroalgal forest community composition. We also found a greater occurrence of Sargassopsis, Caulerpa, Sirophysalis and Hormophysa in the lagoon where sediment cover/depth was high. Canopy height and cover of canopy forming macroalgae was also greater where sediment loads were high and urchin abundance low. Macroalgal genera with a strong and robust thallus were found in sediment depths up to 6 cm as opposed to those with softer, fragile thalli that were found in sediments

Canopy-forming macroalgae can construct extensive meadow habitats in tropical seascapes occupied by fishes that span a diversity of taxa, life-history stages and ecological roles. Our synthesis assessed whether these tropical macroalgal habitats have unique fish assemblages, provide fish nurseries and support local fisheries. We also applied a meta-analysis of independent surveys across 23 tropical reef locations in 11 countries to examine how macroalgal canopy condition is related to the abundance of macroalgal-associated fishes. Over 627 fish species were documented in tropical macroalgal meadows, with 218 of these taxa exhibiting higher local abundance within this habitat (cf. nearby coral reef) during at least one life-history stage. Major overlap (40%-43%) in local fish species richness among macroalgal and seagrass or coral reef habitats suggest macroalgal meadows may provide an important habitat refuge. Moreover, the prominence of juvenile fishes suggests macroalgal meadows facilitate the triphasic life cycle of many fishes occupying diverse tropical seascapes. Correlations between macroalgal canopy structure and juvenile abundance suggests macroalgal habitat condition can influence levels of replenishment in tropical fish populations, including the majority of macroalgal-associated fishes that are targeted by commercial, subsistence or recreational fisheries. While many macroalgal-associated fishery species are of minor commercial value, their local importance for food and livelihood security can be substantial (e.g. up to 60% of landings in Kenyan reef fisheries). Given that macroalgal canopy condition can vary substantially with sea temperature, there is a high likelihood that climate change will impact macroalgal-associated fish and fisheries.

Keystone species can provide a focal point for designing conservation and management strategies that protect a diversity of social–ecological values in aquatic ecosystems; however, to avoid bias towards a subset of values associated with a single activity, such as fishing, stakeholder consultations must cover a spectrum of social perspectives. Using the Murray crayfish (Euastacus armatus) as a model, this study explored how Aboriginal Traditional Owners, landowners, tourism businesses, scientific researchers, non‐governmental organizations, and government agencies valued this threatened freshwater species across south‐east Australia. Qualitative methods revealed that E. armatus is a culturally significant species, targeted for fishing, but is also valued for a range of non‐extractive reasons that support social–ecological linkages between people and freshwater ecosystems. Perceived as an iconic species by most stakeholders, there was general support for E. armatus to be used as a flagship for conserving a spectrum of social–ecological values (e.g. Aboriginal Traditional Owner totem species), attached to their local freshwater ecosystems. Although stakeholders were conflicted over whether fishing should continue, four themes emerged on how to develop more equitable and effective conservation and management strategies: increased public education, co‐management with non‐government stakeholders, federal government co‐ordination, and spatial protection of critical areas. The protection of aquatic species in ways that support their full range of cultural, economic, and ecological values will require more bottom‐up (i.e. stakeholder‐led) approaches to conservation and management design. Broader stakeholder engagement and co‐management should reduce perceptions that local stakeholders are isolated from management processes, while increasing the capacity and confidence of managers to implement strategies that bolster both the social and ecological resilience of aquatic ecosystems.

Tropical river and estuarine food webs sustain diverse biodiversity values and are important sources of nutrients and energy for connected aquatic and terrestrial ecosystems. High-order predators, such as euryhaline elasmobranchs, play critical roles in these food webs, but a lack of detailed information on food web structure limits our ability to manage these species within their ecosystems. We analysed stable carbon (δ13C) and nitrogen (δ15N) isotopes (SI) and fatty acid (FA) biochemical tracers from putative prey species in the estuary of the South Alligator River, northern Australia. These were compared with existing data on four species of elasmobranch from the system to examine food web structure and infer dietary linkages over wet and dry seasons along an environmental gradient of sites. Layman’s SI community metrics indicated that upstream food webs had the greatest trophic diversity, and analyses of FAs revealed distinct prey habitat associations that changed seasonally. Mixing models of SI indicated that most Glyphis glyphis and Glyphis garricki had similar freshwater and mid-river diets whilst Carcharhinus leucas and Rhizoprionodon taylori had largely marine signatures. Multivariate analyses of FA revealed some intraspecific differences, although specialisation indices suggested that the four shark species are trophic generalists. Our results show that riverine food webs can display complex spatiotemporal variations in trophic structure and that coastal and euryhaline mobile elasmobranchs forage in a range of coastal and freshwater habitats, demonstrating their influence on these food webs.

This research is supported by an Australian Government Research Training Program (RTP) Scholarship, as well as with funding provided by the Linnean Society of New South Wales. We also wish to thank Kelsey Sanborn for assistance in the field.

The reef flat is one of the largest and most distinctive habitats on coral reefs, yet its role in reef trophodynamics is poorly understood. Evolutionary evidence suggests that reef flat colonization by grazing fishes was a major innovation that permitted the exploitation of new space and trophic resources. However, the reef flat is hydrodynamically challenging, subject to high predation risks and covered with sediments that inhibit feeding by grazers. To explore these opposing influences, we examine the Great Barrier Reef (GBR) as a model system. We focus on grazing herbivores that directly access algal primary productivity in the epilithic algal matrix (EAM). By assessing abundance, biomass, and potential fish productivity, we explore the potential of the reef flat to support key ecosystem processes and its ability to maintain fisheries yields. On the GBR, the reef flat is, by far, the most important habitat for turf‐grazing fishes, supporting an estimated 79% of individuals and 58% of the total biomass of grazing surgeonfishes, parrotfishes, and rabbitfishes. Approximately 59% of all (reef‐wide) turf algal productivity is removed by reef flat grazers. The flat also supports approximately 75% of all grazer biomass growth. Our results highlight the evolutionary and ecological benefits of occupying shallow‐water habitats (permitting a ninefold population increase). The acquisition of key locomotor and feeding traits has enabled fishes to access the trophic benefits of the reef flat, outweighing the costs imposed by water movement, predation, and sediments. Benthic assemblages on reefs in the future may increasingly resemble those seen on reef flats today, with low coral cover, limited topographic complexity, and extensive EAM. Reef flat grazing fishes may therefore play an increasingly important role in key ecosystem processes and in sustaining future fisheries yields.

L.N.W. was supported by an Honours Scholarship from the Australian National University (ANU). Funding was provided by the Australian Academy of Science (Thomas Davies Research Award to C.J.F.), the Research School of Biology at ANU and a Julian E. Tenison Woods Award to L.N.W. from the Linnean Society of NSW.

Remote underwater video (RUV) cameras are commonly used in marine environments to sample fish, but to date have infrequently been used in freshwater environments. We tested the utility of a range of underwater video camera deployments (floating/benthic and fixed/moving) for surveying fish assemblages within tropical wetland habitats of Kakadu National Park, Australia. RUV cameras in both fixed and moving configurations were able to detect a range of fish species in various habitat types, with shy and/or flighty species readily detected. Cameras also performed well in a variety of conditions, although dense macrophytes posed a challenge for all video deployment types. RUV camera survey data compared favourably to two traditional fish survey techniques (visual census and pop netting). However, fixed camera deployments more closely resembled data collected via traditional techniques; whereas moving RUV deployments were consistently lower than any other method. We find that RUV cameras are a valuable monitoring and sampling technique for assessing freshwater fish assemblages in tropical wetlands, and are especially useful where remoteness, difficult access, variable water quality, complex habitats and interactions between humans and dangerous aquatic life can limit the use of other traditional fish sampling techniques.

Identifying and protecting nursery habitats for species is a key conservation strategy for the long-term sustainability of populations. In tropical ecosystems, macroalgal habitats have recently been identified as nurseries for fish of commercial and conservation significance. Here, we explore how local-scale variations in seaweed habitat quality interact with large-scale climatic conditions (Southern Oscillation Index, SOI) to influence the recruitment of three tropical fish species (Lethrinus spp.), often targeted by fishers. New fish recruits and juveniles of all species were almost exclusively found in macroalgal nursery habitats, while adults of two of these species were predominantly found on adjacent coral reefs. Annual supply rates of new recruits were found to be strongly correlated to variations in the SOI, with La Nina conditions associated with higher recruitment. However, local rates of recruitment were generally poor predictors of older juvenile abundance. Instead, local juvenile abundance was more closely related to structural characteristics of macroalgae nursery habitat quality (density, canopy height, canopy cover) and/or predator biomass, at the time of survey, with species-specific habitat associations apparent. Given the dynamic nature of fish recruitment supply to the SOI, coupled with the effects of climatic and oceanic processes on the structure of macroalgal patches, these results suggest protection of macroalgal nursery habitats that maintain high canopy density, height and cover is critical to supporting the conservation of fish populations.

Species with specialized resource use can display strong spatial heterogeneity in abundance according to the availability of their preferred habitats. If these preferences shift with ontogeny, then a wide range of habitats may need to be protected in order to support both adult populations and their replenishment. We explored whether microhabitat selectivity interacts with habitat availability to provide an effective suite of indicators for regional fish abundance and replenishment, using offshore rocky reefs in south-eastern Australia as a case study. We examined generalized additive mixed models (GAMMs) in a full subsets approach to infer the best predictors for adult and juvenile fish density in four diverse families (Labridae, Odacidae, Pomacentridae, Serranidae), based on rapid underwater visual surveys across transects (⿼500 m 2 ), wave exposures (0.3⿿1 km), and sites (0.3⿿48 km). We then examined whether these regional fish-habitat models aligned with the microhabitat electivity of individuals (at scale of 2 ). Microhabitat selection by reef fishes at the local scale underpinned the most effective habitat indicators for regional heterogeneity in fish abundance, and pointed to critical nursery habitats that support hotspots of juvenile recruitment. Strong species-habitat relationships, such as these, can be combined with broad-scale habitat mapping to assess the potential carrying capacity of focal areas, spatial management zone placements, and nursery habitats that warrant special protection. A number of emerging threats to these key habitat types indicates an urgent need for habitat-based protection and monitoring as a key part of holistic marine ecosystem conservation and management.

Fatty acid (FA) analysis can provide an effective, non-lethal method of elucidating the trophic ecology of fish. One method utilised in the field is to collect biopsied muscle tissue, but this can be problematic in live sharks due to a thick dermal layer with extensive connective tissue. The aim of this research was to determine whether fin and muscle tissue yield similar FA profiles in three species of tropical euryhaline sharks: Carcharhinus leucas, Glyphis garricki and Glyphis glyphis. Fatty acid profiles were detectable in fin clips as small as 20 mg (~ 5 mm × 6 mm) and muscle biopsies > 10 mg mass. Overall profiles in relative (%) FA composition varied significantly between fin and muscle tissues for C. leucas and G. garricki (global R-values = 0.204 and 0.195, P

Aim: The dispersal and distribution patterns of many marine organisms are driven by oceanographic conditions, which are influenced by global climate. Climate-driven oceanographic changes are thus likely to result in biogeographical changes. We assess how recent and predicted oceanographic changes affect the dispersal capacities and distributions of ecologically important (especially habitat-forming) marine organisms. Location: We include studies from tropical, temperate and sub-polar regions to draw globally relevant conclusions. Methods: We review biogeographical, biological and oceanographic studies to critically evaluate emerging trends in biogeographical responses to climate-driven oceanographic changes, and predict how future changes will affect marine ecosystems. Results: Many oceanic dispersal pathways are being altered by climate change. These changes will affect marine ecosystems by differentially affecting the replenishment potential and connectivity of key habitat-forming species. In particular, the length of propagule pre-competency periods, propagule behaviour and the geographical distance between areas of suitable habitat will be critical in determining how oceanographic changes affect the pattern and success of dispersal events, including the likelihood of species experiencing poleward range shifts in response to a warming climate. Main conclusions: Future climate-driven oceanographic changes are likely to strengthen or weaken different oceanic dispersal pathways, which will either increase or decrease the potential for dispersal and connectivity in various marine taxa according to the interaction between the local oceanographic, geographical and taxon-specific biological factors. A key focus for future work should be the development of fine-scale near-shore ocean circulation models that can be used to assess the dispersal response of key marine taxa under various marine climate change scenarios.

1. Crayfish are culturally and ecologically important species in freshwater ecosystems, but many are now threatened with extinction, due to threats such as habitat loss. Depending on their habitat selectivity and sensitivity, freshwater crayfish could provide effective targets for stream monitoring, restoration and conservation. This study used repeated field surveys of the threatened Murray crayfish, Euastacus armatus (family Parastacidae), to establish their habitat preferences and sensitivity to habitat loss across mesohabitat and microhabitat scales within upland streams of south-east Australia. 2. Selectivity analysis revealed that upland populations of E. armatus displayed a strong preference for areas of intermediate water flow velocity, deeper water, and stream beds dominated by boulders and gravel. Variations in E. armatus density among and within the two upland streams aligned with these microhabitat preferences, with best-subsets analyses revealing that E. armatus abundance hotspots were best predicted by models combining water depth with percentage cover of boulders, gravel and overhanging riparian vegetation. 3. Major shifts in stream habitat condition from 2009 to 2015 (e.g. 32% and 50% decline in boulder and overhanging vegetation cover, respectively) was associated with a 91% decline in E. armatus mean density within glide-pool mesohabitats. 4. These findings highlight how habitat specialization in threatened crayfish such as E. armatus may render them sensitive to changes in stream habitat condition, and how targeted monitoring, restoration and conservation of their preferred habitats could yield multiple benefits for montane freshwater ecosystems. Copyright © 2016 John Wiley & Sons, Ltd.

Tropical reefs have been subjected to a range of anthropogenic pressures such as global climate change, overfishing and eutrophication that have raised questions about the prominence of macroalgae on tropical reefs, whether they pose a threat to biodiversity, and how they may influence the function of tropical marine ecosystems. We synthesise current understanding of the structure and function of tropical macroalgal reefs and how they may support various ecosystem goods and services. We then forecast how key stressors may alter the role of macroalgal reefs in tropical seascapes of the Anthropocene. High levels of primary productivity from tropical canopy macroalgae, which rivals that of other key producers (e.g., corals and turf algae), can be widely dispersed across tropical seascapes to provide a boost of secondary productivity in a range of biomes that include coral reefs, and support periodic harvests of macroalgal biomass for industrial and agricultural uses. Complex macroalgal reefs that comprise a mixture of canopy and understorey taxa can also provide key habitats for a diverse community of epifauna, as well as juvenile and adult fishes that are the basis for important tropical fisheries. Key macroalgal taxa (e.g., Sargassum) that form complex macroalgal reefs are likely to be sensitive to future climate change. Increases in maximum sea temperature, in particular, could depress biomass production and/or drive phenological shifts in canopy formation that will affect their capacity to support tropical marine ecosystems. Macroalgal reefs can support a suite of tropical marine ecosystem functions when embedded within an interconnected mosaic of habitat types. Habitat connectivity is, therefore, essential if we are to maintain tropical marine biodiversity alongside key ecosystem goods and services. Consequently, complex macroalgal reefs should be treated as a key ecological asset in strategies for the conservation and management of diverse tropical seascapes. A plain language summary is available for this article.

Crustaceans are one of the most influential groups in aquatic trophic networks by providing a major connection between primary production and higher consumers. Although coral reefs support a high diversity and abundance of crustaceans and crustacean predators, their trophic interrelationships remain unclear. Using predator gut content analyses, we investigated trophic relationships between Crustacea and adult fishes of the family Labridae, which are one of the most abundant and diverse families of marine crustacean predators. Crustaceans were present within the guts of 93 % of the 30 wrasse genera investigated. We found a distinct division between micro- and macro-crustacean predators: wrasses 90 mm SL displayed a predominantly macro-Crustacea diet. Notably, micro-crustacean predators tended to specialise on certain crustacean taxa, whereas macro-crustacean predators consumed mostly brachyurans. Our findings highlight complex patterns of feeding diversity within crustacean predators that prompt a more nuanced approach to defining the role of crustacean-feeding fishes in coral reef trophodynamics.

Here we report on the efficacy of manual and video-based underwater visual census (UVC) for recording the swimming behaviour of fishes within complex coral reef habitats. Focusing upon four common fish species from the Great Barrier Reef (Acanthurus nigrofuscus, Chaetodon lunulatus, Siganus doliatus and Sufflamen chrysopterus), we compared manual recordings by divers against post-field analysis of underwater video of the same species in the ability to detect the different fin types used by fishes while they foraged over the reef. Both video and manual UVC methods detected similar trends in the number of fins and the proportional use of each fin type by reef fishes engaged in different activities (e.g., travelling, searching, feeding). While estimates of fin use from the two methods were largely within 15% of each other, video UVC tended to record higher proportions of fin use within each species due to a better detection of rare and/or rapid fin movements. Such differences were most extreme for the balistiform-swimming S. chrysopterus, where video detected a significantly higher proportion of fins used by this species. Notably, the sampling effort required to improve precision and gain sufficient independent replicates was much higher for video-based versus manual UVC. Our findings reflect the relative strengths of each UVC method for studies of fish behavioural ecology in the wild, with the various benefits of each method likely to align with different research questions and fish species of interest, within the logistical constraints of funding and field safety.

Morays occupy unique interstitial habitats and function as key predators in marine ecosystems. Conversely, there is limited understanding of the ecology of Gymnothorax polyuranodon, the lone representative of the family Muraenidae known to reside in freshwater systems. In this study, we used field-based encounters over a 3-year period in three short-steep-coastal-streams of the Australian Wet Tropics to find that most G. polyuranodon individuals (74%) occupied pools, with very few individuals observed in run (23%) or riffle (3%) mesohabitats. Moreover, G. polyuranodon positively selected microhabitats of slow flow ( 80 cm), while avoiding high flows (>0.5 ms � 1 ) and shallow water (

An ecological release from competition or predation is a frequent adaptive explanation for the colonization of novel environments, but empirical data are limited. On the island of Rarotonga, several blenny fish species appear to be in the process of colonizing land. Anecdotal observations have implied that aquatic predation is an important factor in prompting such amphibious fish behavior. We provide evidence supporting this hypothesis by demonstrating that amphibious blennies shift their abundance up and down the shoreline to remain above predatory fishes that periodically move into intertidal areas during high tide. A predation experiment using blenny mimics confirmed a high risk of aquatic predation for blennies, significantly higher than predation experienced on land. These data suggest that predation has played an active role in promoting terrestrial activity in amphibious blennies and provide a rare example of how ecological release from predation could drive the colonization of a novel envi...

Hard structural complexity is widely recognised as important for assessing fish habitat quality, but our understanding of the importance of soft habitat microstructure for temperate marine fishes is less developed. We used best-subsets modelling of underwater surveys in sponge, soft coral, and macroalgae mesohabitats within a temperate estuary to assess what measures of soft habitat structure best predicted differences in wrasse (family: Labridae) fish community composition. We found that significant differences in the labrid fish community among and within mesohabitat types were best explained by a combination of percent canopy cover and soft canopy height, with increased canopy height being correlated with increased fish abundance and species richness. Sponge and macroalgae mesohabitats emerged as particularly important, but vulnerable habitats for a diversity of fishes unique to these mesohabitat types. Ultimately, mesohabitats with high percent canopy cover and height appear to be particularly valuable for supporting estuarine fish communities. Due to this importance, and the potential for decadal-scale recovery times within sponge canopies, we suggest patches with high-quality canopy structure warrant special protection from local threats, such as anchor and fishing damage.

The integration of scientific information into the decision-making process for the management of marine resources remains a significant challenge, with the inaccessibility of primary scientific literature to environmental practitioners identified as a key limiting factor. Here, we quantify the use of primary scientific literature in environmental management plans, and explore potential barriers to the efficient integration of such scientific information into the decision-making process. Through a case study of coral dominated Marine Protected Areas (MPAs) spanning three countries (Australia, Kenya and Belize), we find that primary scientific literature represents only 14% of information cited in management plans. Such a low proportion is likely to be symptomatic of several issues regarding the accessibility of primary scientific literature to MPA managers, such as: 1. Long publication times for articles (average 40.2 ± 1.8 months); 2. Subscription-only access (up to 56% of articles behind paywalls); and/or 3. Poor articulation of management implications (only 19% of articles provided clear outcomes relevant to management). Such impediments can undermine the adaptive governance of MPAs, so we suggest improvements to knowledge transfer among scientists and managers via a diversity of approaches including knowledge brokers, boundary organisations, knowledge co-production and management-orientated summaries in research articles.

Obtaining biological and spatial information of the early life history (ELH) phases of fishes has been problematic, such that larval and juvenile phases are often referred to as the 'black box' of fish population biology and ecology. However, a potent source of life-history data has been mined from the earstones (otoliths) of bony fishes. We systematically reviewed 476 empirical papers published between 2005 and 2012 (inclusive) that used otoliths to examine fish ELH phases, which has been an area of increasing attention over this period. We found that otolith-based research during this period could be split into two broad themes according to whether studies examined: (i) biological objectives related to intrinsic processes such as larval and juvenile age, growth and mortality, and/or (ii) spatial objectives, such as habitat use, dispersal and migration. Surprisingly, just 24 studies (5%) explored a combined biological-spatial objective by simultaneously exploiting biological and spatial information from otoliths, suggesting much more scope for such integrated research objectives to be answered via the use of multiple otolith-based techniques in a single study. Mapping otolith analytical techniques across these two approaches revealed that otolith structural analysis was mainly used to investigate biological processes, while otolith chemical analyses were most often applied to spatial questions. Heavy skew in research effort was apparent across biomes, with most (62%) publications specific to marine species, despite comparable levels of species richness and the importance of freshwater taxa (just 15% of papers). Indeed, around 1% (380 species) of a possible 31400+ extant species were examined in our surveyed papers, with a strong emphasis on temperate marine species of commercial value. Potential model species for otolith-based ELH ecology research are arising, with the eel genus Anguilla (24 studies) and the European anchovy Engraulis encrasicolis (14 studies) attracting more research effort than most other taxa. While there is a preponderance of common techniques (e.g. daily otolith increment counts, increment widths), novel techniques such as transgenerational marking and computed X-ray tomography, are increasingly being applied in published studies. The application of an integrative approach based on a combination of emerging techniques and traditional methods holds promise for major advances in our understanding of ELH fish ecology and to shine light into the 'black box' of fish ecology.

Endemic species are assumed to have a high risk of extinction because their restricted geographic range is often associated with low abundance and high ecological specialization. This study examines the abundance of Chaetodon butterflyfishes at Lord Howe Island in the south-west Pacific, and compares interspecific differences in local abundance to the feeding behavior and geographic range of these species. Contrary to expected correlations between abundance and geographic range, the single most abundant species of butterflyfish was Chaetodon tricinctus, which is endemic to Lord Howe Island and adjacent reefs; densities of C. tricinctus (14.1 ± 2.1 SE fish per 200m(2)) were3 times higher than the next most abundant butterflyfish (Chaetodon melannotus), and even more abundant than many other geographically widespread species. Dietary breadth for the five dominant butterflyfishes at Lord Howe Island was weakly and generally negative correlated with abundance. The endemic C. tricinctus was a distinct outlier in this relationship, though our extensive feeding observations suggest some issues with the measurements of dietary breadth for this species. Field observations revealed that all bites taken on benthic substrates by C. tricinctus were from scleractinian corals, but adults rarely, if ever, took bites from the benthos, suggesting that they may be feeding nocturnally and/or using mid-water prey, such as plankton. Alternatively, the energetic demands of C. tricinctus may be fundamentally different to other coral-feeding butterflyfishes. Neither dietary specialization nor geographic range accounts for interspecific variation in abundance of coral reef butterflyfishes at Lord Howe Island, while much more work on the foraging behavior and population dynamics of C. tricinctus will be required to understand its' abundance at this location.

We thank staff at the Department of Parks and Wildlife Exmouth for field support, AIMS 2013 Appropriation funding 3.3.5 and the Australian Research Council for financial support.

Understanding the foraging patterns of reef fishes is crucial for determining patterns of resource use and the sensitivity of species to environmental change. While changes in prey availability and interspecific competition have been linked to patterns of prey selection, body condition, and survival in coral reef fishes, rarely has the influence of abiotic environmental conditions on foraging been considered. We used underwater digital video to explore how prey availability and wave exposure influence the behavioural time budgets and prey selectivity of four species of obligate coral-feeding butterflyfishes. All four species displayed high selectivity towards live hard corals, both in terms of time invested and frequency of searching and feeding events. However, our novel analysis revealed that such selectivity was sensitive to wave exposure in some species, despite there being no significant differences in the availability of each prey category across exposures. In most cases, these obligate corallivores increased their selectivity towards their most favoured prey types at sites of high wave exposure. This suggests there are costs to foraging under different wave environments that can shape the foraging patterns of butterflyfishes in concert with other conditions such as prey availability, interspecific competition, and territoriality. Given that energy acquisition is crucial to the survival and fitness of fishes, we highlight how such environmental forcing of foraging behaviour may influence the ecological response of species to the ubiquitous and highly variable wave climates of shallow coral reefs.

Field observations using underwater video were used to reveal differences in the duration and frequency that fish engaged in daily behaviours such as chasing, searching, feeding, and travelling, according to their social patterns [passive or aggressive terminal phases (TPs), pair-spawning, or promiscuous groups] and intraspecific status (terminal or initial colour phases). Marked differences were apparent according to status, but this was not consistent among the three species; TP Cheilinus fasciatus tended to swim in longer bouts with less frequent searching or feeding than initial phase (IP) conspecifics; TP Cirrhilabrus punctatus exhibited less frequent feeding and travelling than IP conspecifics, while the most aggressive species Stethojulis bandanensis displayed no significant intraspecific differences. We highlight the importance of social context and individual status when examining fish foraging activities and the utility of underwater video for recording the duration and frequency that fish engage in essential daily activities.

Understanding the movement patterns of fishes in the wild requires an awareness of the intrinsic and extrinsic factors underlying their behaviour. Using field observations, we explored whether eight species of coral reef fish display modality in their swimming behaviour, which is a convergence in fin use patterns among and within species when they conduct daily activities (e.g. feeding, travelling, chasing). While a range of different fins were used during steady swimming by each species, most fishes converged towards median-paired fin use (e.g. pelvics, pectorals) when undertaking searching and feeding. Conversely, all species adopted caudal fin use during high-speed activities such as chasing. Such modality in fin use was relatively conserved across juvenile and adult conspecifics and transcended differences in phylogenetic history and trophic preferences, suggesting that overarching constraints underpin patterns of fish swimming behaviour in complex habitats.

We thank P. Tinkler and staff of the Exmouth Office of the Department of Environment and Conservation Western Australia for field assistance; A. Heyward, R. Lowe, and C. Simpson for helpful discussions; the Australian Research Council, Australian Institute of Marine Science, Western Australian Marine Science Institute, and the Department of Environment and Conservation Western Australia for funding; and two anonymous reviewers for helpful comments. Data collection was conducted in the traditional country of the Jinigudira and Bayungu tribes of the Thalanyji people.

This experimental study compared the precision and accuracy of the biological intercept (BI), modified fry (MF) and time-varying growth (TVG) backcalculation models in estimating the early growth of the tropical freshwater purple-spotted gudgeon Mogurnda adspersa. Larvae were reared up to 41 days post hatching under two temperatures and four different feeding regimes. Food and temperature treatments induced complex growth profiles among fish, and although total length (LT) and otolith radius were related under all conditions, some uncoupling was evident in the otolith–somatic-growth (OSG) relationship of fish subjected to periods of changing food availability. Furthermore, otolith growth was found to be significantly influenced by temperature, but not by food availability. Analysis of backcalculation residuals by linear mixed effects modelling revealed that BI and TVG were equally precise in predicting somatic growth, with the highest accuracy provided by TVG. The performance of all the three models declined as the OSG relationship weakened under low-food conditions, with maximum errors estimated to be 39, 60 and 36% of observed LT for the BI, MF and TVG models, respectively. The need for careful validation of backcalculation models is emphasized when examining fishes subjected to variable environmental conditions, and when exploring the differential influence of temperature and food on fish LT and otolith growth.

While morphological variation across geographical clines has been well documented, it is often unclear whether such changes enhance individual performance to local environments. We examined whether the damselfish Acanthochromis polyacanthus display functional changes in swimming phenotype across a 40-km cline in wave-driven water motion on the Great Barrier Reef, Australia. A. polyacanthus populations displayed strong intraspecific variation in swimming morphology and performance that matched local levels of water motion: individuals on reefs subject to high water motion displayed higher aspect-ratio fins and faster swimming speeds than conspecifics on sheltered reefs. Remarkably, intraspecific variation within A. polyacanthus spanned over half the diversity seen among closely related damselfish species from the same region. We find that local selection driven by wave-induced abiotic stress is an overarching ecological mechanism shaping the inter- and intraspecific locomotor diversity of coral reef fishes.

1. Water flow is a critical driver of aquatic ecosystem health and function. Amid rising concerns over changing flow regimes, there is an urgent need to understand the functional mechanisms by which flow influences patterns of freshwater biodiversity. 2. We explored the functional link between flow velocity and microhabitat specialisation in a speciose group of freshwater gobies (comprising over half the total fish species richness) within insular streams of the Australian Wet Tropics under base flow conditions. We addressed two particular questions: (i) What is the relative selectivity of species towards streambed composition and water flow velocity? and (ii) Can patterns of microhabitat occupation be explained by differences in intrinsic flow performance among species? To answer these questions, we combined visual field observations of microhabitat use with flow tank assessments of flow speed performance. 3. Tropical freshwater gobies displayed strong specificity towards flow velocities, while being relatively non-selective towards streambed composition. At opposite extremes of the spectrum, we found Sicyopterus lagocephalus occupying high-flow (>1.0 ms⁻¹) microhabitats while Redigobius bikolanus selected slower-flow (

Species habitat associations are often complex, making it difficult to assess their influence on populations. Among coral reef fishes, habitat requirements vary among species and with ontogeny, but the relative importance of nursery and adult-preferred habitats on future abundances remain unclear. Moreover, adult populations may be influenced by recruitment of juveniles and assessments of habitat importance should consider relative effects of juvenile abundance. We conducted surveys across 16 sites and 200 km of reef to identify the microhabitat preferences of juveniles, sub-adults and adults of the damselfish Pomacentrus moluccensis . Microhabitat preferences at different life-history stages were then combined with 6 years of juvenile abundance and microhabitat availability data to show that the availability of preferred juvenile microhabitat (corymbose corals) at the time of settlement was a strong predictor of future sub-adult and adult abundance. However, the influence of nursery microhabitats on future population size differed spatially and at some locations abundance of juveniles and adult microhabitat (branching corals) were better predictors of local populations. Our results demonstrate that while juvenile microhabitats are important nurseries, the abundance of coral-dependent fishes is not solely dependent on these microhabitats, especially when microhabitats are readily available or following large influxes of juveniles.

Phenotypic adaptations can allow organisms to relax abiotic selection and facilitate their ecological success in challenging habitats, yet we have relatively little data for the prevalence of this phenomenon at macroecological scales. Using data on the relative abundance of coral reef wrasses and parrotfishes (f. Labridae) spread across three ocean basins and the Red Sea, we reveal the consistent global dominance of extreme wave‐swept habitats by fishes in the genus Thalassoma, with abundances up to 15 times higher than any other labrid. A key locomotor modification—a winged pectoral fin that facilitates efficient underwater flight in high‐flow environments—is likely to have underpinned this global success, as numerical dominance by Thalassoma was contingent upon the presence of high‐intensity wave energy. The ecological success of the most abundant species also varied with species richness and the presence of congeneric competitors. While several fish taxa have independently evolved winged pectoral fins, Thalassoma appears to have combined efficient high‐speed swimming (to relax abiotic selection) with trophic versatility (to maximize exploitation of rich resources) to exploit and dominate extreme coral reef habitats around the world.

International audience; Corals and coral-associated species are highly vulnerable to the emerging effects of global climate change. The widespread degradation of coral reefs, which will be accelerated by climate change, jeopardizes the goods and services that tropical nations derive from reef ecosystems. However, climate change impacts to reef social–ecological systems can also be bi-directional. For example, some climate impacts, such as storms and sea level rise, can directly impact societies, with repercussions for how they interact with the environment. This study identifies the multiple impact pathways within coral reef social–ecological systems arising from four key climatic drivers: increased sea surface temperature, severe tropical storms, sea level rise and ocean acidification. We develop a novel framework for investigating climate change impacts in social–ecological systems, which helps to highlight the diverse impacts that must be considered in order to develop a more complete understanding of the impacts of climate change, as well as developing appropriate management actions to mitigate climate change impacts on coral reef and people.

Habitat availability can be a key driver for the distribution and abundance of animals occupying heterogeneous landscapes. How species respond to regular changes in patch habitat structure, however, remains poorly understood, especially within seasonal seascapes. We explored the importance of patch habitat quality for the seasonal population dynamics of a widespread reef fish, Leptoscarus vaigiensis, within a shifting mosaic of seaweed patch habitats. Following dietary and behavioral assessments of L. vaigiensis microhabitat preferences, we used best subsets model selection to explore the relative importance of seaweed canopy attributes (cover, height, density) and the abundance of putative competitors and predators for explaining regional variations in L. vaigiensis density across summer and winter. Dietary analysis (n = 53 individuals) and behavioral observations (n = 1014) indicated that L. vaigiensis are habitat specialists that primarily consume brown seaweeds and prefer areas within patches that have tall (>30 cm height) canopy-forming seaweeds (Sargassum, Sargassopsis) at low to intermediate densities (1–5 holdfasts per m2). Accordingly, we found seaweed percent cover and canopy height were two of the most powerful predictors for L. vaigiensis abundance, with major seasonal shifts in L. vaigiensis abundance from summer to winter strongly related to patch-level changes in canopy cover and height. We conclude that patch habitat quality, based upon microhabitat preferences, can be a powerful predictor for the response of species to a seasonally shifting habitat mosaic, and that high-quality patches that provide seasonal refuges should be a focus for spatial conservation and management.

Flexible traits can be crucial in helping animals meet the challenges of a highly variable environment. We examined whether coral reef fishes systematically alter their swimming behaviour in response to temporal changes in hydrodynamic conditions. Exploiting site-based differences in wave energy impinging on reef habitats over calm and rough weather, we found many reef fishes changed their swimming behaviour alongside increases in wave-driven water motion. Most fishes tended to orient their bodies parallel to oncoming wave-driven flow and recruited additional stabilising fins during rough weather; such changes in swimming behaviour aid stability and minimise drag. However, not all species displayed such flexibility, with fishes possessing highly tapered pectoral fins and high levels of swimming performance continuing to successfully navigate reef habitats without significantly altering their swimming behaviour. We highlight how labile behaviours augment the morphology and performance of species to underpin their occupation of habitats subject to variable environmental conditions.