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For many animals, making informed decisions is crucial to survival. A critical problem is how to make optimal decisions in the face of incomplete, unreliable or conflicting information. In many aquatic environments, fish use visual information to guide key behaviours, but the environment itself can alter or mask the very signals they rely on. Here, we asked how a highly visual species, Rhinecanthus aculeatus , responds to a learned discrimination task as signal reliability decreases, and whether probabilistic information gained during previous experience can be incorporated into their decision strategy. Fish were first trained to select a target (dark grey circle) from three distractors (light grey circles). In the first experiment, the target was more likely to appear in one of four possible stimulus positions. In the second experiment, the target appeared in all positions equally. In a series of trials, the difference in brightness between the target and distractors was reduced until all four stimuli were identical. We found that target selection accuracy decreased with decreasing target and distractor disparity. In experiment 1 where the target was more likely to be in one position, fish increasingly selected stimuli in the biased position as target selection accuracy decreased, but not in experiment 2. These results demonstrate (1) that fish learned more than a simple select/avoid rule based on stimulus brightness; they also integrated information (stimulus position), which could be considered ancillary to the primary task. (2) Fish can learn probability distributions and apply this knowledge as uncertainty increases, ultimately increasing the overall frequency of correct choices. Our results reveal that probabilistic decision rules can be used by fish when visual information is unreliable, indicating a possible mechanism for decision making given the inherent noise in incoming sensory information. • Optimal decision making is critical to survival. • Animals must often make decisions when information is unreliable or incomplete. • When uncertain, fish used probabilistic rules based on previous experience. • This may be a powerful mechanism for adaptive decision making in dynamic conditions. [ABSTRACT FROM AUTHOR]

Acanthurus nigrofuscus (Acanthuridae), a common fish on the coral reefs of the Ryukyu Islands, southern Japan, is considered to be important for maintaining the health of coral reef ecosystems. However, the life history of the species in Japan is largely unknown. In this study, age, growth and maturation of A. nigrofuscus was determined from 395 specimens [44.7–174.5 mm fork length (FL)] collected between September 2020 and March 2022 on the Miyagi coast, located on the west coast of Okinawa-jima Island, central Ryukyu Islands. Mean gonadosomatic indices were high in September 2020 and from May to August 2021 for both sexes, with histological observations of the gonads revealing that individuals with developed oocytes (migratory nucleus and hydrated stages) occurred from May to September. Postovulatory follicles were observed in individuals collected in September 2020 and from May to August 2021. The length (age) at 50% maturity was 104.1 mm FL (1.0 yr) for females and 93.9 mm FL (0.5 yr) for males, the age range being 0–25 yr (n = 193) for females and 0–20 yr (n = 170) for males, with von Bertalanffy growth functions of Lt = 148.6 {1 − exp [−0.51 (t + 1.55)]} for females, Lt = 156.0 {1 − exp [−0.38 (t + 2.01)]} for males, and Lt = 151.8 {1 − exp [−0.40 (t + 2.11)]} for both sexes combined. Similar to other species of Acanthridae, A. nigrofuscus has a long-lived biphasic growth trajectory, with rapid initial growth and a long lifespan after reaching asymptotic size. [ABSTRACT FROM AUTHOR]

The authors studied the structure of the coastal fish assemblage in a temperate coral reef within a marine protected area in order to provide a baseline information on the occurrence and temporal distribution of fish and to highlight the importance of the coral reef to ichthyofauna. The coastal fish assemblage was investigated at two sites in Veliko jezero (Mljet National Park) in the southern Adriatic Sea with a non-destructive SCUBA visual technique in the period from 2013 to 2021. Altogether, 38 fish taxa were recorded on the right bank (coral reef) and 36 species on the left bank. The presence of the coral reef at a depth range between 9 m to 12 m is the main factor differentiating the fish fauna in these two areas, which are otherwise governed by the same environmental factors. At the coral reef a decrease in fish diversity was discovered with a steady regression from 2013 to 2021. [ABSTRACT FROM AUTHOR]

Nearly all organisms must cope with parasitic infestation, and most research on parasite ecology in marine systems has focused on the variety of both direct and indirect impacts that parasites can have on hosts. In coral reef ecosystems, gnathiid isopods are one of the most common ectoparasites of fishes. For individuals infested with gnathiids, there is a heavy reliance on intraspecific mutualisms where specialist species groom or "clean" parasites off host fishes. However, gnathiids spend most of their time free-living and not associated with a host and are thus susceptible to consumption by non-cleaner fish species. Here, we investigated if non-cleaner and facultative (less specialized) cleaner fish consume ectoparasitic gnathiid isopods as often or in similar quantities as dedicated (highly specialized) cleaners. To do so, we sampled the gut contents of 797 fishes, representing 61 species and including both cleaner and non-cleaner fishes, to compare their consumption of gnathiid isopods. We found that although there is some site level variation, cleaner fishes eat significantly more gnathiids, and eat them more frequently, compared to non-cleaner fishes. Our results highlight the importance of both dedicated and facultative cleaners as consumers of ectoparasites and show that their role is unlikely to be supplanted by non-cleaner consumers. Furthermore, we suggest that different cleaner species act as complementary rather than redundant specialists. [ABSTRACT FROM AUTHOR]

Feeding activities by fishes are among the key ecological processes that sustain coral reef functioning. Those trophic-based processes are known to vary across space and across seasons or years. However, there is still little knowledge about their variability within and between days as well as whether these processes are dominated by the same species across time. Using remote underwater cameras, we quantified rates of three feeding activities (corallivory, herbivory and invertivory) for three one-hour time slots (morning, midday, afternoon) over two days on two coral reefs around Mayotte Island (Western Indian Ocean). Feeding activities were highly variable at within and between-day scales and concentrated in a few pulses. Herbivory was the highest in the afternoon which aligns with previous findings regarding activity of herbivorous fishes. Corallivory was the highest in the morning, which highlights the advantage of long-duration benthic remote underwater videos to accurately assess all trophic activities. Trophic-related processes were dominated by the same few species in both sites and across time of the day. This study pinpoints the importance of including within-day and between-day variations when studying ecological processes, as neglecting these variations may introduce biases into our understanding of these processes. [ABSTRACT FROM AUTHOR]

Coral reefs are highly productive ecosystems, in part due to the productivity of planktivorous fishes. The planktivorous fish community contains two distinct groups which target either the gelatinous or the non-gelatinous fractions of the incoming zooplankton. However, the nutritional value of these prey fractions and, consequently, their potential contribution to planktivorous fish productivity are poorly understood. We explored the zooplankton fractions potential contribution to planktivorous fish productivity (our function of interest), by quantifying the nutritional content a key trait of the gelatinous and non-gelatinous prey fractions which are accessible to reef-associated diurnal planktivores. By combining vertical plankton tows with stoichiometric analyses, we found that the three zooplankton community fractions—gelatinous, > 2 mm non-gelatinous and < 2 mm non-gelatinous—were all relatively good sources of nitrogen, with median C:N values of 4.81:1, 4.22:1 and 4.62:1, respectively. The delivery of gN m−2 to our study reef over a flood tide was then estimated. The abundant < 2 mm non-gelatinous community delivered the largest gN m−2 (median: 0.88 gN m−2 6 h−1), which was estimated to be one to two orders of magnitude greater than the delivery from the > 2 mm non-gelatinous (0.06 gN) and gelatinous (0.03 gN) communities, respectively. Overall, our results highlight the quality of both gelatinous and non-gelatinous zooplankton as prey for planktivorous fishes, emphasizing the potential importance of the often-overlooked gelatinous fraction. [ABSTRACT FROM AUTHOR]

Seascape connectivity can facilitate key ecosystem functions in complex ecosystems like coral reefs. Many reef fishes move across the seascape, bridging different ecosystems. However, their role in shaping important functions, such as biomass production and nutrient cycling, is still poorly understood. This study, therefore, assesses the extent of natural movements of cardinalfishes (Apogonidae), one of the major contributors to nocturnal fish biomass production with the potential for a major role in transferring energy and nutrients between sandy ecosystems and adjacent coral reefs. Consistent with previous work, showing their ability to move distances of 100 s to 1000 s of metres when displaced, we reveal that these small fishes undergo major voluntary nocturnal foraging forays extending up to at least 145 m from reef structures. Their estimated daily movement distances are at least 430 times greater than expected based solely on body size-home range expectations. Given their large travel distances and strong homing abilities, apogonids may provide a major conduit for material transfer between lagoonal soft sediment habitats and adjacent coral reefs. These results highlight the potential importance of apogonids in the cross-system or cross-habitat transport of energy and nutrients on coral reefs. [ABSTRACT FROM AUTHOR]

Herbivorous fishes are a key functional group in coral reef ecosystems and have been the focus of a vast body of research. While substantial progress has been made in research, challenges persist, especially in respect to quantifying patterns versus processes. Despite this challenge being recognised over 40 years ago. To help clarify such challenges, and work towards solutions, in this perspective we explore how the definition of 'herbivorous reef fishes' precludes an easy translation between patterns of herbivore abundance and the process of herbivory. Indeed, if herbivorous fishes are defined as, a fish in which the diet is predominantly based on plant material, then this encompasses a diverse suite of fishes which all remove primary producers to varying extents and have markedly different impacts on reef functioning. Given this situation, we explore how our approaches to directly quantifying herbivory on reefs have progressed. We highlight how lessons learnt from macroalgal assays could be applied to the direct quantification of herbivory from algal turfs in the epilithic algal matrix (EAM); a community of primary producers that are invariably difficult to work with and quantify. Nevertheless, given the abundance of turfs on coral reefs, and their relative importance in herbivore dynamics, widespread process-based assessment of EAM herbivory represents an avenue for expanding future research. Recognising the difficulty of translating patterns in herbivore abundance to the process of herbivory, and an enhanced focus on EAM herbivory, will be necessary to comprehensively quantify the process of herbivory on Anthropocene coral reefs. [ABSTRACT FROM AUTHOR]

That coral reefs are in decline worldwide, particularly in the Caribbean, will come as no surprise. This decades-long decline has reached a potential tipping point as the weight of the effects of climate change have come decidedly to bear on the planet's most diverse marine ecosystem. Whether coral reefs can persist without restorative intervention is debatable, which has prompted a surge in coral reef restoration projects focusing primarily on the cultivation and transplantation of coral fragments onto degraded reefs. But that widespread approach does little to address the underlying causes of coral loss, one of which is the proliferation of macroalgae that are deleterious to corals. An emerging solution to this problem is the enhancement of herbivory on coral reefs through improved management of herbivores, artificial enhancement of herbivore settlement, or their mariculture and subsequent stocking. This review explores the nuances of the biology of wellstudied Caribbean coral reef herbivores (fishes, sea urchins, and crabs) as it relates to their mariculture and investigates the promise of herbivore stocking onto coral reefs as a restoration strategy. Fish, urchin, and crab herbivores differ appreciably in life histories, which confers advantages and disadvantages with respect to their mariculture and effectiveness as grazers. Mariculture of herbivorousmarine fish for reef restoration is essentially non-existent so the reestablishment of grazing fish abundance on coral reefs focuses primarily on their protection through fishery regulations, but only at a fewlocations in the Caribbean. Mariculture of herbivorous urchins and crabs for restoration purposes is in its infancy, but promising especially for crabs whose larval rearing is less difficult. Perhaps the biggest challenge for the mariculture of either taxon is "scaling-up" from research settings to large-scale mariculture needed for stocking. Numerous studies extol the benefits of functional redundancy and complementarity for coral reef ecosystem stability, but whether this principal applies to the restoration of grazing function is untested. We identify gaps in our knowledge of best practices for the restoration of grazing function on coral reefs and conclude with some practical guidance on the establishment of targets for macroalgal reduction, alongwith strategic advice on grazer stocking in a given reef habitat. [ABSTRACT FROM AUTHOR]

Objective: The White‐barred Goby Amblygobius phalaena is a popular ornamental fish in the marine aquarium market. To achieve successful commercial production, efficient larval rearing techniques are crucial. Previous studies have achieved successful cultivation of White‐barred Goby larvae by using a combination of three live feed organisms—the ciliate Euplotes sp., the rotifer Brachionus rotundiformis, and the copepod Apocyclops royi nauplii—during the first feeding stage. However, the specific contributions of these live feed organisms to larval survival and growth remain unclear. Moreover, the optimal feeding density for the critical initial live feed organism has not been determined experimentally. In this study, we aimed to enhance the larviculture protocol for White‐barred Goby by introducing Portuguese oyster Crassostrea angulata trochophores and by addressing these knowledge gaps. Methods: Larvae were initially cultured through individual and combined feeding with four live feed organisms: Euplotes sp., Portuguese oyster trochophores, B. rotundiformis, and A. royi nauplii. The objective was to identify the optimal initial live feed organism during the first feeding stage by assessing the survival and growth performance of larvae. Subsequently, using this optimal live feed organism, larvae were cultured at four feeding densities (2, 5, 10, and 20 individuals/mL). Through evaluating feeding incidence, feeding intensity, survival, and growth performance, the aim was to determine the optimal feeding density for the selected live prey. Result: Our experiments revealed that White‐barred Goby larvae could consume both oyster trochophores and Euplotes sp. during the first feeding stage. However, larvae exhibited superior survival and growth performance when fed oyster trochophores. The optimal feeding density of oyster trochophores was determined to be 10 individuals/mL, while a feeding density as high as 20 individuals/mL resulted in decreased larval feeding incidence. Conclusion: These findings have significant implications for enhancing larval production programs for marine ornamental gobies and promoting their sustainable commercialization. Impact statementOur study enhances the larval rearing of the popular marine ornamental fish, the White‐barred Goby. Feeding them with oyster trochophores at appropriate densities improves their survival and growth. This leads to more efficient commercial production, alleviating fishing pressure on wild populations. It marks a significant stride in preserving the diversity of coral reef fish and fostering a sustainable aquarium industry. [ABSTRACT FROM AUTHOR]

Sounds from fish and invertebrates in coral reefs can create persistent cacophonies that can be recorded for ecosystem monitoring, including during nighttime hours where visual surveys are typically not feasible. Here we use soundscape measurements in Hawaii to demonstrate that multiple coral reef communities are rapidly responsive to shifts in nighttime ambient light, with sustained changes in biological sound between moonrise and moonset. High frequency pulse train sounds from fish (0.5-1.5 kHz) are found to increase during moonlight hours, while low frequency fish vocalizations (0.1-0.3 kHz) and invertebrate sounds (2-20 kHz) are found to decrease during moonlight hours. These discoveries suggest that the rising and setting of the moon triggers regular shifts in coral reef ecosystem interactions. Future acoustic monitoring of reef health may be improved by comparing soundscapes during moonlight and non-moonlight hours, which may provide early indicators of shifts in the relative abundance of separate reef communities. [ABSTRACT FROM AUTHOR]

Cryptobenthic reef fishes (CRFs) are often neglected in reef biodiversity assessments, trophodynamic studies, and biomass models. This oversight is due to the challenges associated with recording them in traditional underwater visual surveys and the scarcity of literature detailing their life history, ecology, and body growth parameters. Given their pivotal role in the functioning and maintenance of coral reef ecosystems, addressing these information gaps for CRF species is of great importance. In this study, we have computed the length-weight relationships (LWRs) for 32 CRF species spanning seven families in the Red Sea. This marks the first comprehensive report of LWR parameters for CRFs from this region, and for 31 of these species, it serves as their first LWR data report. The coefficient of determination (r2) ranged from 0.82 to 0.99, indicating a good fit for the LWRs. Half of the presented species belong to the Gobiidae family, including three undescribed species. In addition, we present LWRs for species from the families Blenniidae (5 spp.), Tripterygiidae (2 spp.), Apogonidae (4 spp.), Pseudochromidae (3 spp.), Plesiopidae (1 spp.), and Scorpaenidae (1 spp.). This research contributes invaluable insights into the growth patterns of CRFs not only in a global context but also beyond, as 50% of the recorded species are endemic to the region. The data generated holds great significance for conducting functional diversity analyses, ecosystem assessments, and coral reef health monitoring. By capturing this critical information, this work provides foundational metrics to take significant strides toward the conservation of these essential coral reef fishes. [ABSTRACT FROM AUTHOR]

The article focuses on the 102nd annual meeting of the American Society of Ichthyologists and Herpetologists (ASIH) held in conjunction with the Herpetologists' League (HL), the Society for the Study of Amphibians and Reptiles (SSAR), and the American Elasmobranch Society (AES) in Norfolk, Virginia. Topics covered include the acknowledgment of Indigenous land, student representation, and discussions on virtual meetings and financial reports.

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This document is a reference list or bibliography for a scientific article published in Frontiers in Marine Science. The article focuses on the fish biodiversity of Courtown Cays in the Seaflower Biosphere Reserve in the Colombian Caribbean. The study recorded 223 fish species, with Serranidae and Labridae being the most species-rich families. The article emphasizes the importance of protecting vulnerable ecosystems like oceanic coral reefs and highlights the need for conservation and sustainable use of these resources. The dataset from the study is available through online repositories. The document also includes a list of references cited in the article, covering topics such as fish biodiversity, coral reef ecosystems, and marine conservation. [Extracted from the article]

Semi‐enclosed seas are often associated with elevated local threats and distinct biogeographic patterns among marine fishes, but our understanding of how fish assemblage dynamics vary in relation to relatively small semi‐enclosed seas (e.g., the Gulf of Aqaba) remains limited. Baited remote underwater video surveys (n = 111) were conducted across ~300 km of coral reef habitats in the Gulf of Aqaba and the northern Red Sea. A total of 55 predatory fish species were detected, with less than half of all species (n = 23) observed in both basins. Relative abundance patterns between the Gulf of Aqaba and the northern Red Sea were variable among taxa, but nearly twice as many predatory fish were observed per unit of effort in the northern Red Sea. In general, assemblages in both basins were dominated by three taxa (Epinephelinae, Carangidae, and Lethrinidae). Large‐bodied and threatened species were recorded at very low abundances. Multivariate analysis revealed distinct assemblage structuring of coral reef predators between the Gulf of Aqaba and the northern Red Sea. Most of the species driving these differences were recorded in both basins, but occurred at varying levels of abundance. Environmental factors were largely unsuccessful in explaining variation in assemblage structuring. These findings indicate that biological assemblages in the Gulf of Aqaba are more distinct than previously reported and that reef fish assemblage structuring can occur even within a relatively small semi‐enclosed sea. Despite inter‐basin assemblage structuring, the overall low abundance of vulnerable fish species is suggestive of overexploitation in both the Gulf of Aqaba and the northern Red Sea of Saudi Arabia. As the region surveyed is currently undergoing large‐scale coastal development, the results presented herein aim to guide spatial management and recovery plans for these coral reef systems in relation to this development. [ABSTRACT FROM AUTHOR]

The majority of the transcribed genome does not have coding potential but these non‐coding transcripts play crucial roles in transcriptional and post‐transcriptional regulation of protein‐coding genes. Regulation of gene expression is important in shaping an organism's response to environmental changes, ultimately impacting their survival and persistence as population or species face global change. However, the roles of long non‐coding RNAs (lncRNAs), when confronted with environmental changes, remain largely unclear. To explore the potential role of lncRNAs in fish exposed to ocean acidification (OA), we analyzed publicly available brain RNA‐seq data from a coral reef fish Acanthochromis polyacanthus. We annotated the lncRNAs in its genome and examined the expression changes of intergenic lncRNAs (lincRNAs) between A. polyacanthus samples from a natural CO2 seep and a nearby control site. We identified 4728 lncRNAs, including 3272 lincRNAs in this species. Remarkably, 93.03% of these lincRNAs were species‐specific. Among the 125 highly expressed lincRNAs and 403 differentially expressed lincRNAs in response to elevated CO2, we observed that lincRNAs were either neighboring or potentially trans‐regulating differentially expressed coding genes associated with pH regulation, neural signal transduction, and ion transport, which are known to be important in the response to OA in fish. In summary, lncRNAs may facilitate fish acclimation and mediate the responses of fish to OA by modulating the expression of crucial coding genes, which offers insight into the regulatory mechanisms underlying fish responses to environmental changes. [ABSTRACT FROM AUTHOR]

An important, yet overlooked form of anthropogenic pollution is sensory pollution, and one of the most pervasive forms of sensory pollution is artificial light at night (ALAN). Despite the growing use of ALAN across the globe, limited research has examined the impacts of ALAN on coral reef fish. This study aims to further our understanding of the behavioural impacts of light pollution on fish by exposing the humbug damselfish (Dascyllus aruanus) to ALAN (∼15–25 lux, white LED light) over a period of 14 days, in situ. We assessed nocturnal activity, and diurnal shelter use and emergence time following a simulated threat in natural (control) and ALAN conditions. D. aruanus colonies exposed to ALAN were active at night and were lacking cryptic colouration observed in control fish, however this altered nocturnal activity did not appear to impact the diurnal behaviours we measured. Our findings provide critical insight into the impact of ALAN exposure to nocturnal behaviour of a diurnal fish and highlight the potential for increased risk of nocturnal predation under ALAN. Further studies with a longer ALAN exposure time will help illuminate the extent of behavioural changes and implications caused by ALAN in shallow coral reef systems. [Display omitted] [ABSTRACT FROM AUTHOR]

The abundance and distribution of demersal fishes rely on larvae successfully settling from the pelagic environment to a benthic habitat and their subsequent survival. With high mortality rates during this life stage, settling to a habitat that maximizes survival is critical. However, relationships between settlement choices and subsequent survival are poorly understood and may vary among species with different habitat preferences. To test this, we focused on five congeneric (Pomacentrus) damselfish species that are known to differ in their habitat choices and explored whether habitat associations at settlement influenced survival. Newly settled individuals were tagged and monitored daily for two weeks to estimate natural mortality rates. Morphological attributes of fish and characteristics of settlement habitats, including depth, rugosity, benthic substrata, and local fish assemblages, were used to predict mortality. We found that some species displayed stronger associations with specific benthic substrata at settlement, but contrary to expectations, these selected habitat characteristics were relatively weak predictors of survivorship. Our survival analysis revealed that the best predictors of survivorship were rugosity (P. adelus and P. amboinensis) and two morphological traits, body depth and ocellus size (P. chrysurus and P. adelus). Interestingly, we found that P. moluccensis that settled in areas of high coverage of mounding coral experienced increased mortality. Of the remaining substrata, analysis showed that instead of associating with habitat characteristics enhancing survivorship, individuals tended not to associate with habitats characteristics that increased mortality (e.g., Turbinaria and sand). This study highlights the species-specific drivers of early post-settlement mortality in coral reef fishes. [ABSTRACT FROM AUTHOR]

Dispersal, the movement of individuals away from their natal location to another location, is a basic driver of ecological and evolutionary processes. Direct measures of marine fish larval dispersal have shown that individual dispersal distances vary over several orders of magnitude within a species. We currently do not know the causes of this intraspecific variation. One plausible explanation is dispersal plasticity. Dispersal plasticity, especially as an adaptive parental effect where parents alter the dispersal phenotype of their offspring, is widespread in terrestrial systems, but has yet to be described in marine fishes. In this study, we address a key, although often untested, condition for the evolution of dispersal plasticity as an adaptive parental effect: whether parents can reliably predict the environmental conditions that their offspring will encounter. Using a wild population of orange anemonefish, Amphiprion percula, we investigate habitat quality predictability by testing for spatial autocorrelation in three habitat quality indicators: anemone size, female size, and egg clutch size. We found strong, positive spatial autocorrelation for all three habitat quality indicators to about 500 m. This suggests selection might favor parents that increase allocation to offspring that stay within 500 m if they are in good habitat and increase allocation to offspring that travel farther if they are in poor habitat. Results from this study lay solid foundations for further investigation of dispersal plasticity in A. percula and other marine fishes. Incorporating dispersal plasticity in our investigations of marine fish larval dispersal could contribute to a greater understanding of marine fish metapopulation dynamics, and therefore fisheries recovery and reserve management. [ABSTRACT FROM AUTHOR]

Coral reefs are in global decline primarily due to climate change. Herbivory is often viewed as key to maintaining coral‐dominated reefs, and herbivore management is gaining traction as a possible strategy for promoting reef resilience. The functional impact of herbivorous fishes has typically been inferred from total biomass, but robust estimates of ecological processes are needed to better inform management targets. Here, we provide a framework to calculate rates of herbivory across Pacific reefs. We synthesized available observations of foraging metrics in relation to fish body size and found considerable variation, even among closely related species. We then applied these allometric functions to survey data and calculated rates of herbivory for acanthurids and scarines, which make up the vast majority of herbivorous fish biomass in the Pacific. Estimated rates of algal consumption, area scraped, and bioerosion varied across islands, with noticeable differences that may align with the relative influence of human population density among underlying herbivore functional groups. We found no evidence of compensatory relationships among herbivore processes whereby decreasing rates in one type of herbivory is offset by increasing rates in another. We observed nonlinear, positive relationships between fish biomass and rates of herbivory. Yet, for a given biomass, the corresponding rates of herbivory varied among regions, and we observed instances where islands with the greatest biomass did not also have the highest rates of herbivory. Islands with the largest size classes of herbivores did not consistently exhibit greater rates of herbivory, and we did not find a clear, consistent pattern between the number of fish species and corresponding rates of herbivore processes. Cropping Acanthurus spp. provided the greatest proportion of algal consumption at every island, yet no single species accounted for the majority of this process, whereas we identified parrotfish species that provided >75% of scraping or bioerosion at certain islands. Our results emphasize the importance of considering the species and size composition of herbivore assemblages when estimating processes, rather than relying on total biomass alone. Lastly, we highlight gaps in foraging observations and additional work needed to further broaden our ability to quantify the ecological processes of herbivores. [ABSTRACT FROM AUTHOR]

A new labrid fish species, Halichoeres sanchezi n. sp., is described from eight specimens collected in the Revillagigedo Archipelago in the tropical eastern Pacific Ocean, off the coast of Mexico. The new species belongs to the Halichoeres melanotis species complex that is found throughout the region, differing by 2.4% in the mtDNA cytochrome c oxidase I sequence from its nearest relative, H. melanotis from Panama, and 2.9% from Halichoeres salmofasciatus from Cocos Island, off Costa Rica. The complex is distinguished from others in the region by having a black spot on the opercular flap and a prominent black area on the caudal fin of males. The juveniles and initial phase of the new species closely resemble those of H. salmofasciatus and Halichoeres malpelo from Malpelo Island of Colombia, differing in having an oblong black spot with a yellow dorsal margin on the mid-dorsal fin of initial-phase adults as well as on juveniles. In contrast, the terminal-phase male color pattern is distinct from other relatives, being vermilion to orangish brown with dark scale outlines, a white patch on the upper abdomen, and a prominent black band covering the posterior caudal peduncle and base of the caudal fin. The new species adds to the list of endemic fish species for the isolated archipelago and is an interesting case of island endemism in the region. The discovery was made during the joint 2022 collecting expedition to the archipelago, which featured a pioneering collaborative approach to an inventory of an island ichthyofauna, specifically including expert underwater photographers systematically documenting specimens in situ, before hand-collection, and then photographed fresh, tissue-sampled, and subsequently vouchered in museum collections. [ABSTRACT FROM AUTHOR]

Overfishing remains a threat to coral reef fishes worldwide, with large carnivores often disproportionately vulnerable. Marine protected areas (MPAs) can restore fish populations and biodiversity, but their effect has been understudied in mesophotic coral ecosystems (MCEs), particularly in the Coral Triangle.Videos were analysed from baited remote underwater video systems deployed in 2016 to investigate the assemblage structure of large carnivorous fishes at shallow (4–12 m) and mesophotic (45–96 m) depths in two of the largest and most isolated MPAs in the Philippines: an uninhabited, fully no‐take MPA enacted in 1988 (Tubbataha Reefs Natural Park) and an archipelagic municipality surrounded by an extensive but not fully no‐take MPA declared in 2016 (Cagayancillo). Taxa focused on were groupers (Serranidae), snappers (Lutjanidae), emperors (Lethrinidae), jacks (Carangidae) and the endangered Cheilinus undulatus (Labridae).Mean abundance and species richness were not greater in TRNP than in Cagayancillo regardless of depth despite long‐term protection in the former. Limited impacts of fishing in Cagayancillo may explain this result. Differentiation of fish assemblages was evident between TRNP and Cagayancillo but more obvious between depths at each location, probably due more to habitat than MPA effects. In Cagayancillo, overall carnivorous reef fish, grouper and jack mean abundance were 2, 2 and 10 times higher, respectively, at mesophotic depths, suggesting that MCEs can serve as deep refugia from fishing.These findings of differentiation between depths and higher abundance of certain taxa in mesophotic depths emphasize that MCEs are distinct from shallow reefs, serve as important habitat for species susceptible to overfishing and, thus, must be explicitly included in the design of MPAs. This study also highlights the value of maintaining strict protection of MPAs like TRNP for the Coral Triangle and an opportunity to safeguard intact fish assemblages in Cagayancillo by expanding its no‐take zones. [ABSTRACT FROM AUTHOR]

– We describe a new species of the progenetic gobiid fish genus Schindleria from Rapa Nui (Easter Island, Chile). Schindleria squirei n. sp. belongs to the long dorsal-fin type (LDF) of Schindleria. The new species is characterized by an in vivo translucent, elongate and slender body; a dorsal fin longer than the anal fin (predorsal-fin length 60.2% in SL vs. preanal-fin length 70.4% in SL); a short tail (29.8% in SL); a short (10.9% in SL) and massive head (48.7% width in head length) with a convex dorsal profile; a long and relative narrow pectoral-radial plate (52.4% width of pectoral-radial plate length); 20-21 dorsal-fin rays; 12 anal-fin rays; first anal-fin ray situated opposite the dorsal-fin ray 9-10; teeth on both jaws tiny, conical, densely set; a straight, thin, rod-like maxilla, posteriorly flattened, and with a plate-like expansion; a lower jaw which forms a wide arch with a truncated, at the symphysis somewhat dented, margin and only slightly exceeding the upper jaw; black eyes; a dorsally pigmented swim-bladder; and no other external pigmentation on its body, in preserved specimens. [ABSTRACT FROM AUTHOR]

Climate-driven species redistributions are facilitated by niche modifications that increase a species's chances of establishment in novel communities. It is well understood how range-extending species adjust individual niche traits when entering novel environments, yet whether modification of ecological niche traits collectively alters the pace of range extensions or contractions remains unknown. We quantified habitat niche, abundance, physiological performance and cellular defence/damage of range-extending coral reef fishes and coexisting local temperate fishes along a 2000 km latitudinal gradient. We also assessed their dietary and behavioural niches, and establishment potential, to understand whether ecological generalism facilitates successful range extension of coral reef fishes. The coral reef fish that increased all ecological niches, showed stronger establishment, increased physiological performance and cellular damage, but decreased cellular defence at their cold-range edge, whereas tropical species that showed unmodified ecological niches showed lower establishment. One temperate species showed decreased abundance, habitat niche width and body condition, but increased cellular defence, cellular damage and energy reserves at their warm-trailing range, while other temperate species showed contrasting responses. Therefore, ecological generalists might be more successful than ecological specialists during the initial stages of climate change, with increasing future warming strengthening this pattern by physiologically benefitting tropical generalists but disadvantaging temperate specialists. [ABSTRACT FROM AUTHOR]

Biting to obtain attached benthic prey characterizes a large number of fish species on coral reefs, and is a feeding mode that contributes to important ecosystem functions. We use high-speed video to reveal the mechanisms used by a surgeonfish, Acanthurus leucosternon, to detach algae. After gripping algae in its jaws, the species pulls it by ventrally rotating both the head and the closed jaws, in a novel use of the intra-mandibular joint. These motions remain in the plane of the fish, reducing the use of a lateral head flick to detach the algae. The novel ability to bite and pull algae off the substrate without bending the body laterally minimizes exposure to high water flows, and may be an adaptation to feeding in challenging reef habitats such as the crest and flat. Therefore, our results could potentially represent a key milestone in the evolutionary history of coral reef trophodynamics. High-speed video of feeding in a surgeonfish reveals novel functions, and suggests an adaptation to feeding in high flow environments, as well as how fish interact with the substrate [ABSTRACT FROM AUTHOR]

This work aimed to study the diversity and abundance of the common commercial fish communities at six coastal coral reef bays around Marsa Alam city on the southern coast of the Egyptian Red Sea. Fish communities were counted at six sites, Marsa Saifen, Marsa Shoni2, Marsa Shoni4, Marsa Fujiri, Marsa Nakari and Marsa Hamata using underwater visual census technique (UVC). A total of 2458 fish belonging to 16 families and 44 species of commercial fish were identified. Five families (Scaridae, Serranidae, Mullidae, Lutjanidae and Lethrinidae) contained 27 species (61.4% of the total number of species). Four families (Mullidae, Siganidae, Scaridae and Lutjanidae) were the most abundant and they formed about 91.3% of the total number of recorded individuals. Mullidae was the most abundant constituting about 63.5% of the fish community. The most abundant species was Mulloidichthys flavolineatus, of the family Mullidae with 1390 individuals forming 56.5%, followed by Siganus rivulatus of the family Siganidae (251, 10.2%). The highest fish abundance was recorded in Marsa Saifen (609 individuals) and the lowest abundance was recorded at Hamata (271 individuals). The highest number of species (23 species) was observed in Marsa Fujiri, whereas the lowest number of species (17 species ( was recorded in Hamata. The knowledge of the ecology of marine fish communities in the Red Sea is sparse.Hence, the quantitative ecological studies are needed. Action plans and research programs must be developed to reduce early stages bycatch and initiate fisheries management strategies for commercially exploited species. [ABSTRACT FROM AUTHOR]

Predation is a crucial ecosystem function, transferring nutrients and shaping the abundance and diversity of animals within communities. On coral reefs, fish-fish predation (i.e., piscivory) is arguably one of the best known ecosystem functions, yet is also one of the least well quantified. Recent work has suggested that the prey capture performance of piscivorous fishes may differ when feeding on actively swimming vs. cryptobenthic fish prey. However, the extent of this difference remains unquantified. Our goal, therefore, was to conduct performance-based experiments comparing piscivorous fishes feeding on two different fish prey types, namely, actively swimming vs. cryptobenthic prey (i.e., prey sitting on the benthos). While predators were able to immediately detect actively swimming prey, when feeding on cryptobenthic prey, predators were generally unable to detect the prey until it moved. Both focal predators, the grabber Pseudochromis fuscus and the engulfer Pterois volitans were less successful at capturing cryptobenthic prey (mean 28% probability of capture), compared to actively swimming prey (85%). Overall, our study demonstrates the heterogeneous nature of fish predation on coral reefs, and the challenges of feeding on different prey functional groups. [ABSTRACT FROM AUTHOR]

Ravikumar, T.; Neethirajan, N.; Chandran, S.; Sangaralingam, M.; Natarajan, J.; Umamaheswar, T., and Padmavathy, P., 2024. Ichthyofaunal diversity from longline catches in the Gulf of Mannar (GoM), southeast coast of India. Journal of Coastal Research, 40(1), 115–128. Charlotte (North Carolina), ISSN 0749-0208. The present study aimed to document the spatial and temporal ichthyofaunal diversity of reef associated fishes caught with experimental longlines fitted with different "J" hook sizes (no. 12, no. 9, and no. 6) and shapes (Straight, Kirbed, and Reversed) from the Therespuram and Mundhal fish landing centres of Gulf of Mannar (GoM), Southeast Coast of India. Sampling was done at a fortnightly interval from February 2020 to January 2022. The total of 21,322 fish diversity includes 37 species of fish belonging to 15 genera, 10 families, and seven orders have been recorded during the study period. Order wise and species wise landing revealed the dominance of Perciformes with five families (Haemulidae, Lethrinidae, Lutjanidae, Nemipteridae, and Serranidae) and 28 species while in the case of order Centrarchiformes it represented with only one species. Fish diversity of GoM was assessed by calculating the various diversity indices such as Shannon–Weiner biodiversity index (H′) ranged from 2.31 to 3.29, Simpson's Dominance Index (1-λ′) ranged from 1.80 to 4.73, Pielou's Species Evenness index (J′) ranged from 0.90 to 0.99, and Margalef index (d) of species richness ranged from 2.03 to 4.73. The results of the present study revealed that the experimental longlines caught one endangered (3%), four vulnerable (11%), two not evaluated (5%), one data deficient (3%), and 29 species (78%) of least concern as per the International Union for Conservation of Nature status. The assessment is a prerequisite for understanding the biodiversity and to help fishery managers to evolve new strategies for the sustainable exploitation and conservation of coral reef associated fishes in this region. [ABSTRACT FROM AUTHOR]

This document discusses the effects of a sudden cold snap on reef fishes in Okinawa-jima Island, Japan. The researchers conducted surveys on two beaches and recorded a total of 169 stranded dead fishes from 17 families. The highest fish mortality was observed during the peak of the cold snap, with a significant decline in mortality on the following day. The majority of the dead fishes belonged to the cardinalfish family. The study highlights the vulnerability of small and thermally sensitive fish individuals to rapid temperature changes and emphasizes the importance of temperature change rate as a stressor for reef fishes. [Extracted from the article]

Global degradation of coral reefs is reflected in the destruction of shelters in various environments and threatens the stability of marine ecosystems. Artificial shelters offer an alternative, but their design could be more challenging due to limited knowledge regarding desired inhabitants' shelter characteristics and preferences. Investigating these preferences is resource-intensive, particularly regarding small shelters that mimic natural reef conditions. Furthermore, for statistical analysis in small shelters, fish abundance may need to be higher. We propose a method to characterize the species-specific shelter preferences using low-volume data. During a study conducted from January 2021 to April 2022, round clay artificial shelters (RAS) were deployed on an abandoned oil pier to examine a coral reef fish community. We recorded 92 species from 30 families and grouped them into systematic (families) and functional (dietary group) classes. Grouping enabled us to examine each group's preference, while crossing these group preferences revealed species-specific preferences, which matched field observations. This approach proved effective in profiling the shelter preferences of 17 species while having limited resources. These profiles may later allow the establishment of ecological-oriented artificial reefs. Moreover, this method can be applied to other applications using other shelter designs, sizes, and research sites. [ABSTRACT FROM AUTHOR]

Triphenyltin (TPT), a kind of persistent pollutant, is prevalent in the aquatic environment and could pose a threat to coral reef fish. However, little is known about the toxicity of TPT on coral reef fish, especially regarding the representative characteristics of body coloration. Therefore, this study chose the clownfish (Amphiprion ocellaris) in order to investigate the effects of TPT exposure on its carotenoid-based body coloration under the environmentally relevant concentrations (0, 1, 10 and 100 ng/L). After TPT exposure for 60 d, the carotenoid contents were decreased and histological damage in the liver was found, shown as nuclear pyknosis and shift, lipid deposition and fibrotic tissue hyperplasia. Liver transcriptomic analysis showed that TPT exposure interfered with oxidative phosphorylation and fatty acid metabolism pathways, which related to carotenoids uptake and metabolism. Furthermore, TPT exposure led to oxidative damage in the liver, which is responsible for the changes in the antioxidant capacity of enzymes, including GSH, MDA, POD, CAT and T-SOD. TPT exposure also affected the genes (Scarb1, CD36, Stard3 and Stard5) related to carotenoid absorption and transport, as well as the genes (GstP1 and Bco2) related to carotenoid deposition and decomposition. Taken together, our results demonstrate that TPT influenced carotenoid-based coloration in coral reef fish by disrupting carotenoid metabolism, which complements the ecotoxicological effects and toxic mechanisms of TPT and provides data for the body color biology of coral reef fishes. [ABSTRACT FROM AUTHOR]

The establishment of protected areas to face global diversity declines has mainly prioritized taxonomic diversity, leaving aside phylogenetic and functional diversities, which determine ecosystem functioning and resilience. Furthermore, the assessment of protected areas' effectiveness is mainly done using short‐duration surveys (<2 h), which may undermine the detection of rare species.Through a long‐duration video approach, reef fish taxonomic, phylogenetic and functional facets of diversity were assessed for 3 days within a fully protected area and a nearby poorly protected area in Mayotte Island (Western Indian Ocean).We found that temporally rare species contributed to more than 60% of the taxonomic facet and 85% of the functional facet of biodiversity found on each site. Those rare species, which harbour the most distinct trait values, also make reef fish diversity particularly vulnerable to their loss. Taxonomic, phylogenetic and functional richness were similar between the fully protected area and the poorly protected area, while the species, lineage and trait compositions were markedly different.These results pinpoint the importance of considering taxonomic, functional and phylogenetic dissimilarities while assessing protected areas' effectiveness, instead of using only richness. In addition, benefits of the fully protected area were detected only using more than 15 h of video survey, which emphasizes the importance of long‐duration remote approaches to capture the within‐ and between‐day temporal variations. [ABSTRACT FROM AUTHOR]

Simple Summary: Adaptive radiation can lead to both morphological convergence and divergence. Understanding the molecular mechanisms driving these changes is essential for deciphering evolutionary relationships among species and the ecological implications of phenotypic variations in organisms' natural habitats. The humpback grouper Cromileptes altivelis represents a distinctive coral reef fish classified in a monotypic genus due to its unique morphology. However, molecular phylogenetic analysis challenges this classification, suggesting its placement within the genus Epinephelus. Interestingly, the characteristic 'sunken head and humpback' does not manifest in C. altivelis during the early differentiation stages but gradually emerges during its developmental stages. Investigating the genetic basis of this phenotypic specialization feature is expected to provide evidence for resolving taxonomic controversies and advancing our understanding of speciation studies. In this study, we identified the important contribution of frontal bone remodeling in shaping the 'sunken head and humpback' appearance in C. altivelis. Our investigation identified a developmental milestone at a total length of 5–6 cm, making the onset of its morphologic specialization in this species. A comparative analysis with closely related species reveals heightened activity in the frontal osteoblasts of the humpback grouper, potentially providing a physiological basis for its remodeling. Furthermore, our findings highlight that a significant upregulation in the expression levels of Ihhb, Ptch1, and Gli2a genes was seen in C. altivelis within the specified developmental stage, indicating an important involvement of the Ihhb-Ptch1-Gli2a signaling pathway in initiating the morphological specialization. We hypothesized that Ihh signaling could be attributed to shifts in mechanical stress, resulting from muscle traction on the frontal bone due to changes in swimming patterns during development. This study not only offers significant insights into unraveling the molecular mechanisms that govern phenotypic specialization and ecological adaptations in the humpback grouper but also serves as a valuable reference for studies on fishes with a controversial morphology and molecular phylogeny. [ABSTRACT FROM AUTHOR]

In March 2020, the world went into lockdown to curb the spread of the novel coronavirus (SARS-CoV-2), with immediate impacts on wildlife across ecosystems. The strict 2-year long lockdown in Grand Cayman provided an unprecedented opportunity to assess how the 'human confinement experiment' influenced the community composition of reef fish. Using a suite of multivariate statistics, our findings revealed a stark increase in reef fish biomass during the 2 years of lockdown, especially among herbivores, including parrotfish, with drastic increases in juvenile parrotfishes identified. Additionally, when comparing baseline data of the community from 2018 to the 2 years during lockdown, over a three-fold significant increase in mean reef fish biomass was observed, with a clear shift in community composition. Our findings provide unique insights into the resilience of reef fish communities when local anthropogenic stressors are removed for an unprecedented length of time. Given the functional role of herbivores including parrotfish, our results suggest that reductions in human water-based activities have positive implications for coral reef ecosystems and should be considered in future management strategies. [ABSTRACT FROM AUTHOR]

Appreciation for the role of cryptofauna in ecological systems has increased dramatically over the past decade. The impacts blood-feeding arthropods, such as ticks and mosquitos, have on terrestrial communities are the subject of hundreds of papers annually. However, blood-feeding arthropods have been largely ignored in marine environments. Gnathiid isopods, often referred to as "ticks of the sea", are temporary external parasites of fishes. They are found in all marine environments and have many consequential impacts on host fitness. Because they are highly mobile and only associated with their hosts while obtaining a blood meal, their broader trophic connections are difficult to discern. Conventional methods rely heavily on detecting gnathiids on wild-caught fishes. However, this approach typically yields few gnathiids and does not account for hosts that avoid capture. To overcome this limitation, we sequenced blood meals of free-living gnathiids collected in light traps to assess the host range and community-dependent exploitation of Caribbean gnathiid isopods. Using fish-specific COI (cox1) primers, sequencing individual blood meals from 1060 gnathiids resulted in the identification of 70 host fish species from 27 families. Comparisons of fish assemblages to blood meal identification frequencies at four collection sites indicated that fishes within the families Haemulidae (grunts) and Lutjanidae (snappers) were exploited more frequently than expected based on their biomass, and Labrid parrotfishes were exploited less frequently than expected. The broad host range along with the biased exploitation of diel-migratory species has important implications for the role gnathiid isopods play in Caribbean coral reef communities. [ABSTRACT FROM AUTHOR]

Parrotfishes are a functionally critical component of Caribbean reef fish assemblages, with large‐bodied parrotfish species exerting particularly important top‐down control on macroalgae. Despite their importance, low biomasses of large‐bodied parrotfishes on many reefs hamper our ability to study and understand their ecology. Florida reefs, where most parrotfish fishing has been illegal since 1992, present a unique opportunity to explore covariates of their distribution. Using boosted regression tree models and 23 covariates, this study identified the major predictors of four species of Atlantic large‐bodied parrotfishes. Maximum hard substrate relief, the area of the surrounding reef, and the availability of seagrass habitat were each positively related to parrotfish presence. Strong positive relationships between parrotfish presence and biomass and the biomass of other parrotfishes on a reef suggest that all four species responded to a similar subset of environmental conditions. However, relationships between parrotfish presence and biomass and depth, habitat type, coral cover, and the proximity of a reef to deepwater habitats differed among species, highlighting distinct habitat preferences. These results can improve managers' ability to target important biophysical correlates of large‐bodied parrotfishes with appropriate management interventions and identify areas for protection. [ABSTRACT FROM AUTHOR]

Anthropogenic stressors are causing widespread coral mortality, leading to loss of coral cover and decreased structural complexity that threatens reef biodiversity, functioning, and ecosystem services. Reef fishes are intimately linked to coral reef complexity, but we lack a generic understanding of which species are particularly affected by reef flattening and what traits make them susceptible. We used extensive species‐ and trait‐based analyses to build a framework for western Atlantic fish association with both structural complexity and coral cover to better understand the implications of reef degradation. These analyses also highlighted the relative importance of live coral versus the structure it provides to reef fishes, which currently remains unclear. We modeled how 25 biophysical and anthropogenic factors correlated with the densities of 109 fish species across 3292 Floridian reef sites. The importance of a metric of structural complexity and coral cover to the abundance of each species was then isolated. Species with positive associations were categorized as likely future 'losers' and negative associations as 'winners'. We predicted that 53% of species will be losers on low‐relief reefs, while only 11% were losers with decreased coral cover. We found morphological, behavioral, and ecological traits, not phylogeny, mediate species' responses to reef degradation and that the loss of structure seemed more critical than the loss of coral cover. Eight traits explained 79.7% of the variation in species' associations with relief and six traits explained 27.8% of associations with coral cover. Smaller, streamlined, habitat and trophic generalists are more likely winners on flattened reefs and large‐bodied predators, among other taxa, are likely losers of reef flattening. Identifying these important traits provides insight into mechanisms that may link fish and complex habitats, which allows us to better predict assemblage‐wide responses to future reef flattening. [ABSTRACT FROM AUTHOR]

Understanding the relative effectiveness and enabling conditions of different area‐based management tools is essential for supporting efforts that achieve positive biodiversity outcomes as area‐based conservation coverage increases to meet newly set international targets. We used data from a coastal social–ecological monitoring program in 6 Indo‐Pacific countries to analyze whether social, ecological, and economic objectives and specific management rules (temporal closures, fishing gear‐specific, species‐specific restrictions) were associated with coral reef fish biomass above sustainable yield levels across different types of area‐based management tools (i.e., comparing those designated as marine protected areas [MPAs] with other types of area‐based management). All categories of objectives, multiple combinations of rules, and all types of area‐based management had some sites that were able to sustain high levels of reef fish biomass—a key measure for coral reef functioning—compared with reference sites with no area‐based management. Yet, the same management types also had sites with low biomass. As governments advance their commitments to the Kunming–Montreal Global Biodiversity Framework and the target to conserve 30% of the planet's land and oceans by 2030, we found that although different types of management can be effective, most of the managed areas in our study regions did not meet criteria for effectiveness. These findings underscore the importance of strong management and governance of managed areas and the need to measure the ecological impact of area‐based management rather than counting areas because of their designation. [ABSTRACT FROM AUTHOR]

Synchronous multispecific coral spawning generally occurs annually and forms an integral part of the coral life cycle. Apart from spawning times and species participation, however, much else remains unknown. Here, we applied environmental DNA (eDNA) metabarcoding to study two tropical reef sites of contrasting coral cover before, during and after coral spawning. Using coral‐ITS2 and vertebrate‐12S markers, we evaluated eDNA as an alternative monitoring tool by assessing its capabilities in detecting spawning species and tracking relative abundances of coral and fish eDNA. Over 3 years, elevated eDNA coral signals during the event (proportional read increase of up to five‐fold) were observed, detecting a total of 38 coral and 133 fish species with all but one of the coral species visually observed to be spawning. This is also the first demonstration that eDNA metabarcoding can be used to infer the diurnal partitioning of night‐ and day‐time spawning, spawning in coral species overlooked by visual surveys, and the associated changes in fish trophic structures as an indicator of spawning events. Our study paves the way for applied quantitative eDNA metabarcoding approaches to better study ephemeral and important biological events. [ABSTRACT FROM AUTHOR]

Virtual reality (VR) enables standardized stimuli to provoke behavioural responses in animals; however, in fish studies VR has been limited to either basic virtual simulation projected below the bowl for freely swimming individuals or a simple virtual arena rendered over a large field of view for head-restrained individuals. We developed a novel immersive VR set-up with real-time rendering of animated 3D scenarios, validated in a proof-of-concept study on the behaviour of coral reef postlarval fish. Fish use a variety of cues to select a habitat during the recruitment stage, and to recognize conspecifics and predators, but which visual cues are used remains unknown. We measured behavioural responses of groups of five convict postlarval surgeonfish, Acanthurus triostegus , to simulations of habitats, static or moving shoals of conspecifics, predators and nonaggressive heterospecifics. Postlarval fish were consistently attracted to virtual corals and conspecifics presented statically, but repulsed by their predators (bluefin jacks, Caranx melampygus). When simulated shoals repeatedly passed nearby, they were again attracted by conspecifics, showing a tendency to follow the shoal, whereas they moved repeatedly to the back of the passing predator shoal. They also discriminated between species of similar sizes: they were attracted more to conspecifics than butterflyfish, Forcipiger longirostris , and repulsed more by predators than parrotfish, Scarus psittacus. The quality of visual simulations was high enough to identify visual cues (size, body shape, colour pattern) used by postlarval fish in species recognition. Despite a tracking technology limited to fish 2D positions in the aquarium, preventing the real-time updating of the rendered viewpoint, we could show that VR and modern tracking technologies offer new possibilities to investigate fish behaviour through the quantitative analysis of their physical reactions to highly controlled scenarios. • Immersive virtual reality set-up with automated tracking for fish behaviour. • Highly realistic and well-controlled animated 3D scenarios. • Real-time collection of numerous parameters about fish kinematics. • Proof of concept study on postlarval surgeonfish, Acanthurus triostegus. • Modelling of reactions to virtual habitat, adult conspecifics and predators. [ABSTRACT FROM AUTHOR]

We examined reef fish assemblages in and adjacent to a newly established coral bed (subtropical Pocillopora aliciae) in temperate south-eastern Australia, to understand whether novel coral habitat is facilitating assemblages of range-expanding tropical and local temperate fishes. This is the first comprehensive assessment of fish species associating with this novel coral habitat within a temperate environment. Twenty fish species were observed associating with the coral (8 tropical and 12 temperate). Both temperate and tropical species were observed at greater (up to 48 times higher) densities on the coral than on nearby temperate rocky reef in the area, suggesting that the corals generally concentrate fish and may aid in tropicalisation for species that use subtropical coral as habitat. Future research should investigate the ongoing expansion of this coral, the relative quality of coral habitat for fish in temperate regions and the potential implications for functioning of temperate rocky reef ecosystems. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the residual concentrations of four heavy metals; mercury (Hg), arsenic (As), lead (Pb), and cadmium (Cd) in Mullet, Brush tooth lizard, and Coral fish collected from fish markets in Zagazig city, Sharkia Governorate, Egypt. Besides, metal's dietary intake and public health risk were calculated. Atomic absorption spectrometry (AAS) was used to analyze these toxic heavy metals in 60 fish samples of Mullet, Brush tooth lizard, and Coral (20 of each). The concentration (mg/ kg) of Hg were the same value (0.02±0.01) in Mullet, Brush tooth lizard, and Coral fish. However, for As were 0.35±0.10, 0.32±0.10, and 0.30±0.08, respectively; meanwhile, Pb concentration was 0.09±0.04 for both Mullet and Brush tooth lizard and it was 0.10±0.04 for Coral fish Cd concentrations were 0.02±0.01 in all examined fish. The estimated daily intake (EDI) of Hg, As, Pb, and Cd were 0.011, 0.191,, 0.049 and 0.011µg/ kg BW/ day, respectively in Mullet; 0.011, 0.174, 0.049, and 0.011 µg/ kg BW/ day in, respectively Brush tooth lizard; 0.011, 0.163, 0.054, and 0.011 µg/ kg BW/ day, respectively in Coral fish, that was below the tolerable daily intake (TDI) recommended by Joint Expert Committee on Food Additives (JECFA). The Target hazard quotient (THQ) of Hg, As, Pb, and Cd from consumption of examined fish was less than one which means that there was no hazard from consumption of these fish. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) such as superoxide radicals O2−, hydroxyl radicals OH−, and hydrogen peroxide H2O2 may have detrimental effects on marine organisms, including their integuments and visual appearances. Although some studies have described the impact of ROS on marine ecosystems and species ecology, the influence on the optical response of the integuments of marine species and on their visual appearances remains unknown. In this article, we used histology and optical characterisation to show, for the first time, that skin melanophores (melanin-containing chromophores) of the coral reef fish, Stegastes apicalis, change their shapes and fluorescent proprieties upon oxidation with H2O2 radicals. Our observations also suggest that pheomelanosomes may occur in fish integuments, where, previously, it was thought that fish melanosomes only contain eumelanin. This investigation relied on light and electron microscopy and steady-state fluorimetry, as well as time-resolved streak imaging systems. We suggest that the changes in the morphological and spectral characteristics of melanophores can be used as a marker of physiological stress induced by environmental factors such as ROS. Moreover, S. apicalis may be used as a potential model for studying the interaction between the surrounding environment and natural organisms in biologically diverse ecosystems, such as the Great Barrier Reef in Australia. [ABSTRACT FROM AUTHOR]

Ecosystems around the world are continuously undergoing recovery from anthropogenic disturbances like climate change, overexploitation, and habitat destruction. Coral reefs are a prime example of a threatened ecosystem and coral recruitment is a critical component of reef recovery from disturbances. Reef fishes structure this recruitment by directly consuming macroalgae and coral recruits or by indirectly altering the substrate to facilitate coral settlement (e.g., grazing scars). However, how these direct and indirect mechanisms vary through time remains largely unknown. Here, we quantified coral recruitment on settlement tiles with divots that mimic grazing scars and caging treatments to exclude or allow fish feeding over 3 years at Palmyra Atoll in the Pacific Ocean. We found that the positive and negative effects of fishes on coral recruitment varies through time. After 3 years, both grazing scars and fish grazing no longer predicted coral recruitment, suggesting that the role of fishes decreases over time. Our results emphasize that reef fish populations are important in promoting initial coral recovery after disturbances. However, over time, factors like the environment may become more important. Future work should continue to explore how the strength and direction of top-down control by consumers varies through time across multiple ecosystems. [ABSTRACT FROM AUTHOR]

Simple Summary: Underwater mountains, or seamounts, are deep-sea habitats collectively forming an area as large as Europe. Yet, they are one of the least studied ecosystems on earth. Known for supporting rich marine life compared to surrounding deep-sea environments, we have no information on how seamounts truly compare to other iconic biodiversity hotspots like shallow coral reefs. To assess the effective ecological value of seamounts, we compared fish communities in coral reefs and seamounts up to 500 m deep using two techniques: environmental DNA to detect the presence of species by filtering fragments of DNA lost by organisms in seawater, and underwater cameras to directly measure fish abundance and size. We found that the deepest seamounts had almost 10 times fewer fish species than coral reefs. However, the shallowest seamounts had larger fish species, including sharks, than coral reefs. We conclude that while seamounts are important and unique ecosystems, they may not be as diverse for fish species as previously thought (diversity hotspots) but rather biomass oases and refuges for endangered species. This study therefore calls for protecting the shallowest seamounts, as they are critical areas for marine life. Seamounts are the least known ocean biome. Considered biodiversity hotspots, biomass oases, and refuges for megafauna, large gaps exist in their real diversity relative to other ecosystems like coral reefs. Using environmental DNA metabarcoding (eDNA) and baited video (BRUVS), we compared fish assemblages across five environments of different depths: coral reefs (15 m), shallow seamounts (50 m), continental slopes (150 m), intermediate seamounts (250 m), and deep seamounts (500 m). We modeled assemblages using 12 environmental variables and found depth to be the main driver of fish diversity and biomass, although other variables like human accessibility were important. Boosted Regression Trees (BRT) revealed a strong negative effect of depth on species richness, segregating coral reefs from deep-sea environments. Surprisingly, BRT showed a hump-shaped effect of depth on fish biomass, with significantly lower biomass on coral reefs than in shallowest deep-sea environments. Biomass of large predators like sharks was three times higher on shallow seamounts (50 m) than on coral reefs. The five studied environments showed quite distinct assemblages. However, species shared between coral reefs and deeper-sea environments were dominated by highly mobile large predators. Our results suggest that seamounts are no diversity hotspots for fish. However, we show that shallower seamounts form biomass oases and refuges for threatened megafauna, suggesting that priority should be given to their protection. [ABSTRACT FROM AUTHOR]

10.1111/1365-2664.13463 20 Pereira PH, Macedo CH, Nunes JD, Marangoni LF, Bianchini A. Effects of depth on reef fish communities: Insights of a "deep refuge hypothesis" from Southwestern Atlantic reefs. The most conspicuous organisms in the benthic cover of unprotected coastal reefs (reef tops and walls) are the reef-building corals I Montastraea cavernosa i and I Mussismilia hispida i , while in the protected Abrolhos Archipelago, the coral cover is mainly characterized by I Mussismilia braziliensis i (Francini-Filho et al. [7]; Fig. Asterisks above boxplots indicate significance level (Mann-Whitney U Test): * p < 0.05, ** p < 0.01, and *** p < 0.001 Differences in fish sizes between coastal and mid-shelf reefs is another key aspect that clearly influences the results of Leitão et al. ([15]). Leitão et al. ([15]) aimed to assess the effects of human impacts (namely overfishing) on the foraging niche of herbivorous reef fishes by comparing areas with different levels of protection in the largest coral reef complex in the South Atlantic: the Abrolhos Bank. [Extracted from the article]