Comparison of cryptobenthic reef fish communities among microhabitats in the Red Sea

Knowledge of community structure within an ecosystem is essential when trying to understand the function and importance of the system and when making related management decisions. Within the larger ecosystem, microhabitats play an important role by providing inhabitants with a subset of available resources. On coral reefs, cryptobenthic fishes encompass many groups and make up an important proportion of the biodiversity. However, these fishes are relatively small, exhibit extreme visual or behavioral camouflage, and, therefore, are often overlooked. We examined the differences in fish community structure between three common reef microhabitats (live hard coral, dead coral rubble, and sand) using ichthyocide stations in the central Red Sea. Using a combination of morphological and genetic (cytochrome oxidase I (COI) barcoding) techniques, we identified 326 individuals representing 73 species spread across 17 families, from fifteen 1 m2 quadrats. Fish assemblages in the three microhabitats were significantly different from each other. Rubble microhabitats yielded the highest levels of fish abundance, richness, and diversity, followed by hard coral, and then sand. The results show that benthic composition, even at a small scale, influences cryptobenthic communities. This study also provides new COI sequence data to public databases, in order to further the research of cryptobenthic fishes in the Red Sea region

Gene expression correlates of social evolution in coral reef butterflyfishes

Animals display remarkable variation in social behaviour. However, outside of rodents, little is known about the neural mechanisms of social variation, and whether they are shared across species and sexes, limiting our understand- ing of how sociality evolves. Using coral reef butterflyfishes, we examined gene expression correlates of social variation (i.e. pair bonding versus solitary living) within and between species and sexes. In several brain regions, we quantified gene expression of receptors important for social variation in mammals: oxytocin (OTR), arginine vasopressin (V1aR), dopamine (D1R, D2R) and mu-opioid (MOR). We found that social variation across individuals of the oval butterflyfish, Chaetodon lunulatus, is linked to differences in OTR, V1aR, D1R, D2R and MOR gene expression within several forebrain regions in a sexually dimorphic manner. However, this contrasted with social variation among six species representing a single evolutionary transition from pair- bonded to solitary living. Here, OTR expression within the supracommissural part of the ventral telencephalon was higher in pair-bonded than solitary species, specifically in males. These results contribute to the emerging idea that nonapeptide, dopamine and opioid signalling is a central theme to the evolution of sociality across individuals, although the precise mechanism may be flexible across sexes and species

Pair bond endurance promotes cooperative food defense and inhibits conflict in coral reef butterflyfish

Pair bonding is generally linked to monogamous mating systems, where the reproductive benefits of extended mate guarding and/or of bi-parental care are considered key adaptive functions. However, in some species, including coral reef butterflyfishes (f. Chaetodonitidae), pair bonding occurs in sexually immature and homosexual partners, and in the absence of parental care, suggesting there must be non-reproductive adaptive benefits of pair bonding. Here, we examined whether pair bonding butterflyfishes cooperate in defense of food, conferring direct benefits to one or both partners. We found that pairs of Chaetodon lunulatus and C. baronessa use contrasting cooperative strategies. In C. lunulatus, both partners mutually defend their territory, while in C. baronessa, males prioritize territory defence; conferring improvements in feeding and energy reserves in both sexes relative to solitary counterparts. We further demonstrate that partner fidelity contributes to this function by showing that re-pairing invokes intra-pair conflict and inhibits cooperatively-derived feeding benefits, and that partner endurance is required for these costs to abate. Overall, our results suggest that in butterflyfishes, pair bonding enhances cooperative defense of prey resources, ultimately benefiting both partners by improving food resource acquisition and energy reserves

MammalNet: A Large-scale Video Benchmark for Mammal Recognition and Behavior Understanding

Monitoring animal behavior can facilitate conservation efforts by providing key insights into wildlife health, population status, and ecosystem function. Automatic recognition of animals and their behaviors is critical for capitalizing on the large unlabeled datasets generated by modern video devices and for accelerating monitoring efforts at scale. However, the development of automated recognition systems is currently hindered by a lack of appropriately labeled datasets. Existing video datasets 1) do not classify animals according to established biological taxonomies; 2) are too small to facilitate large-scale behavioral studies and are often limited to a single species; and 3) do not feature temporally localized annotations and therefore do not facilitate localization of targeted behaviors within longer video sequences. Thus, we propose MammalNet, a new large-scale animal behavior dataset with taxonomy-guided annotations of mammals and their common behaviors. MammalNet contains over 18K videos totaling 539 hours, which is ~10 times larger than the largest existing animal behavior dataset. It covers 17 orders, 69 families, and 173 mammal categories for animal categorization and captures 12 high-level animal behaviors that received focus in previous animal behavior studies. We establish three benchmarks on MammalNet: standard animal and behavior recognition, compositional low-shot animal and behavior recognition, and behavior detection. Our dataset and code have been made available at: https://mammal-net.github.io.Comment: CVPR 2023 proceedin

Remote marine protected area reveals unusual social behaviour in Chaetodon trifascialis

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Marine Biodiversity 48 (2018): 155-156, doi:10.1007/s12526-016-0531-0.The research expedition was funded by New England Aquarium, Woods Hole Oceanographic Institution and King Abdullah University of Science and Technology

The contribution of macroalgae-associated fishes to small-scale tropical reef fisheries

Macroalgae-dominated reefs are a prominent habitat in tropical seascapes that support a diversity of fishes, including fishery target species. To what extent, then, do macroalgal habitats contribute to small-scale tropical reef fisheries? To address this question we: (1) Quantified the macroalgae-associated fish component in catches from 133 small-scale fisheries, (2) Compared life-history traits relevant to fishing (e.g. growth, longevity) in macroalgal and coral-associated fishes, (3) Examined how macroalgae-associated species can influence catch diversity, trophic level and vulnerability and (4) Explored how tropical fisheries change with the expansion of macroalgal habitats using a case study of fishery-independent data for Seychelles. Fish that utilised macroalgal habitats comprise 24% of the catch, but very few fished species relied entirely on macroalgal or coral habitats post-settlement. Macroalgal and coral-associated fishes had similar life-history traits, although vulnerability to fishing declined with increasing contribution of macroalgae association to the catch, whilst mean trophic level and diversity peaked when macroalgal-associated fish accounted for 20%-30% of catches. The Seychelles case study revealed similar total fish biomass on macroalgal and coral reefs, although the biomass of primary target species increased as macroalgae cover expanded. Our findings reinforce that multiple habitat types are needed to support tropical fishery stability and sustainability. Whilst coral habitats have been the focus of tropical fisheries management, we show the potential for macroalgae-associated fish to support catch size and diversity in ways that reduce vulnerability to overfishing. This is pertinent to seascapes where repeated disturbances are facilitating the replacement of coral reef with macroalgal habitats

The importance of live coral habitat for reef fishes and its role in key ecological processes

Climate change is having major impacts in all the world’s ecosystems. On coral reefs, the most conspicuous and devastating effects of climate change relate to widespread bleaching and resulting mortality of key habitat-forming corals. This, in turn, has affects on reef fishes that recruit, feed and shelter on live corals. Bleaching events often cause declines in abundance and diversity of coral associated fishes, but the proximate causes of these declines remain largely unknown. Specifically, it is unclear why coral-dwelling fishes disappear from bleached coral hosts, even though these corals continue to provide a physical habitat structure. The purpose of this research is to document the importance of live coral habitat for reef fishes, in order to understand the likely effects of coral loss caused by current and ongoing climate change.\ud \ud Critical first steps to understanding the effects of coral depletion on reef fishes is to establish the range of fishes that associate with live coral habitats, and to determine which species of corals are most important as habitat. Chapter 2 combines a comprehensive literature review with independent field surveys to directly record fishes that use live coral habitats. A total of 320 different fish species, representing approximately 8% of reef fishes globally, were recorded to use live coral habitats. These fishes, from 39 different families, used a wide range (93 species) of different corals. However, reef fishes mainly used branching corals from Acroporidae and Pocilloporidae families. This study shows that many species of reef fish will be affected by extensive coral loss, especially considering that the corals most important in providing habitat are among the most susceptible corals to both biological and physical disturbances.foreseeable future.\ud \ud Coral bleaching initiates a sequence of changes in the biological and physical structure of habitat-forming corals, although the degradation of physical habitat structure can take several years. Yet well before major structural degradation transpires, coral-dwelling fishes often decline in abundance on bleached or dead corals even though they would still be expected to offer protection from predators. The aim of Chapter 3 was to test for changes in predation risk among i) healthy coral colonies, ii) bleached, but living coral colonies, iii) recently dead coral colonies, and iv) dead coral colonies that had been colonised by algae. Psedochromis fuscus, a common predatory reef fish, was found to avoid bleached and recently dead habitats, but targeted prey fishes on habitats with degraded pigmentation more than fishes on healthy coral habitats. This suggests that fish are visually more vulnerable to predators when associated with bleached and recently dead coral habitats. Direct measures of predation showed a decline in prey fish survivorship with declines in habitat condition from healthy through to algal covered habitats (75-58% respectively). This shows that bleached and algal covered habitats provide reduced protection for coral-dwelling fishes from predators. Moreover, the growth of algae, sponges and other invertebrates that colonise dead coral skeletons reduce access to the valuable refuge spaces and limit their ability to effectively avoid predators and explains why these habitats are often devoid of coral-dwelling fishes. \ud \ud While coral-dwelling fishes typically associate with a single host colony, changes in habitat structure and increased exposure to predators following coral bleaching may provide strong motivation for fishes to vacate degraded habitats and relocate to alternative healthy habitats. Chapter 4 investigated the response of a common coral-dwelling fish (Dascyllus aruanus) to host coral bleaching and the loss of their coral habitat. Following host coral bleaching there was no movement of fish from corals that bleached but retained their live tissue cover. In contrast, 67% of fish vacated dead but structurally intact corals and migrated to neighbouring healthy coral colonies. Manipulative experiments revealed that selection of new habitats by relocating fishes was largely influenced by the presence of conspecifics. These results suggest that coral-dwelling fishes have the capacity to move between habitats and therefore the ability to withstand moderate levels of host coral depletion. However, with disturbances predicted to become more severe and widespread, the availability of alternative habitats becomes reduced and the distance between healthy habitats increases. This may further reduce the potential to relocate and therefore mediate habitat loss.\ud \ud Many coral-dwelling fishes live in stable and hierarchically organised social groups. Therefore, it is likely that intra-specific competition will have a strong influence on the success of displaced fishes in colonising new habitats. Chapter 5 used manipulative experiments to explore intra-specific competition and colonisation of new habitats by the coral-dwelling damselfish, D. aruanus. Relatively few individuals (11%) were able to successfully join existing groups of conspecifics, with neither group-size nor body-size distribution predicting their success. Resident individuals similar and slightly larger in size than the intruding fish displayed the greatest levels of aggression, possibly because these individuals have the most to lose if the intruder gains entry. Competition between displaced individuals and group members will substantially reduce population resilience through relocation among coral-dwelling fishes following habitat degradation.\ud \ud The recovery of fish communities following biological and physical disturbance is important in order to maintain key ecological functions. Many studies have independently investigated the effects of live coral cover and structural complexity on fish recruitment, but little is known about the combined effects these two factors. Chapter 6 involved manipulation of patch reefs to investigate the combined effect of high, medium and low live coral cover and high and low structural complexity on reef fish recruitment. In the first month following establishment of patch reefs, there were significant differences in abundance and diversity of recruiting fishes among the six treatments, but there was no consistent difference through time. However, species composition showed significant differences among the different habitat treatments. Overall, live coral cover drove the differences, with coral-dependent species recruiting to high coral and high complexity reefs, and rubble-associated species recruiting to degraded reefs. SIMPER analysis revealed that some species of fish with no obvious dependence on live corals, still recruit preferentially to patch reefs with high coral cover. This suggests that some non-coral dependent species depend on live coral at recruitment and emphasizes that healthy live coral habitat can also be important for fishes that have no obvious dependence on live coral in their adult stage for recruitment.\ud \ud This thesis elucidates the importance of live coral for reef fishes. It demonstrates that many reef fish species currently rely on live coral as a habitat. Among these coral-dependent fishes, it identifies key ecological processes that are affected once the coral habitat becomes degraded. Taken together, the findings of this thesis suggest that a degraded biological and physical structure of reef habitat may significantly affect a wide range of reef fishes, potentially undermining the success of key ecological functions. Such a scenario has far reaching implications towards the biodiversity and productivity of coral reef ecosystems, and therefore the goods and services they provide

Habitat Use and Spatial Variability of Hawkfishes with a Focus on Colour Polymorphism in Paracirrhites forsteri.

Identifying relationships between fishes and their environment is an integral part of understanding coral reef ecosystems. However, this information is lacking for many species, particularly in understudied and remote regions. With coral reefs continuing to face environmental pressures, insight into abundance and distribution patterns along with resource use of fish communities will aid in advancing our ecological understanding and management processes. Based on ecological surveys of hawkfish assemblages (Family: Cirrhitidae) in the Red Sea, we reveal distinct patterns in the distribution and abundance across the continental shelf, wave exposure, and with depth, particularly in the four colour morphs of Paracirrhites forsteri. Distinct patterns were observed among hawkfishes, with higher abundance of all species recorded on reefs farther from shore and on wave exposed reef zones. Cirrhitus spilotoceps was only recorded on the exposed crest, but unlike the other species, did not associate with live coral colonies. Overall, the most abundant species was P. forsteri. This species exploited a variety of habitats but showed an affinity for complex habitats provided by live and dead coral colonies. No difference in habitat use was observed among the four colour morphs, but distinct patterns were apparent in distribution and abundance with depth. This study suggests that in addition to P. forsteri exhibiting diverse colour morphologies, these various morphotypes appear to have corresponding ecological differences in the Red Sea. To better understand this, further studies are needed to identify what these differences extend to and the mechanisms involved

Importance of live coral habitat for reef fishes

Live corals are the key habitat forming organisms on coral reefs, contributing to both biological and physical structure. Understanding the importance of corals for reef fishes is, however, restricted to a few key families of fishes, whereas it is likely that a vast number of fish species will be adversely affected by the loss of live corals. This study used data from published literature together with independent field based surveys to quantify the range of reef fish species that use live coral habitats. A total of 320 species from 39 families use live coral habitats, accounting for approximately 8 % of all reef fishes. Many of the fishes reported to use live corals are from the families Pomacentridae (68 spp.) and Gobiidae (44 spp.) and most (66 %) are either planktivores or omnivores. 126 species of fish associate with corals as juveniles, although many of these fishes have no apparent affiliation with coral as adults, suggesting an ontogenetic shift in coral reliance. Collectively, reef fishes have been reported to use at least 93 species of coral, mainly from the genus Acropora and Porities and associate predominantly with branching growth forms. Some fish associate with a single coral species, whilst others can be found on more than 20 different species of coral indicating there is considerable variation in habitat specialisation among coral associated fish species. The large number of fishes that rely on coral highlights that habitat degradation and coral loss will have significant consequences for biodiversity and productivity of reef fish assemblages