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Global reef fish diversity is studied with metrics incorporating species abundances and functional traits; these identify diversity hotspots corresponding to the diversity of functional traits amongst individuals in the community, and greater evenness in the abundance of reef fishes at higher latitudes, findings that contrast with patterns reported previously using traditional richness-based methods. Cooler biodiversity hotspots revealed Traditional measures of biodiversity record species richness across different areas — in other words, they just count the number of species. This approach takes no account of the fact that different species will have different abundances, or that the range of functional traits present in a community is not dependent solely on the number of species. This paper presents a new measure of functional diversity, incorporating species abundances and functional traits into a global census of a vertebrate group —2,473 marine reef fish species — at 1,844 sites. The results reveal previously unknown diversity hotspots in temperate regions and in the Tropical Eastern Pacific, which are outside the species-rich tropical regions traditionally associated with high biodiversity. Species richness has dominated our view of global biodiversity patterns for centuries 1 , 2 . The dominance of this paradigm is reflected in the focus by ecologists and conservation managers on richness and associated occurrence-based measures for understanding drivers of broad-scale diversity patterns and as a biological basis for management 3 , 4 . However, this is changing rapidly, as it is now recognized that not only the number of species but the species present, their phenotypes and the number of individuals of each species are critical in determining the nature and strength of the relationships between species diversity and a range of ecological functions (such as biomass production and nutrient cycling) 5 . Integrating these measures should provide a more relevant representation of global biodiversity patterns in terms of ecological functions than that provided by simple species counts. Here we provide comparisons of a traditional global biodiversity distribution measure based on richness with metrics that incorporate species abundances and functional traits. We use data from standardized quantitative surveys of 2,473 marine reef fish species at 1,844 sites, spanning 133 degrees of latitude from all ocean basins, to identify new diversity hotspots in some temperate regions and the tropical eastern Pacific Ocean. These relate to high diversity of functional traits amongst individuals in the community (calculated using Rao’s Q 6 ), and differ from previously reported patterns in functional diversity and richness for terrestrial animals, which emphasize species-rich tropical regions only 7 , 8 . There is a global trend for greater evenness in the number of individuals of each species, across the reef fish species observed at sites (‘community evenness’), at higher latitudes. This contributes to the distribution of functional diversity hotspots and contrasts with well-known latitudinal gradients in richness 2 , 4 . Our findings suggest that the contribution of species diversity to a range of ecosystem functions varies over large scales, and imply that in tropical regions, which have higher numbers of species, each species contributes proportionally less to community-level ecological processes on average than species in temperate regions. Metrics of ecological function usefully complement metrics of species diversity in conservation management, including when identifying planning priorities and when tracking changes to biodiversity values.

Human society is dependent on nature 1 , 2 , but whether our ecological foundations are at risk remains unknown in the absence of systematic monitoring of species’ populations 3 . Knowledge of species fluctuations is particularly inadequate in the marine realm 4 . Here we assess the population trends of 1,057 common shallow reef species from multiple phyla at 1,636 sites around Australia over the past decade. Most populations decreased over this period, including many tropical fishes, temperate invertebrates (particularly echinoderms) and southwestern Australian macroalgae, whereas coral populations remained relatively stable. Population declines typically followed heatwave years, when local water temperatures were more than 0.5 °C above temperatures in 2008. Following heatwaves 5 , 6 , species abundances generally tended to decline near warm range edges, and increase near cool range edges. More than 30% of shallow invertebrate species in cool latitudes exhibited high extinction risk, with rapidly declining populations trapped by deep ocean barriers, preventing poleward retreat as temperatures rise. Greater conservation effort is needed to safeguard temperate marine ecosystems, which are disproportionately threatened and include species with deep evolutionary roots. Fundamental among such efforts, and broader societal needs to efficiently adapt to interacting anthropogenic and natural pressures, is greatly expanded monitoring of species’ population trends 7 , 8 . A systematic census at 1,636 sites around Australia from 2008 to 2021 finds that more than 30% of shallow invertebrate species in cool latitudes exhibit a high extinction risk due to declining populations and oceanic barriers, but tropical coral species remain relatively stable.

Marine Protected Areas (MPAs) offer a unique opportunity to test the assumption that fishing pressure affects some trophic groups more than others. Removal of larger predators through fishing is often suggested to have positive flow-on effects for some lower trophic groups, in which case protection from fishing should result in suppression of lower trophic groups as predator populations recover. We tested this by assessing differences in the trophic structure of reef fish communities associated with 79 MPAs and open-access sites worldwide, using a standardised quantitative dataset on reef fish community structure. The biomass of all major trophic groups (higher carnivores, benthic carnivores, planktivores and herbivores) was significantly greater (by 40% - 200%) in effective no-take MPAs relative to fished open-access areas. This effect was most pronounced for individuals in large size classes, but with no size class of any trophic group showing signs of depressed biomass in MPAs, as predicted from higher predator abundance. Thus, greater biomass in effective MPAs implies that exploitation on shallow rocky and coral reefs negatively affects biomass of all fish trophic groups and size classes. These direct effects of fishing on trophic structure appear stronger than any top down effects on lower trophic levels that would be imposed by intact predator populations. We propose that exploitation affects fish assemblages at all trophic levels, and that local ecosystem function is generally modified by fishing.

Sixty nine hammerhead sharks, Sphyrna lewini, were tagged at Malpelo Island (Colombia) with ultrasonic transmitters during March 2006, 2007 and 2008, as part of a study to understand their residency at the island and their horizontal and vertical movements. Five sharks visited Cocos Island, 627 km distant from Malpelo. One of the sharks that appeared at Cocos Island also visited the Galapagos Islands, 710 km from Cocos, a month later. There is connectivity of Sphyrna lewini between Malpelo, Cocos and the Galapagos Islands, but the frequency of movements between the islands appears to be relatively low (<7% of the tagged sharks). The most common depth at which the sharks swam coincided with the thermocline ( rs  = 0.72, p  < 0.01). The depth of the thermocline varied depending on the time of the year. Nocturnal detections of the sharks were more frequent during the cold season than during the warm season (W = 60, p  < 0.01). We also found that hammerheads spent significantly more time on the up-current side of the island (Kruskal-Wallis = 31.1008; p  < 0.01). This study contributes to the knowledge of hammerhead sharks not only in Malpelo Island but also at a regional level in the Eastern Tropical Pacific.

Many species of sharks form aggregations around oceanic islands, yet their levels of residency and their site specificity around these islands may vary. In some cases, the waters around oceanic islands have been designated as marine protected areas, yet the conservation value for threatened shark species will depend greatly on how much time they spend within these protected waters. Eighty-four scalloped hammerhead sharks (Sphyrna lewini Griffith & Smith), were tagged with acoustic transmitters at Cocos Island between 2005-2013. The average residence index, expressed as a proportion of days present in our receiver array at the island over the entire monitoring period, was 0.52±0.31, implying that overall the sharks are strongly associated with the island. Residency was significantly greater at Alcyone, a shallow seamount located 3.6 km offshore from the main island, than at the other sites. Timing of presence at the receiver locations was mostly during daytime hours. Although only a single individual from Cocos was detected on a region-wide array, nine hammerheads tagged at Galapagos and Malpelo travelled to Cocos. The hammerheads tagged at Cocos were more resident than those visiting from elsewhere, suggesting that the Galapagos and Malpelo populations may use Cocos as a navigational waypoint or stopover during seasonal migrations to the coastal Central and South America. Our study demonstrates the importance of oceanic islands for this species, and shows that they may form a network of hotspots in the Eastern Tropical Pacific.

Using k-nearest neighbour procedures to predict prey type and linear models to predict mean prey size, we developed a 2-step dietary model based on the stomach contents of fish of known species, size and location from Western Port, Victoria (Australia). The model, nicknamed ‘Consume’, was used to assess the relative extent to which fish diet varied with body size, species identity, season, and location. Both prey type (mean overlap between predicted and actual prey types = 77%) and mean prey size (r² between predicted and observed mean prey size = 93%) were predicted with reasonable accuracy when species identity and length of consumer fish were known. The most important predictor for prey type was the size of the individual consumer, while the most important predictor for mean prey size was the consumer’s taxonomic identity. Predictors were individually removed from both k-nearest neighbour and linear models to assess their relative contributions to the model. Little loss of accuracy (1%) was evident when family rather than species identity was used for both prey type and mean prey size. Environmental information associated with the time and location of fish sampling (habitat, site and season) contributed only marginally to predictions of prey type. Use of the Consume model will allow for an improved understanding of community-level trophic pathways through the integration of prey type and size predictions for consumer fishes.

More than 5% of the world population lives with a hearing impairment. The main factors responsible for hearing degeneration are ototoxic drugs, aging, continued exposure to excessive noise and infections. The pool of adult stem cells in the inner ear drops dramatically after birth, and therefore an endogenous cellular source for regeneration is absent. Hearing loss can emerge after the degeneration of different cochlear components, so there are multiple targets to be reached, such as hair cells (HCs), spiral ganglion neurons (SGNs), supporting cells (SCs) and ribbon synapses. Important discoveries in the hearing regeneration field have been reported regarding stem cell transplantation, migration and survival; genetic systems for cell fate monitoring; and stem cell differentiation to HCs, SGNs and SCs using adult stem cells, embryonic stem cells and induced pluripotent stem cells. Moreover, some molecular mediators that affect the establishment of functional synapses have been identified. In this review, we will focus on reporting the state of the art in the regenerative medicine field for hearing recovery. Stem cell research has enabled remarkable advances in regeneration, particularly in neuronal cells and synapses. Despite the progress achieved, there are certain issues that need a deeper development to improve the results already obtained, or to develop new approaches aiming for the clinical application.

The reactive oxygen species (ROS)-generating NADPH oxidase NOX3 isoform is highly and specifically expressed in the inner ear. NOX3 is needed for normal vestibular development but NOX-derived ROS have also been implicated in the pathophysiology of sensorineural hearing loss. The role of NOX-derived ROS in noise-induced hearing loss, however, remains unclear and was addressed with the present study. Two different mouse strains, deficient in NOX3 or its critical subunit p22 phox , were subjected to a single noise exposure of 2 h using an 8–16 kHz band noise at an intensity of 116–120 decibel sound pressure level. In the hours following noise exposure, there was a significant increase in cochlear mRNA expression of NOX3 in wild type animals. By using RNAscope in situ hybridization, NOX3 expression was primarily found in the Rosenthal canal area, colocalizing with auditory neurons. One day after the noise trauma, we observed a high frequency hearing loss in both knock-out mice, as well as their wild type littermates. At day seven after noise trauma however, NOX3 and p22 phox knockout mice showed a significantly improved hearing recovery and a marked preservation of neurosensory cochlear structures compared to their wild type littermates. Based on these findings, an active role of NOX3 in the pathophysiology of noise-induced hearing loss can be demonstrated, in line with recent evidence obtained in other forms of acquired hearing loss. The present data demonstrates that the absence of functional NOX3 enhances the hearing recovery phase following noise trauma. This opens an interesting clinical window for pharmacological or molecular intervention aiming at post prevention of noise-induced hearing loss.

Cisplatin is a lifesaving chemotherapeutic drug with marked ototoxic adverse effects. Cisplatin-induced hearing loss affects a significant part of cancer-surviving patients and is an unmet clinical need with important socioeconomic consequences. Unfortunately, in current preclinical animal models of cisplatin ototoxicity, which are mainly based on systemic delivery, important morbidity is observed, leading to premature death. This methodology not only raises obvious animal welfare concerns but also increases the number of animals used in ototoxicity studies to compensate for dropouts related to early death. To overcome these important limitations, we developed a local delivery model based on the application of a cisplatin solution directly into the otic bulla through a retroauricular approach. The local delivery model reliably induced significant hearing loss with a mean threshold shift ranging from 10 to 30 dB, strongly affecting the high frequencies (22 and 32 kHz). Importantly, mice did not show visible stress or distress indicators and no significant morbidity in comparison with a traditional systemic delivery control group of mice injected intraperitoneally with 10 mg/kg cisplatin, where significant weight loss >10% in all treated animals (without any recovery) led to premature abortion of experiments on day 3. Mass spectrometry confirmed the absence of relevant systemic uptake after local delivery, with platinum accumulation restricted to the cochlea, whereas important platinum concentrations were detected in the liver and kidney of the systemic cisplatin group. A clear correlation between the cochlear platinum concentration and the auditory threshold shift was observed. Immunohistochemistry revealed statistically significant loss of outer hair cells in the basal and apical turns of the cochlea and an important and statistically significant loss of auditory neurons and synapses in all cochlear regions. In conclusion, local cisplatin delivery induces robust hearing loss with minimal morbidity, thereby offering a reliable rodent model for human cisplatin ototoxicity, reducing the number of animals required and showing improved animal welfare compared with traditional systemic models.

Marine top predators are common at offshore bathymetric features such as islands, atolls, and seamounts, where most pelagic reef fish reside, while certain sharks perform inter-island movements between these formations. Scalloped hammerhead sharks are known to school in great numbers at small islands and seamounts in the eastern tropical Pacific (ETP) and are very susceptible to fisheries while moving into the open sea. It is, therefore, essential to understand hammerhead inter-island movements and environmental effects to provide baseline information for their conservation and management within and beyond an insular marine protected area. Movements of scalloped hammerheads were analyzed in the Galapagos Marine Reserve (GMR) and ETP, and environmental factors were linked to their movements. Hammerheads were tagged (N = 134) with V16 coded pingers (July 2006 to July 2010) in the northern Galapagos and detected at listening stations around four islands in the GMR and two isolated islands in the ETP, 700 and 1,200 km away. Hammerheads formed daytime schools at specific locations, but dispersed at night. Overall, more daytime than nighttime detections were recorded at all receivers in the northern Galapagos Islands, and more detections in the up-current sides of these islands. Hammerheads remained more days at the northern islands during part of the warm season (December–February) compared to the cool; however, fewer individuals were present in March–June. Movement modes were diel island excursions (24-h cycles) in the northern Galapagos and inter-island in the GMR and ETP at different scales: (1) short back-and-forth (<50 km, SBF), <5 days cycles, (2) medium distance (50–300 km, MDT), 5–20 days, and (3) long distance (>300 km, LDT), 15–52 days. The high degree of inter-island connectivity of hammerheads within the northern GMR is striking compared to the almost nil movement to the central GMR. A seasonal migratory pattern to locations offshore is indicated by (1) fewer hammerheads observed in the northern GMR during part of the warm season (March–June) and (2) evidence of LDT movements from the northern GMR to other islands in the ETP. LDT movements of mature female hammerheads are possibly associated with pupping areas. Our results indicate that currents, season, and individual behavior mainly drive inter-island movements of hammerheads at small (SBF) and medium (MDT) scales. These findings have important implications for the management of a highly mobile and endangered top predator within a marine protected area and beyond.