ABSTRACT Aim To investigate how functional traits shape the composition and functional structure of coastal fish assemblages across the four North‐East Atlantic archipelagos, providing insights into the ecological drivers of species distributions and trait patterns in oceanic island systems. Location Four North‐East Atlantic oceanic archipelagos within Macaronesia: the Azores, Madeira, Canary Islands and Cabo Verde. Taxon Coastal marine fishes occurring up to 200 m depth, comprising 682 species. Methods We compiled a validated checklist of coastal fish species (≤ 200 m depth) for each archipelago and integrated these data with a functional trait matrix comprising size category, trophic category, habitat affinity, milieu and climatic affinity. Generalised Linear Models (GLMs) were used to assess the influence of traits on species occurrences. Functional community structure was quantified using six functional diversity indices: functional richness (FRic), evenness (FEve), divergence (FDiv), dispersion (FDis), Rao's quadratic entropy (RaoQ) and FRic intersection (FRic Inter). Model performance was evaluated using AIC, BIC, pseudo R 2 and post hoc comparisons. Trait‐based GLMs were complemented with assemblage‐level RLQ ordination and fourth‐corner tests to evaluate trait–environment coupling while accounting for species co‐occurrence. Results Species richness followed a clear latitudinal gradient, peaking in the Canary Islands and declining towards higher latitudes. RLQ revealed strong global trait–environment co‐structure (Axis 1 = 91.7% of projected inertia), whereas Fourth‐Corner tests detected no individually significant trait–environment associations after Holm correction. RV tests indicated a significant link between trait structure and species composition (Q–L), but not between environmental context and species composition (R–L). Among traits, body size and habitat affinity were the strongest predictors of species occurrences, with larger‐bodied and reef‐associated species more frequent in the southern archipelagos. Functional richness was highest in the Azores, indicating functional distinctiveness despite comparatively low species richness. Incorporating functional diversity indices into GLMs did not improve explanatory power beyond species‐level traits. Main Conclusions Body size and habitat affinity are key determinants of coastal fish assemblages across the Macaronesia archipelagos. Functional diversity peaks in the Azores, while Madeira exhibits intermediate trait compositions between temperate and tropical systems. These patterns provide insight into community assembly mechanisms and may inform predictions of species turnover under future climate change scenarios.

BackgroundSpecies functional traits provide critical insights into how organisms interact with and respond to their environment. Key characteristics, such as body size, dispersal ability and trophic specialisation influence species' survival, reproduction and adaptability. Island ecosystems, particularly oceanic archipelagos like the Azores, serve as ideal natural laboratories for studying these traits due to their unique biogeographic history and high endemism. Arthropods, as dominant colonisers and ecosystem engineers, exhibit rapid adaptation and trait diversification in these isolated settings. However, island arthropods face escalating threats from habitat loss, climate change and invasive species, which disrupt ecological functions and increase extinction risks. Under the scope of BALA (Biodiversity of Arthropods from the Laurisilva of Azores) project (1999-2021) and SLAM (Long Term Ecological Study of the Impacts of Climate Change in the natural forest of Azores) project (2012-2025), we obtained a comprehensive and standardised dataset of arthropods functional traits currently known to occur in the Azores Archipelago.New informationWe present a standardised functional trait database for Azorean arthropods, building on 25 years of research on 602 species and subspecies across seven classes and 27 orders. The dataset includes endemic, native non-endemic and exotic species, with traits selected for their relevance to disturbance responses (e.g. body size, dispersal, verticality) and ecological interactions (e.g. trophic level, feeding behaviour). By synthesising these data, we aim to support predictive modelling of biodiversity responses to environmental change and provide information for conservation strategies. This resource provides a foundation for global comparisons and advances in trait-based ecology in island systems.

SUMMARY Chaetomorpha , Pseudorhizoclonium , and Rhizoclonium have been reported from the Brazilian coast and oceanic islands; however, molecular data are currently restricted to Pseudorhizoclonium . We aimed to investigate the diversity of Chaetomorpha and Pseudorhizoclonium in the Southwestern Atlantic based on LSU and SSU sequences, as well as morphological data. Samples were collected from the Brazilian coast (Alagoas State) and along three oceanic archipelagos (São Pedro e São Paulo, Fernando de Noronha, and Trindade). Our data confirmed the occurrence of Chaetomorpha antennina and Pseudorhizoclonium mangroviorum , extending the known morphological characterization of both species and expanding the documented distribution range of P. mangroviorum to include northeastern Brazil. Additionally, based on newly generated phylogenetic data, we propose the description of Chaetomorpha costacoralla sp. nov. and Chaetomorpha insularis sp. nov. Morphologically, Ch costacoralla is similar to Chaetomorpha gracilis and is currently restricted to the northeastern Brazilian coast. On the other hand, Ch. insularis is a microfilamentous taxon found only as an epiphyte on other macroalgae in Fernando de Noronha. Our data suggest that Chaetomorpha diversity along the Brazilian coast is currently underestimated, as seen by the description of two new species and the identification of a potential novel species within the Chaetomorpha spiralis complex.

Shark hotspot: Drivers for distribution and conservation in a tropical oceanic archipelago of the Atlantic Ocean

Montebello Islands marine sediment retains nuclear weapons-derived radionuclide contamination 70years after detonations.

Evidence suggests that the Pacific Island states and the French overseas collectivities of the Pacific may provide a unique perspective from which to assess the legacy of interactions between China and the Pacific Ocean archipelagos, both in the imperial era and in contemporary times. This article analyzes the connections—mainly human, diplomatic, and cultural—established between France and the People's Republic of China in this region, especially in French Polynesia and New Caledonia. It emphasizes the multifacetedness of existing Chinese communities in the French Pacific entities, and it examines the intermediary role of those communities in the strengthening of the local Franco–Chinese relations. It highlights how the historical evolution went from the establishment of restrictive policies by the French government in these entities, to the acclimatization of this community , now considered a model of integration. This article examines the idea that the Franco–Chinese heritage in the French overseas collectivities, linked to migrations, could constitute an original model. But it will also underline that, compared with the diplomatic dynamics of other states in the region, boosted in recent years by the Belt and Road initiative, it seems that the links between French Polynesia, New Caledonia and the People's Republic of China remain unbalanced and fragile.

Inside the mesophotic zone: taxonomic and trait diversity of epifauna associated with black coral forests across an oceanic archipelago

Abstract Upwelling delivers key nutritional and energetic subsidies to coral reef communities that affect the growth, abundance, and ecology of organisms across trophic levels. However, the cross‐scale oceanographic and atmospheric drivers of localized upwelling on many reefs remain unresolved, limiting our ability to predict how climate change might disrupt upwelling patterns and impact reef communities across geographies. Using high temporal resolution (10 second) in situ temperature measurements collected over 18 months that encompassed the strongest positive Indian Ocean Dipole phase of this century, we demonstrate a highly nonlinear effect of climate‐driven mixed layer depth on upwelling intensity across the latitudinal range of the Chagos Archipelago (~ 200 km). The exposure of shallow (10–25 m depth) reef communities to deeper upwelled waters was maximized when the mixed layer depth was shallower than ~ 40 m, but virtually absent when the mixed layer depth was deeper than ~ 60 m. By combining these temperature data with nitrogen stable isotopes (δ 15 N) from a common macroalga, we show these variations in upwelling correlate with altered nutrient sources that have direct measurable impacts on reef organisms across the Archipelago. We further show that over the past 40 years, positive phases of the Indian Ocean Dipole correlate with an anomalously deep surface mixed layer on these reefs, each time likely restricting upwelling. Given these extreme events are increasing in frequency under climate change, this poses the possibility of a markedly different upwelling regime across the Archipelago over the coming century, with currently unknown ecological consequences.

Marine protected areas (MPAs) often lack adequate data on the status of marine assemblages to support evidence‐based management. Stereo baited remote underwater video (BRUV) systems offer a powerful, low‐cost tool for collecting ecological data, yet they remain underutilized in the North East Atlantic, especially compared to more invasive methods such as fisheries surveys. Here, we demonstrate how a spatially comprehensive stereo‐BRUV survey can generate benchmark data to support MPA management at an ecosystem scale, using an ecologically distinct oceanic archipelago as a case study. The archipelago's habitats were found to support high abundances of regionally targeted commercial species, including benthic catsharks (Scyliorhinidae) and European spiny lobster (Palinurus elephas), with ~12,000 individuals recorded representing 64 species and 44 families. Deeper, topographically complex reefs were found to support higher levels of richness and biomass, with sediment‐specific increases in depth also driving demersal abundance. Stereo technology was additionally able to provide body size data for 43 species, with remoteness and shelter from exposure found to be common drivers of increased body size for indicator taxa. Survey results represent a contemporary benchmark for measuring changes in local MPA management, fisheries practices, and climate change impacts. The results also illustrate how spatially robust sampling methods and stereo‐BRUV systems can facilitate more holistic, fisheries‐independent data collection in UK and European waters.

A recommendation of: Baptiste Brée, Thomas J. Matthews, José María Fernandez-Palacios, Christian Paroissin, Kostas A. Triantis, Robert J. Whittaker, François Rigal The biogeography of evolutionary radiations on oceanic archipelagos https://doi.org/10.1101/2024.10.07.616413

BackgroundOceanic islands are globally recognised for their exceptional levels of biodiversity and endemism, often resulting from unique evolutionary processes in isolated environments. However, this biodiversity is also disproportionately threatened by anthropogenic pressures including habitat loss, invasive species and climate change. Targeted, long-term biodiversity monitoring is essential for detecting changes in these vulnerable ecosystems and providing information for conservation strategies.The EU BIODIVERSA + project BioMonI aims at building a global long-term monitoring network specifically tailored to the pressing needs of biodiversity conservation and monitoring on islands. In BioMonI, we use a novel approach that considers mapping previous and current monitoring schemes on islands, developing a harmonised monitoring scheme for island biodiversity and mobilising existing monitoring data. We are assembling data from BioMonI-Plot, a long-term vegetation plot network to understand biodiversity and ecosystem change. It will use baseline data from three focal archipelagos (Azores, Canary Islands and Mascarenes), but we aim to mobilise data from archipelagos worldwide.Plot-based data are a cornerstone of effective biodiversity monitoring on islands. These standardised data collections within permanent plots allow for consistent, replicable observations across temporal and spatial scales. Initiatives like the Global Island Monitoring Scheme (GIMS) highlight the value of permanent plots in capturing ecological gradients and anthropogenic disturbance patterns. Such data underpin the detection of subtle shifts in community composition, functional diversity and species distributions, which are critical for assessing the effectiveness of conservation actions and predicting future ecological scenarios.In summary, plot-based data are indispensable for targeted and effective biodiversity monitoring on islands. They provide the empirical backbone necessary to provide information for adaptive management strategies and contribute to global biodiversity targets.New informationThe BioMonI-Plot baseline data consist of 10 plots in each of the following islands: Terceira (Azores), Tenerife (Canaries) and Réunion Island (Mascarenes). As a first step, we describe the diversity and abundance of all woody species shoots with a diameter at breast height (DBH) ≥ 1 cm in each of the 10 plots of each Island. The majority of taxa belonged to the phylum Magnoliophyta, which accounted for 96.66% of the total species and subspecies, followed by Pteridophyta (2.22%) and Pinophyta (1.11%). Réunion Island exhibited the highest species richness, with 66 identified taxa, followed by Tenerife (16 taxa) and Terceira (11 taxa). Only one species, Morellafaya, was shared between the islands, occurring in both Terceira and Tenerife. Most of the recorded species were classified as endemic according to their colonisation status. Specifically, 32 species were endemic to the Mascarene Islands, 22 to Réunion, nine to the Azores, eleven to Macaronesia and four to the Canary Islands.The data presented in this Data Paper provide a valuable proxy for evaluating the ecological integrity and overall habitat quality of native montane forests across three oceanic archipelagos: the Azores, Canary Islands and Mascarene Islands. By focusing on tree species as primary ecological indicators, the dataset offers insights into essential structural and compositional attributes of these ecosystems, including species richness, relative abundance and patterns of dominance.The comprehensive species-level information contained in this dataset allows for comparisons of forest composition across islands and biogeographic regions, contributing to our understanding of insular forest dynamics, endemism patterns and conservation priorities in tropical and subtropical montane environments.

A recommendation of: Baptiste Brée, Thomas J. Matthews, José María Fernandez-Palacios, Christian Paroissin, Kostas A. Triantis, Robert J. Whittaker, François Rigal The biogeography of evolutionary radiations on oceanic archipelagos https://doi.org/10.1101/2024.10.07.616413

Interannual health status stability of the reef-building coral Montastraea cavernosa in a Southwestern Atlantic marginal reef.

A recommendation of: Baptiste Brée, Thomas J. Matthews, José María Fernandez-Palacios, Christian Paroissin, Kostas A. Triantis, Robert J. Whittaker, François Rigal The biogeography of evolutionary radiations on oceanic archipelagos https://doi.org/10.1101/2024.10.07.616413

Abstract Effective biodiversity conservation requires accurate assessments to inform management decisions, particularly in biodiversity‐rich regions. The Gran Canaria Biosphere Reserve (GCBR) is located in one of the Canary Islands, an oceanic archipelago that belongs to the Mediterranean biodiversity hotspot and lies <100 km from NW Africa. We aim to help improve conservation in this territory by complementing traditional biodiversity metrics with phylogenetic analyses, using the two official plant DNA barcode sequences (matK and rbcL), and distribution data for 202 endemic angiosperm taxa within the GCBR, which encompasses about 42% of Gran Canaria's territory. We compare the geographical patterns of Phylogenetic Diversity (PD) and Phylogenetic Endemism (PE) with traditional diversity metrics such as Species Richness (SR) and Weighted Endemism (WE), and we use categorical analyses of neo‐and paleo‐endemism. Our results highlight significant centres of PD and PE that do not entirely overlap with those detected for SR and WE. Notably, the northern region of the GCBR includes important conservation areas, representing either accumulations of ancestral diversity or spots of incipient speciation. Moreover, evolutionarily significant areas displaying high values of neo‐ and paleo‐phylogenetic endemism were identified in the east and southeast of the GCBR beyond the current core zones and protected areas. These results highlight the enhanced resolution provided by PD and related metrics, and offer a more nuanced understanding of plant biodiversity compared to SR alone. This study underscores the need to establish a new core zone to preserve all key plant evolutionary sites within the GCBR and to ensure comprehensive protection of the endemic flora, which will require coordination among conservation biologists and decision‐makers. The methodology used showcases the value of integrating taxonomic and phylogenetic diversity metrics for guiding the design of protected areas and improving territorial management in the Canaries and other oceanic archipelagos.

Hawaiian lobeliads exhibit extensive adaptive radiations and are considered the largest plant clade (143 species) endemic to any oceanic archipelago. Rapid insular radiations are prone to reticulate evolution, yet detecting hybridization is often limited by inadequate sampling of taxa or independent loci. We analyzed 633 nuclear loci (including tetraploid duplications) and whole plastomes for 89% of extant species to derive phylogenies for the Hawaiian lobeliads. Nuclear data provide strong support for nine major clades in both likelihood and ASTRAL analyses. All genera/sections are monophyletic except Clermontia and Cyanea. Nuclear and plastome phylogenies conflict on short, deep branches; the nuclear tree resolves a fleshy-fruited clade of Hawaiian Clermontia/Cyanea-Brighamia/Delissea, sister to Polynesian Sclerotheca, with both sister to a capsular-fruited Hawaiian clade. Incomplete lineage sorting in a rapid radiation starting 8.5-11.3 Ma is sufficient to explain uncertainty and cytonuclear discordance along the backbone. Sequence data support reticulation within Clermontia and especially Cyanea. Nuclear data identify 42 interisland dispersal events: 89% accord with the strict progression rule, involving movement to the next younger island in the hotspot chain, consistent with theory. Plastid data overestimate such events by 17%. Cyanea and Clermontia have undergone parallel adaptive radiations in elevational distribution and flower length on all major islands, with multiple founders and some interisland differences. Hawaiian lobeliad diversification was driven by an early intergeneric divergence in habitat, followed by parallel adaptive radiation and ecological speciation within Clermontia/Cyanea, combined with widespread single-island endemism, frequent interisland dispersal, and occasional hybridization.

Abstract The discipline of functional island biogeography and studies on plant ecological strategies shaping island assemblages have emerged only recently. Due to volcanic activity, primary succession is an important natural process driving ecosystem dynamics on oceanic islands. However, our knowledge about plant functional traits in explaining the mechanism of ecological succession on these islands characterized by impoverished and disharmonic, but endemic‐rich floras, is limited. We investigated the distribution of plants with respect to nine functional traits related to resource use, reproduction, and growth as well as their overall functional diversity during primary succession using a chronosequence on 10 lava flows of La Palma, Canary Islands. We analysed changes of single traits with age using community‐weighted trait means and applied ordination techniques to evaluate changes in trait composition. Based on ecological succession theory, we tested several hypotheses for changes of functional traits along the successional gradient. We also analysed the role of endemic and introduced plants in structuring successional communities. Both the single‐trait and trait compositional approach revealed that the composition of plants displaying core traits related to leaf economics and dispersal ability shifted with substrate age showing a change from acquisitive to conservative traits and from anemochory to zoochory along the gradient. These shifts were entirely driven by endemic shrubs, while other growth forms contributed to the increase in species and functional richness with lava age but little to vegetation structure. Introduced species were almost absent in successional trajectories. Functional dispersion increased whereas trait turnover was constant and low during succession. Synthesis. Our island system reflects a directional succession governed by the selection of functional traits related to environmental conditions and acquisitive‐conservative strategies as well as to dispersal capacity in early stages followed by a gradual modification of the environment and an expansion of the niche space linked to functional divergence in later stages. Major changes in functional traits occurred five hundred years after the eruptions indicating that primary succession in this dry environment is very slow. The dominance of endemic shrubs and the lack of introduced plants at all successional stages highlight the importance of evolutionary processes in shaping species ecological strategies linked to disturbances like volcanism on this oceanic archipelago.

Wasmannia auropunctata, also known as the ‘little fire ant’ or ‘electric ant’, is an invasive species that represents a serious threat to biodiversity and public health globally due to its intrinsic characteristics and low detectability. Here, through a combination of morphological and molecular identification, the first record of this species in the oceanic archipelago of the Canary Islands is presented. Molecular data reveal that the population from the Canary Islands is completely different from another population established in Málaga (mainland Spain), which suggests that the western Palearctic has been colonised from at least two independent events. The early detection of this species in a very limited area provides an important temporal window for its eradication and the prevention of its dispersal to other areas.

Abstract The success of invasive species is largely dependent on their ability to adapt to new environmental contexts. In dioecious species, adaptive responses can differ between males and females because of variation in the influence of sexual selection and/or the potential for inter-sexual niche differentiation. In invasive species, these effects may be augmented by ecological release, under which the constraints imposed by inter-specific competition on intra-specific niche divergence are shed. Differences in invaded environments, or between invaded and native environments, could therefore lead to different degrees of sexual dimorphism, which could influence intra-specific competition and invasive success. In this study, we investigate the potential for sexual divergence in adaptive change in invasive populations of the Green Anole, Anolis carolinensis, in the Ogasawara Islands, an oceanic archipelago in Japan. We find that limb length is correlated with variation in habitat structure across the islands in male lizards, but not in female lizards. We suggest that the resulting variation in sexual dimorphism is driven by exploitation of the available niche space, with male habitat use diverging further from that of females where local conditions allow. These findings represent evidence that community-level patterns observed among other anole species are mirrored by local, intra-specific patterns in this population, and add to growing evidence of the importance of ecological drivers of sexual dimorphism.

A recommendation of: Baptiste Brée, Thomas J. Matthews, José María Fernandez-Palacios, Christian Paroissin, Kostas A. Triantis, Robert J. Whittaker, François Rigal The biogeography of evolutionary radiations on oceanic archipelagos https://doi.org/10.1101/2024.10.07.616413