Changes in biogeographic patterns of coastal fishes: Indicators of tropicalization in the Canary Islands over the last 40 years

The Canary Islands are a key marine biodiversity hotspot in the eastern-central Atlantic. Coastal fishes, characterized by extensive taxonomic and functional diversity, serve as a highly representative group in nearshore environments, occupying a wide range of ecosystems. This study focuses on three significant milestones in the publication of comprehensive checklists for the Canary Islands' ichthyofauna during 1985-1991, 2002, and 2019-2024. Coastal fish species (0-200 m depth) were reviewed and updated, revealing biogeographic patterns and vertical distribution ranges for the region. The primary aim is to evaluate potential indicators of tropicalization by examining changes in the percentage of fish species with warm-water affinities, thereby identifying shifts in the composition of the Canarian marine ichthyofauna. This approach provides a distinct and complementary perspective on the tropicalization process, particularly its initial phase. Special emphasis is placed on the increasing proportion of warm-water species compared to those with Atlanto-Mediterranean (temperate-water) affinities. Additionally, an inventory was compiled documenting historical records of primarily exotic and non-native species, including their biogeographic patterns, dispersal mechanisms, observed bathymetric ranges, year of first record, current status, and criteria used to classify them as established in the Canary Islands.

Stomach Microbiome Simplification of a Coral Reef Fish at Its Novel Cold-Range Edge Under Climate Change

Climate-driven range extensions of animals into higher latitudes are often facilitated by phenotypic plasticity. Modifications to habitat preference, behaviour and diet can increase the persistence of range-extending species in novel high-latitude ecosystems. These strategies may be influenced by changes in their gut and stomach microbial communities that are critical to host fitness and potentially adaptive plasticity. Yet, it remains unknown if the gut and stomach microbiome of range-extending species is plastic in their novel ranges to help facilitate these modifications. Here, we categorised stomach microbiome communities of a prevalent range-extending coral reef fish along a 2000-km latitudinal gradient in a global warming hotspot, extending from their tropical core range to their temperate cold range edge. At their cold range edge, the coral reef fish's stomach microbiome showed a 59% decrease in bacterial diversity and a 164% increase in the relative abundance of opportunistic bacteria (Vibrio) compared to their core range. Microbiome diversity was unaffected by fish body size, water temperature, physiology (cellular defence and damage) and habitat type (turf, barren, oyster, kelp and coral) across their range. The observed shifts in microbiome composition suggest dysbiosis and low plasticity of tropical range-extending fishes to novel environmental conditions (e.g., temperate prey and lower seawater temperature) at their novel range edges, which may increase their susceptibility to disease in temperate ecosystems. We conclude that fishes extending their ranges to higher latitudes under ocean warming can experience a simplification (i.e., reduced diversity) of their stomach microbiome, which could restrict their current rate of range extensions or establishment in temperate ecosystems.

Marine species and assemblage change foreshadowed by their thermal bias over Early Jurassic warming

A mismatch of species' thermal preferences to their environment may indicate how they will respond to future climate change. Averaging this mismatch across species may forewarn that some assemblages will undergo greater reorganization, extirpation, and possibly extinction, than others. Here, we examine how regional warming determines species occupancy and assemblage composition of marine bivalves, brachiopods, and gastropods over one-million-year time steps during the Early Jurassic. Thermal bias, the difference between modelled regional temperatures and species' long-term thermal optima, predicts a gradient of species occupancy response to warming. Species that become extirpated or extinct tend to have cooler temperature preferences than immigrating species, while regionally persisting species fell midway. Larger regional changes in summer seawater temperatures (up to +10 °C) strengthen the relationship between species thermal bias and the response gradient, which is also stronger for brachiopods than for bivalves, while the relationship collapses during severe seawater deoxygenation. At +3 °C regional seawater warming, around 5 % of pre-existing benthic species in a regional assemblage are extirpated, and immigrating species comprise around one-fourth of the new assemblage. Our results validate thermal bias as an indicator of immigration, persistence, extirpation, and extinction of marine benthic species and assemblages under modern-like magnitudes of climate change.

New York State Climate Impacts Assessment Chapter 05: Ecosystems

The people of New York have long benefited from the state's diversity of ecosystems, which range from coastal shorelines and wetlands to extensive forests and mountaintop alpine habitat, and from lakes and rivers to greenspaces in heavily populated urban areas. These ecosystems provide key services such as food, water, forest products, flood prevention, carbon storage, climate moderation, recreational opportunities, and other cultural services. This chapter examines how changes in climatic conditions across the state are affecting different types of ecosystems and the services they provide, and considers likely future impacts of projected climate change. The chapter emphasizes how climate change is increasing the vulnerability of ecosystems to existing stressors, such as habitat fragmentation and invasive species, and highlights opportunities for New Yorkers to adapt and build resilience.

Mycorrhizal status regulates plant phenological mismatch caused by warming

Mycorrhiza is an important functional feature of plants, which plays a vital role in regulating plant phenology in response to environmental changes. However, the effect of mycorrhiza on plant phenological asymmetry in response to climate changes is still rarely reported. Based on a global database of mycorrhizal statuses (obligately mycorrhizal, OM and facultatively mycorrhizal, FM) and phenology, we demonstrated that mycorrhizas reduce the phenological mismatches between above- and below-ground plant responses to climate warming under OM status. The mismatch of above- and below-ground growing season length of FM plants to warming was as high as 10.65 days, 9.1925 days and 12.36 days in total, herbaceous and woody plants, respectively. The mismatch of growing season length of OM plants was only 2.12 days, -0.61 days and 7.64 days among plant groups, which was much lower than that of FM plants. Correlation analysis indicated that OM plants stabilized plant phenology by regulating the relationship between the start of the growing season and the length of the growing season. Path analysis found that herbaceous plants and woody plants reduced phenological mismatches by stabilizing below-ground and above-ground phenology, respectively. In exploring the effects of mycorrhizal status on early- or late-season phenophases, we found that different mycorrhizal statuses affected the response of early- or late-season phenophase to warming. OM promoted the advance of early-season phenophase, and FM promoted the delay of late-season phenophase among different plant groups. In different regions, OM and FM promoted the advance of early-season phenophase in temperate and boreal regions, respectively. Our results indicate that mycorrhizal status mediates plant phenological response to warming, so the potential effects of mycorrhizal status should be considered when studying plant phenology changes.

Method of estimating sea-surface paleotemperatures through biotic proxies: A case study in Upper Paleozoic paleoclimatic, paleogeographic and paleotectonic reconstructions of Siberia

This study introduces a novel approach for quantitatively assessing sea-surface paleotemperatures examined in the Upper Paleozoic of Siberia, utilizing the obtained in the region data as a case study of the use of this method. The method relies on evaluating the taxonomic composition and ecological proxies of biota. It utilizes a comprehensive dataset encompassing the geographic distribution and ecology of various biotic groups in Siberia and adjacent regions, leveraging the newly developed by the authors large PaleoSib database and partially the Paleobiology Database (paleobiology.org) The taxonomy has been used according to the database of Global Biodiversity Information Facility (gbif.org). Fossils collected from individual locations often exhibit a wide spectrum of paleotemperatures. To address this variability, we developed an algorithm for calculating average biotic paleotemperatures in each locality/time slice. Our computations of the available data have unveiled a coherent pattern of paleoclimate dynamics, particularly Sea Surface Temperature, across Siberian basins and surrounding areas during the Late Paleozoic era. These findings significantly contribute to a refined comprehension of paleoclimate and paleotectonic dynamics in the region during that specific time. To enhance paleotemperature analyses, we have integrated lithological indices with biotic ones, fortifying the overall methodology and furnishing a more robust framework for interpreting paleoclimate data. The method could be a helpful tool in regional and interregional studies, regardless of the utilized rock's age and fossil groups.

Predicting the future distribution of the Barbary ground squirrel (Atlantoxerus getulus) under climate change using niche overlap analysis and species distribution modeling

This study combines niche overlap analysis with species distribution modeling (SDM) to examine the niche dynamics of Atlantoxerus getulus, a ground squirrel native to Morocco and Algeria that has been introduced to the Canary Islands. We compiled 1272 records of A. getulus in its native and exotic ranges and five bioclimatic variables for present and future climate conditions for the years 2050 and 2070. We assessed the ecological niche of the species using exploratory and ordination analyses, followed by the prediction of its distribution using the SpatialMaxent model. Our results showed that the niches of A. getulus exhibited equivalence (p > 0.05) and significant similarity (p < 0.05) between the native and exotic ranges. No observed niche expansion in the exotic area is shown to be associated with complete niche stability. However, 90% of the niche in the Canary Islands remains unfilled, suggesting potential for further invasion. Our results highlighted habitat contractions ranging from 41% (SSP245-2050) to 60% (SSP585-2070), associated with a shift in the centroid of suitable habitat towards the Atlantic coast. These contractions are particularly severe in Algeria, where suitable habitats could disappear by 2050, contrasting with stable habitats maintained in the Canary Islands under all scenarios. Urgent habitat restoration in Algeria is crucial, including efforts to combat poaching. In Morocco, targeted in situ conservation is recommended, while in the Canary Islands, the focus should be on invasive species management and public awareness campaigns to prevent further spread.

Unexpected westward range shifts in European forest plants link to nitrogen deposition

Climate change is commonly assumed to induce species' range shifts toward the poles. Yet, other environmental changes may affect the geographical distribution of species in unexpected ways. Here, we quantify multidecadal shifts in the distribution of European forest plants and link these shifts to key drivers of forest biodiversity change: climate change, atmospheric deposition (nitrogen and sulfur), and forest canopy dynamics. Surprisingly, westward distribution shifts were 2.6 times more likely than northward ones. Not climate change, but nitrogen-mediated colonization events, possibly facilitated by the recovery from past acidifying deposition, best explain westward movements. Biodiversity redistribution patterns appear complex and are more likely driven by the interplay among several environmental changes than due to the exclusive effects of climate change alone.

Disentangling the effect of space, time, and environmental and anthropogenic drivers on coastal macrobenthic β diversity in contrasting habitats over 15 years

Coastal zones are biodiversity hotspots and deliver essential ecosystem functions and services, yet they are exposed to multiple and interacting anthropogenic and environmental constraints. The individual and cumulative effects of these constraints on benthic communities, a key component of coastal ecosystems, and their variability across space and time, remains to be thoroughly quantified to guide conservation actions. Here, we explored how the presence of biogenic habitats influences the response of benthic communities to natural and anthropogenic constraints. We investigated this effect in both intertidal and subtidal habitats exposed to different pressures. We used data collected in the North-East Atlantic over 15 years (2005-2019) as part of the REBENT monitoring program, covering 38 sites of bare sediments, intertidal seagrass beds and maerl beds. We collected a range of environmental variables and proxies of anthropogenic pressures and used variation and hierarchical partitioning with redundancy analyses to estimate their relative effect on macrobenthic communities. We used descriptors modeling spatial and temporal structures (dbMEMs) to explore the scale of their effects and potential missing predictors. The selected variables explained between 53 % and 64 % of macrobenthic β diversity depending on habitat and depth. Fishing pressures, sedimentary and hydrodynamics variables stood out as the most important predictors across all habitats while proxies of anthropogenic pressures were overall more important in intertidal habitats. In the intertidal, presence of biogenic habitat strongly modulated the amount of explained variance and the identity of the selected variable. Across both tidal levels, analysis of models' residuals further indicated that biogenic habitats might mitigate the effect of extreme environmental events. Our study provides a hierarchy of the most important drivers of benthic communities across different habitats and tidal levels, emphasizing the prominence of anthropogenic pressures on intertidal communities and the role of biogenic habitats in mitigating environmental changes.

Modeling Habitat Suitability for Cerithidea rhizophorarum and Telescopium telescopium in Indo-West Pacific Mangroves

Mangroves provide habitat for a diverse array of marine species, especially snails. We used a MaxEnt model to predict potential global suitable habitat for Cerithidea rhizophorarum and Telescopium telescopium in the family Potamididae. A total of 667 occurrence data were obtained from the Global Biodiversity Information Facility (GBIF) with the following sub-data set contribution, "iNaturalist Research Grade Observations" (85%), "International Barcode of Life project (iBOL)" (7%), "FBIP: SeaKeys_SANBI: Marine images iSpot_2013" (1%), "A dataset of marine macroinvertebrate diversity from Mozambique and São Tomé and Príncipe" (1%), occurrence data of some marine invertebrates and freshwater crabs housed in the natural history collection at the National Museums of Kenya (1%), and Natural History Museum Rotterdam-Specimens (1%). Our results showed that temperature with a contribution of above 80% in the present and future model is the most important driver of the distribution of mangrove snails. In the present and future models, the most potentially suitable habitats for C. rhizophorarum and T. telescopium were observed along coastal areas with a temperature between 20°C-21°C and 30°C, respectively. Our model predicts that by 2100, high-suitability areas will shrink as a result of global warming. The vulnerability of mangrove snails under future climate conditions is evident in our results. Our findings contribute significant insights into the intricate relationship between mangrove habitats and mangrove snails, offering a valuable foundation for conservation initiatives aimed at safeguarding the biodiversity and ecological functions of these crucial coastal ecosystems in the face of changing global environmental conditions.

The genetic legacy of the Quaternary ice ages for West Palearctic butterflies

The interplay between geographic barriers and climatic oscillations over the past 2.6 million years structured genetic variation at the continental scale. The genetic legacy of the Quaternary ice ages (GLQ) hypothesis outlines this phenomenon for Europe, but a comprehensive data-driven assessment is lacking. Using innovative genetic landscape methods, we model the GLQ in the West Palearctic based on 31,653 Cytochrome c oxidase subunit 1 (COI) sequences from 494 butterfly species and three functional traits. Seven distinct bioregions with varying levels of genetic endemicity emerge, revealing a latitudinal gradient in variation that confirms the "southern richness, northern purity" hypothesis. Through shift from case studies to a comparative approach, we objectively identify the main glacial refugia, colonization routes, and barriers to dispersal. Our findings offer a quantitative model of the GLQ across Europe, North Africa, and neighboring Asia, with broader applicability to other taxa and potentially scalable to encompass life on Earth.

Mediterranean octocoral populations exposed to marine heatwaves are less resilient to disturbances

The effects of climate change are now more pervasive than ever. Marine ecosystems have been particularly impacted by climate change, with marine heatwaves (MHWs) being a strong driver of mass mortality events. Even in the most optimistic greenhouse gas emission scenarios, MHWs will continue to increase in frequency, intensity and duration. For this reason, understanding the resilience of marine species to the increase of MHWs is crucial to predicting their viability under future climatic conditions. In this study, we explored the consequences of MHWs on the resilience (the ability of a population to resist and recover after a disturbance) of a Mediterranean key octocoral species, Paramuricea clavata, to further disturbances to their population structure. To quantify P. clavata's capacity to resist and recover from future disturbances, we used demographic information collected from 1999 to 2022, from two different sites in the NW Mediterranean Sea to calculate the transient dynamics of their populations. Our results showed that the differences in the dynamics of populations exposed and those not exposed to MHWs were driven mostly by differences in mean survivorship and growth. We also showed that after MHWs P. clavata populations had lower resistance and slower rates of recovery than those not exposed to MHWs. Populations exposed to MHWs had lower resistance elasticity to most demographic processes compared to unexposed populations. In contrast, the only demographic process showing some differences when comparing the speed of recovery elasticity values between populations exposed and unexposed to MHWs was stasis. Finally, under scenarios of increasing frequency of MHWs, the extinction of P. clavata populations will accelerate and their capacity to resist and recover after further disturbances will be hampered. Overall, these findings confirm that future climatic conditions will make octocoral populations even more vulnerable to further disturbances. These results highlight the importance of limiting local impacts on marine ecosystems to dampen the consequences of climate change.

Multidecadal changes in coastal benthic species composition and ecosystem functioning occur independently of temperature-driven community shifts

Rising global temperatures are often identified as the key driver impacting ecosystems and the services they provide by affecting biodiversity structure and function. A disproportionate amount of our understanding of biodiversity and function is from short-term experimental studies and static values of biodiversity indices, lacking the ability to monitor long-term trends and capture community dynamics. Here, we analyse a biennial dataset spanning 32 years of macroinvertebrate benthic communities and their functional response to increasing temperatures. We monitored changes in species' thermal affinities to examine warming-related shifts by selecting their mid-point global temperature distribution range and linking them to species' traits. We employed a novel weighted metric using Biological Trait Analysis (BTA) to gain better insights into the ecological potential of each species by incorporating species abundance and body size and selecting a subset of traits that represent five ecosystem functions: bioturbation activity, sediment stability, nutrient recycling and higher and lower trophic production. Using biodiversity indices (richness, Simpson's diversity and vulnerability) and functional indices (richness, Rao's Q and redundancy), the community structure showed no significant change over time with a narrow range of variation. However, we show shifts in species composition with warming and increases in the abundance of individuals, which altered ecosystem functioning positively and/or non-linearly. Yet, when higher taxonomic groupings than species were excluded from the analysis, there was only a weak increase in the measured change in community-weighted average thermal affinities, suggesting changes in ecosystem functions over time occur independently of temperature increase-related shifts in community composition. Other environmental factors driving species composition and abundance may be more important in these subtidal macrobenthic communities. This challenges the prevailing emphasis on temperature as the primary driver of ecological response to climate change and emphasises the necessity for a comprehensive understanding of the temporal dynamics of complex systems.

Temporal dynamics of climate change exposure and opportunities for global marine biodiversity

Climate change is exposing marine species to unsuitable temperatures while also creating new thermally suitable habitats of varying persistence. However, understanding how these different dynamics will unfold over time remains limited. We use yearly sea surface temperature projections to estimate temporal dynamics of thermal exposure (when temperature exceeds realised species' thermal limits) and opportunity (when temperature at a previously unsuitable site becomes suitable) for 21,696 marine species globally until 2100. Thermal opportunities are projected to arise earlier and accumulate gradually, especially in temperate and polar regions. Thermal exposure increases later and occurs more abruptly, mainly in the tropics. Assemblages tend to show either high exposure or high opportunity, but seldom both. Strong emissions reductions reduce exposure around 100-fold whereas reductions in opportunities are halved. Globally, opportunities are projected to emerge faster than exposure until mid-century when exposure increases more rapidly under a high emissions scenario. Moreover, across emissions and dispersal scenarios, 76%-97% of opportunities are projected to persist until 2100. These results indicate thermal opportunities could be a major source of marine biodiversity change, especially in the near- and mid-term. Our work provides a framework for predicting where and when thermal changes will occur to guide monitoring efforts.

Fish and tips: Historical and projected changes in commercial fish species' habitat suitability in the Southern Hemisphere

Global warming has significantly altered fish distribution patterns in the ocean, shifting towards higher latitudes and deeper waters. This is particularly relevant in high-latitude marine ecosystems, where climate-driven environmental changes are occurring at higher rates than the global average. Species Distribution Models (SDMs) are increasingly being used for predicting distributional shifts in habitat suitability for marine species as a response to climate change. Here, we used SDMs to project habitat suitability changes for a range of high-latitude, pelagic and benthopelagic commercial fish species and crustaceans (10 species); from 1850 to two future climate change scenarios (SSP1-2.6: low climate forcing; and SSP5-8.5: high climate forcing). The study includes 11 Large Marine Ecosystems (LME) spanning South America, Southern Africa, Australia, and New Zealand. We identified declining and southward-shifting patterns in suitable habitat areas for most species, particularly under the SSP5-8.5 scenario and for some species such as Argentine hake (Merluccius hubbsi) in South America, or snoek (Thyrsites atun) off Southern Africa. Geographical constraints will likely result in species from Southern Africa, Australia, and New Zealand facing the most pronounced habitat losses due to rising sea surface temperatures (SST). In contrast, South American species might encounter greater opportunities for migrating southward. Additionally, the SSP5-8.5 scenario predicts that South America will be more environmentally stable compared to other regions. Overall, our findings suggest that the Patagonian shelf could serve as a climate refuge, due to higher environmental stability highlighting the importance of proactive management strategies in this area for species conservation. This study significantly contributes to fisheries and conservation management, providing valuable insights for future protection efforts in the Southern Hemisphere.

Harmful Ostreopsis cf. ovata blooms could extend in time span with climate change in the Western Mediterranean Sea

Fast environmental changes and high coastal human pressures and impacts threaten the Mediterranean Sea. Over the last decade, recurrent blooms of the harmful dinoflagellate Ostreopsis cf. ovata have been recorded in many Mediterranean beaches. These microalgae produce toxins that affect marine organisms and human health. Understanding the environmental conditions that influence the appearance and magnitude of O. cf. ovata blooms, as well as how climate change will modify its future distribution and dynamics, is crucial for predicting and managing their effects. This study investigates whether the spatio-temporal distribution of this microalga and the frequency of its blooms could be altered in future climate change scenarios in the Mediterranean Western basin. For the first time, an ecological habitat model (EHM) is forced by physico-chemical climate change simulations at high-resolution, under the strong greenhouse gas emission trajectory (RCP8.5). It allows to characterize how O. cf. ovata may respond to projected conditions and how its distribution could shift over a wide spatial scale, in this plausible future. Before being applied to the EHM, future climate simulations are further refined by using a statistical adaptation method (Cumulative Distribution Function transform) to improve the predictions robustness. Temperature (optimum 23-26 °C), high salinity (>38 psu) and high inorganic nutrient concentrations (nitrate >0.25 mmol N·m-3 and phosphate >0.035 mmol P·m-3) drive O. cf. ovata abundances. High spatial disparities in future abundances are observed. Namely, O. cf. ovata abundances could increase on the Mediterranean coasts of France, Spain and the Adriatic Sea while a decrease is expected in the Tyrrhenian Sea. The bloom period could be extended, starting earlier and continuing later in the year. From a methodological point of view, this study highlights best practices of EHMs in the context of climate change to identify sensitive areas for current and future harmful algal blooms.

Pushed waves, trailing edges, and extreme events: Eco-evolutionary dynamics of a geographic range shift in the owl limpet, Lottia gigantea

As climatic variation re-shapes global biodiversity, understanding eco-evolutionary feedbacks during species range shifts is of increasing importance. Theory on range expansions distinguishes between two different forms: "pulled" and "pushed" waves. Pulled waves occur when the source of the expansion comes from low-density peripheral populations, while pushed waves occur when recruitment to the expanding edge is supplied by high-density populations closer to the species' core. How extreme events shape pushed/pulled wave expansion events, as well as trailing-edge declines/contractions, remains largely unexplored. We examined eco-evolutionary responses of a marine invertebrate (the owl limpet, Lottia gigantea) that increased in abundance during the 2014-2016 marine heatwaves near the poleward edge of its geographic range in the northeastern Pacific. We used whole-genome sequencing from 19 populations across >11 degrees of latitude to characterize genomic variation, gene flow, and demographic histories across the species' range. We estimated present-day dispersal potential and past climatic stability to identify how contemporary and historical seascape features shape genomic characteristics. Consistent with expectations of a pushed wave, we found little genomic differentiation between core and leading-edge populations, and higher genomic diversity at range edges. A large and well-mixed population in the northern edge of the species' range is likely a result of ocean current anomalies increasing larval settlement and high-dispersal potential across biogeographic boundaries. Trailing-edge populations have higher differentiation from core populations, possibly driven by local selection and limited gene flow, as well as high genomic diversity likely as a result of climatic stability during the Last Glacial Maximum. Our findings suggest that extreme events can drive poleward range expansions that carry the adaptive potential of core populations, while also cautioning that trailing-edge extirpations may threaten unique evolutionary variation. This work highlights the importance of understanding how both trailing and leading edges respond to global change and extreme events.

Dilute concentrations of maritime fuel can modify sediment reworking activity of high-latitude marine invertebrates

Multiple expressions of climate change, in particular warming-induced reductions in the type, extent and thickness of sea ice, are opening access and providing new viable development opportunities in high-latitude regions. Coastal margins are facing these challenges, but the vulnerability of species and ecosystems to the effects of fuel contamination associated with increased maritime traffic is largely unknown. Here, we show that low concentrations of the water-accommodated fraction of marine fuel oil, representative of a dilute fuel oil spill, can alter functionally important aspects of the behaviour of sediment-dwelling invertebrates. We find that the response to contamination is species specific, but that the range in response among individuals is modified by increasing fuel concentrations. Our study provides evidence that species responses to novel and/or unprecedented levels of anthropogenic activity associated with the opening up of high-latitude regions can have substantive ecological effects, even when human impacts are at, or below, commonly accepted safe thresholds. These secondary responses are often overlooked in broad-scale environmental assessments and marine planning yet, critically, they may act as an early warning signal for impending and more pronounced ecological transitions.

Ocean warming and acidification adjust inter- and intra-specific variability in the functional trait expression of polar invertebrates

Climate change is known to affect the distribution and composition of species, but concomitant alterations to functionally important aspects of behaviour and species-environment relations are poorly constrained. Here, we examine the ecosystem ramifications of changes in sediment-dwelling invertebrate bioturbation behaviour-a key process mediating nutrient cycling-associated with near-future environmental conditions (+ 1.5 °C, 550 ppm [pCO2]) for species from polar regions experiencing rapid rates of climate change. We find that responses to warming and acidification vary between species and lead to a reduction in intra-specific variability in behavioural trait expression that adjusts the magnitude and direction of nutrient concentrations. Our analyses also indicate that species behaviour is not predetermined, but can be dependent on local variations in environmental history that set population capacities for phenotypic plasticity. We provide evidence that certain, but subtle, aspects of inter- and intra-specific variation in behavioural trait expression, rather than the presence or proportional representation of species per se, is an important and under-appreciated determinant of benthic biogeochemical responses to climate change. Such changes in species behaviour may act as an early warning for impending ecological transitions associated with progressive climate forcing.

Temporal variability of sea surface temperature affects marine macrophytes range retractions as well as gradual warming

Record mean sea surface temperatures (SST) during the past decades and marine heatwaves have been identified as responsible for severe impacts on marine ecosystems, but the role of changes in the patterns of temporal variability under global warming has been much less studied. We compare descriptors of two time series of SST, encompassing extirpations (i.e. local extinctions) of six cold-temperate macroalgae species at their trailing range edge. We decompose the effects of gradual warming, extreme events and intrinsic variability (e.g. seasonality). We also relate the main factors determining macroalgae range shifts with their life cycles characteristics and thermal tolerance. We found extirpations of macroalgae were related to stretches of coast where autumn SST underwent warming, increased temperature seasonality, and decreased skewness over time. Regardless of the species, the persisting populations shared a common environmental domain, which was clearly differentiated from those experiencing local extinction. However, macroalgae species responded to temperature components in different ways, showing dissimilar resilience. Consideration of multiple thermal manifestations of climate change is needed to better understand local extinctions of habitat-forming species. Our study provides a framework for the incorporation of unused measures of environmental variability while analyzing the distributions of coastal species.

Poleward migration of tropical corals inhibited by future trends of seawater temperature and calcium carbonate (CaCO3) saturation

Poleward range expansion of marine organisms is commonly attributed to anthropogenic ocean warming. However, the extent to which a single species can migrate poleward remains unclear. In this study, we used molecular data to examine the current distribution of the Pocillopora damicornis species complex in Taiwan waters and applied niche modeling to predict its potential range through the end of the 21st Century. The P. damicornis species complex is widespread across shallow, tropical and subtropical waters of the Indo-Pacific regions. Our results revealed that populations from subtropical nonreefal coral communities are P. damicornis, whose native geographical ranges are approximately between 23°N and 35°N. In contrast, those from tropical reefs are P. acuta. Our analysis of 50 environmental data layers demonstrated that the concentrations of CaCO3 polymorphs had the greatest contributions to the distributions of the two species. Future projections under intermediate shared socioeconomic pathways (SSP) 2-4.5 and very high (SSP5-8.5) scenarios of greenhouse gas emissions showed that while sea surface temperature (SST) isotherms would shift northwards, saturation isolines of two CaCO3 polymorphs, calcite (Ωcal) and aragonite (Ωarag), would shift southwards by 2100. Subsequent predictions of future suitable habitats under those conditions indicated that distinct delimitation of geographical ranges for the two species would persist, and neither would extend beyond its native geographical zones, indicating that tropical Taiwan waters are the northern limit for P. acuta. In contrast, subtropical waters are the southern limit for P. damicornis. We concluded that the decline in CaCO3 saturation would make high latitudes less inhabitable, which could be one of the boundary elements that limit poleward range expansion driven by rising SSTs and preserve the latitudinal diversity gradient (LDG) on Earth. Consequently, poleward migration of tropical reef corals to cope with warming oceans should be reevaluated.

Hurricanes are limiting the mangrove canopy heights in the Gulf of Mexico

Mangrove canopy height (MCH) has been described as a leading characteristic of mangrove forests, protecting coastal economic interests from hurricanes. Meanwhile, winter temperature has been considered the main factor controlling the MCH along subtropical coastlines. However, the MCH in Cedar Key, Florida (∼12 m), is significantly higher than in Port Fourchon, Louisiana (∼2.5 m), even though these two subtropical locations have similar winter temperatures. Port Fourchon has been more frequently impacted by hurricanes than Cedar Key, suggesting that hurricanes may have limited the MCH in Port Fourchon rather than simply winter temperatures. This hypothesis was evaluated using novel high-resolution remote sensing techniques that tracked the MCH changes between 2002 and 2023. Results indicate that hurricanes were the limiting factor keeping the mean MCH at Port Fourchon to <1 m (2002-2013), as the absence of hurricane impacts between 2013 and 2018 allowed the mean MCH to increase by 60 cm despite the winter freezes in Jan/2014 and Jan/2018. Hurricanes Zeta (2020) and Ida (2021) caused a decrease in the mean MCH by 20 cm, breaking branches, defoliating the canopy, and toppling trees. The mean MCH (∼1.6 m) attained before Zeta and Ida has not yet been recovered as of August 2023 (∼1.4 m), suggesting a longer-lasting impact (>4 years) of hurricanes on mangroves than winter freezes (<1 year). The high frequency of hurricanes affecting mangroves at Port Fourchon has acted as a periodic "pruning," particularly of the tallest Avicennia trees, inhibiting their natural growth rates even during quiet periods following hurricane events (e.g., 12 cm/yr, 2013-2018). By contrast, the absence of hurricanes in Cedar Key (2000-2020) has allowed the MCH to reach 12 m (44-50 cm/yr), implying that, besides the winter temperature, the frequency and intensity of hurricanes are important factors limiting the MCH on their latitudinal range limits in the Gulf of Mexico.

Modulations of ocean-atmosphere interactions on squid abundance over Southwest Atlantic

Anthropogenic shifts in seas are reshaping fishing trends, with significant implications for aquatic food sources throughout this century. Examining a 21-year abundance dataset of Argentine shortfin squids Illex argentinus paired with a regional oceanic analysis, we noted strong correlations between squid annual abundance and sea surface temperature (SST) in January and February and eddy kinetic energy (EKE) from March to May in the Southwest Atlantic. A deeper analysis revealed combined ocean-atmosphere interactions, pinpointed as the primary mode in a rotated empirical orthogonal function analysis of SST. This pattern produced colder SST and amplified EKE in the surrounding seas, factors crucial for the unique life stages of squids. Future projections from the CMIP6 archive indicated that this ocean-atmosphere pattern, referred to as the Atlantic symmetric pattern, would persist in its cold SST phase, promoting increased squid abundance. However, rising SSTs due to global warming might counteract the abundance gains. Our findings uncover a previously unrecognized link between squids and specific environmental conditions governed by broader ocean-atmosphere interactions in the Southwest Atlantic. Integrating these insights with seasonal and decadal projections can offer invaluable information to stakeholders in squid fisheries and marine conservation under a changing climate.

Towards a novel biosphere in 2300: rapid and extensive global and biome-wide climatic novelty in the Anthropocene

Recent climate change has effectively rewound the climate clock by approximately 120 000 years and is expected to reverse this clock a further 50 Myr by 2100. We aimed to answer two essential questions to better understand the changes in ecosystems worldwide owing to predicted climate change. Firstly, we identify the locations and time frames where novel ecosystems could emerge owing to climate change. Secondly, we aim to determine the extent to which biomes, in their current distribution, will experience an increase in climate-driven ecological novelty. To answer these questions, we analysed three perspectives on how climate changes could result in novel ecosystems in the near term (2100), medium (2200) and long term (2300). These perspectives included identifying areas where climate change could result in new climatic combinations, climate isoclines moving faster than species migration capacity and current environmental patterns being disaggregated. Using these metrics, we determined when and where novel ecosystems could emerge. Our analysis shows that unless rapid mitigation measures are taken, the coverage of novel ecosystems could be over 50% of the land surface by 2100 under all change scenarios. By 2300, the coverage of novel ecosystems could be above 80% of the land surface. At the biome scale, these changes could mean that over 50% of locations could shift towards novel ecosystems, with the majority seeing these changes in the next few decades. Our research shows that the impact of climate change on ecosystems is complex and varied, requiring global action to mitigate and adapt to these changes. This article is part of the theme issue 'Biodiversity dynamics and stewardship in a transforming biosphere'. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

The exposure of the world's mountains to global change drivers

Global change affects mountain areas at different levels, with some mountains being more exposed to change in climate or environmental conditions and others acting as local refugia. We quantified the exposure of the world's mountains to three drivers of change, climate, land use, and human population density, using two spatial-temporal metrics (velocity and magnitude of change). We estimated the acceleration of change for these drivers by comparing past (1975-2005) vs. future (2020-2050) exposure, and we also compared exposure in lowlands vs. mountains. We found Africa's tropical mountains facing the highest future exposure to multiple drivers of change, thus requiring targeted adaptation and mitigation strategies to preserve biodiversity. European and North America's mountains, in contrast, experience more limited exposure to global change and could act as local refugia for biodiversity. This knowledge can be used to prioritize local-scale interventions and planning long-term monitoring to reduce the risks faced by mountain biodiversity.

Reassessment of the risks of climate change for terrestrial ecosystems

Forecasting the risks of climate change for species and ecosystems is necessary for developing targeted conservation strategies. Previous risk assessments mapped the exposure of the global land surface to changes in climate. However, this procedure is unlikely to robustly identify priority areas for conservation actions because nonlinear physiological responses and colimitation processes ensure that ecological changes will not map perfectly to the forecast climatic changes. Here, we combine ecophysiological growth models of 135,153 vascular plant species and plant growth-form information to transform ambient and future climatologies into phytoclimates, which describe the ability of climates to support the plant growth forms that characterize terrestrial ecosystems. We forecast that 33% to 68% of the global land surface will experience a significant change in phytoclimate by 2070 under representative concentration pathways RCP 2.6 and RCP 8.5, respectively. Phytoclimates without present-day analogue are forecast to emerge on 0.3-2.2% of the land surface and 0.1-1.3% of currently realized phytoclimates are forecast to disappear. Notably, the geographic pattern of change, disappearance and novelty of phytoclimates differs markedly from the pattern of analogous trends in climates detected by previous studies, thereby defining new priorities for conservation actions and highlighting the limits of using untransformed climate change exposure indices in ecological risk assessments. Our findings suggest that a profound transformation of the biosphere is underway and emphasize the need for a timely adaptation of biodiversity management practices.

Climate velocities and species tracking in global mountain regions

Mountain ranges contain high concentrations of endemic species and are indispensable refugia for lowland species that are facing anthropogenic climate change1,2. Forecasting biodiversity redistribution hinges on assessing whether species can track shifting isotherms as the climate warms3,4. However, a global analysis of the velocities of isotherm shifts along elevation gradients is hindered by the scarcity of weather stations in mountainous regions5. Here we address this issue by mapping the lapse rate of temperature (LRT) across mountain regions globally, both by using satellite data (SLRT) and by using the laws of thermodynamics to account for water vapour6 (that is, the moist adiabatic lapse rate (MALRT)). By dividing the rate of surface warming from 1971 to 2020 by either the SLRT or the MALRT, we provide maps of vertical isotherm shift velocities. We identify 17 mountain regions with exceptionally high vertical isotherm shift velocities (greater than 11.67 m per year for the SLRT; greater than 8.25 m per year for the MALRT), predominantly in dry areas but also in wet regions with shallow lapse rates; for example, northern Sumatra, the Brazilian highlands and southern Africa. By linking these velocities to the velocities of species range shifts, we report instances of close tracking in mountains with lower climate velocities. However, many species lag behind, suggesting that range shift dynamics would persist even if we managed to curb climate-change trajectories. Our findings are key for devising global conservation strategies, particularly in the 17 high-velocity mountain regions that we have identified.

Incorporating otolith-isotope inferred field metabolic rate into conservation strategies

Fluctuating ocean conditions are rearranging whole networks of marine communities-from individual-level physiological thresholds to ecosystem function. Physiological studies support predictions from individual-level responses (biochemical, cellular, tissue, respiratory potential) based on laboratory experiments. The otolith-isotope method of recovering field metabolic rate has recently filled a gap for the bony fishes, linking otolith stable isotope composition to in situ oxygen consumption and experienced temperature estimates. Here, we review the otolith-isotope method focusing on the biochemical and physiological processes that yield estimates of field metabolic rate. We identify a multidisciplinary pathway in the application of this method, providing concrete research goals (field, modeling) aimed at linking individual-level physiological data to higher levels of biological organization. We hope that this review will provide researchers with a transdisciplinary 'roadmap', guiding the use of the otolith-isotope method to bridge the gap between individual-level physiology, observational field studies, and modeling efforts, while ensuring that in situ data is central in marine policy-making aimed at mitigating climatic and anthropogenic threats.

Speed of environmental change frames relative ecological risk in climate change and climate intervention scenarios

Stratospheric aerosol injection is a potential method of climate intervention to reduce climate risk as decarbonization efforts continue. However, possible ecosystem impacts from the strategic design of hypothetical intervention scenarios are poorly understood. Two recent Earth system model simulations depict policy-relevant stratospheric aerosol injection scenarios with similar global temperature targets, but a 10-year delay in intervention deployment. Here we show this delay leads to distinct ecological risk profiles through climate speeds, which describe the rate of movement of thermal conditions. On a planetary scale, climate speeds in the simulation where the intervention maintains temperature are not statistically distinguishable from preindustrial conditions. In contrast, rapid temperature reduction following delayed deployment produces climate speeds over land beyond either a preindustrial baseline or no-intervention climate change with present policy. The area exposed to threshold climate speeds places different scenarios in context to their relative ecological risks. Our results support discussion of tradeoffs and timescales in future scenario design and decision-making.

Increasing spread rates of tropical non-native macrophytes in the Mediterranean Sea

Warming as well as species introductions have increased over the past centuries, however a link between cause and effect of these two phenomena is still unclear. Here we use distribution records (1813-2023) to reconstruct the invasion histories of marine non-native macrophytes, macroalgae and seagrasses, in the Mediterranean Sea. We defined expansion as the maximum linear rate of spread (km year-1) and the accumulation of occupied grid cells (50 km2) over time and analyzed the relation between expansion rates and the species' thermal conditions at its native distribution range. Our database revealed a marked increase in the introductions and spread rates of non-native macrophytes in the Mediterranean Sea since the 1960s, notably intensifying after the 1990s. During the beginning of this century species velocity of invasion has increased to 26 ± 9 km2 year-1, with an acceleration in the velocity of invasion of tropical/subtropical species, exceeding those of temperate and cosmopolitan macrophytes. The highest spread rates since then were observed in macrophytes coming from native regions with minimum SSTs two to three degrees warmer than in the Mediterranean Sea. In addition, most non-native macrophytes in the Mediterranean (>80%) do not exceed the maximum temperature of their range of origin, whereas approximately half of the species are exposed to lower minimum SST in the Mediterranean than in their native range. This indicates that tropical/subtropical macrophytes might be able to expand as they are not limited by the colder Mediterranean SST due to the plasticity of their lower thermal limit. These results suggest that future warming will increase the thermal habitat available for thermophilic species in the Mediterranean Sea and continue to favor their expansion.

Bioenergetic status of swordfish (Xiphias gladius) during the El Niño Southern Oscillation (ENSO) in the Southeast Pacific Ocean: An interannual scale

The bioenergetic status of fishes has been used to study their physiological responses to temporal changes at interannual scales. We evaluated the physiological responses of swordfish at an interannual scale from the El Niño Southern Oscillation (ENSO): warm phase "El Niño" in 2015 to the cold phase "La Niña" in 2017 and under neutral conditions as well in 2019. Herein, muscle samples from females and males were analyzed to evaluate the bioenergetic status from their biochemical constituents (L: lipids, P: proteins and G: glucose, E: total energy, and FAs: fatty acid profile), elemental composition (C: carbon, N: nitrogen, H: hydrogen), and nutritional indices (L:P, C:N, DHA/C18:1n-3, DHA/C16:0 and ω3/ω6 FAs). The physiological response of swordfish showed an interaction between the year and sex. Herein, the L and E showed similar trends, with the lowest female values found in 2015 and the highest in 2019. Contrary, males showed their highest values in 2015 and lowest in 2019. FA profile differed among years and highlighted significant differences between females and males in 2019. Although the female L:P and C:N ratios were lower in 2015 than in 2017, a decreasing trend in these ratios was found from 2017 to 2019. Moreover, DHA/C18:1n-3, DHA/C16:0 and ω3/ω6 showed higher ratios in females than males in 2019. Our results coincide with the beginning of the ENSO phases; it is therefore likely that the swordfish diet changed in response to the disturbances in environmental conditions. Furthermore, the degree of individual dietary specialization found under the neutral conditions could indicate differences in the feeding behaviors of males vs. females, which may be an adaptive strategy in this species. These findings will aid in understanding the bioenergetic status of swordfish under different climatic scenarios and the current global warming, providing relevant information for the management of this resource.

A species distribution model of the giant kelp Macrocystis pyrifera: Worldwide changes and a focus on the Southeast Pacific

Worldwide climate-driven shifts in the distribution of species is of special concern when it involves habitat-forming species. In the coastal environment, large Laminarian algae-kelps-form key coastal ecosystems that support complex and diverse food webs. Among kelps, Macrocystis pyrifera is the most widely distributed habitat-forming species and provides essential ecosystem services. This study aimed to establish the main drivers of future distributional changes on a global scale and use them to predict future habitat suitability. Using species distribution models (SDM), we examined the changes in global distribution of M. pyrifera under different emission scenarios with a focus on the Southeast Pacific shores. To constrain the drivers of our simulations to the most important factors controlling kelp forest distribution across spatial scales, we explored a suite of environmental variables and validated the predictions derived from the SDMs. Minimum sea surface temperature was the single most important variable explaining the global distribution of suitable habitat for M. pyrifera. Under different climate change scenarios, we always observed a decrease of suitable habitat at low latitudes, while an increase was detected in other regions, mostly at high latitudes. Along the Southeast Pacific, we observed an upper range contraction of -17.08° S of latitude for 2090-2100 under the RCP8.5 scenario, implying a loss of habitat suitability throughout the coast of Peru and poleward to -27.83° S in Chile. Along the area of Northern Chile where a complete habitat loss is predicted by our model, natural stands are under heavy exploitation. The loss of habitat suitability will take place worldwide: Significant impacts on marine biodiversity and ecosystem functioning are likely. Furthermore, changes in habitat suitability are a harbinger of massive impacts in the socio-ecological systems of the Southeast Pacific.

Fecal DNA metabarcoding reveals seasonal and annual variation in willow ptarmigan diet

Understanding spatio-temporal variation in the diet of alpine herbivores is important to predict how a changing climate will affect these species in the future. We examined the spatio-temporal variation in willow ptarmigan (Lagopus l. lagopus) diet using DNA metabarcoding of fecal pellets sampled from winter to early summer over three consecutive years. Furthermore, we assessed how snow cover and vegetation phenology affected diet variation. We also investigated sex differences in diet composition. We identified 18 important diet taxa and the genera Betula, Vaccinium and Empetrum occurred most frequently. Diet composition and richness varied within and between years. Seasonally, there was a shift from a narrow winter diet dominated by trees and dwarf shrubs to a broader spring diet with more nutritious field vegetation. This seasonal progression differed among years. The temporal variation in diet was better explained by day of year than by snow cover and vegetation phenology. Females had a more diverse diet than males, but there were no sex differences in diet composition. Our results demonstrate that metabarcoding of fecal samples provides the opportunity to assess factors affecting diet composition of species in alpine ecosystems in the context of a changing climate.

Climate-limited vegetation change in the conterminous United States of America

The effects of climate change on vegetation composition and distribution are evident in different ecosystems around the world. Although some climate-derived alterations on vegetation are expected to result in changes in lifeform fractional cover, disentangling the direct effects of climate change from different non-climate factors, such as land-use change, is challenging. By applying "Liebig's law of the minimum" in a geospatial context, we determined the climate-limited potential for tree, shrub, herbaceous, and non-vegetation fractional cover change for the conterminous United States and compared these potential rates to observed change rates for the period 1986 to 2018. We found that 10% of the land area of the conterminous United States appears to have climate limitations on the change in fractional cover, with a high proportion of these sites located in arid and semiarid ecosystems in the Southwest part of the country. The rates of change in lifeform fractional cover for the remaining area of the country are likely limited by non-climate factors such as the disturbance regime, land management, land-use history, soil conditions, and species interactions and adaptations.

Vulnerability of protected areas to future climate change, land use modification, and biological invasions in China

Anthropogenic climate change, land use modifications, and alien species invasions are major threats to global biodiversity. Protected areas (PAs) are regarded as the cornerstone of biodiversity conservation, however, few studies have quantified the vulnerability of PAs to these global change factors together. Here, we overlay the risks of climate change, land use change, and alien vertebrate establishment within boundaries of a total of 1020 PAs with different administrative levels in China to quantify their vulnerabilities. Our results show that 56.6% of PAs will face at least one stress factor, and 21 PAs are threatened under the highest risk with three stressors simultaneously. PAs designed for forest conservation in Southwest and South China are most sensitive to the three global change factors. In addition, wildlife and wetland PAs are predicted to mainly experience climate change and high land use anthropogenetic modifications, and many wildlife PAs can also provide suitable habitats for alien vertebrate establishment. Our study highlights the urgent need for proactive conservation and management planning of Chinese PAs by considering different global change factors together.

Microclimate reveals the true thermal niche of forest plant species

Species distributions are conventionally modelled using coarse-grained macroclimate data measured in open areas, potentially leading to biased predictions since most terrestrial species reside in the shade of trees. For forest plant species across Europe, we compared conventional macroclimate-based species distribution models (SDMs) with models corrected for forest microclimate buffering. We show that microclimate-based SDMs at high spatial resolution outperformed models using macroclimate and microclimate data at coarser resolution. Additionally, macroclimate-based models introduced a systematic bias in modelled species response curves, which could result in erroneous range shift predictions. Critically important for conservation science, these models were unable to identify warm and cold refugia at the range edges of species distributions. Our study emphasizes the crucial role of microclimate data when SDMs are used to gain insights into biodiversity conservation in the face of climate change, particularly given the growing policy and management focus on the conservation of refugia worldwide.

Protection promotes energetically efficient structures in marine communities

The sustainability of marine communities is critical for supporting many biophysical processes that provide ecosystem services that promote human well-being. It is expected that anthropogenic disturbances such as climate change and human activities will tend to create less energetically-efficient ecosystems that support less biomass per unit energy flow. It is debated, however, whether this expected development should translate into bottom-heavy (with small basal species being the most abundant) or top-heavy communities (where more biomass is supported at higher trophic levels with species having larger body sizes). Here, we combine ecological theory and empirical data to demonstrate that full marine protection promotes shifts towards top-heavy energetically-efficient structures in marine communities. First, we use metabolic scaling theory to show that protected communities are expected to display stronger top-heavy structures than disturbed communities. Similarly, we show theoretically that communities with high energy transfer efficiency display stronger top-heavy structures than communities with low transfer efficiency. Next, we use empirical structures observed within fully protected marine areas compared to disturbed areas that vary in stress from thermal events and adjacent human activity. Using a nonparametric causal-inference analysis, we find a strong, positive, causal effect between full marine protection and stronger top-heavy structures. Our work corroborates ecological theory on community development and provides a quantitative framework to study the potential restorative effects of different candidate strategies on protected areas.

Pre-fertilization gamete thermal environment influences reproductive success, unmasking opposing sex-specific responses in Atlantic salmon (Salmo salar)

The environment gametes perform in just before fertilization is increasingly recognized to affect offspring fitness, yet the contributions of male and female gametes and their adaptive significance remain largely unexplored. Here, we investigated gametic thermal plasticity and its effects on hatching success and embryo performance in Atlantic salmon (Salmo salar). Eggs and sperm were incubated overnight at 2°C or 8°C, temperatures within the optimal thermal range of this species. Crosses between warm- and cold-incubated gametes were compared using a full-factorial design, with half of each clutch reared in cold temperatures and the other in warm temperatures. This allowed disentangling single-sex interaction effects when pre-fertilization temperature of gametes mismatched embryonic conditions. Pre-fertilization temperature influenced hatch timing and synchrony, and matching sperm and embryo temperatures resulted in earlier hatching. Warm incubation benefited eggs but harmed sperm, reducing the hatching success and, overall, gametic thermal plasticity did not enhance offspring fitness, indicating vulnerability to thermal changes. We highlight the sensitivity of male gametes to higher temperatures, and that gamete acclimation may not effectively buffer against deleterious effects of thermal fluctuations. From an applied angle, we propose the differential storage of male and female gametes as a tool to enhance sustainability within the hatcheries.

Aerobic metabolic scope mapping of an invasive fish species with global warming

Climate change will exacerbate the negative effects associated with the introduction of non-indigenous species in marine ecosystems. Predicting the spread of invasive species in relation to environmental warming is therefore a fundamental task in ecology and conservation. The Baltic Sea is currently threatened by several local stressors and the highest increase in sea surface temperature of the world's large marine ecosystems. These new thermal conditions can further favour the spreading of the invasive round goby (Neogobius melanostomus), a fish of Ponto-Caspian origin, currently well established in the southern and central parts of the Baltic Sea. This study aims to assess the thermal habitat suitability of the round goby in the Baltic Sea considering the past and future conditions. The study combines sightings records with known physiological models of aerobic performance and sea surface temperatures. Physiological models read these temperatures, at sighting times and locations, to determine their effects on the aerobic metabolic scope (AMS) of the fish, a measure of its energetic potential in relation to environmental conditions. The geographical mapping of the AMS was used to describe the changes in habitat suitability during the past 3 decades and for climatic predictions (until 2100) showing that the favourable thermal habitat in the Baltic Sea has increased during the past 32 years and will continue to do so in all the applied climate model predictions. Particularly, the predicted new thermal conditions do not cause any reduction in the AMS of round goby populations, while the wintertime cold ranges are likely expected to preserve substantial areas from invasion. The results of this research can guide future monitoring programs increasing the chance to detect this invader in novel areas.

PlasPi TDM: Augmentation of a low-cost camera platform for advanced underwater physical-ecological observations

Marine ecosystem dynamics in the context of climate change is a growing scientific, political and social concern requiring regular monitoring through appropriate observational technologies and studies. Thus, a wide range of tools comprising chemical, biogeochemical, physical, and biological sensors, as well as other platforms exists for marine monitoring. However, their high acquisition and maintenance costs are often a major obstacle, especially in low-income developing countries. We designed an advanced low-cost synoptic marine ecosystem observation system that operates at relatively high temporal frequencies, named PlasPi TDM. This instrument is an improved version of the camera system (PlasPI marine cameras) developed in 2020 by Autun Purser from the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (Germany), and collaborators. It incorporates several innovative developments such as multispectral (records the spectrum of any object photographed), temperature and pressure sensors. The PlasPi TDM operates to a depth of 200 m. The various field deployments demonstrate the operational capability of the PlasPi TDM for different applications and illustrate its considerable potential for in-situ observations and marine surveillance in Africa. This device is intended as an open-source project and its continued development is encouraged for a more integrated, sustainable and low-cost ocean observing system.

Dryness limits vegetation pace to cope with temperature change in warm regions

Climate change leads to increasing temperature and more extreme hot and drought events. Ecosystem capability to cope with climate warming depends on vegetation's adjusting pace with temperature change. How environmental stresses impair such a vegetation pace has not been carefully investigated. Here we show that dryness substantially dampens vegetation pace in warm regions to adjust the optimal temperature of gross primary production (GPP) (T opt GPP ) in response to change in temperature over space and time.T opt GPP spatially converges to an increase of 1.01°C (95% CI: 0.97, 1.05) per 1°C increase in the yearly maximum temperature (Tmax ) across humid or cold sites worldwide (37o S-79o N) but only 0.59°C (95% CI: 0.46, 0.74) per 1°C increase in Tmax across dry and warm sites.T opt GPP temporally changes by 0.81°C (95% CI: 0.75, 0.87) per 1°C interannual variation in Tmax at humid or cold sites and 0.42°C (95% CI: 0.17, 0.66) at dry and warm sites. Regardless of the water limitation, the maximum GPP (GPPmax ) similarly increases by 0.23 g C m-2 day-1 per 1°C increase inT opt GPP in either humid or dry areas. Our results indicate that the future climate warming likely stimulates vegetation productivity more substantially in humid than water-limited regions.

Diversity, distribution and intrinsic extinction vulnerability of exploited marine bivalves

Marine bivalves are important components of ecosystems and exploited by humans for food across the world, but the intrinsic vulnerability of exploited bivalve species to global changes is poorly known. Here, we expand the list of shallow-marine bivalves known to be exploited worldwide, with 720 exploited bivalve species added beyond the 81 in the United Nations FAO Production Database, and investigate their diversity, distribution and extinction vulnerability using a metric based on ecological traits and evolutionary history. The added species shift the richness hotspot of exploited species from the northeast Atlantic to the west Pacific, with 55% of bivalve families being exploited, concentrated mostly in two major clades but all major body plans. We find that exploited species tend to be larger in size, occur in shallower waters, and have larger geographic and thermal ranges-the last two traits are known to confer extinction-resistance in marine bivalves. However, exploited bivalve species in certain regions such as the tropical east Atlantic and the temperate northeast and southeast Pacific, are among those with high intrinsic vulnerability and are a large fraction of regional faunal diversity. Our results pinpoint regional faunas and specific taxa of likely concern for management and conservation.

Little directional change in the timing of Arctic spring phenology over the past 25 years

With the global change in climate, the Arctic has been pinpointed as the region experiencing the fastest rates of change. As a result, Arctic biological responses-such as shifts in phenology-are expected to outpace those at lower latitudes. 15 years ago, a decade-long dataset from Zackenberg in High Arctic Greenland revealed rapid rates of phenological change.1 To explore how the timing of spring phenology has developed since, we revisit the Zackenberg time series on flowering plants, arthropods, and birds. Drawing on the full 25-year period of 1996-2020, we find little directional change in the timing of events despite ongoing climatic change. We attribute this finding to a shift in the temporal patterns of climate conditions, from previous directional change to current high inter-annual variability. Additionally, some taxa appear to have reached the limits of their phenological responses, resulting in a leveling off in their phenological responses in warm years. Our findings demonstrate the importance of long-term monitoring of taxa from across trophic levels within the community, allowing for detecting shifts in sensitivities and responses and thus for updated inference in the light of added information.

Biogeography of Fungal Communities Associated with Pinus sylvestris L. and Picea abies (L.) H. Karst. along the Latitudinal Gradient in Europe

We assessed the diversity and composition of fungal communities in different functional tissues and the rhizosphere soil of Pinus sylvestris and Picea abies stands along the latitudinal gradient of these tree species distributions in Europe to model possible changes in fungal communities imposed by climate change. For each tree species, living needles, shoots, roots, and the rhizosphere soil were sampled and subjected to high-throughput sequencing. Results showed that the latitude and the host tree species had a limited effect on the diversity and composition of fungal communities, which were largely explained by the environmental variables of each site and the substrate they colonize. The mean annual temperature and mean annual precipitation had a strong effect on root fungal communities, isothermality on needle fungal communities, mean temperature of the warmest quarter and precipitation of the driest month on shoot fungal communities, and precipitation seasonality on soil fungal communities. Fungal communities of both tree species are predicted to shift to habitats with a lower annual temperature amplitude and with increasing precipitation during the driest month, but the suitability of these habitats as compared to the present conditions is predicted to decrease in the future.

Rapid tropicalization evidence of subtidal seaweed assemblages along a coastal transitional zone

Anthropogenic climate change, particularly seawater warming, is expected to drive quick shifts in marine species distribution transforming coastal communities. These shifts in distribution will be particularly noticeable in biogeographical transition zones. The continental Portuguese coast stretches from north to south along 900 km. Despite this short spatial scale, the strong physical gradient intensified by the Iberian upwelling creates a transition zone where seaweed species from boreal and Lusitanian-Mediterranean origin coexist. On the northern coast, kelp marine forests thrive in the cold, nutrient-rich oceanic waters. In the south, communities resemble Mediterranean-type seaweed assemblages and are dominated by turfs. Recent evidence suggests that in these coastal areas, marine intertidal species are shifting their distribution edges as a result of rising seawater temperatures. Taking advantage of previous abundance data collected in 2012 from subtidal seaweed communities, a new sampling program was carried out in the same regions in 2018 to assess recent changes. The results confirmed the latitudinal gradient in macroalgal assemblages. More importantly we found significant structural and functional changes in a short period of six years, with regional increases of abundance of warm-affinity species, small seaweeds like turfs. Species richness, diversity, and biomass increase, all accompanied by an increase of community temperature index (CTI). Our findings suggest that subtidal seaweed communities in this transitional area have undergone major changes within a few years. Evidence of "fast tropicalization" of the subtidal communities of the Portuguese coast are strong indication of the effects of anthropic climate change over coastal assemblages.

Looking back on biodiversity change: lessons for the road ahead

Estimating biodiversity change across the planet in the context of widespread human modification is a critical challenge. Here, we review how biodiversity has changed in recent decades across scales and taxonomic groups, focusing on four diversity metrics: species richness, temporal turnover, spatial beta-diversity and abundance. At local scales, change across all metrics includes many examples of both increases and declines and tends to be centred around zero, but with higher prevalence of declining trends in beta-diversity (increasing similarity in composition across space or biotic homogenization) and abundance. The exception to this pattern is temporal turnover, with changes in species composition through time observed in most local assemblages. Less is known about change at regional scales, although several studies suggest that increases in richness are more prevalent than declines. Change at the global scale is the hardest to estimate accurately, but most studies suggest extinction rates are probably outpacing speciation rates, although both are elevated. Recognizing this variability is essential to accurately portray how biodiversity change is unfolding, and highlights how much remains unknown about the magnitude and direction of multiple biodiversity metrics at different scales. Reducing these blind spots is essential to allow appropriate management actions to be deployed. This article is part of the theme issue 'Detecting and attributing the causes of biodiversity change: needs, gaps and solutions'.

Temperature dependence of parasitoid infection and abundance of a diatom revealed by automated imaging and classification

Diatoms are a group of phytoplankton that contribute disproportionately to global primary production. Traditional paradigms that suggest diatoms are consumed primarily by larger zooplankton are challenged by sporadic parasitic "epidemics" within diatom populations. However, our understanding of diatom parasitism is limited by difficulties in quantifying these interactions. Here, we observe the dynamics of Cryothecomonas aestivalis (a protist) infection of an important diatom on the Northeast U.S. Shelf (NES), Guinardia delicatula, with a combination of automated imaging-in-flow cytometry and a convolutional neural network image classifier. Application of the classifier to >1 billion images from a nearshore time series and >20 survey cruises across the broader NES reveals the spatiotemporal gradients and temperature dependence of G. delicatula abundance and infection dynamics. Suppression of parasitoid infection at temperatures <4 °C drives annual cycles in both G. delicatula infection and abundance, with an annual maximum in infection observed in the fall-winter preceding an annual maximum in host abundance in the winter-spring. This annual cycle likely varies spatially across the NES in response to variable annual cycles in water temperature. We show that infection remains suppressed for ~2 mo following cold periods, possibly due to temperature-induced local extinctions of the C. aestivalis strain(s) that infect G. delicatula. These findings have implications for predicting impacts of a warming NES surface ocean on G. delicatula abundance and infection dynamics and demonstrate the potential of automated plankton imaging and classification to quantify phytoplankton parasitism in nature across unprecedented spatiotemporal scales.

Abrupt expansion of climate change risks for species globally

Climate change is already exposing species to dangerous temperatures driving widespread population and geographical contractions. However, little is known about how these risks of thermal exposure will expand across species' existing geographical ranges over time as climate change continues. Here, using geographical data for approximately 36,000 marine and terrestrial species and climate projections to 2100, we show that the area of each species' geographical range at risk of thermal exposure will expand abruptly. On average, more than 50% of the increase in exposure projected for a species will occur in a single decade. This abruptness is partly due to the rapid pace of future projected warming but also because the greater area available at the warm end of thermal gradients constrains species to disproportionately occupy sites close to their upper thermal limit. These geographical constraints on the structure of species ranges operate both on land and in the ocean and mean that, even in the absence of amplifying ecological feedbacks, thermally sensitive species may be inherently vulnerable to sudden warming-driven collapse. With higher levels of warming, the number of species passing these thermal thresholds, and at risk of abrupt and widespread thermal exposure, increases, doubling from less than 15% to more than 30% between 1.5 °C and 2.5 °C of global warming. These results indicate that climate threats to thousands of species are expected to expand abruptly in the coming decades, thereby highlighting the urgency of mitigation and adaptation actions.

Reorganization of seagrass communities in a changing climate

Although climate change projections indicate significant threats to terrestrial biodiversity, the effects are much more profound and striking in the marine environment. Here we explore how different facets of locally distinctive α- and β-diversity (changes in spatial composition) of seagrasses will respond to future climate change scenarios across the globe and compare their coverage with the existing network of marine protected areas. By using species distribution modelling and a dated phylogeny, we predict widespread reductions in species' range sizes that will result in increases in seagrass weighted and phylogenetic endemism. These projected increases of endemism will result in divergent shifts in the spatial composition of β-diversity leading to differentiation in some areas and the homogenization of seagrass communities in other regions. Regardless of the climate scenario, the potential hotspots of these projected shifts in seagrass α- and β-diversity are predicted to occur outside the current network of marine protected areas, providing new priority areas for future conservation planning that incorporate seagrasses. Our findings report responses of species to future climate for a group that is currently under represented in climate change assessments yet crucial in maintaining marine food chains and providing habitat for a wide range of marine biodiversity.

A metric-based framework for climate-smart conservation planning

Climate change is already having profound effects on biodiversity, but climate change adaptation has yet to be fully incorporated into area-based management tools used to conserve biodiversity, such as protected areas. One main obstacle is the lack of consensus regarding how impacts of climate change can be included in spatial conservation plans. We propose a climate-smart framework that prioritizes the protection of climate refugia-areas of low climate exposure and high biodiversity retention-using climate metrics. We explore four aspects of climate-smart conservation planning: (1) climate model ensembles; (2) multiple emission scenarios; (3) climate metrics; and (4) approaches to identifying climate refugia. We illustrate this framework in the Western Pacific Ocean, but it is equally applicable to terrestrial systems. We found that all aspects of climate-smart conservation planning considered affected the configuration of spatial plans. The choice of climate metrics and approaches to identifying refugia have large effects in the resulting climate-smart spatial plans, whereas the choice of climate models and emission scenarios have smaller effects. As the configuration of spatial plans depended on climate metrics used, a spatial plan based on a single measure of climate change (e.g., warming) will not necessarily be robust against other measures of climate change (e.g., ocean acidification). We therefore recommend using climate metrics most relevant for the biodiversity and region considered based on a single or multiple climate drivers. To include the uncertainty associated with different climate futures, we recommend using multiple climate models (i.e., an ensemble) and emission scenarios. Finally, we show that the approaches we used to identify climate refugia feature trade-offs between: (1) the degree to which they are climate-smart, and (2) their efficiency in meeting conservation targets. Hence, the choice of approach will depend on the relative value that stakeholders place on climate adaptation. By using this framework, protected areas can be designed with improved longevity and thus safeguard biodiversity against current and future climate change. We hope that the proposed climate-smart framework helps transition conservation planning toward climate-smart approaches.