Intertidal organisms are exposed to extreme and variable thermal conditions due to periodic aerial exposure by tides. For sessile species that cannot seek refuge, heat stress is strongly influenced by the timing of low tides, which in semidiurnal tidal systems is governed by the spring-neap tidal cycle. Here, we deployed biomimetic loggers, designed to replicate body temperature of the mussel Mytilus edulis, at two climatologically similar yet tidally distinct sites in Wales, UK, to examine how interactions between climate and tidal phasing regulate intertidal heat stress. Despite comparable weather conditions, South Wales mussels-exposed during midday spring low tides-experienced daily maximum body temperatures over 3 degrees C higher compared to North Wales, where exposure occurred during morning and evening spring low tides. Consequently, South Wales mussels exceed critical temperature thresholds more frequently. Based on the observations, we developed and validated a mussel body temperature model incorporating readily available tidal and climatic data, which accurately reproduced observed logger temperatures and successfully simulated a 2018 mass mortality event in the English Channel. Model experiments showed that tidal phasing can modulate 95th-percentile daily maxima by up to 5.5 degrees C, with midday spring low tides producing the warmest possible conditions. Long-term simulations (1990-2023) further revealed a 2 to 2.5-fold increase in extreme temperature exposure since 2020. These results demonstrate that tidal characteristics in semidiurnal systems can amplify or mitigate intertidal thermal stress as strongly as local climate, and that simple, process-based models can forecast heat exposure and ecological vulnerability under future climate change.

The study of competition in crustaceans spans many decades and has led to numerous advances in understanding how animals interact to secure limited resources, be they food, space, refugia, or access to a mate or host. This chapter considers different approaches to studying competition in crustaceans, from controlled experiments in mesocosms to models based on long-term, large-scale data sets, and introduces various model taxa, including barnacles, hermit crabs, and amphipods. Intraspecific and interspecific interactions are described that lead to changes in demography, behavior, morphology, and distribution, as well as consequences for evolutionary processes. In doing so, reference to both interference and exploitation competition is made. Crustacean research also provides insights into changing patterns of competition, principally due to global redistribution of taxa through human vectors. Notable global examples include the case of the shore crab Carcinus maenas, which has formed new populations around the globe since at least the 19th century. While true competition for a shared resource is the main focus here, apparent competition involving crustacean taxa is also described, whereby negative indirect interactions between species arise because they share a common enemy. This chapter brings together a diverse range of ecological work to demonstrate the pervasive influence of competition across crustacean taxa, from individuals through populations to communities and ecosystems. In addition, it shows that crustacean-focused research, and the adoption of particular model crustacean taxa, has had a significant impact in enhancing our understanding of competition in structuring populations, communities, and influencing the pathway of evolutionary processes.

For many species targeted by static gear fisheries, the relationship between catch per unit effort (CPUE) and density on the seabed is poorly understood. One aspect that is crucial in understanding this relationship is the area from which catches are drawn, known as the trapping area, yet this remains largely unquantified. In this paper we investigate the size of the trapping area for the commercially important common whelk (Buccinum undatum) by studying variations in CPUE in relation to the distance between pots. With declining spacing, the sphere of attraction will increasingly overlap, leading to reductions in catches and allowing the density of catchable animals to be estimated. Experimental fishing took place with pot distances ranging from 4 to 50 m, with catches recorded for over 500 pots over a week-long period. In addition to pot spacing, deployment location and haul date were significant factors influencing CPUE. For the study site, and based on environmental conditions at the time, the trapping area was estimated to be 120 m2, indicating whelk pots spaced at least 12-13 m apart are likely to fish independently of each other. This resulted in a density estimate of 0.9 individuals m-2, with spatial variation between 0.4 and 1.2 individuals m-2. Results suggest pot spacings in the local fishery are sufficient to avoid interactions, and there is potential to predict densities from commercial CPUE, although further work is needed to understand variability in the size of the trapping area in relation to environmental and biotic factors.

Rocky shorelines are characterised by vulnerability to both land- and sea-derived impacts. They face acute impacts such as pollution from shipping accidents, chronic pollution from point sources, run-off and catchments plus disturbances by food gathering, recreation and sediment deposition in sheltered areas. Coastal urbanisation can both impact natural shores and create impoverished artificial rocky shores. Superimposed upon local and regional scale impacts are global environmental changes including warming, sea-level rise, increasing storm frequency, ocean acidification and non-native invasive species. Rocky shores are, however, amenable to long-term ecological monitoring and ecological experimentation. Thompson, Crowe and Hawkins (2002) reviewed anthropogenic impacts on rocky intertidal habitats and forecasted their status for the next 25 years. The paper was critiqued by invited experts (Branch, Castilla) at a subsequent conference in 2003 (Environmental Future of Aquatic Ecosystems, Zurich, 23-27 March 2003), culminating in a consensus chapter in Aquatic Ecosystems: Trends and Global Prospects (Branch et al., 2008). Nearly 25 years later, we revisit and evaluate their predictions to explore implications for the next 25 years as new potential impacts emerge in parallel with societal attempts to transition to net zero carbon outputs. An update is provided on what was largely correct (oil-spills, food harvest, invasive species, sedimentation/run-off, organotins, global-change, artificial habitats, recreation/research/education) and what was partially/completely wrong (eutrophication, aquaculture/GMOs, renewable energy, UV radiation) or omitted (coastal mining, ocean acidification, plastic, light, noise pollution). We also consider the challenges and uncertainties inherent in predicting impacts of environmental changes by using hindsight to inform foresight.

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Trap fisheries targeting invertebrates are economically important but many of the target species lack stock assessments. One reason for this is the difficulty of estimating density. One important means by which density can be estimated uses the catch rates of baited traps that are spaced at different distances. With declining spacing, the sphere of attraction will increasingly overlap, leading to reductions in catches, allowing for the estimation of the density that is catchable by traps on the seabed. Here we review the analytical methods adopted across a range of studies and find that no consensus on robust methods exists. We propose an analytical method that assumes the trapping area is circular and that the chance of catching an individual declines linearly with distance from the trap. We apply this method to estimate the density and the trapping radius of crabs and gastropods from real and simulated datasets. The method estimated a trapping radius of between 4 and 86 m, and densities that are up to 2.5 times less and 13 times greater than estimates provided in the original sources, illustrating the sensitivity to methodology. In conclusion, we provide and test a standardized method to estimate the density of benthic invertebrates.

Rocky shore communities are shaped by complex interactions among environmental drivers and a range of biological processes. Here, we investigated the importance of abiotic and biotic drivers on the population structure of key rocky intertidal species at 62 sites, spanning 50% of the Brazilian rocky shoreline (i.e., 500 km). Large-scale population patterns were generally explained by differences in ocean temperature and wave exposure. For the gastropod species Lottia subrugosa, differences at smaller scales (i.e., 0.1-1 km) were better explained by other abiotic influences such as freshwater discharge and substrate roughness. Based on the general population patterns of intertidal species identified, three main oceanographic groups were observed: a coldoligotrophic grouping at northern sites (Lakes sub-region), a eutrophic group associated with large estuaries and urban zones (Santos and Guanabara bays); and a transitional warm-water group found between the two more productive areas. Larger individuals of Stramonita brasiliensis, L. subrugosa and Echinolittorina lineolata were generally found in the cold-oligotrophic system (i.e., upwelling region), while small suspension feeders dominate the warm-eutrophic systems. Evidence of bottom-up regulation was not observed, and top-down regulation effects were only observed between the whelk S. brasiliensis and its mussel prey Perna perna. Environmental drivers as compared to biotic interactions, therefore, play a key role determining the population structure of multiple intertidal species, across a range of spatial scales along the SW Atlantic shores.

Achieving net-zero global emissions of carbon dioxide (CO2), with declining emissions of other greenhouse gases, is widely expected to halt global warming. CO2 emissions will continue to drive warming until fully balanced by active anthropogenic CO2 removals. For practical reasons, however, many greenhouse gas accounting systems allow some 'passive' CO2 uptake, such as enhanced vegetation growth owing to CO2 fertilization, to be included as removals in the definition of net anthropogenic emissions. By including passive CO2 uptake, nominal net-zero emissions would not halt global warming, undermining the Paris Agreement. Here we discuss measures to address this problem, to ensure residual fossil fuel use does not cause further global warming: land management categories should be disaggregated in emissions reporting and targets to better separate the role of passive CO2 uptake; where possible, claimed removals should be additional to passive uptake; and targets should acknowledge the need for Geological Net Zero, meaning one tonne of CO2 permanently restored to the solid Earth for every tonne still generated from fossil sources. We also argue that scientific understanding of Net Zero provides a basis for allocating responsibility for the protection of passive carbon sinks during and after the transition to Geological Net Zero.

Identifying and understanding environmental drivers responsible for fluctuations in stock biomass remains a key knowledge gap in data limited commercial crustacean fisheries such as the brown crab Cancer pagurus. This study investigated the use of historic beam trawl data as a fishery independent density index and its relationship with fishery dependent data. The role of the North Atlantic Oscillation (NAO), a key latent predictor, and other environmental drivers (brooding temperature, larval development temperature and phytoplankton density) on density of C. pagurus in the North West Irish Sea was also investigated. The identification of a significant relationship between fisheries dependent and independent data demonstrates the role of fisheries independent survey data to monitor changes in density in C. pagurus populations. Lagged NAO, brooding temperature and larval temperatures had significant effects on C. pagurus density, with negative NAO phases and increasing brooding and larvaal temperatures resulting in increased C. pagurus density. The significance of these relationships is explored in the context of our understanding of relative stock status and future sustainable fisheries management for C. pagurus in the North East Atlantic.

The production and use of fossil fuels need to decline rapidly to limit global warming. Although global net-zero scenarios abound, the associated development ramifications for fossil fuel-producing low and lower–middle income countries (LLMICs), as well as adequate international responses, have been underexplored. Here we conceptualize that, depending on country context, three types of development transition follow from declining fossil fuel production and use for LLMIC producers, namely an energy transition, an economic transition and an equitable fossil fuel production transition. We propose a classification of these transitions, arguing that heterogeneity in LLMICs’ fossil fuel production and usage substantially impacts their pathways towards low-carbon development. We illustrate this by discussing different cases of fossil fuel-producing LLMICs, focusing on Mozambique, India, Lao PDR and Angola. We conclude by detailing context-specific international support portfolios to foster low-carbon development in fossil fuel-producing LLMICs, and call for a re-orientation of international support along principles of global solidarity.

Abstract Coastal communities and their landscapes are subject to constant change, and today face new challenges as a result of climate change and the sustainable energy transition. To ensure the resilience of coastal communities to ongoing changes in the natural and constructed environment, it is imperative that planners and other decision‐makers understand the importance of local places to residents. We used an interdisciplinary, mixed‐methods approach to study relationships between coastal residents and places in south Co. Wicklow, Ireland, introducing the concept of ‘affective engagement’. Grounded in new materialist theory (notably actor–network theory), this term connects the meaning derived by residents from their relationships with coastal places (‘affect’) to the extent of their material interactions (‘engagement’). ‘Affect’ was determined from thematic analysis of interviews and open questionnaire responses, as well as place attachment scales included in the questionnaire. Measures describing the strength of the relationship between residents and coastal places were used as a proxy for ‘engagement’. To understand how experienced meaning and material interaction interlink, principal component analysis (PCA) was used to join and visually explore the different measures of ‘affect’ and ‘engagement’. Potentially mediating sociodemographic variables were investigated using a permutational multivariate analysis of variance (PERMANOVA). The majority of self‐selected study participants displayed strong place attachment to their most frequently visited places. We found that affective engagement does not vary with age, gender or type of place. Participants favoured natural and constructed places in equal measure. This implies that constructed places can be of high value due to their different functions for different individuals, and that landscape transformations may impact on coastal residents if they cause a change in functionality. We found two domains comprising affective engagement that are not measurable by quantitative or qualitative data alone. The first of these domains is driven by attachments to places, and the other by meanings relating to either personal or social fulfilment afforded by a place. Our findings may help planners better understand the meanings behind local support for (or resistance against) landscape transformations, and how residents' affective engagement might be impacted by proposed interventions. Read the free Plain Language Summary for this article on the Journal blog.

Marine species raft on floating litter, including various plastics, potentially spreading non-native species and threatening global marine habitats. Despite limited attention, Didemnum vexillum, an invasive colonial tunicate in Europe, colonised coasts of southwest Scotland (2009) and northeast Ireland (2012), likely transported via rafting. We studied D. vexillum survival and performance on three plastic types (Polyethylene, Polypropylene and Polystyrene) finding high survival rates over 42 days, with colonies thriving best on PS. Using these data, hydrodynamic and particle tracking models simulated dispersal from existing Irish Sea colonies, projecting potential rafting distances of up to ∼150 km for surface particles influenced by tide and wind, and half that for neutrally-buoyant mid-depth particles driven by tidal currents alone. Hence, the modelling supports the potential for dispersion of this species within the Irish Sea via rafting. This study highlights marine plastics as a vector that may facilitate widespread dispersal of non-native species.

Simple climate models (also known as emulators) have re-emerged as critical tools for the analysis of climate policy. Emulators are efficient and highly parameterised, where the parameters are tunable to produce a diversity of global mean surface temperature (GMST) response pathways to a given emission scenario. Only a small fraction of possible parameter combinations will produce historically consistent climate hindcasts, a necessary condition for trust in future projections. Alongside historical GMST, additional observed (e.g. ocean heat content) and emergent climate metrics (such as the equilibrium climate sensitivity) can be used as constraints upon the parameter sets used for climate projections. This paper describes a multi-variable constraining package for the Finite-amplitude Impulse Response (FaIR) simple climate model (FaIR versions 2.1.0 onwards) using a Bayesian framework. The steps are, first, to generate prior distributions of parameters for FaIR based on the Coupled Model Intercomparison Project (CMIP6) Earth system models or Intergovernmental Panel on Climate Change (IPCC)-assessed ranges; second, to generate a large Monte Carlo prior ensemble of parameters to run FaIR with; and, third, to produce a posterior set of parameters constrained on several observable and assessed climate metrics. Different calibrations can be produced for different emission datasets or observed climate constraints, allowing version-controlled and continually updated calibrations to be produced. We show that two very different future projections to a given emission scenario can be obtained using emissions from the IPCC Sixth Assessment Report (AR6) (fair-calibrate v1.4.0) and from updated emission datasets through 2022 (fair-calibrate v1.4.1) for similar climate constraints in both cases. fair-calibrate can be reconfigured for different source emission datasets or target climate distributions, and new versions will be produced upon availability of new climate system data.

While international climate policies now focus on limiting global warming to well below 2 degrees C or pursuing a 1.5 degrees C level of global warming, the climate modelling community has not provided an experimental design in which all Earth system models (ESMs) converge and stabilize at the same prescribed global warming levels. This gap hampers accurate estimations based on comprehensive ESMs of the carbon emission pathways and budgets needed to meet such agreed warming levels and of the associated climate impacts under temperature stabilization. Here, we apply the Adaptive Emission Reduction Approach (AERA) with ESMs to provide such simulations in which all models converge at 1.5 and 2.0 degrees C warming levels by adjusting their emissions over time. These emission-driven simulations provide a wide range of emission pathways and resulting atmospheric CO2 projections for a given warming level, uncovering uncertainty ranges that were previously missing in the traditional Coupled Model Intercomparison Project (CMIP) scenarios with prescribed greenhouse gas concentration pathways. Meeting the 1.5 degrees C warming level requires a 40 % (full model range: 7 % to 76 %) reduction in multi-model mean CO2-forcing-equivalent (CO2-fe) emissions from 2025 to 2030, a 98 % (57 % to 127 %) reduction from 2025 to 2050, and a stabilization at 1.0 (-1.7 to 2.9) PgC yr-1 from 2100 onward after the 1.5 degrees C global warming level is reached. Meeting the 2.0 degrees C warming level requires a 47 % (8 % to 92 %) reduction in multi-model mean CO2-fe emissions until 2050 and a stabilization at 1.7 (-1.5 to 2.7) PgC yr-1 from 2100 onward. The on-average positive emissions under stabilized global temperatures are the result of a decreasing transient climate response to cumulative CO2-fe emissions over time under stabilized global warming. This evolution is consistent with a slightly negative zero emissions commitment - initially assumed to be zero - and leads to an increase in the post-2025 CO2-fe emission budget by a factor of 2.2 (-0.8 to 6.9) by 2150 for the 1.5 degrees C warming level and a factor of 1.4 (0.9 to 2.4) for the 2.0 degrees C warming level compared to its first estimate in 2025. The median CO2-only carbon budget by 2150, relative to 2020, is 800 GtCO2 for the 1.5 degrees C warming level and 2250 GtCO2 for the 2.0 degrees C warming level. These median values exceed the median IPCC AR6 estimates by 60 % for the 1.5 degrees C warming level and 67 % for 2.0 degrees C. Some of the differences may be explained by the choice of the mitigation scenario for non-CO2 radiative agents. Our simulations highlight shifts in carbon uptake dynamics under stabilized temperature, such as a cessation of the carbon sinks in the North Atlantic and in tropical forests. On the other hand, the Southern Ocean remains a carbon sink centuries after temperatures stabilize. Overall, this new type of warming-level-based emission-driven simulation offers a more coherent assessment across climate models and opens up a wide range of possibilities for studying both the carbon cycle and climate impacts, such as extreme events, under climate stabilization.

AbstractMost ecological studies attempting to understand causes of population dynamics and community structure disregard intraspecific trait variation. We quantified the importance of natural intra‐cohort variation in body size and density of juveniles for recruitment of a sessile marine organism, the barnacle Semibalanus balanoides. Barnacles are representative of species organised in metapopulations, that is, as open local populations connected by larval dispersal. We tracked the individual growth and survival of a cohort of juvenile barnacles from two shores of North Wales. Barnacles settled as larvae in spring of 2002 on previously cleared rock. The density of these new recruits was experimentally manipulated in June and randomly selected individuals were monitored from June to October to evaluate the role of barnacle size and density in predicting survival. In doing so we characterised density at three spatial scales (quadrat: 25 cm2, cells within quadrats: 25 mm2 and neighbourhood: number of neighbours in physical contact with the target barnacle). At all scales, variations in juvenile body size exacerbated the effect of density‐dependent mortality on population size. While density‐dependent mortality was very intense in the small‐sized individuals, large‐sized individuals experienced very weak density‐dependent mortality and showed high survival rates. Using the concept of ‘Jensen inequality’, we show that important biases in estimations of survival, based on population size only, occur at high barnacle densities, where survival is low. Our study highlights the role of body size variation in understanding dynamics of open populations.

Baited static gear fisheries targeting benthic invertebrates have expanded at a global scale. While improvements have been made in the monitoring and management of these fisheries, reliable survey methods for stock assessments of many key species are lacking. In this study we examine the viability of a baited remote underwater video (BRUV) system for obtaining abundance indices for a data-limited stock (common whelk, Buccinum undatum), and compare this method to catch per unit effort (CPUE) from commercial fishing. BRUVs capable of collecting 15 hours of timelapse footage were deployed on pot strings in two distinct whelk fishing sites, with replication over a spring-neap tidal cycle. Three potential BRUV metrics-the maximum (MaxN) and mean (MeanN) abundance and time of first arrival (T1)-were calculated for each deployment, and significant linear relationships were identified between MaxN, MeanN, and CPUE across sites. Temporal variability in BRUV indices driven by tidal dynamics was minimal, although results suggest high current speeds may reduce abundance estimates, and a potential method for predicting density on the seabed using arrival rates is also demonstrated. BRUVs are a valuable tool in developing stock assessment surveys for static gear fisheries.

The growth of human activity and infrastructure has led to an unprecedented rise in the use of Artificial Light at Night (ALAN) with demonstrable impacts on ecological communities and ecosystem services. However, there remains very little information on how ALAN interacts with or obscures light from celestial bodies, which provide vital orientating cues in a number of species. Furthermore, no studies to date have examined how climatic conditions such as cloud cover, known to influence the intensity of skyglow, interact with lunar irradiance and ALAN over the course of a lunar cycle to alter migratory abilities of species. Our night-time field study aimed to establish how lunar phase and climatic conditions (cloud cover) modulate the impact of ALAN on the abundance and migratory behaviour of Talitrus saltator, a key sandy beach detritivore which uses multiple light associated cues during nightly migrations. Our results showed that the number and size of individuals caught decreased significantly as ALAN intensity increased. Additionally, when exposed to ALAN more T. saltator were caught travelling parallel to the shoreline, indicating that the presence of ALAN is inhibiting their ability to navigate along their natural migration route, potentially impacting the distribution of the population. We found that lunar phase and cloud cover play a significant role in modifying the impact of ALAN, highlighting the importance of incorporating natural light cycles and climatic conditions when investigating ALAN impacts. Critically we demonstrate that light levels as low as 3 lx can have substantial effects on coastal invertebrate distributions. Our results provide the first evidence that ALAN impacted celestial migration can lead to changes to the distribution of a species.

Intergovernmental Panel on Climate Change (IPCC) assessments are the trusted source of scientific evidence for climate negotiations taking place under the United Nations Framework Convention on Climate Change (UNFCCC). Evidence-based decision-making needs to be informed by up-to-date and timely information on key indicators of the state of the climate system and of the human influence on the global climate system. However, successive IPCC reports are published at intervals of 5–10 years, creating potential for an information gap between report cycles. We follow methods as close as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One (WGI) report. We compile monitoring datasets to produce estimates for key climate indicators related to forcing of the climate system: emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, the Earth's energy imbalance, surface temperature changes, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. The purpose of this effort, grounded in an open-data, open-science approach, is to make annually updated reliable global climate indicators available in the public domain (https://doi.org/10.5281/zenodo.11388387, Smith et al., 2024a). As they are traceable to IPCC report methods, they can be trusted by all parties involved in UNFCCC negotiations and help convey wider understanding of the latest knowledge of the climate system and its direction of travel. The indicators show that, for the 2014–2023 decade average, observed warming was 1.19 [1.06 to 1.30] °C, of which 1.19 [1.0 to 1.4] °C was human-induced. For the single-year average, human-induced warming reached 1.31 [1.1 to 1.7] °C in 2023 relative to 1850–1900. The best estimate is below the 2023-observed warming record of 1.43 [1.32 to 1.53] °C, indicating a substantial contribution of internal variability in the 2023 record. Human-induced warming has been increasing at a rate that is unprecedented in the instrumental record, reaching 0.26 [0.2–0.4] °C per decade over 2014–2023. This high rate of warming is caused by a combination of net greenhouse gas emissions being at a persistent high of 53±5.4 Gt CO2e yr−1 over the last decade, as well as reductions in the strength of aerosol cooling. Despite this, there is evidence that the rate of increase in CO2 emissions over the last decade has slowed compared to the 2000s, and depending on societal choices, a continued series of these annual updates over the critical 2020s decade could track a change of direction for some of the indicators presented here.