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Biogeographical shifts are a ubiquitous global response to climate change. However, observed shifts across taxa and geographical locations are highly variable and only partially attributable to climatic conditions. Such variable outcomes result from the interaction between local climatic changes and other abiotic and biotic factors operating across species ranges. Among them, external directional forces such as ocean and air currents influence the dispersal of nearly all marine and many terrestrial organisms. Here, using a global meta-dataset of observed range shifts of marine species, we show that incorporating directional agreement between flow and climate significantly increases the proportion of explained variance. We propose a simple metric that measures the degrees of directional agreement of ocean (or air) currents with thermal gradients and considers the effects of directional forces in predictions of climate-driven range shifts. Ocean flows are found to both facilitate and hinder shifts depending on their directional agreement with spatial gradients of temperature. Further, effects are shaped by the locations of shifts in the range (trailing, leading or centroid) and taxonomic identity of species. These results support the global effects of climatic changes on distribution shifts and stress the importance of framing climate expectations in reference to other non-climatic interacting factors.

We review how intertidal biodiversity is responding to globally driven climate change, focusing on long-term data from rocky shores in the British Isles. Physical evidence of warming around the British Isles is presented and, whilst there has been considerable fluctuation, sea surface temperatures are at the highest levels recorded, surpassing previous warm periods (i.e. late 1950s). Examples are given of species that have been advancing or retreating polewards over the last 50 to 100 yr. On rocky shores, the extent of poleward movement is idiosyncratic and dependent upon life history characteristics, dispersal capabilities and habitat requirements. More southern, warm water species have been recorded advancing than northern, cold water species retreating. Models have been developed to predict likely assemblage composition based on future environmental scenarios. We present qualitative and quantitative forecasts to explore the functional consequences of changes in the identity, abundance and species richness of gastropod grazers and foundation species such as barnacles and canopy-forming algae. We forecast that the balance of primary producers and secondary consumers is likely to change along wave exposure gradients matching changes occurring with latitude, thereby shifting the balance between export and import of primary production. Increases in grazer and sessile invertebrate diversity are likely to be accompanied by decreasing primary production by large canopy-forming fucoids. The reasons for such changes are discussed in the context of emerging theory on the relationship between biodiversity and ecosystem functioning.

Warming of the planet has accelerated in recent years and is predicted to continue over the next 50 to 100 yr. Evidence of responses to present warming in marine ecosystems include shifts in the geographic range of species as well as in the composition of pelagic and demersal fish, benthic and intertidal assemblages. Here we provide a review of the changes in geographic distributions and population abundance of species detected on rocky shores of the NE Atlantic over the last 60 yr. This period encompassed the warm 1950s, a colder period between 1963 and the late 1980s and the recent period of accelerating warming to levels above those of the 1950s. The likely consequences of these responses are then explored. To do this, a summary of the dynamic balance between grazers, macroalgae and barnacles in structuring mid-shore communities is given before outlining experimental work on interactions between key components of rocky shore communities. Modelling and quantitative forecasting were used to predict changes in community composition and dynamics in a warmer world and their consequences for ecosystem functioning discussed. We then identify areas that need further work before making a case for the use of rocky shore species not just as inexpensive indicators of change offshore, but as tractable models to explore the direct and indirect effects of climate change in marine and coastal ecosystems. We also provide a societal perspective emphasising the value of long-term studies in informing adaptation to climate change.

Marine biodiversity and ecosystem functioning are facing unprecedented pressures in the Anthropocene, with climate change being a primary stressor. To understand the biological response mechanisms along coastlines, the international scientific community requires coordinated action, integrating obervations through observatory networks and spatially extensive experiments using standardized approaches over broad geographic scales. Currently, however, a multinational, integrated approach is lacking, with little application of standard methodologies or data sharing across countries. Changes in the abundance, distribution and competitive dominance of rocky intertidal organisms are useful sentinels of climate change because these communities are easy to observe and long-term time series exist. Europe is in a prime position to lead by example, building on the extensive history of sustained observations and experimental research to establish an integrated network of studies and monitoring programmes. These will improve our understanding of how organismal responses translate into biogeographic range shifts, and generate more biologically realistic predictions of future climate change impacts with which to design mitigation, adaptation and conservation strategies.

Patellid limpets are dominant grazers on intertidal rocky shores of NW Europe with a key role in structuring the eulittoral community. Localised loss of limpets and the subsequent reduction in grazing pressure is known to result in important changes in community structure, through the development of canopy-forming macroalgae, and an associated increase in species diversity and community complexity. The level of determinism in the community level response to localised loss of patellid limpets was assessed at spatial scales from 100s of kilometres to 10s of metres and temporal scales from weeks to months at mid-tide level of exposed rocky shores. Limpets were removed and excluded from experimental plots to simulate localised limpet loss and appropriate controls established. Experimental plots were established in replicate patches at 2 shores at each of 2 regional locations, separated by approximately 500 km: the Isle of Man and SW England. Removals were conducted on 2 dates within each of 2 seasons (summer and winter) and the community level response monitored for a period of 12 mo. There was a clear effect of limpet loss at all spatial and temporal scales, with rapid development of green ephemeral algae followed by a fucoid canopy. However, the degree of determinism in the development of canopy-forming algae differed markedly between the 2 locations. At the northerly location, the Isle of Man, fucoid algae developed quickly and dominated all areas of limpet exclusion; there was little variability between plots. In contrast, in SW England, the abundance of fucoid algae was significantly lower and much more variable. Such geographic changes in the development of macroalgae in the absence of the dominant grazer are discussed in relation to rocky shore community dynamics and the latitudinal change in balance between grazers and algae over the wave exposure gradient.

In species with complex life cycles, laboratory studies have shown that variations in the traits of settling larvae can affect post-settlement survival and influence recruitment and benthic–pelagic coupling. However, we still know little about the magnitude and spatial scale of natural trait variation. We studied spatial variation in body size and nutritional reserves (carbon, nitrogen and lipids) of settled cyprids of the barnacle Semibalanus balanoides along the coast of West Scotland. We quantified variation among regions (north vs. south: range ∼700 km), locations (∼50 km), shores (∼10 km) and within shores (∼10 m). We also evaluated trait responses to gradients in chlorophyll and shore openness and compared swimming vs. settled cyprids in order to infer the likely influence of costs of substratum search on trait variation. Variability between regions was large, with higher trait values (e.g. carbon cyprid−1: 35 to 50% higher) in the north. Most traits correlated negatively with pelagic chlorophyll a (a proxy for larval/juvenile food availability); this counter-gradient pattern suggests an adaptive role of increased reserves, buffering benthic juveniles from low food availability during the critical early post-settlement period. Body size and nitrogen content correlated positively with shore openness; lower than expected carbon content suggest increased costs of substratum search on open shorelines. Higher nitrogen content but lower percent carbon was found in settled vs. swimming larvae, suggesting costs of substratum search at the time of settlement. Overall, we uncovered the spatial scales at which trait variation, shaped by pelagic processes, can affect post-metamorphic survival, recruitment and benthic–pelagic coupling.

An integrated ecosystem model including fishing and the impact of rising temperatures, relative to species’ thermal ranges, was used to assess the cumulative effect of future climate change and sustainable levels of fishing pressure on selected target species. Historically, important stocks of cod and whiting showed declining trends caused by high fisheries exploitation and strong top-down control by their main predators (grey seals and saithe). In a no-change climate scenario these stocks recovered under sustainable management scenarios due to the cumulative effect of reduced fishing and predation mortalities cascading through the food-web. However, rising temperature jeopardised boreal stenothermal species: causing severe declines in grey seals, cod, herring and haddock, while eurythermal species were not affected. The positive effect of a higher optimum temperature for whiting, in parallel with declines of its predators such as seals and cod, resulted in a strong increase for this stock under rising temperature scenarios, indicating a possible change in the contribution of stocks to the overall catch by the end of the century. These results highlight the importance of including environmental change in the ecosystem approach to achieve sustainable fisheries management.

Since the rate of global climate change began to accelerate in the 1980s, the coastal seas of Britain have warmed by up to 1°C. Locations close to the northern range edges of a southern trochid gastropod Osilinus lineatus in Britain previously surveyed in the 1950s and 1980s were resurveyed during 2002–2004 to determine whether changes in the success of near-limit populations had occurred during the period of climate warming. Between the 1980s and the 2000s, the range limits had extended by up to 55 km. Populations sampled over a latitudinal extent of 4 degrees from northern limits towards the centre of the range showed synchronous increases in abundance throughout the years sampled, suggesting a large-scale factor such as climate was driving the observed changes. These increases in abundance and changes in range limits are likely to have occurred via increased recruitment success in recent years.

Regional oceanographic processes are emerging as strong influences on growth and recruitment of intertidal species, with important consequences for populations. Yet local conditions such as wave exposure are also important. To disentangle these effects for the intertidal barnacle Semibalanus balanoides, we surveyed 259 sites around Scotland in July and August over 6 yr (from 2001 to 2006). Scaled digital photographs at 3 shore levels gave sizes and densities of juvenile and adult barnacles for comparison with wave fetch, remotely sensed chlorophyll a (chl a) concentration and seasonal sea surface temperature (SST). Patterns were also compared with site 'openness': the area of connected open sea <30 km away. Patterns at the 3 shore levels were similar. Hierarchical partitioning (HP) showed that survey year had the biggest effect and improved the predictive power of other variables: wave fetch for adult and juvenile densities, chl a for juvenile size and openness for adult size. SST had little effect. Regression models selected using information theoretic measures included positive effects of chl a, varying among surveys, on average size of barnacles (R super(2) from 0.5 to 0.6), and larger high shore barnacles in greater wave exposure. Population densities of adults and juveniles increased with wave fetch, with chl a only influencing density at high shore levels (R super(2) from 0.1 to 0.4). Despite temporal and spatial variation in responses to chl a and wave fetch among surveys, relationships were consistent with growth and size in S. balanoides being limited by food supply, and increased recruitment and adult densities in increased wave exposure. Large-scale ecological patterns in this rocky intertidal species thus result from large-scale oceanographic effects on food concentration with habitat-scale wave-mediated effects on supply of food and larvae.

Stratified depth sampling was used to investigate the distributional changes of newly settled plaicePleuronectes platessaand dabsLimanda limanda, and resident populations of shrimpCrangon crangonon a sandy beach. During the settlement period, the smallest newly settled plaice are found in deeper water than the larger fish that settled earlier. After settlement, plaice concentrate in water <1 m deep and there is a positive relationship between length and depth. Later in the year the fish gradually migrate into deeper water as they grow. Dabs settle later and in deeper water than plaice. Shrimp are concentrated in deeper water early in the year but migrate onshore in the summer. The movements of plaice are considered to be related to the predation risk caused by the shrimp and other predators in deeper water and to the higher temperatures in shallow water that promote faster growth. Once a size refuge from predators has been reached, the plaice move into deeper water. Intertidal pools probably serve as refuges for the smallest sizes of plaice because predators are less numerous in pools than in the sea. The use of shallow water by plaice represents the occupation of a niche which not only reduces predation and maximises growth, but may also greatly reduce competition for food in the earliest stages when densities are highest and competition with dabs is likely to be greatest.