Predicting ecosystem shifts requires new approaches that integrate the effects of climate change across entire systems.

Most studies that forecast the ecological consequences of climate change target a single species and a single life stage. Depending on climatic impacts on other life stages and on interacting species, however, the results from simple experiments may not translate into accurate predictions of future ecological change. Research needs to move beyond simple experimental studies and environmental envelope projections for single species towards identifying where ecosystem change is likely to occur and the drivers for this change. For this to happen, we advocate research directions that (i) identify the critical species within the target ecosystem, and the life stage(s) most susceptible to changing conditions and (ii) the key interactions between these species and components of their broader ecosystem. A combined approach using macroecology, experimentally derived data and modelling that incorporates energy budgets in life cycle models may identify critical abiotic conditions that disproportionately alter important ecological processes under forecasted climates

Impacts of climate change on intertidal habitats, relevant to the coastal and marine environment around the UK

The lack of dramatic observed responses of intertidal species from 2002 to 2018 is consistent with the lack of increase in sea temperatures since 2000. Despite the continued global upward trend in temperature, UK regional sea temperatures have remained stable or declined over the same period, with only those in western Scotland increasing. This hiatus followed a period of rapid warming from 1980 to 2000 when many range shifts occurred. • Short-term fluctuations in abundance of climate-sensitive species have continued through the mid-2010s, and most of these changes in abundance are consistent with changes in temperature at timescales of less than a decade, offering further evidence for the continued sensitivity of intertidal species to climate. • Leading range edges of Lusitanian topshells are continuing to move northwards in North Wales and south-east England. The Community Temperature Index (CTI) shows considerable promise for use as a measure of the combined response of multiple species to climate change. Preliminary analysis of spatial patterns in UK rocky shore communities shows that the CTI follows temperature closely, and that changes in sea-surface temperature over time are matched by changes in CTI. • The lack of an upward trend in UK sea temperatures is unlikely to continue, since longer-term trends appear to be less regionalised than short-term ones, and further changes are likely to be more dramatic in the next decade as local temperatures catch up with global trends. • A heatwave event in summer 2018 caused heat damage to the high and midshore fucoids in UK regional seas

Shoreline sentinels of global change show the consequences of extreme events

Anthropogenic climate change along with the more frequent extreme weather it prompts, are having direct and indirect effects on distributions and abundance of species with consequence for community structure—especially if habitat providers are lost. Rocky shores have long been recognized as tractable experimental arenas for ecology contributing to theory. They have also emerged as important sentinel systems for tracking climate change responses of marine biodiversity and ecosystems, capitalizing on both historic broadscale surveys and time series. Combining these twin traditions is a powerful approach for better understanding and forecasting climate change impacts. Sustained observing allows extreme events to be detected and explored by in-parallel experimentation

Evolutionary Phycology: Toward a Macroalgal Species Conceptual Framework

Species concepts formalize evolutionary and ecological processes, but often conflict with one another when considering the mechanisms that ultimately lead to species delimitation. Evolutionary biologists are, however, recognizing that the conceptualization of a species is separate and distinct from the delimitation of species. Indeed, if species are generally defined as separately evolving metapopulation lineages, then characteristics, such as reproductive isolation or monophyly, can be used as evidence of lineage separation and no longer conflict with the conceptualization of a species. However, little of this discussion has addressed the formalization of this evolutionary conceptual framework for macroalgal species. This may be due to the complexity and variation found in macroalgal life cycles. While macroalgal mating system variation and patterns of hybridization and introgression have been identified, complex algal life cycles generate unique eco-evolutionary consequences. Moreover, the discovery of frequent macroalgal cryptic speciation has not been accompanied by the study of the evolutionary ecology of those lineages, and, thus, an understanding of the mechanisms underlying such rampant speciation remain elusive. In this perspective, we aim to further the discussion and interest in species concepts and speciation processes in macroalgae. We propose a conceptual framework to enable phycological researchers and students alike to portray these processes in a manner consistent with dialogue at the forefront of evolutionary biology. We define a macroalgal species as an independently evolving metapopulation lineage, whereby we can test for reproductive isolation or the occupation of distinct adaptive zones, among other mechanisms, as secondary lines of supporting evidence

Impacts of Pervasive Climate Change and Extreme Events on Rocky Intertidal Communities: Evidence From Long-Term Data

Annual surveys of the abundance of intertidal invertebrates and macroalgae have been made at between 70 and 100 rocky intertidal time-series sites around the United Kingdom coastline since 2002 under the MarClim project. The data provide a unique opportunity to investigate the impacts of both pervasive climate change and their punctuation by extreme events on intertidal species. After the extreme storm events in the 2013/2014 winter season and the record heatwaves in the summers of 2018 and 2020, MarClim surveys recorded both physical and biological changes to rocky shore habitats. Subsequent surveys reassessed the effects on community structure via analysis of those species that resisted storm damage, those species that returned after the extreme storm events, and species that opportunistically occupied vacant habitat after storm-induced species loss. In addition, biannual storm damage surveys documenting communities recovery were carried out in the spring and winter of each year from 2014 to 2020 at three MarClim sites in north Cornwall (Crackington Haven, Trevone, and St. Ives), which experienced different types of abiotic and biotic damage resulting from these storms. Impacts of heatwaves and cold spells on the abundance of species were determined by regression on frequencies of event per year. Species of invertebrates and macroalgae generally declined in years of more frequent winter cold spells and summer heatwaves, while winter heatwaves and summer cold spells had similar numbers of positive and negative effects across species. Winter warm spells tended to have a more negative effect on cold-affinity species than on warm-affinity species. No abrupt shift was recorded after the 2013/2014 storms. Whilst a short-term change in some species was recorded in quantitative quadrat surveys, the biological communities returned to the long-term species composition and abundance within 2 years. The heatwave events caused sublethal heat damage in macroalgae, evidenced as dried areas of tissue on many individuals, with mortality-induced reductions in the abundance of only a few invertebrate species, recorded in Scotland and southwest England after the heatwave events in 2018 and 2020. MarClim and storm-damage surveys indicate that there have been no sustained impacts from either extreme thermal or storm events across the rocky intertidal communities, and biodiversity has not been significantly altered as a result. The abundance and biogeographical distributions of rocky intertidal species and communities around the United Kingdom are being driven by longer-term, large scale, pervasive change in environmental conditions, with a gradual shift towards dominance of Lusitanian species from the early 2000s in responses to warming of the marine climate

Identifying conservation priorities for gorgonian forests in Italian coastal waters with multiple methods including citizen science and social media content analysis

Aim Gorgonian forests are among the most complex of subtidal habitats in the Mediterranean Sea, supporting high biodiversity and providing diverse ecosystem services. Despite their iconic status, the geographical distribution and condition of gorgonian species is poorly known. Using multiple online data sources, our primary aims were to compile, map and analyse observations of gorgonian forests in Italian coastal waters to assess the biological complexity of gorgonian forests, evaluate impacts and vulnerable species, and identify areas of special interest inside and outside of marine protected areas (MPAs) to help prioritize conservation strategies and actions. Location Italy. Mediterranean Sea. Methods Using a multi-source data integration approach, we collected and integrated data from scientific publications, the World Wide Web including social media platforms, citizen science projects and SCUBA diver questionnaires into a unified spatial framework. This method provided up-to-date information on the geographical distribution, abundance, and health of major habitat-forming gorgonian species in Italian coastal waters. Results Higher abundance and complexity of gorgonian species occurred outside MPAs. Areas of Special Interest (n = 167) were identified (80 inside and 87 outside MPAs). Three locations supported all seven focal species: Capo Caccia MPA, Portofino MPA and Catania (unprotected). The purple gorgonian (Paramuricea clavata), the most abundant and geographically widespread species with highest forest complexity, was affected by multiple stressors including thermal stress, disease and fishing. Main conclusions The multi-source approach was a rapid and cost-effective tool to gather, analyse and map disparate data on gorgonian forests spanning 27 years of underwater observations both inside and outside of MPAs. The unique perspective given by this approach demonstrates the suboptimal protection of several habitat-forming gorgonian species. The approach has great potential for wider application and offers a more inclusive participatory model for crowdsourcing and repurposing under-utilized observations while also increasing ocean literacy

Using historical data to detect temporal changes in the abundances of intertidal species on Irish shores

An historical data set, collected in 1958 by Southward and Crisp, was used as a baseline for detecting change in the abundances of species in the rocky intertidal of Ireland. In 2003, the abundances of each of 27 species was assessed using the same methodologies (ACFOR [which stands for the categories: abundant, common, frequent, occasional and rare] abundance scales) at 63 shores examined in the historical study. Comparison of the ACFOR data over a 45-year period, between the historical survey and re-survey, showed statistically significant changes in the abundances of 12 of the 27 species examined. Two species (one classed as northern and one introduced) increased significantly in abundance while ten species (five classed as northern, one classed as southern and four broadly distributed) decreased in abundance. The possible reasons for the changes in species abundances were assessed not only in the context of anthropogenic effects, such as climate change and commercial exploitation, but also of operator error. The error or differences recorded among operators (i.e. research scientists) when assessing species abundance using ACFOR categories was quantified on four shores. Significant change detected in three of the 12 species fell within the margin of operator error. This effect of operator may have also contributed to the results of no change in the other 15 species between the two census periods. It was not possible to determine the effect of operator on our results, which can increase the occurrence of a false positive (Type 1) or of a false negative (Type 2) outcom