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As on land, oceans exhibit high temporal and spatial temperature variation. This ocean weather contributes to the physiological and ecological processes that ultimately determine the patterns of species distribution and abundance, yet is often unrecognized, especially in tropical oceans. Here, we tested the paradigm of temperature stability in shallow waters (

Physical principles and laws determine the set of possible organismal phenotypes. Constraints arising from development, the environment, and evolutionary history then yield workable, integrated phenotypes. We propose a theoretical and practical framework that considers the role of changing environments. This 'ecomechanical approach' integrates functional organismal traits with the ecological variables. This approach informs our ability to predict species shifts in survival and distribution and provides critical insights into phenotypic diversity. We outline how to use the ecomechanical paradigm using drag-induced bending in trees as an example. Our approach can be incorporated into existing research and help build interdisciplinary bridges. Finally, we identify key factors needed for mass data collection, analysis, and the dissemination of models relevant to this framework.

Aim: Ocean warming and marine heatwaves are rapidly reconfiguring the composition of seaweed forests—the world's largest coastal vegetated biome. Seaweed forest responses to climate change in remote locations, which constitute the majority of the forest biome, remain however poorly quantified. Here, we examine the temporal stability of the seaweed forests across a global seaweed biodiversity hotspot where several species are predicted to undergo severe range contractions in this century. Location: Western south coast of Australia. Methods: Seaweed forest canopies were censused at 18 shallow (< 10 m) sheltered reefs between 1997 and 2006 and again between 2021 and 2024 (six sites per location). We also surveyed 24 sites to examine whether temporal changes differed over gradients of wave exposure and depth. Results: Seaweed forest canopies across all locations showed surprisingly little change in biomass, cover, stand density and species composition over two decades, with strong spatial structuring across depth and exposure gradients persisting over time. The average thermal affinity of forest canopies (i.e., the community temperature index, CTI) did not track warming, suggesting that factors other than temperature (e.g., wave exposure and depth) are more important drivers of forest stand structure and/or that key thermal thresholds have not yet been crossed. Forests in the location with the most pronounced warming exhibited increased thermal bias over time (total bias of 0.8°C–2.2°C), indicating they were dominated by species with cooler affinities than their local temperatures. Main Conclusions: The greater thermal bias in forests at the warmer edge of southern Australia suggests these will be more susceptible to future warming‐related compositional changes than forests in cooler locations. The relative stability we found contrasts with a current context of rapidly changing seaweed forests nationally and globally, highlighting the need to deepen our ecological understanding of the region so that future changes to its unique biodiversity and ecosystem services can be predicted and mitigated. [ABSTRACT FROM AUTHOR]

Branching stipe morphologies have evolved multiple times across the kelp (Laminariales) lineage, creating morphological forms that drive the complexity of kelp forest habitats. Although branching is likely a complicated developmental process, it has evolved repeatedly through kelp evolution and the processes facilitating the emergence of branched forms from unbranched ancestors remain unclear. Here I report on abnormally branched individuals (n = 9) from five kelp species found in British Columbia, Canada that had atypical bifurcations in their stipes, creating a single dichotomous branch. One of these species generally lacks branching entirely (Laminaria ephemera) while the other four exhibit some branching but typically lack this stipe bifurcation (Alaria marginata, Laminaria setchellii, Nereocystis luetkeana, Pterygophora californica). These unusually branched individuals exhibited replicated morphological subunits distal to the stipe bifurcation, including more blades, pneumatocysts, and sporophylls than is typical. This suggests that unbranched species possess an inherent developmental capacity for modularity with autonomy in the development of individual modules that may have helped to facilitate the widespread emergence of branched morphologies. Given the role of kelp forests in coastal environments, branching may influence habitat characteristics, potentially influencing community dynamics, and is thus a trait of particular evolutionary interest. These findings highlight the need for experiments that manipulate kelp development to better characterise the ontogenetic processes of these globally important taxa. [ABSTRACT FROM AUTHOR]

Marine heatwaves (MHWs), increasing in duration and intensity because of climate change, are now a major threat to marine life and can have lasting effects on the structure and function of ecosystems. However, the responses of marine taxa and ecosystems to MHWs can be highly variable, making predicting and interpreting biological outcomes a challenge. Here, we review how biological responses to MHWs, from individuals to ecosystems, are mediated by fine‐scale spatial variability in the coastal marine environment (hereafter, local gradients). Viewing observed responses through a lens of ecological theory, we present a simple framework of three 'resilience processes' (RPs) by which local gradients can influence the responses of marine taxa to MHWs. Local gradients (1) influence the amount of stress directly experienced by individuals, (2) facilitate local adaptation and acclimatization of individuals and populations, and (3) shape community composition which then influences responses to MHWs. We then synthesize known examples of fine‐scale gradients that have affected responses of benthic foundation species to MHWs, including kelp forests, coral reefs, and seagrass meadows and link these varying responses to the RPs. We present a series of case studies from various marine ecosystems to illustrate the differential impacts of MHWs mediated by gradients in both temperature and other co‐occurring drivers. In many cases, these gradients had large effect sizes with several examples of local gradients causing a 10‐fold difference in impacts or more (e.g., survival, coverage). This review highlights the need for high‐resolution environmental data to accurately predict and manage the consequences of MHWs in the context of ongoing climate change. While current tools may capture some of these gradients already, we advocate for enhanced monitoring and finer scale integration of local environmental heterogeneity into climate models. This will be essential for developing effective conservation strategies and mitigating future marine biodiversity loss. [ABSTRACT FROM AUTHOR]

Background and Aims Climate change, including gradual changes and extreme weather events, is driving widespread species losses and range shifts. These climatic changes are felt acutely in intertidal ecosystems, where many organisms live close to their thermal limits and experience the extremes of both marine and terrestrial environments. A recent series of multiyear heatwaves in the northeast Pacific Ocean might have impacted species even towards their cooler, northern range edges. Among them, the high intertidal kelp Postelsia palmaeformis has traits that could make it particularly vulnerable to climate change, but it is critically understudied. Methods In 2021 and 2022, we replicated in situ and aerial P. palmaeformis surveys that were conducted originally in 2006 and 2007, in order to assess the state of northern populations following recent heatwaves. Changes in P. palmaeformis distribution, extent, density and morphometrics were assessed between these two time points over three spatial scales, ranging from 250 m grid cells across the entire 167 km study region, to within grid cells and the individual patch. Key Results We found evidence consistent with population stability at all three scales: P. palmaeformis remained present in all 250 m grid cells in the study region where it was previously found, and neither the extent within cells nor the patch density changed significantly between time points. However, there was evidence of slight distributional expansion, increased blade lengths and a shift to earlier reproductive timing. Conclusions We suggest that apparent long-term stability of P. palmaeformis might be attributable to thermal buffering near its northern range edge and from the wave-exposed coastlines it inhabits, which may have decreased the impacts of heatwaves. Our results highlight the importance of multiscale assessments when examining changes within species and populations, in addition to the importance of dispersal capability and local conditions in regulating the responses of species to climate change. [ABSTRACT FROM AUTHOR]

Summary: Extreme environments have driven the evolution of some of the most inspiring adaptations in nature. In the intertidal zone of wave‐swept shores, organisms face physical forces comparable to hurricanes and must further endure thermal and desiccation stress during low tides, compromising their physiological and biomechanical performance.We examine how these multiple stressors have influenced the evolution of tissue properties during desiccation using eight phylogenetically independent pairs of intertidal and subtidal macrophytes.Intertidal species generally lost water more slowly than their subtidal counterparts, presumably as an adaption to regular emersion. Under partial desiccation, breaking force, strength, and extensibility of intertidal species generally exceeded those of subtidal species, although important differences existed among phylogenetic pairs. This was often true even when subtidal relatives resisted greater forces or were more extensible under full hydration. The interacting effects of mechanical forces and desiccation during low tide are likely a major selective agent in determining macrophyte performance and fitness.Overall, we found that lineages that have independently evolved to occupy the wave‐swept intertidal have converged on performance metrics that are likely to be adaptive to the interacting stressors associated with their extreme niches. [ABSTRACT FROM AUTHOR]