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Topographic heterogeneity sets the stage for community assembly, but its effects on ecosystem functioning remain poorly understood. Here, we test the hypothesis that topographic heterogeneity underpins multiple cascading species interactions and functional pathways that indirectly control multifunctionality. To do so, we combined experimental manipulation of a form of topographic heterogeneity on rocky shores (holes of various sizes) with a comprehensive assessment of naturally assembled communities and multifunctionality. Structural equation modeling indicated that heterogeneity: (1) enhanced biodiversity by supporting filter feeder richness; (2) triggered a facilitation cascade via reef-forming (polychaete) and biomass-dominant (macroalga) foundation species, which in turn broadly supported functionally diverse epibiotic and understory assemblages; and (3) inhibited a key consumer (limpet). The model supported that these mechanisms exerted complementary positive effects on individual functions (e.g., water filtration, ecosystem metabolism, nutrient uptake) and, in turn, collectively enhanced multifunctionality. Topographic heterogeneity may therefore serve as a cornerstone physical attribute by initiating multiple cascades that propagate through ecological communities via foundation species, ultimately manifesting disproportionate effects on ecosystem multifunctionality., (© 2024 The Author(s). Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

In response to ongoing coastal urbanization, it is critical to develop effective methods to improve the biodiversity and ecological sustainability of artificial shorelines. Enhancing the topographic complexity of coastal infrastructure through the mimicry of natural substrata may facilitate the establishment of ecosystem engineering species and associated biogenic habitat formation. However, interactions between ecosystem engineers and their substratum are likely determined by organismal size and resource needs, thus making responses to topography highly scale-dependent. Here, we assessed the topographic properties (rugosity, surface area, micro-surface orientations) that underpin the abundance and distribution of two ecosystem engineers (fucoids, limpets) across six spatial scales (1-500 mm). Furthermore, we assessed the 'biogenic' rugosity created by barnacle matrices across fine scales (1-20 mm). Field surveys and 3D scanning, conducted across natural and artificial substrata, showed major effects of rugosity and associated topographic variables on ecosystem engineer assemblages and spatial occupancy, while additional abiotic environmental factors (compass direction, wave exposure) and biotic associations only had weak influences. Natural substrata exhibited ≤67 % higher rugosity than artificial ones. Fucoid-covered patches were predominantly associated with high-rugosity substrata and horizontal micro-surfaces, while homescars of limpets (≥15 mm shell length) predominated on smoother substratum patches. Barnacle-driven rugosity homogenized substrata at scales ≤10 mm. Our findings suggest that scale-dependent rugosity is a key driver of fucoid habitat formation and limpet habitat use, with wider eco-engineering applications for mimicking ecologically impactful topography on coastal infrastructure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Ecosystem restoration can increase the health and resilience of nature and humanity. As a result, the international community is championing habitat restoration as a primary solution to address the dual climate and biodiversity crises. Yet most ecosystem restoration efforts to date have underperformed, failed, or been burdened by high costs that prevent upscaling. To become a primary, scalable conservation strategy, restoration efficiency and success must increase dramatically. Here, we outline how integrating ten foundational ecological theories that have not previously received much attention - from hierarchical facilitation to macroecology - into ecosystem restoration planning and management can markedly enhance restoration success. We propose a simple, systematic approach to determining which theories best align with restoration goals and are most likely to bolster their success. Armed with a century of advances in ecological theory, restoration practitioners will be better positioned to more cost-efficiently and effectively rebuild the world's ecosystems and support the resilience of our natural resources., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Topographic complexity is often considered to be closely associated with habitat complexity and niche diversity; however, complex topography per se does not imply habitat suitability. Rather, ecologically suitable habitats may emerge if topographic features interact with environmental factors and thereby alter their surrounding microenvironment to the benefit of local organisms (e.g., resource provisioning, stress mitigation). Topography may thus act as a key modulator of abiotic stressors and biotic pressures, particularly in environmentally challenging intertidal systems. Here, we review how topography can alter microhabitat conditions with respect to four resources required by intertidal organisms: a source of energy (light, suspended food particles, prey, detritus), water (hydration, buffering of light, temperature and hydrodynamics), shelter (temperature, wave exposure, predation), and habitat space (substratum area, propagule settlement, movement). We synthesize mechanisms and quantitative findings of how environmental factors can be altered through topography and suggest an organism-centered 'form-follows-ecological-function' approach to designing multifunctional marine infrastructure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Coastal saltmarshes provide globally important ecosystem services including 'blue carbon' sequestration, flood protection, pollutant remediation, habitat provision and cultural value. Large portions of marshes have been lost or fragmented as a result of land reclamation, embankment construction, and pollution. Sea level rise threatens marsh survival by blocking landward migration where coastlines have been developed. Research-informed saltmarsh conservation and restoration efforts are helping to prevent further loss, yet significant knowledge gaps remain. Using a mixed methods approach, this paper identifies ten research priorities through an online questionnaire and a residential workshop attended by an international, multi-disciplinary network of 35 saltmarsh experts spanning natural, physical and social sciences across research, policy, and practitioner sectors. Priorities have been grouped under four thematic areas of research: Saltmarsh Area Extent, Change and Restoration Potential (including past, present, global variation), Spatio-social contexts of Ecosystem Service delivery (e.g. influences of environmental context, climate change, and stakeholder groups on service provisioning), Patterns and Processes in saltmarsh functioning (global drivers of saltmarsh ecosystem structure/function) and Management and Policy Needs (how management varies contextually; challenges/opportunities for management). Although not intended to be exhaustive, the challenges, opportunities, and strategies for addressing each research priority examined here, providing a blueprint of the work that needs to be done to protect saltmarshes for future generations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Coastal ecosystems such as sand dunes, mangrove forests, and salt marshes provide natural storm protection for vulnerable shorelines. At the same time, storms erode and redistribute biological materials among coastal systems via wrack. Yet how such cross-ecosystem subsidies affect post-storm recovery is not well understood. Here, we report an experimental investigation into the effect of storm wrack on eco-geomorphological recovery of a coastal embryo dune in north-eastern Florida, USA, following hurricane Irma. We contrasted replicated 100-m2 wrack-removal and unmanipulated (control) plots, measuring vegetation and geomorphological responses over 21 months. Relative to controls, grass cover was reduced 4-fold where diverse storm wrack, including seagrass rhizomes, seaweed, and wood, was removed. Wrack removal was also associated with a reduction in mean elevation, which persisted until the end of the experiment when removal plots had a 14% lower mean elevation than control plots. These results suggest that subsides of wrack re-distributed from other ecosystem types (e.g. seagrasses, macroalgae, uplands): i) enhances the growth of certain dune-building grasses; and ii) boosts the geomorphological recovery of coastal dunes. Our study also indicates that the practice of post-storm beach cleaning to remove wrack-a practice widespread outside of protected areas-may undermine the resilience of coastal dunes and their services., Competing Interests: The authors have declared that no competing interests exist.

Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass ( Zostera marina ), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.

Background and Aims: Sand dunes reduce the impact of storms on shorelines and human infrastructure. The ability of these ecosystems to provide sustained coastal protection under persistent wave attack depends on their resistance to erosion. Although flume experiments show that roots of perennial plants contribute to foredune stabilization, the role of other plant organs, and of annual species, remains poorly studied. Furthermore, it remains unknown if restored foredunes provide the same level of erosion resistance as natural foredunes. We investigated the capacity of three widespread pioneer foredune species (the perennial Ammophila arenaria and the annuals Cakile maritima and Salsola kali) to resist dune erosion, and compared the erosion resistance of Ammophila at natural and restored sites., Methods: Cores collected in the field were tested in a flume that simulated a wave swash. A multi-model inference approach was used to disentangle the contributions of different below-ground compartments (i.e. roots, rhizomes, buried shoots) to erosion resistance., Key Results: All three species reduced erosion, with Ammophila having the strongest effect (36 % erosion reduction versus unvegetated cores). Total below-ground biomass (roots, rhizomes and shoots), rather than any single compartment, most parsimoniously explained erosion resistance. Further analysis revealed that buried shoots had the clearest individual contribution. Despite similar levels of total below-ground biomass, coarser sediment reduced erosion resistance of Ammophila cores from the restored site relative to the natural site., Conclusions: The total below-ground biomass of both annual and perennial plants, including roots, rhizomes and buried shoots, reduced dune erosion under a swash regime. Notably, we show that (1) annual pioneer species offer erosion protection, (2) buried shoots are an important plant component in driving sediment stabilization, and (3) management must consider both biological (plants and their traits) and physical (grain size) factors when integrating dunes into schemes for coastal protection., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Activities involving observation of wild organisms (e.g. wildlife watching, tidepooling) can provide recreational and learning opportunities, with biologically diverse animal assemblages expected to be more stimulating to humans. In turn, more diverse communities may enhance human interest and facilitate provisioning of cultural services. However, no experimental tests of this biodiversity-interest hypothesis exist to date. We therefore investigated the effects of different dimensions of animal biodiversity (species richness, phyletic richness and functional diversity) on self-reported interest using tide pools as a model system. We performed two experiments by manipulating: (1) the richness of lower (species) and higher taxonomic levels (phyla) in an image based, online survey, and (2) the richness of the higher taxonomic level (phyla) in live public exhibits. In both experiments, we further quantified functional diversity, which varied freely, and within the online experiment we also included the hue diversity and colourfulness arising from the combination of organisms and the background scenes. Interest was increased by phyletic richness (both studies), animal species richness (online study) and functional diversity (online study). A structural equation model revealed that functional diversity and colourfulness (of the whole scene) also partially mediated the effects of phyletic richness on interest in the online study. In both studies, the presence of three of four phyla additively increased interest, supporting the importance of multiple, diverse phyla rather than a single particularly interesting phylum. These results provide novel experimental evidence that multiple dimensions of biodiversity enhance human interest and suggest that conservation initiatives that maintain or restore biodiversity will help stimulate interest in ecosystems, facilitating educational and recreational benefits.

Droughts are increasing in severity and frequency, yet the mechanisms that strengthen ecosystem resilience to this stress remain poorly understood. Here, we test whether positive interactions in the form of a mutualism between mussels and dominant cordgrass in salt marshes enhance ecosystem resistance to and recovery from drought. Surveys spanning 250 km of southeastern US coastline reveal spatially dispersed mussel mounds increased cordgrass survival during severe drought by 5- to 25-times. Surveys and mussel addition experiments indicate this positive effect of mussels on cordgrass was due to mounds enhancing water storage and reducing soil salinity stress. Observations and models then demonstrate that surviving cordgrass patches associated with mussels function as nuclei for vegetative re-growth and, despite covering only 0.1-12% of die-offs, markedly shorten marsh recovery periods. These results indicate that mutualisms, in supporting stress-resistant patches, can play a disproportionately large, keystone role in enhancing ecosystem resilience to climatic extremes.

It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16-32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.

Theory suggests that predators of soil-improving, plant-facilitating detritivores (e.g. earthworms) should suppress plant growth via a negative tri-trophic cascade, but the empirical evidence is still largely lacking. We tested this prediction in an alpine meadow on the Tibetan Plateau by manipulating predatory beetles (presence/absence) and quantifying (i) direct effects on the density and behaviour of earthworms; and (ii) indirect effects on soil properties and above-ground plant biomass. In the absence of predators, earthworms improved soil properties, but did not significantly affect plant biomass. Surprisingly, the presence of predators strengthened the positive effect of earthworms on soil properties leading to the emergence of a positive indirect effect of predators on plant biomass. We attribute this counterintuitive result to: (i) the inability of predators to suppress overall earthworm density; and (ii) the predator-induced earthworm habitat shift from the upper to lower soil layer that enhanced their soil-modifying, plant-facilitating, effects. Our results reveal that plant-level consequences of predators as transmitted through detritivores can hinge on behaviour-mediated indirect interactions that have the potential to overturn predictions based solely on trophic interactions. This work calls for a closer examination of the effects of predators in detritus food webs and the development of spatially explicit theory capable of predicting the occurrence and consequences of predator-induced detritivore behavioural shifts., (© 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.)

Invasive species have transformed local, regional and global biotas; however, few generalities about the mechanisms driving impacts of invaders have emerged. To explain variation in impacts among studies, we propose a broad framework that separates drivers of impacts into universal and unique attributes of the invasive species and the invaded habitat. Universal attributes are relevant to all invasions whereas unique attributes are distinct to a specific invasion. For example, impacts associated with the abundance of any invader or the properties of a specific invader (e.g., a rare toxin) represent a universal and unique impact attribute. Through meta-analyses of aquatic field experiments, we demonstrate the utility of our framework, documenting that both the abundance and the taxonomic identity of the invader significantly influence invasion outcomes for marine and freshwater plant and animal invaders. Our review also highlights that many more experiments are needed to test for universal attributes, such as priority effects, age and size, and how the attributes of the invaded habitat further modify invasion impacts. We hope that our framework will stimulate experimental invasion ecology and begin to reconcile the idiosyncrasies that currently impede the development of a unified framework for invasion impacts., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The link between biodiversity and ecosystem functioning is now well established, but the challenge remains to develop a mechanistic understanding of observed effects. Predator-prey interactions provide an opportunity to examine the role of resource partitioning, thought to be a principal mediator of biodiversity-function relationships. To date, interactions between multiple predators and their prey have typically been investigated in simplified agricultural systems with limited scope for resource partitioning. Thus there remains a dearth of studies examining the functional consequences of predator richness in diverse food webs. Here, we manipulated a species-rich intertidal food web, crossing predator diversity with total predator density, to simultaneously examine the independent and interactive effects of diversity and density on the efficiency of secondary resource capture. The effect of predator diversity was only detectable at high predator densities where competitive interactions between individual predators were magnified; the rate of resource capture within the species mixture more than doubled that of the best-performing single species. Direct observation of species-specific resource use in monoculture, as quantified by patterns of prey consumption, provided clear evidence that species occupied distinct functional niches, suggesting a mechanistic explanation of the observed diversity effect.

While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.

Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 37° of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas in situ water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simply increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in predation intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions.