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While marine kelp forests have provided valuable ecosystem services for millennia, the global ecological and economic value of those services is largely unresolved. Kelp forests are diminishing in many regions worldwide, and efforts to manage these ecosystems are hindered without accurate estimates of the value of the services that kelp forests provide to human societies. Here, we present a global estimate of the ecological and economic potential of three key ecosystem services - fisheries production, nutrient cycling, and carbon removal provided by six major forest forming kelp genera ( Ecklonia, Laminaria, Lessonia, Macrocystis, Nereocystis , and Saccharina ). Each of these genera creates a potential value of between $64,400 and $147,100/hectare each year. Collectively, they generate between $465 and $562 billion/year worldwide, with an average of $500 billion. These values are primarily driven by fisheries production (mean $29,900, 904 Kg/Ha/year) and nitrogen removal ($73,800, 657 Kg N/Ha/year), though kelp forests are also estimated to sequester 4.91 megatons of carbon from the atmosphere/year highlighting their potential as blue carbon systems for climate change mitigation. These findings highlight the ecological and economic value of kelp forests to society and will facilitate better informed marine management and conservation decisions. By combining fisheries, nutrient, and carbon cycling data, this synthesis suggests that marine kelp forests, a dominant but often undescribed habitat, provide services with a potential value of $111,000/ha/year and a global yearly value of $500 billion.

Predators can exert top-down control on lower trophic levels, such that their removal or addition may trigger trophic cascades. Despite coastal ecosystems containing well known trophic cascades, there remains uncertainty about the abiotic and biotic factors governing the occurrence and strength of these cascades. Here, we sought to explain the variability of trophic cascades in benthic marine ecosystems by conducting a meta-analysis of experimental (n = 17) and observational (n = 22) studies that recorded herbivore and producer populations in the presence and absence of a predator. From these data (147 predator–herbivore–producer measurements), we show that predators decreased herbivore populations between 2.1–4.76 times and increased producer populations by 1.62−2.83 times their original biomass, abundance, or density. Contrary to past research, these values are comparable to other ecosystems. Biotic factors related to species body size were most influential in determining herbivore population responses to the presence of predators, while abiotic factors, including nutrient concentration, best determined producer population responses. Our results also show that producers responded more strongly to changes in herbivore populations in high-nutrient and low-temperature environments. We found that herbivore populations in marine reserves were 2.83 times lower on average compared to areas outside the reserve, while producer populations were on average 1.90 times higher. Overall, this work advances understanding of factors modulating trophic cascade strength, demonstrates that reserves can have ecosystem-wide impacts, and provides new information about the average strength of trophic cascades in benthic marine ecosystems.

Sustainably managing kelp forest ecosystems is critical to maintaining marine biodiversity, supporting coastal communities, and meeting global conservation targets such as the Kunming‐Montreal Global Biodiversity Framework's 30 × 30 and Kelp Forest Challenge. Effective kelp forest management frequently depends on selecting environmentally suitable sites that align with species‐specific environmental requirements. This paper introduces a novel kelp forest environmental niche mapping tool that synthesizes the realized environmental niche of 65 kelp species across 25 biophysical factors. Using over 426,000 global observations of kelp and high‐resolution oceanographic datasets, the tool provides quantitative environmental niche data summarized by species and ecoregion. It focuses on key biophysical variables such as temperature, salinity, light, and nutrient availability, offering users practical guidance to identify optimal locations for kelp growth and survival. The tool is accessible via an interactive web application and supports conservation practitioners, policymakers, and researchers by enabling evidence‐based site selection, maximizing conservation success, and informing broader marine ecosystem management. This tool presents a useful advancement in kelp forest management, facilitating global restoration efforts and contributing to the ambitious goal of restoring one million hectares of kelp forest by 2040. Future developments will address qualitative ecological factors and socio‐cultural considerations to enhance its utility. The kelp niche explorer is a tool which allows users to understand the optimal environmental conditions for kelp forest conservation at the regional level. The tool is adaptable and provides an easy to use graphical dashboard for users to understand kelp forest environmental niches around the world.

Kelp forests are highly productive foundation species along much of the world’s coastline. As a result, kelp are crucial to the ecological, social, and economic well-being of coastal communities. Yet, due to a combination of acute and chronic stressors, kelp forests are under threat and have declined in many locations worldwide. Active restoration of kelp ecosystems is an emerging field that aims to reverse these declines by mitigating negative stressors and then, if needed, introducing biotic material into the environment. To date, few restoration efforts have incorporated positive species interactions. This gap presents a potential shortcoming for the field as evidence from other marine ecosystems illustrates that the inclusion of positive species interactions can enhance restoration success. Additionally, as the climate continues to warm, this approach will be particularly pertinent as positive interactions can also expand the range of physical conditions under which species can persist. Here we highlight how practitioners can use positive density dependence within and amongst kelp species to increase the chances of restoration success. At higher trophic levels, we emphasize how co-restoring predators can prime ecosystems for restoration. We also investigate how emerging technologies in genetic and microbial selection and manipulation can increase the tolerance of target species to warming and other stressors. Finally, we provide examples of how we can use existing anthropogenic activities to facilitate restoration while performing alternative purposes. As kelp forests continue to decline and the field of kelp restoration continues to develop, it is also important that we monitor these potential advancements and ensure they do not have unintended ecosystem effects, particularly with untested techniques such as genetic and microbial manipulations. Nevertheless, incorporating positive species interactions into future restoration practice stands to promote a more holistic form of restoration that also increases the likelihood of success in a shifting seascape.

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combine surveys of natural fish communities (conducted in July and August 2016) with morphological trait data to examine relationships between biodiversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54°N, 130°W). We employ both taxonomic and functional trait measures of diversity to investigate whether ecosystem function is best predicted by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we find that fish community biomass is maximized when taxonomic richness and functional evenness are low, and in communities dominated by species with particular trait values, specifically those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is often positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization. We tested whether more fish species living in seagrass meadows in northern Canada was related to the function of that ecosystem. Instead of more species equally more functioning, we found that dominant species were the most important factor.

Kelps form extensive underwater forests that underpin valuable ecosystem goods and services in temperate and polar rocky coastlines globally. Stressors, such as ocean warming and pollution are causing regional declines of kelp forests and their associated services worldwide. Kelp forest restoration is becoming a prominent management intervention, but we have little understanding of what drives restoration success at appropriate spatial scales. Though most restoration guidelines stress the importance of planning, stressor mitigation and ecological knowledge, other factors, such as lack of resources or institutional support are rarely discussed despite being potentially critical to achieving desired restoration outcomes. In this paper, we work to understand the importance of finances and institutions in the context of four of the world’s largest kelp restoration projects. These projects span four countries, six kelp genera and were initiated in response to different causes of decline. We argue that to restore kelp at desired scales, adequate financing, and institutional support are critical to overcome ecological and environmental limitations. Acknowledging limitations, we outline ways to mobilize resources and encourage institutions to support kelp restoration.

We must integrate effective protection with scalable restoration to ensure resilient coastal ecosystems. We identify five challenges, including unequal ecosystem coverage, spatial protections that are weak or centered offshore, compartmentalized restoration efforts, and policies that are not fit for purpose, and propose actionable solutions for scaling effective marine conservation. Emphasizing underserved habitats like kelp forests and seagrasses, we call for integrated, equitable, and community-supported strategies that align with global agendas and promote future coastal ecosystems.

Today, all ecosystems are undergoing environmental change due to human activity, and in many cases the rate of change is accelerating due to climate change. Consequently, conservation programs are increasingly focused on the response of organisms, populations, and ecosystems to novel conditions. In parallel, the field of conservation biology is developing and deploying new tools to assist adaptation, which we define as aiming to increase the probability that organisms, populations, and ecosystems successfully adapt to ongoing change in biotic and abiotic conditions. Practitioners are aiming to assist a suite of adaptive processes, including acclimatization, range shifts, and evolution, at the individual and population level, while influencing the aggregate of these responses to assist ecosystem reorganization. The practice of assisting adaptation holds promise for environmental conservation, but effective policy and implementation will require thoughtful consideration of potential social and biological benefits and risks.

Marine kelp forests cover 1/3 of our world's coastlines, are heralded as a nature-based solution to address socio-environmental issues, connect hundreds of millions of people with the ocean, and support a rich web of biodiversity throughout our oceans. But they are increasingly threatened with some areas reporting over 90% declines in kelp forest cover in living memory. Despite their importance and the threats they face, kelp forests are entirely absent from the international conservation dialogue. No international laws, policies, or targets focus on kelp forests and very few countries consider them in their national policy. The Kelp Forest Challenge addresses that gap. Together with 252 kelp experts, professionals, and citizens from 25 countries, the Kelp Forest Challenge was developed as a grassroots vision of what the world can achieve for kelp forest conservation. It is a global call to restore 1 million and protect 3 million hectares of kelp forests by 2040. This is a monumental challenge, that will require coordination across multiple levels of society and the mobilization of immense resources. Pledges may therefore include area for protection or restoration, enabling pledges which assist in conservation (funding, equipment, professional expertise, capacity building), or awareness-based pledges which increase awareness or education about kelp forests. Correspondingly, participants may be from government, scientific institutions, private sector, NGOs, community groups, or individuals. This challenge is the beginning of a 17-year mission to save our kelp forests and anyone and any organisation is invited to participate.