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Ecosystem‐based management (EBM) is promoted in scholarly literature and international policy as a way to improve marine ecosystem outcomes, through the integration of marine law and policies across sectors, communities, and scales. A legal and policy framework that supports EBM at appropriate temporal and spatial scales is fundamental to the successful deployment of EBM. However, marine management is typically fragmented and misaligned, with a range of laws, policies, governance institutions, and sectoral frameworks applying to different marine spaces and working on varying timescales. In this focus article, we draw on our comprehensive study of Aotearoa New Zealand's marine law and policy to analyze the challenges scale mismatches present for marine law and policy implementation, focusing on key policy areas across fisheries, environment, conservation, and Indigenous rights and interests. We identify key opportunities to better align marine law and policy to ecosystem scale dynamics, revealing critical lessons for the imperative of scale‐sensitive marine law and policy design, globally. This article is categorized under:Policy and Economics > Research and DevelopmentPolicy and Economics > Governance and RegulationClimate and Environment > Ecosystem Services [ABSTRACT FROM AUTHOR]

The migratory behavior of Atlantic salmon (Salmo salar) post‐smolts in coastal waters is poorly understood. In this collaborative study, 1914 smolts, from 25 rivers, in four countries were tagged with acoustic transmitters during a single seasonal migration. In total, 1105 post‐smolts entered the marine study areas and 438 (39.6%) were detected on a network of 414 marine acoustic receivers and an autonomous underwater vehicle. Migration pathways (defined as the shortest distance between two detections) of up to 575 km and over 100 days at sea were described for all 25 populations. Post‐smolts from different rivers, as well as individuals from the same river, used different pathways in coastal waters. Although difficult to generalize to all rivers, at least during the year of this study, no tagged post‐smolts from rivers draining into the Irish Sea were detected entering the areas of sea between the Hebrides and mainland Scotland, which is associated with a high density of finfish aquaculture. An important outcome of this study is that a high proportion of post‐smolts crossed through multiple legislative jurisdictions and boundaries during their migration. This study provides the basis for spatially explicit assessment of the impact risk of coastal pressures on salmon during their first migration to sea. [ABSTRACT FROM AUTHOR]

The threat from novel marine species introductions is a global issue. When non‐native marine species are introduced to novel environments and become invasive, they can affect biodiversity, industry, ecosystem function, and both human and wildlife health. Isolated areas with sensitive or highly specialised endemic species can be particularly impacted. The global increase in the scope of tourism and other human activities, together with a rapidly changing climate, now put these remote ecosystems under threat. In this context, we analyse invasion pathways into South Georgia and the South Sandwich Islands (SGSSI) for marine non‐native species via vessel biofouling. The SGSSI archipelago has high biodiversity and endemism, and has historically been highly isolated from the South American mainland. The islands sit just below the Polar Front temperature boundary, affording some protection against introductions. However, the region is now warming and SGSSI increasingly acts as a gateway port for vessel traffic into the wider Antarctic, amplifying invasion likelihood. We use remote Automatic Identification System vessel‐tracking data over a 2‐year period to map vessel movement and behaviour around South Georgia, and across the 'Scotia Sea', 'Magellanic' and northern 'Continental High Antarctic' ecoregions. We find multiple vessel types from locations across the globe frequently now enter shallow inshore waters and stop for prolonged periods (weeks/months) at anchor. Vessels are active throughout the year and stop at multiple port hubs, frequently crossing international waters and ecoregions. Management recommendations to reduce marine invasion likelihood within SGSSI include initiating benthic and hull monitoring at the identified activity/dispersion hubs of King Edward Point, Bay of Isles, Gold Harbour, St Andrews Bay and Stromness Bay. More broadly, regional collaboration and coordination is necessary at neighbouring international ports. Here vessels need increased pre‐ and post‐arrival biosecurity assessment following set protocols, and improved monitoring of hulls for biofouling to pre‐emptively mitigate this threat. [ABSTRACT FROM AUTHOR]

Anthropogenic carbon emissions and associated climate change are driving rapid warming, acidification, and deoxygenation in the ocean, which increasingly stress marine ecosystems. On top of long‐term trends, short term variability of marine stressors can have major implications for marine ecosystems and their management. As such, there is a growing need for predictions of marine ecosystem stressors on monthly, seasonal, and multi‐month timescales. Previous studies have demonstrated the ability to make reliable predictions of the surface ocean physical and biogeochemical state months to years in advance, but few studies have investigated forecast skill of multiple stressors simultaneously or assessed the forecast skill below the surface. Here, we use the Community Earth System Model (CESM) Seasonal to Multiyear Large Ensemble (SMYLE) along with novel observation‐based biogeochemical and physical products to quantify the predictive skill of dissolved inorganic carbon (DIC), dissolved oxygen, and temperature in the surface and subsurface ocean. CESM SMYLE demonstrates high physical and biogeochemical predictive skill multiple months in advance in key oceanic regions and frequently outperforms persistence forecasts. We find up to 10 months of skillful forecasts, with particularly high skill in the Northeast Pacific (Gulf of Alaska and California Current Large Marine Ecosystems) for temperature, surface DIC, and subsurface oxygen. Our findings suggest that dynamical marine ecosystem prediction could support actionable advice for decision making. Plain Language Summary: Human‐driven climate change is rapidly altering the global ocean, with strong warming, increasing acidity, and declining oxygen trends. On top of long‐term trends, short term variations can lead to rapid changes that can have major effects on marine ecosystems. There is a growing need to predict these short‐term changes in order to better inform marine fisheries managers. In this study, we use a climate model designed to predict changes in the real world months‐to‐years in advance to better determine our ability to forecast changes. Previous studies with similar goals have been limited by sparse observations of acidity and oxygen. We utilize brand new observational products that estimate acidity and oxygen levels in the subsurface ocean for the first time to analyze subsurface forecasts. Our results demonstrate a high potential to predict warming, acidity, and oxygen levels in key marine ecosystems with this climate model. These results suggest that there is potential for eventual operational forecasts of marine ecosystems to better inform marine managers. Key Points: Community Earth System Model Seasonal to Multiyear Large Ensemble (SMYLE) forecasts variations in multiple marine stressors up to a year in advance and outperforms statistical persistenceNovel observation‐based products allow for the first skill analysis of subsurface carbon and oxygenAnalysis of predictability from the SMYLE reconstruction reveals high potential to gain additional temperature and oxygen forecast skill [ABSTRACT FROM AUTHOR]

To preserve natural ecosystems and their biodiversity, there is a need to anticipate future ecosystem changes through better understanding of underlying drivers and assembly processes determining community composition. Assembly processes can be understood as a set of filters acting at different spatio‐temporal scales that jointly define the structure and composition of communities. Here, we explore the underlying assembly processes shaping marine fish species distribution and composition, using the heavily exploited North Sea. Our aims are to study 1) the relative importance of the different assembly processes shaping marine fish communities, 2) the key environmental drivers determining species distributions and composition, and to 3) quantify the role of traits in determining species niches and responses to the environment. Specifically, we fit a joint species distribution model (JSDM) using 31 years of standardized scientific bottom trawl survey data for 67 fish species. We use a set of environmental variables and species' traits representing morphology, life history, reproduction and diet, while also accounting for phylogenetic relationships of species. Environmental variables, primarily related to temperature, explained over one third of the variance in species occurrence, while spatial effects explained half of the variability across species. This shows that environmental filtering and spatially‐structured processes are the main drivers shaping the community assembly. Furthermore, among the total variance of individual species occurrences, 12.5% could be explained by traits, which improve the mechanistic understanding on species responses to environmental change. Hence, model predictions from JSDMs accounting for traits, environmental niches and potential interactions among multiple species can provide relevant simulations and forecasts with the potential to inform spatial management and conservation efforts aiming to preserve biodiversity and its associated services vital for human well‐being. [ABSTRACT FROM AUTHOR]

1. Designated using a Statutory Instrument in 2008, Lyme Bay marine-protected area (MPA) is the UK's first and largest example of an ambitious, whole-site approach to management, to recover and protect reef biodiversity. The whole-site approach applies consistent management, in this case excluding bottom towed fishing, across the full 206 km² extent of the MPA, thus protecting a mosaic of reef-associated habitats from regular damage, while still allowing less destructive fishing methods, such as static gear, rod and line, and diving. 2. To assess the effectiveness of this management strategy for mobile taxa and the sustainability for those taxa that continue to be targeted, Exploited and Non-Exploited species' populations were compared inside the MPA, relative to open control sites spanning 11 of the 12 years of designation. baited remote underwater video systems (BRUVs) were deployed annually to assess mobile benthic and demersal fauna. 3. Overall, the number of taxa significantly increased in the MPA relative to the open controls while total abundance increased in both treatments. 4. Exploited fish showed increases in number of taxa (430%) and total abundance (370%) inside the MPA over 11 years. 5. Likewise, but to a lesser degree in the open controls, number of taxa of commercially Exploited fish increased over time, potentially showing 'spillover' effects from the MPA. 6. Non-Exploited fish did not show such changes. Regardless of constituting the majority of the fishery value, highly valuable Exploited invertebrates showed no significant changes over time. 7. Synthesis and applications. The Lyme Bay marine-protected area shows importance of protecting a whole site, comprising mosaics of different benthic habitats, through protection of sessile organisms that contribute to essential fish habitats. This Ecosystem Approach to Fisheries Management can benefit and maintain sustainable fisheries and species of conservation importance. [ABSTRACT FROM AUTHOR]

In a context of increasing global food demand, the aquaculture sector, and more particularly bivalve mariculture, has expanded significantly. While the impact of bivalve mariculture was initially overlooked, it is now widely recognized that this industry can significantly impact the ecosystem and its services. Carrying capacity assessment tools have been developed accordingly and have proved to be a useful and efficient aid for mariculture management. However, carrying capacity assessment tools have been mostly designed and implemented in developed temperate countries, while bivalve mariculture is mainly expanding today in tropical and subtropical zones. To what extent the existing carrying capacity assessment tools are suited for use in tropical and subtropical regions has received little attention, and thus constitutes a major issue. The present review aims to fill this gap and highlights the key points to consider for the carrying capacity assessment of bivalve mariculture in tropical and subtropical regions. In line with the requirements for the sustainable development of human activities, and increasing recognition of the need for better integration of social aspects in the management processes, carrying capacity assessment should be undertaken in a more holistic way. Thus, the social, economic and environmental aspects are taken into account in our analysis. A step‐process plan for the sustainable management of bivalve mariculture in tropical and subtropical countries, through the assessment of carrying capacity, is proposed and discussed to offer guidance for managers. [ABSTRACT FROM AUTHOR]

Connectivity of marine populations and ecosystems is crucial to maintaining and enhancing their structure, distribution, persistence, resilience and productivity. Artificial hard substrate, such as that associated with oil and gas platforms, provides settlement opportunities for species adapted to hard substrates in areas of soft sediment. The contribution of artificial hard substrate and the consequences of its removal (e.g. through decommissioning) to marine connectivity is not clear, yet such information is vital to inform marine spatial planning and future policy decisions on the use and protection of marine resources.This study demonstrates the application of a social network analysis approach to quantify and describe the ecological connectivity, informed by particle tracking model outputs, of hard substrate marine communities in the North Sea. Through comparison of networks with and without artificial hard substrate, and based on hypothetical decommissioning scenarios, this study provides insight into the contribution of artificial hard substrate, and the consequence of decommissioning, to the structure and function of marine community connectivity.This study highlights that artificial hard substrate, despite providing only a small proportion of the total area of hard substrate, increases the geographic extent and connectivity of the hard substrate network, bridging gaps, thereby providing 'stepping stones' between otherwise disconnected areas of natural hard substrate. Compared to the baseline scenario, a decommissioning scenario with full removal of oil and gas platforms results in a nearly 60% reduction in connectivity. Such reduction in connectivity may have negative implications for species' distribution, gene flow and resilience following disturbance or exploitation of marine hard substrate communities.Synthesis and applications. Social network analysis can provide valuable insight into connectivity between marine communities and enable the evaluation of impacts associated with changes to the marine environment. Providing standardized, transparent and robust outputs, such a tool is useful to facilitate understanding across different disciplines, including marine science, marine spatial planning and marine policy. Social network analysis therefore has great potential to address current knowledge gaps with respect to marine connectivity and crucially facilitate assessment of the impacts of changes in offshore substrate as part of the marine spatial planning process, thereby informing policy and marine management decisions. [ABSTRACT FROM AUTHOR]

The national extinction risk of 103 New Zealand chondrichthyans (sharks, rays, and chimaeras), ~10% of the global chondrichthyan fauna, was evaluated for the first time using the International Union for Conservation of Nature Red List of Threatened Species Categories and Criteria. Across 32 families, 103 species were assessed.New Zealand holds a high degree of species endemism (20%) with deepwater species dominating the fauna (77%). Sharks were the most speciose group with 68 species (66%), followed by 24 rays (23%), and 11 chimaeras (10%).Most species were assessed as Least Concern (60%, 62 species) or Data Deficient (32%, 33 species), with four (3.8%) species listed as Near Threatened and four (3.8%) in a threatened category (Vulnerable, Endangered, Critically Endangered). Threatened species are all oceanic pelagic, of which two are only visitors to New Zealand waters, and their status the result of broader regional declines.These results are in stark contrast to other recent regional assessments in Europe and the Arabian Sea and adjacent areas, where up to half of species were listed in a threatened category. However, given New Zealand's extensive deepwater fishing effort and rapid collapses of deepwater chondrichthyan fisheries elsewhere, it is possible that New Zealand populations of many deepwater species are the remnants of previously reduced populations that are now at a low, yet stable level. Ongoing species‐level catch monitoring will be required to ensure these species do not become threatened.Recommendations for future research and conservation efforts include resolving taxonomic uncertainties, understanding habitat use, and increasing regional collaborations to better understand the effects of fishing on wider‐ranging species. [ABSTRACT FROM AUTHOR]

Monitoring communities of fish is important for the management and sustainability of fisheries and marine ecosystems. Baited remote underwater video systems (BRUVs) are among the most effective nondestructive techniques for sampling bony fishes and elasmobranchs (sharks, rays, and skates). However, BRUVs sample visually conspicuous biota; hence, some taxa are undersampled or not recorded at all. We compared the diversity of fishes characterized using BRUVs with diversity detected via environmental DNA (eDNA) metabarcoding. We sampled seawater and captured BRUVs imagery at 48 locales that included reef and seagrass beds inside and outside a marine reserve (Jurien Bay in Western Australia). Eighty‐two fish genera from 13 orders were detected, and the community of fishes described using eDNA and BRUVs combined yielded >30% more generic richness than when either method was used alone. Rather than detecting a homogenous genetic signature, the eDNA assemblages mirrored the BRUVs' spatial explicitness; differentiation of taxa between seagrass and reef was clear despite the relatively small geographical scale of the study site (∼35 km2). Taxa that were not sampled by one approach, due to limitations and biases intrinsic to the method, were often detected with the other. Therefore, using BRUVs and eDNA in concert provides a more holistic view of vertebrate marine communities across habitats. Both methods are noninvasive, which enhances their potential for widespread implementation in the surveillance of marine ecosystems. Article impact statement: Use of video and environmental genomics in conservation will greatly improve capacity to effectively monitor fish biodiversity. [ABSTRACT FROM AUTHOR]

Marine Protected Areas (MPAs) are a major tool to conserve marine ecosystems but are also strongly attractive to tourists, the increased numbers of which can cause environmental issues if not properly managed.Proposing an MPA and then failing to establish it risks advertising the beauty of a marine area without managing the unavoidable increase in tourism. This is what happened at Gallinara Island (Ligurian Sea, north‐western Mediterranean), where an MPA was proposed in 1990 but has not yet been established.Benthic data collected soon after the proposal (1990–92) have been compared with similar information obtained in subsequent periods (2009 and 2016): change has been assessed both visually and statistically, using multivariate and univariate techniques.The Gallinara sea floor supported five epibenthic communities in 1991, four of which corresponded to European Nature Information System (EUNIS) habitats; the fifth epibenthic community, characterized by the erect sponge Axinella polypoides, should be included in the next revision of EUNIS.In the 25 years since the original MPA proposal, all epibenthic communities have exhibited a reduction in their three‐dimensional structure and biotic homogenization, and severe decreases in species diversity, and the sea floor has been littered with derelict fishing gear and other waste from boats.In absence of the MPA, proposals to develop a management plan for a marine Site of Community Importance (SCI) have been provided, to reduce sea‐based human pressures. The dramatic alteration of Gallinara sea floor after 25 years of negligence and inaction is a sad warning for other unmanaged yet beautiful natural areas within urbanized regions of the world. [ABSTRACT FROM AUTHOR]

Aim Marine reef habitats are typically defined subjectively. We provide a continental-scale assessment of dominant reef habitats through analysis of macroalgae and sessile animal taxa at sites distributed around Australia. Relationships between reef habitats and environmental and anthropogenic factors are assessed, and potential changes in the future distribution and persistence of habitats are considered. Location Shallow rocky and coral reefs around the Australian coast. Methods Cover of 38 sessile biota functional groups was recorded in diver-based surveys using quadrats at 1,299 sites. Classification analyses based on the functional groups were used to identify an unambiguous set of 'biogenic habitat types'. Random forest and distance-based linear modelling were used to investigate correlations between these habitats and environmental and anthropogenic variables. Results Cluster analyses revealed tropical and temperate 'realms' in benthic substratum composition, each with finer-scale habitats: four for the temperate realm (canopy algae, barren, epiphytic algae-understorey and turf) and five for the tropical realm (coral, coral-bacterial mat, turf-coral, calcified algae-coral and foliose algae). Habitats were correlated with different sets of environmental and anthropogenic conditions, with key associations in the temperate realm between mean sea temperature and canopy-forming algae (negative) and barren habitat (positive). Variation in sea temperature was also an important correlate in the tropical realm. Main conclusions Quantitative delineation of inshore reef habitats at a continental scale identifies many of the same habitat types traditionally recognized through subjective methods. Importantly, many biogenic reef habitats were closely related to environmental parameters and anthropogenic variables that are predicted to change. Consequently, habitats have differing likelihood of persistence. Structurally complex habitats in the temperate realm are at greater risk than more 'two-dimensional' habitats (e.g., canopy-forming versus turfing algae). In the tropical realm, offshore and coastal habitats differed greatly, highlighting the importance of large-scale oceanic conditions in shaping biogenic structure. [ABSTRACT FROM AUTHOR]

Species invasions have a range of negative effects on recipient ecosystems, and many occur at a scale and magnitude that preclude complete eradication. When complete extirpation is unlikely with available management resources, an effective strategy may be to suppress invasive populations below levels predicted to cause undesirable ecological change. We illustrated this approach by developing and testing targets for the control of invasive Indo-Pacific lionfish (Pterois volitans and P. miles) on Western Atlantic coral reefs. We first developed a size-structured simulation model of predation by lionfish on native fish communities, which we used to predict threshold densities of lionfish beyond which native fish biomass should decline. We then tested our predictions by experimentally manipulating lionfish densities above or below reef-specific thresholds, and monitoring the consequences for native fish populations on 24 Bahamian patch reefs over 18 months. We found that reducing lionfish below predicted threshold densities effectively protected native fish community biomass from predation-induced declines. Reductions in density of 25-92%, depending on the reef, were required to suppress lionfish below levels predicted to overconsume prey. On reefs where lionfish were kept below threshold densities, native prey fish biomass increased by 50-70%. Gains in small (<6 cm) size classes of native fishes translated into lagged increases in larger size classes over time. The biomass of larger individuals (>15 cm total length), including ecologically important grazers and economically important fisheries species, had increased by 10-65% by the end of the experiment. Crucially, similar gains in prey fish biomass were realized on reefs subjected to partial and full removal of lionfish, but partial removals took 30% less time to implement. By contrast, the biomass of small native fishes declined by .50% on all reefs with lionfish densities exceeding reef-specific thresholds. Large inter-reef variation in the biomass of prey fishes at the outset of the study, which influences the threshold density of lionfish, means that we could not identify a single rule of thumb for guiding control efforts. However, our model provides a method for setting reef-specific targets for population control using local monitoring data. Our work is the first to demonstrate that for ongoing invasions, suppressing invaders below densities that cause environmental harm can have a similar effect, in terms of protecting the native ecosystem on a local scale, to achieving complete eradication. [ABSTRACT FROM AUTHOR]

The marine environment is heavily exploited, but unintentional consequences cause wide-ranging negative effects to its characteristics. Linkage frameworks (e.g., DPSIR [driver-pressure-state-impact-response]) are commonly used to describe an interaction between human activities and ecological characteristics of the ecosystem, but as each linkage is viewed independently, the diversity of pressures that affect those characteristics may not be identified or managed effectively. Here we demonstrate an approach for using linkages to build a simple network to capture the complex relationships arising from multiple sectors and their activities. Using data-analysis tools common to ecology, we show how linkages can be placed into mechanistically similar groups. Management measures can be combined into fewer and more simplified measures that target groups of pressures rather than individual pressures, which is likely to increase compliance and the success of the measure while reducing the cost of enforcement. Given that conservation objectives (regional priorities) can vary, we also demonstrate by way of a case study example from the Marine Strategy Framework Directive, how management priorities might change, and illustrate how the approach can be used to identify sectors for control that best support the conservation objectives. [ABSTRACT FROM AUTHOR]

The article presents a study that distinguishes human-induced causes from natural causes of gorgonian mortality and to provide criteria for sustainable management of protected areas. It examines total and partial mortality of adult colonies at four locations, two each representing one of the two situations, heavily dived coastal marine protected areas (MPA) and lightly dived, annually over a 9-year period from 1992 to 2000.

The complex socio‐environmental issues faced by society – including climate change, resource management, and fostering resiliency in landscapes that intermix human and natural features – are difficult challenges that demand contextually appropriate evidence‐based interventions. Institutional arrangements for providing scientific advice range from individual science advisors to large scientific committees or advisory councils, with a great deal of variation in their formal and informal structures. Regardless of the structuring of advisors, however, these arrangements face a common challenge: being required to speak to a wide range of issues in a time‐sensitive manner, each of which has extensive stakeholder communities, deep disciplinary knowledge, and many complicating attributes. It is argued that creating a formally associated, supporting boundary organization that is tasked with supporting the advisory functions can help to resolve this challenge and improve the overall quality of advice offered. Using a case study – the California Ocean Science Trust and its advice on coastal and ocean management issues – it is argued that boundary organizations can help science advisors maintain links with disparate stakeholder communities, adjudicate between competing forms of expertise, help to provide nuance in grappling with the tensions between science and politics, and support an "honest broker" advising function. The quality of scientific advice can be improved through creating supportive boundary organizations. Boundary organizations can help science advisors maintain links with disparate stakeholder communities, adjudicate between competing forms of expertise, help to provide nuance in grappling with the tensions between science and politics, and support an "honest broker" advising function. [ABSTRACT FROM AUTHOR]