What evidence exists on the impacts of human activities on biodiversity and carbon capacity in North-East Atlantic blue carbon ecosystems: a systematic map protocol

Blue carbon ecosystems (BCEs) such as saltmarshes and seagrass meadows, have been recently found to importantly contribute to global regulation services through their ability to sequester and store carbon. They also support a key set of services such as habitat provision, flood and coastal protection, enhancement of water quality and various tangible and intangible cultural services. These multiple co-benefits associated with BCEs underscores the importance of integrating nature-based solutions into climate change mitigation and adaptation strategies. This research aims to assess blue carbon sequestration potential in the Basque estuaries by estimating current blue carbon stock and provide insights for climate change mitigation management strategies involving conservation and restoration of BCEs. To do so, we performed a field campaign in summer 2022 where we sampled 3 BCEs habitat types (saltmarshes, Zostera noltei seagrass meadows and non-vegetated intertidal flats) in 3 different estuaries. In each estuary, we sampled 3 plots for each habitat type. In the plots, we collected 3 sediment cores to estimate total organic carbon (TOC), organic matter and grain size of the sediment; and 3 vegetation quadrants (in vegetated plots of saltmarshes and seagrass) to estimate TOC stored in above- and below-ground biomass. Additionally, we performed a literature review to determine BCEs mean organic carbon value and be able to compare it to that found in our assessment. Existing cartography of BCEs was also compiled to be able to make spatial estimations and identify BCEs hotspots. In the case of Zostera noltei seagrass, a spatio-temporal analysis was performed examining the trends in its distribution. We compared available detailed cartographies from 2008, 2012 and 2021 and a significant increase of the area was detected. Results showed that BCEs from the Basque estuaries might play an important role in mitigating residual anthropogenic carbon emissions.

Abstract. The aim of this work was to explore the feasibility of using plant functional traits to identify differences in sediment organic carbon (OC) storage within seagrass meadows. At 19 sites within three seagrass meadows in the coastal waters of Zanzibar, Tanzania, species cover was estimated along with three community traits hypothesized to influence sediment OC storage (above and belowground biomass, seagrass tissue nitrogen content, and shoot density). Sediments within four biogeographic zones (fore reef, reef flat, tidal channel, and seagrass meadow) of the landscape were characterized, and sediment cores were collected within seagrass meadows to quantify OC storage in the top 25 cm and top meter of the sediment. We identified five distinct seagrass communities that had notable differences in the plant traits, which were all residing within a thin veneer (ranging from 19 to 78 cm thick) of poorly sorted, medium to coarsely grained carbonate sands on top of carbonate rock. One community (B), dominated by Thalassodendron ciliatum, contained high amounts of above (972±74 g DW m−2) and belowground (682±392 g DW m−2) biomass composed of low-elemental-quality tissues (leaf C : N = 24.5; rhizome C : N = 97). While another community (C), dominated by small-bodied ephemeral seagrass species, had significantly higher shoot density (4178 shoots m−2). However, these traits did not translate into differences in sediment OC storage and across all communities the percentage of OC within sediments was similar and low (ranging from 0.15 % to 0.75 %), as was the estimated OC storage in the top 25 cm (14.1±2.2 Mg C ha−1) and top meter (33.9±7.7 Mg C ha−1) of sediment. These stock estimates are considerably lower than the global average (194.2±20.2 Mg C ha−1) reported for other seagrass ecosystems and are on the lower end of the range of estimates reported for the tropical Indo-Pacific bioregion (1.9 to 293 Mg C ha−1). The uniformly low OC storage across communities, despite large inputs of low-quality belowground tissues in community B, indicates that the geophysical conditions of the coarse, shallow sediments at our sites were not conducive to OC stabilization and outweighed any variation in the quantity or quality of seagrass litter inputs. These results add to a growing body of evidence showing that geophysical conditions of the sediment modulate the importance of plant traits in regards to retention of OC within blue carbon ecosystems and cautions against the use of plant traits as a proxy for sediment OC storage across all seagrass ecosystems.

ABSTRACTMicrobial communities underpin biogeochemical processes in Blue Carbon Ecosystems (BCEs); however, a comprehensive review of geographic patterns in microbial diversity, microbial functions, and distribution is currently lacking. Here, for the first time, we have analysed 70 years (1930–2020) of archaeal, bacterial, and fungal diversity and functions in mangrove, saltmarsh, and seagrass ecosystems to elucidate publication and geographic trends in reporting data in BCEs and to identify knowledge gaps. Of the 649 journal articles analysed, research on BCE microbial communities has focused overwhelmingly on assessing bacterial richness and functions in BCEs. Our gap analysis revealed that only ~25%–50% of the countries that have BCEs have been represented, suggesting that our understanding of archaeal, bacterial, and fungal geographic diversity in BCEs is still incomplete. In the context of taxonomic‐based limitations in our study's approach, we have identified gaps of knowledge in archaeal and fungal sediment biodiversity in saltmarsh and seagrass ecosystems. This significantly impacts our ability to forecast ecosystem services amid current and future human and climate pressures in BCEs. The results from this synthesis could serve as a useful reference for microbial baseline data and research trends in BCEs to develop novel hypothesis‐testing research.

Wetland plants form blue carbon ecosystems, which are key for climate change mitigation yet threatened by multiple local and global stresses. The capacity of blue carbon ecosystems to store large amounts of carbon relies on ecological processes, many of them regulated by plant traits that are shaped by the stress that plants encounter. This manuscript provides a perspective to investigate the effects of stress on carbon storage and sequestration capacity of blue carbon ecosystems based on the plant traits. A first step was to identify the biochemical, physiological, morphological and growth and development traits involved in the processes controlling carbon storage and sequestration in blue carbon ecosystems. Second, the existing knowledge on the stress effects on blue carbon processes and ecosystems was evaluated. Finally, the application of the trait‐based approach to understand and predict carbon dynamics in blue carbon ecosystems under different stresses' feedback was discussed. The conclusions provide key recommendations for a trait‐based approach in which the trinomial local and global stresses, plant traits and blue carbon are embraced together to identify the feedbacks between them, along with specific attention to the plant traits across the seascape, the stress interactions and the need of plant trait standardization. Read the free Plain Language Summary for this article on the Journal blog.

BackgroundThe incorporation of multiple types of knowledge (e.g., science, Indigenous knowledge, traditional ecological knowledge) is an important undertaking, which can strengthen the evidence-base for policy advice, decision making, and environmental management. While the benefits of incorporating multiple types of knowledge in environmental research and management are many, successfully doing so has remained a challenge. In response there has been a number of recent reviews that have sought to better understand the what and how, when it comes to bridging Indigenous and science-based knowledge. Yet there continues to be a need for methods, models, and approaches for integrative work. This systematic map seeks to examine the extent, range, and nature of the published literature (i.e., peer-reviewed and grey) that integrates and/or includes Indigenous and science-based knowledge in coastal-marine research, monitoring, or management in Canada. Results from this study can be used to inform new and ongoing research and monitoring efforts and highlight evidence gaps.MethodsThe systematic map will aim to capture all available studies relevant to the question found in the peer-reviewed and grey literature. Accordingly, the search will leverage four databases focused on peer reviewed publications, carefully selected specialist websites, and two web-based search engines. Reference sections of relevant review articles will also be cross-checked to identify articles that were not found using the search strategy. All searches will be conducted in English. Search results will be reviewed in two stages: (1) title and abstract; and (2) full text. All screening decisions will be included in the database. The systematic map will employ a narrative synthesis approach that will include the use of descriptive statistics, tables (including SM database), and figures (including map with the studies geospatially referenced). In addition, an online version of the map and queryable database will be developed similar to other knowledge mobilization tools.

Certain coastal ecosystems such as mangrove, saltmarsh and seagrass habitats have been identified as significant natural carbon sinks, through the sequestration and storage of carbon in their biomass and sediments, collectively known as ‘blue carbon’ ecosystems. These ecosystems can often thrive in extreme environments where terrestrial systems otherwise survive at the limit of their existence, such as in arid and desert regions of the globe. To further our understanding of the capability of blue carbon ecosystems to sequester and store carbon in such extreme climates, we measured carbon sediment stocks in 25 sites along the Western Arabian Gulf coast. While seagrass meadows and saltmarsh habitats were widely distributed along the coast, mangrove stands were much reduced as a result of anthropogenic pressures, with 90% of stands having been lost over the last century. Carbon stocks in 1 m deep surface sediments were similar across all three blue carbon habitats, with comparable stocks for saltmarsh (81 ± 22 Mg Corg ha−1), seagrass (76 ± 20 Mg Corg ha−1) and mangroves (76 ± 23 Mg Corg ha−1). We recorded a 38% decrease in carbon stocks between mature established mangrove stands (91 Mg Corg ha−1) and recently planted mangroves (56 Mg Corg ha−1). Mangroves also had the lowest carbon stock per total area owing to their very limited spatial coverage along the coast. The largest stock per total area belonged to seagrass beds as a result of their large spatial coverage within the Gulf. We employed 210Pb dating to determine the sediment accretion rates in each ecosystem and found mangrove habitats to be the most efficient carbon sequesters over the past century, with the highest carbon burial rate of the three ecosystems (19 g Corg m−2 yr−1), followed by seagrass (9 g Corg m−2 yr−1) and saltmarshes (8 g Corg m−2 yr−1). In this work, we describe a comprehensive comparison of sediment stocks in different blue carbon ecosystems within a single marine environment and across a large geographical area, and discuss our results in a global context for other blue carbon ecosystems in the dry tropics.

BackgroundCoral reefs are rapidly changing in response to local and global stressors. Research to better understand and inform the management of these stressors is burgeoning. However, in situ studies of coral reef ecology are constrained by complex logistics and limited resources. Many reef studies are also hampered by the scale-dependent nature of ecological patterns, and inferences made on causal relationships within coral reef systems are limited by the scales of observation. This is because most socio-ecological studies are conducted at scales relevant to the phenomenon of interest. However, management often occurs across a significantly broader, often geopolitical, range of scales. While there is a critical need for incisive coral reef management actions at relevant spatial and temporal scales, it remains unclear to what extent the scales of empirical study overlap with the scales at which management inferences and recommendations are made. This systematic map protocol will evaluate this potential scale mismatch with the goal of raising awareness about the significance of effectively addressing and reporting the scales at which researchers collect data and make assumptions.MethodsWe will use the Collaboration for Environmental Evidence (CEE) systematic mapping guidelines to identify relevant studies using a framework-based synthesis to summarise the spatial and temporal scales of coral reef fish ecology research and the scales at which management inferences or recommendations are made. Using tested predefined terms, we will search for relevant published academic and grey literature, including bibliographic databases, web-based search engines, and organisational websites. Inclusion criteria for the evidence map are empirical studies that focus on coral reef fish ecological organisation and processes, those informing management interventions and policy decisions, and management documents that cite coral reef research for management decision-making. Study results will be displayed graphically using data matrices and heat maps. This is the first attempt to systematically assess and compare the scales of socio-ecological research conducted on coral reef systems with their management.

BackgroundBamboo has been identified as a potential instrument for socioeconomic development due to its fast growth, perceived environmental benefits, promising material properties, myriad applications, and relative underdevelopment as a global industrial product. Many projects and interventions have been carried out that aim to utilize bamboo’s social and environmental potential in development. However, critical evaluations that demonstrate this effect using real-world evidence and outcomes are rare, and existing case studies have not been collated and analyzed in a systematic way. The proposed systematic map aims to summarize and evaluate evidence on the social, economic, and environmental impact of bamboo industry development initiatives on beneficiary communities and ecosystems, and to identify priority areas for future funding and research.MethodsIn the proposed systematic map, we will collect and thematically categorize evidence on the social, environmental, and economic impact of bamboo development implementations, identifying themes, research gaps, and critical success factors. Literature discussing this type of intervention is published by researchers, organizations, and governments in academic journals, institutional reports, and program evaluations describing various socio-economic and environmental outcomes, impacts and metrics for success. Search sources for this systematic map therefore include bibliographic databases, institutional websites, web-based search engines, and expert consultation. Targeted search strings will be used to identify relevant texts in a two-step review process comprising an abstract and a full-text screening process. Sources describing interventions with a primary aim of bamboo industry development for social benefit that concluded between 1990 and 2021 will be sought. Metadata coded from these texts will be reviewed, categorized, and checked by two reviewers. Reviewers will be checked for consistency on batches of 30 articles using the Kappa interrater reliability test with a goal of a Kappa coefficient of 0.9. Metadata will be coded into different categories including outcomes and impacts using NVivo. Results of both quantitative and qualitative data analysis will be summarized in a searchable online database. Themes will be synthesized and explored in a narrative review and using simple logic models demonstrating theories of change for eligible case studies.

A systematic evidence map protocol for mapping global exposure to bisphenols and their alternatives and social and environmental justice implications

Blue carbon ecosystems, particularly mangroves, seagrasses, and salt marshes, play a crucial role in climate regulation by capturing and storing huge stocks of carbon. Together with supporting fisheries production, protecting shorelines from erosion, and supplying timber and non-timber products to communities, blue carbon ecosystems offer investment opportunities through carbon markets, thus supporting climate change mitigation and sustainable livelihoods. The current study assessed above- and below-ground biomass, sediment carbon, and the capacity of the blue carbon ecosystems in Kwale and Lamu Counties, Kenya, to capture and store carbon. This was followed by mapping of hotspot areas of degradation and the identification of investment opportunities in blue carbon credits. Carbon densities in mangroves were estimated at 560.23 Mg C ha−1 in Lamu and 526.34 Mg C ha−1 in Kwale, with sediments accounting for more than 70% of the stored carbon. In seagrass ecosystems, carbon densities measured 171.65 Mg C ha−1 in Lamu and 220.29 Mg C ha−1 in Kwale, values that surpass the national average but are consistent with global figures. Mangrove cover is declining at 0.49% yr−1 in Kwale and 0.16% yr−1 in Lamu, while seagrass losses in Lamu are 0.67% yr−1, with a 0.34% yr−1 increase in Kwale. Under a business-as-usual scenario, mangrove loss over 30 years will result in emissions of 4.43 million tCO2e in Kwale and 18.96 million tCO2e in Lamu. Effective interventions could enhance carbon sequestration from 0.12 to 3.86 million tCO2e in Kwale and 0.62 to 19.52 million tCO2e in Lamu. At the same period, seagrass losses in Lamu would emit 5.21 million tCO2e. With a conservative carbon price of 20 USD per tCO2e, projected annual revenues from mangrove carbon credits amount to USD 3.59 million in both Lamu and Kwale, and USD 216,040 for seagrass carbon credits in Lamu. These findings highlight the substantial climate and financial benefits of investing in the restoration and protection of the two ecosystems.

BackgroundShallow, tropical coral reefs face compounding threats from habitat degradation due to coastal development and pollution, impacts from storms and sea-level rise, and pulse disturbances like blast fishing, mining, dredging, and ship groundings that reduce coral reefs’ height and variability. One approach toward restoring coral reef structure from these threats is deploying built structures. Built structures range from engineered modules and repurposed materials to underwater sculptures and intentionally placed natural rocks. Restoration practitioners and coastal managers increasingly consider incorporating built structures, including nature-based solutions, into coral reef-related applications. Yet, synthesized evidence on the ecological and physical performance of built structure interventions across a variety of contexts (e.g., restoration, coastal protection, mitigation, tourism) is not readily available to guide decisions. To help inform management decisions, here we aim to document the global evidence base on the ecological and physical performance of built structures in shallow (≤ 30 m) tropical (35° N to 35° S latitude) coral ecosystems. The collated evidence base on use cases and associated ecological and physical outcomes of built structure interventions can help inform future consideration of built structures in reef restoration design, siting, and implementation.MethodTo discover evidence on the performance of built structures in coral reef-related applications, such as restoration, mitigation, and coastal protection, primary literature will be searched across indexing platforms, bibliographic databases, open discovery citation indexes, a web-based search engine, a novel literature discovery tool, and organizational websites. The geographic scope of the search is global, and there is no limitation to temporal scope. Primary literature will be screened first at the level of title and abstract and then at the full text level against defined eligibility criteria for the population, intervention, study type, and outcomes of interest. Metadata will be extracted from studies that pass both screening levels. The resulting data will be analyzed to determine the distribution and abundance of evidence. Results will be made publicly available and reported in a systematic map that includes a narrative description, identifies evidence clusters and gaps, and outlines future research directions on the use of built structures in coral reef-related applications.

Background Agriculture and agricultural intensification can have significant negative impacts on the environment, including nutrient and pesticide leaching, spreading of pathogens, soil erosion and reduction of ecosystem services provided by terrestrial and aquatic biodiversity. The establishment and management of vegetated strips adjacent to farmed fields (including various field margins, buffer strips and hedgerows) are key mitigation measures for these negative environmental impacts and environmental managers and other stakeholders must often make decisions about how best to design and implement vegetated strips for a variety of different outcomes. However, it may be difficult to obtain relevant, accurate and summarised information on the effects of implementation and management of vegetated strips, even though a vast body of evidence exists on multipurpose vegetated strip interventions within and around fields. To improve the situation, we describe a method for assembling a database of relevant research relating to vegetated strips undertaken in boreo-temperate farming systems (arable, pasture, horticulture, orchards and viticulture), according to the primary question: What evidence exists regarding the effects of field margins on nutrients, pollutants, socioeconomics, biodiversity, and soil retention? Methods We will search 13 bibliographic databases, one search engine and 37 websites for stakeholder organisations using a predefined and tested search string that focuses on a comprehensive list of vegetated strip synonyms. Non-English language searches in Danish, Finnish, German, Spanish, and Swedish will also be undertaken using a web-based search engine. We will screen search results at title, abstract and full text levels, recording the number of studies deemed non-relevant (with reasons at full text). A systematic map database that displays the meta-data (i.e. descriptive summary information about settings and methods) of relevant studies will be produced following full text assessment. The systematic map database will be displayed as a web-based geographical information system (GIS). The nature and extent of the evidence base will be discussed.

BackgroundReducing greenhouse gas emissions is a vital step in limiting climate change and meeting the goals outlined in the COP 21 Paris Agreement of 2015. Studies have suggested that agriculture accounts for around 11% of total greenhouse gas emissions and the industry has a significant role in meeting international and national climate change reduction objectives. However, there is currently little consensus on the mechanisms that regulate the production and assimilation of greenhouse gases in arable land and the practical factors that affect the process. Practical advice for farmers is often overly general, and models based on the amount of nitrogen fertiliser applied, for example, are used despite a lack of knowledge of how local conditions affect the process, such as the importance of humus content and soil types. Here, we propose a systematic map of the evidence relating to the impact on greenhouse gas flux from the agricultural management of arable land in temperate regions.MethodsUsing established methods for systematic mapping in environmental sciences we will search for, collate and catalogue research studies relating to the impacts of farming in temperate systems on greenhouse gas emissions. We will search 6 bibliographic databases using a tested search string, and will hand search a web-based search engine and a list of organisational web sites. Furthermore, evidence will be sought from key stakeholders. Search results will then be screened for relevance at title, abstract and full text levels according to a predefined set of eligibility criteria. Consistency checking will be employed to ensure the criteria are being applied accurately and consistently. Relevant studies will then be subjected to coding and meta-data extraction, which will be used to populate a systematic map database describing each relevant study’s settings, methods and measured outcomes. The mapping process will help to identify knowledge gaps (subjects lacking in evidence warranting further primary research) and knowledge clusters (subjects with sufficient studies to allow a useful full systematic review), and will highlight best and suboptimal research methods.

BackgroundForests provide an essential resource that support the livelihoods of an estimated 20% of the global population. Forests are thought to serve in three primary roles to support livelihoods: subsistence, safety nets, and pathways to prosperity. While we have a working understanding of how poor people depend on forests in individual sites and countries, much of this evidence is dispersed and not easily accessible. Thus, while the importance of forest ecosystems and resources to contribute to poverty alleviation has been increasingly emphasized in international policies, conservation and development initiatives and investments—the strength of evidence to support how forests can affect poverty outcomes is still unclear. This study takes a systematic mapping approach to scope, identify and describe studies that measure the effect of forest-based activities on poverty outcomes at local and regional scales. This effort builds upon an existing systematic map on linkages between conservation and human well-being in order to make this process more efficient. We will conduct a refined and updated search strategy pertinent to forests-poverty linkages to glean additional evidence from studies outside the scope of the original map. Results of this study can be used for informing conservation and development policy and practices in global forest ecosystems and highlight evidence gaps where future primary studies and systematic reviews can add value.MethodsWe build upon the search strategy outlined in McKinnon et al. (Environ Evid 1–25, 2016) and expand our search to cover a total of 7 bibliographic databases, 15 organizational websites, 8 existing systematic reviews and maps, and evidence gap maps, and solicit key informants. All searches will be conducted in English and encompass all nations. Search results will be screened at title, abstract, and full text levels, recording both the number of excluded articles and reasons for exclusion. Full text assessment will be conducted on all included article and extracted data will be reported in a narrative review that will summarize trends in the evidence, report any knowledge gaps and gluts, and provide insight for policy, practice and future research. The data from this systematic map will be made available as well, through an open access, searchable data portal and visualization tool.

In recent years, researchers have increasingly recognized the need to bridge Western and Indigenous knowledge systems to strengthen research in wildlife conservation. Historically, this arena has not made space for Indigenous knowledge holders to share components of their knowledge systems with agency and to support their own self‐determination as equal partners. Since time immemorial, Indigenous Peoples have been developing, maintaining and refining their own knowledge systems, based on intimate knowledge and relationships with the lands, airs, and waterways. There remains enormous potential for Western scientists to engage in equitable knowledge exchange and co‐production with Indigenous Peoples. This applies to species such as boreal caribou Rangifer tarandus caribou, known by the Dene name, tǫdzı; which hold ecological value and cultural importance for both Indigenous and non‐Indigenous people in the boreal region of Canada. To gain an overarching perspective of this species, we will create a systematic literature map that will examine peer‐reviewed and grey literature involving spatial mapping of all species of caribou Rangifer tarandus based on Indigenous knowledge. This map will (a) characterize available data and previously engaged knowledge holders and (b) identify positive experiences that exemplify best practices for knowledge co‐production. Searches will be conducted in English in selected databases. Search strings will be tested against a collection of benchmark papers of documents previously chosen to determine strings with maximum sensitivity and specificity. Results will be reviewed through the: (1) title and abstract; and (2) full text. All screening decisions will be recorded in a database, with 10% of full‐text screening decisions validated. Items retained for inclusion in the systematic map will be coded using a list of coding questions. Ten percent of coding outcomes will be validated by a second reviewer. The systematic map will employ a narrative synthesis approach that will compare retained studies against a list of best practices from the current proposal. It will examine case studies that performed well according to the list and contribute to a repository of previously documented Indigenous knowledge about caribou to support projects involving Indigenous and Western knowledge co‐production.