• Energy Research

The dataset comprises of above ground vegetation cut to ground level and dried to give indication of standing crop biomass in a 50 centimetre (cm) x 25cm area (taken within a 1metre (m) x 1m quadrat) . Sampling was conducted at six salt marsh sites at four spatial scales: 1 m (the minimal sampling unit) nested within a hierarchy of increasing scales of 1-10 m, 10-100 m and 100-1000 m. Three of the sites were in Morecambe Bay, North West England and three of the sites were in Essex, South East England. All samples were taken during the winter and summer of 2013. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. A 50 centimetre (cm) x 25cm area of above ground vegetation was taken randomly within each 1metre (m) x 1m quadrat, cut to ground level, then dried at 60 degrees Celsius for 72 hours to give an indication of standing crop biomass. Results were recorded onto field sheets. These data were transferred into an Excel file. Results were exported as comma separated value files for ingestion into the EIDC. The location of the sample sites was determined by randomly allocated quadrats. Each site consisted of a rectangular area of saltmarsh between 400 x 500 m to 1000 x 1000 m in size, dependent upon saltmarsh length (parallel to shore) and width (perpendicular to shore), including part of the low, mid and high marsh zones. Twenty two 1 x 1 m quadrats were randomly allocated to each site rectangle using R (R Development Core Team, 2014) to specify four different spatial scales (A = 1 quadrat only, B = 3 quadrats at 1 m to 10 m apart, C = 6 quadrats at 10 m to 100 m apart, D = 12 quadrats at 100 m to 1000 m or site maximum).

Enhanced species richness can stimulate the productivity of plant communities; however, its effect on the belowground production of forests has scarcely been tested, despite the role of tree roots in carbon storage and ecosystem processes. Therefore, we tested for the effects of tree species richness on mangrove root biomass: thirty-two 6 m by 6 m plots were planted with zero (control), one, two or three species treatments of six-month-old Avicennia marina (A), Bruguiera gymnorrhiza (B) and Ceriops tagal (C). A monoculture of each species and the four possible combinations of the three species were used, with four replicate plots per treatment. Above- and belowground biomass was measured after three and four years' growth. In both years, the all-species mix (ABC) had significant overyielding of roots, suggesting complementarity mediated by differences in rhizosphere use amongst species. In year four, there was higher belowground than aboveground biomass in all but one treatment. Belowground biomass was strongly influenced by the presence of the most vigorously growing species, A. marina. These results demonstrate the potential for complementarity between fast- and slow-growing species to enhance belowground growth in mangrove forests, with implications for forest productivity and the potential for belowground carbon sequestration.

Mangroves are intertidal ecosystems that are particularly vulnerable to climate change. At the low tidal limits of their range, they face swamping by rising sea levels; at the high tidal limits, they face increasing stress from desiccation and high salinity. Facilitation theory may help guide mangrove management and restoration in the face of these threats by suggesting how and when positive intra- and interspecific effects may occur: such effects are predicted in stressed environments such as the intertidal, but have yet to be shown among mangroves. Here, we report the results of a series of experiments at low and high tidal sites examining the effects of mangrove density and species mix on seedling survival and recruitment, and on the ability of mangroves to trap sediment and cause surface elevation change. Increasing density significantly increased the survival of seedlings of two different species at both high and low tidal sites, and enhanced sediment accretion and elevation at the low tidal site. IncludingAvicennia marinain species mixes enhanced total biomass at a degraded high tidal site. Increasing biomass led to changed microenvironments that allowed the recruitment and survival of different mangrove species, particularlyCeriops tagal.

AbstractCoastal saltmarshes are found globally, yet are 25%–50% reduced compared with their historical cover. Restoration is incentivised by the promise that marshes are efficient storers of ‘blue’ carbon, although the claim lacks substantiation across global contexts. We synthesised data from 431 studies to quantify the benefits of saltmarsh restoration to carbon accumulation and greenhouse gas uptake. The results showed global marshes store approximately 1.41–2.44 Pg carbon. Restored marshes had very low greenhouse gas (GHG) fluxes and rapid carbon accumulation, resulting in a mean net accumulation rate of 64.70 t CO2e ha−1 year−1. Using this estimate and potential restoration rates, we find saltmarsh regeneration could result in 12.93–207.03 Mt CO2e accumulation per year, offsetting the equivalent of up to 0.51% global energy‐related CO2 emissions—a substantial amount, considering marshes represent <1% of Earth's surface. Carbon accumulation rates and GHG fluxes varied contextually with temperature, rainfall and dominant vegetation, with the eastern coasts of the USA and Australia particular hotspots for carbon storage. While the study reveals paucity of data for some variables and continents, suggesting need for further research, the potential for saltmarsh restoration to offset carbon emissions is clear. The ability to facilitate natural carbon accumulation by saltmarshes now rests principally on the action of the management‐policy community and on financial opportunities for supporting restoration.

The outwelling paradigm argues that mangrove and saltmarsh wetlands export much excess production to downstream marine systems. However, outwelling is difficult to quantify and currently 40-50% of fixed carbon is unaccounted for. Some carbon is thought outwelled through mobile fauna, including fish, which visit and feed on mangrove produce during tidal inundation or early life stages before moving offshore, yet this pathway for carbon outwelling has never been quantified. We studied faunal carbon outwelling in three arid mangroves, where sharp isotopic gradients across the boundary between mangroves and down-stream systems permitted spatial differentiation of source of carbon in animal tissue. Stable isotope analysis (C, N, S) revealed 22-56% of the tissue of tidally migrating fauna was mangrove derived. Estimated consumption rates showed that 1.4% (38 kg C ha-1 yr-1) of annual mangrove litter production was directly consumed by migratory fauna, with <1% potentially exported. We predict that the amount of faunally-outwelled carbon is likely to be highly correlated with biomass of migratory fauna. While this may vary globally, the measured migratory fauna biomass in these arid mangroves was within the range of observations for mangroves across diverse biogeographic ranges and environmental settings. Hence, this study provides a generalized prediction of the relatively weak contribution of faunal migration to carbon outwelling from mangroves and the current proposition, that the unaccounted-for 40-50% of mangrove C is exported as dissolved inorganic carbon, remains plausible.

Las complejas redes de raíces y troncos sobre el suelo hacen que los bosques de manglares atrapen la basura plástica. Probamos cómo los macroplásticos se relacionan con la biomasa de los árboles, la abundancia de raíces, la geomorfología de los manglares y la proximidad a la desembocadura de los ríos, estudiando los márgenes terrestres y marítimos de siete bosques en Filipinas, un punto de acceso global para la contaminación plástica marina. Los macroplásticos fueron abundantes (media ± s.e.: 1.1 ± 0.22 ítems m-2; rango: 0.05 ± 0.05 a 3.79 ± 1.91), más grandes en la zona terrestre (media ± s.e.: 1.60 ± 0.41 m-2) y dominados por ítems derivados de la tierra (sobres, bolsas). La abundancia y el peso del plástico aumentaron con la proximidad a las desembocaduras de los ríos, y la abundancia de las raíces predijo el área de superficie de la basura plástica (es decir, la suma acumulada de todas las áreas de superficie de cada elemento plástico por parcela). El estudio confirma que los ríos son una vía importante para la contaminación plástica marina, y que las raíces de los manglares son el atributo biológico que regula la retención de basura. Los resultados sugieren que la gestión de residuos terrestres que evita que los plásticos entren en los ríos reducirá la contaminación plástica marina en el sudeste asiático. Des réseaux complexes de racines et de troncs hors sol font que les forêts de mangroves piègent les déchets plastiques. Nous avons testé la relation entre les macroplastiques et la biomasse des arbres, l'abondance des racines, la géomorphologie des mangroves et la proximité de l'embouchure des rivières, en étudiant les marges terrestres et maritimes de sept forêts des Philippines, un point chaud mondial pour la pollution plastique marine. Les macroplastiques étaient abondants (moyenne ± s.e. : 1,1 ± 0,22 éléments m-2 ; plage : 0,05 ± 0,05 à 3,79 ± 1,91), les plus importants dans la zone terrestre (moyenne ± s.e. : 1,60 ± 0,41 m-2) et dominés par les éléments d'origine terrestre (sachets, sacs). L'abondance et le poids du plastique augmentent avec la proximité des embouchures des rivières, l'abondance des racines prédisant la surface de la litière en plastique (c'est-à-dire la somme cumulative de toutes les surfaces de chaque élément en plastique par parcelle). L'étude confirme que les rivières sont une voie majeure de pollution plastique marine, les racines de mangrove étant l'attribut biologique qui régule la rétention des litières. Les résultats suggèrent que la gestion des déchets terrestres qui empêche les plastiques de pénétrer dans les rivières réduira la pollution plastique marine en Asie du Sud-Est. Complex networks of above-ground roots and trunks make mangrove forests trap plastic litter. We tested how macroplastics relate to tree biomass, root abundance, mangrove geomorphology and river mouth proximity, surveying landward and seaward margins of seven forests in the Philippines, a global hotspot for marine plastic pollution. Macroplastics were abundant (mean ± s.e.: 1.1 ± 0.22 items m-2; range: 0.05 ± 0.05 to 3.79 ± 1.91), greatest at the landward zone (mean ± s.e.: 1.60 ± 0.41 m-2) and dominated by land-derived items (sachets, bags). Plastic abundance and weight increased with proximity to river mouths, with root abundance predicting plastic litter surface area (i.e., the cumulative sum of all the surface areas of each plastic element per plot). The study confirms rivers are a major pathway for marine plastic pollution, with mangrove roots are the biological attribute that regulate litter retention. The results suggest land-based waste management that prevent plastics entering rivers will reduce marine plastic pollution in Southeast Asia. تجعل الشبكات المعقدة من الجذور والجذوع فوق الأرض غابات المانغروف تحبس القمامة البلاستيكية. اختبرنا كيفية ارتباط اللدائن الكلية بالكتلة الحيوية للأشجار، ووفرة الجذور، والجيومورفولوجيا في غابات المانغروف، وقرب مصب النهر، وقمنا بمسح الهوامش البرية والبحرية لسبع غابات في الفلبين، وهي نقطة ساخنة عالمية للتلوث البلاستيكي البحري. كانت المواد البلاستيكية الكبيرة وفيرة (متوسط ± s.e: 1.1 ± 0.22 عنصر m -2 ؛ النطاق: 0.05 ± 0.05 إلى 3.79 ± 1.91)، وأكبرها في المنطقة البرية (متوسط ± s.e: 1.60 ± 0.41 m -2) وتهيمن عليها العناصر المشتقة من الأرض (الأكياس، الأكياس). زادت الوفرة البلاستيكية والوزن مع القرب من مصبات الأنهار، مع توقع وفرة الجذور لمساحة سطح القمامة البلاستيكية (أي المجموع التراكمي لجميع المساحات السطحية لكل عنصر بلاستيكي لكل قطعة أرض). تؤكد الدراسة أن الأنهار هي مسار رئيسي للتلوث البلاستيكي البحري، مع جذور المنغروف هي السمة البيولوجية التي تنظم الاحتفاظ بالقمامة. تشير النتائج إلى أن إدارة النفايات البرية التي تمنع دخول البلاستيك إلى الأنهار ستقلل من التلوث البلاستيكي البحري في جنوب شرق آسيا.

AbstractAimArtificial coastal defence structures are proliferating in response to rising and stormier seas. These structures provide habitat for many species but generally support lower biodiversity than natural habitats. This is primarily due to the absence of environmental heterogeneity and water‐retaining features on artificial structures. We compared the epibiotic communities associated with artificial coastal defence structures and natural habitats to ask the following questions: (1) is species richness on emergent substrata greater in natural than artificial habitats and is the magnitude of this difference greater at mid than upper tidal levels; (2) is species richness greater in rock pools than emergent substrata and is the magnitude of this difference greater in artificial than natural habitats; and (3) in artificial habitats, is species richness in rock pools greater at mid than upper tidal levels?LocationBritish Isles.MethodsStandard non‐destructive random sampling compared the effect of habitat type and tidal height on epibiota on natural rocky shores and artificial coastal defence structures.ResultsNatural emergent substrata supported greater species richness than artificial substrata. Species richness was greater at mid than upper tidal levels, particularly in artificial habitats. Rock pools supported greater species richness than emergent substrata, and this difference was more pronounced in artificial than natural habitats. Rock pools in artificial habitats supported greater species richness at mid than upper tidal levels.Main conclusionsArtificial structures support lower biodiversity than natural habitats. This is primarily due to the lack of habitat heterogeneity in artificial habitats. Artificial structures can be modified to provide rock pools that promote biodiversity. The effect of rock pool creation will be more pronounced at mid than upper tidal levels. The challenge now is to establish at what tidal height the effect of pools becomes negligible and to determine the rock pool dimensions for optimum habitat enhancement.

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.