China's conservation and restoration of coastal wetlands offset much of the reclamation-induced blue carbon losses.

China's coastal wetlands have experienced large losses and gains with rapid coastal reclamation and restoration since the end of the 20th century. However, owing to the difficulties in mapping soil organic carbon (SOC) in blue carbon stocks of coastal wetlands on a national scale, little is known about the spatial pattern of SOC stock in China's coastal wetlands and the loss and gain of SOC stock following coastal reclamation, conservation, and restoration over the past decades. Here, we developed a SOC stock map in China's coastal wetlands at 30 m spatial resolution, analyzed the spatial variability and driving factors of SOC stocks, and finally estimated SOC losses and gains due to coastal reclamation and wetland management from 1990 to 2020. We found that the total SOC stocks in China's coastal wetlands were 77.8 Tg C by 2020 with 3.6 Tg C in mangroves, 8.8 Tg C in salt marshes, and 65.4 Tg C in mudflats. Temperature, rainfall, and seawater salinity exerted the highest relative contributions to SOC spatial variability. The spatial trend of SOC density gradually decreased from south to north except for Liaoning province, with the lowest density in Shandong province. About 24.9% (19.4 Tg C) of SOC stocks in China's coastal wetlands were lost due to high-intensity reclamation, but SOC stock gained from conservation and restoration offset the reclamation-induced losses by 58.2% (11.3 Tg C) over the past three decades. These findings demonstrated the great potential of conservation and restoration of coastal wetlands in reversing the loss trend of blue carbon and contributing to the mitigation of climate change toward carbon neutrality. Our study provides significant spatial insights into the stocks, sequestration, and recovery capacity of blue carbon following rapid urbanization and management actions, which benefit the progress of global blue carbon management.

Multifarious plant growth-promoting traits of mangrove yeasts: growth enhancement in mangrove seedlings (Rhizophora mucronata) for conservation.

Plant Growth-Promoting Yeasts (PGPY) have garnered significant attention in recent years; however, research on PGPY from mangroves remains a largely unexplored frontier. This study, therefore, focused on exploring the multifaceted plant growth-promoting (PGP) capabilities of yeasts isolated from mangroves of Puthuvype and Kumbalam. The present work found that manglicolous yeasts exhibited diverse hydrolytic properties, with the predominance of lipolytic activity, in addition to other traits such as phosphate solubilization, and production of indole acetic acid, siderophore, ammonia, catalase, nitrate, and hydrogen cyanide. After screening for 15 PGP traits, three strains P 9, PV 23, and KV 35 were selected as the most potent ones. These strains also exhibited antagonistic activity against fungal phytopathogens and demonstrated resilience to abiotic stresses, making them not only promising biocontrol agents but also suited for field application. The potent strains P 9, PV 23, and KV 35 were molecularly identified as Candida tropicalis, Debaryomyces hansenii, and Aureobasidium melanogenum, respectively. The potential of these strains in enhancing the growth performance of mangrove seedlings of Rhizophora mucronata, was demonstrated using the pot-experiment. The results suggested that the consortium of three potent strains (P 9, PV 23, and KV 35) was more effective in increasing the number of shoot branches (89.2%), plant weight (87.5%), root length (83.3%), shoot height (57.9%) and total leaf area (35.1%) than the control seedlings. The findings of this study underscore the significant potential of manglicolous yeasts in contributing to mangrove conservation and restoration efforts, offering a comprehensive understanding of their diverse plant growth-promoting mechanisms and highlighting their valuable role in sustainable ecosystem management.

Effects of perceptions of forest change and intergroup competition on community-based conservation behaviors.

Approximately one quarter of the earth's population directly harvests natural resources to meet their daily needs. These individuals are disproportionately required to alter their behaviors in response to increasing climatic variability and global biodiversity loss. Much of the ever-ambitious global conservation agenda relies on the voluntary uptake of conservation behaviors in such populations. Thus, it is critical to understand how such individuals perceive environmental change and use conservation practices as a tool to protect their well-being. We developed a participatory mapping activity to elicit spatially explicit perceptions of forest change and its drivers across 43 mangrove-dependent communities in Pemba, Tanzania. We administered this activity along with a questionnaire regarding conservation preferences and behaviors to 423 individuals across those 43 communities. We analyzed these data with a set of Bayesian hierarchical statistical models. Perceived cover loss in 50% of a community's mangrove area drove individuals to decrease proposed limits on fuelwood bundles from 2.74 (forest perceived as intact) to 2.37 if participants believed resultant gains in mangrove cover would not be stolen by outsiders. Conversely, individuals who believed their community mangrove forests were at high risk of theft loosened their proposed harvest limits from 1.26 to 2.75 bundles of fuelwood in response to the same perceived forest decline. High rates of intergroup competition and mangrove loss were thus driving a self-reinforcing increase in unsustainable harvesting preferences in community forests in this system. This finding demonstrates a mechanism by which increasing environmental decline may cause communities to forgo conservation practices, rather than adopt them, as is often assumed in much community-based conservation planning. However, we also found that when effective boundaries were present, individuals were willing to limit their own harvests to stem such perceived decline.

Efectos de las percepciones del cambio forestal y la competencia intergrupal en los comportamientos de conservación comunitarios Resumen Aproximadamente una cuarta parte de la población mundial aprovecha directamente los recursos naturales para satisfacer sus necesidades diarias. Estos individuos se ven desproporcionadamente obligados a alterar sus comportamientos en respuesta a la creciente variabilidad climática y la pérdida de biodiversidad global. Gran parte de la ambiciosa agenda de conservación global se basa en la adopción voluntaria de comportamientos de conservación en dichas poblaciones. Por lo tanto, es fundamental comprender cómo esas personas perciben el cambio ambiental y utilizan las prácticas de conservación como herramienta para proteger su bienestar. Desarrollamos una actividad de mapeo participativo para generar percepciones espacialmente explícitas del cambio forestal y sus causantes en 43 comunidades dependientes de manglares en Pemba, Tanzania. Administramos esta actividad junto con un cuestionario sobre preferencias y comportamientos de conservación a 423 personas en esas 43 comunidades. Analizamos estos datos mediante un conjunto de modelos estadísticos jerárquicos bayesianos. La pérdida de cobertura percibida en el 50% del área de manglares de una comunidad llevó a los individuos a reducir los límites propuestos para los paquetes de leña de 2.74 (bosque percibido como intacto) a 2.37 si los participantes creían que las ganancias resultantes en la cobertura de manglares no serían robadas por personas ajenas a la comunidad. Por el contrario, las personas que creían que los bosques de manglares de su comunidad corrían un alto riesgo de robo flexibilizaron los límites de cosecha propuestos de 1.26 a 2.75 haces de leña en respuesta a la misma disminución percibida del bosque. Por lo tanto, las altas tasas de competencia entre grupos y pérdida de manglares estaban impulsando un aumento, que se auto reforzaba, en las preferencias de aprovechamiento insostenibles en los bosques comunitarios de este sistema. Este hallazgo muestra un mecanismo por el cual el creciente deterioro ambiental puede hacer que las comunidades renuncien a las prácticas de conservación, en lugar de adoptarlas, como a menudo se supone en gran parte de la planificación de la conservación basada en la comunidad. Sin embargo, también encontramos que cuando existían límites efectivos, los individuos estaban dispuestos a restringir sus propias cosechas para frenar esa disminución percibida.

Integrating socioeconomic and ecological data into restoration practice.

Driven by the United Nations Decade on Restoration and international funding initiatives, such as the Mangrove Breakthrough, investment in mangrove restoration is expected to increase. Yet, mangrove restoration efforts frequently fail, usually because of ad hoc site-selection processes that do not consider mangrove ecology and the socioeconomic context. Using decision analysis, we developed an approach that accounts for socioeconomic and ecological data to identify sites with the highest likelihood of mangrove restoration success. We applied our approach in the Biosphere Reserve Marismas Nacionales Nayarit, Mexico, an area that recently received funding for implementing mangrove restoration actions. We identified 468 potential restoration sites, assessed their restorability potential based on socioeconomic and ecological metrics, and ranked sites for implementation with spatial optimization. The metrics we used included favorable conditions for propagules to establish and survive under sea-level rise, provision of ecosystem services, and community dynamics. Sites that were selected based on socioeconomic or ecological metrics alone had lower likelihood of mangrove restoration success than sites that were selected based on integrated socioeconomic and ecological metrics. For example, selecting sites based on only socioeconomic metrics captured 16% of the maximum attainable value of functioning mangroves able to provide propagules to potential restoration sites, whereas selecting sites based on ecological and socioeconomic metrics captured 46% of functioning mangroves. Our approach was developed as part of a collaboration between nongovernmental organizations, local government, and academics under rapid delivery time lines given preexisting mangrove restoration implementation commitments. The systematic decision process we used integrated socioeconomic and ecological considerations even under short delivery deadlines, and our approach can be adapted to help mangrove restoration site-selection decisions elsewhere.

Integración de datos socioeconómicos y ecológicos en las prácticas de restauración Resumen Se espera que la inversión en la restauración de los manglares incremente debido a la Década de Restauración de las Naciones Unidad y las iniciativas internacionales de financiamiento, como The Mangrove Breakthrough. Sin embargo, los esfuerzos de restauración de manglares fallan con frecuencia, generalmente por los procesos de selección de sitios ad­hoc que no consideran la ecología del manglar y el contexto socioeconómico. Usamos el análisis de decisiones para desarrollar una estrategia que considera los datos socioeconómicos y ecológicos para identificar los sitios con mayor probabilidad de éxito de restauración. Aplicamos nuestra estrategia en la Reserva de la Biósfera Marismas Nacionales Nayarit, México, un área que recibió financiamiento reciente para la restauración del manglar. Identificamos 468 sitios potencialmente restaurables, evaluamos su potencial de restauración con base en medidas ecológicas y socioeconómicas y clasificamos los sitios para la implementación con la optimización espacial. Las medidas que usamos incluían las condiciones favorables para que los propágulos se establezcan y sobrevivan con el incremento en el nivel del mar, el suministro de servicios ambientales y las dinámicas de la comunidad. Los sitios seleccionados sólo con base en las medidas ecológicas o socioeconómicas tuvieron una menor probabilidad de éxito de restauración que los sitios que se seleccionaron con base en medidas socioeconómicas y ecológicas integradas. Por ejemplo, la selección de sitios con base sólo en las medidas socioeconómicas capturó el 16% del máximo valor alcanzable de manglares funcionales capaces de proporcionar propágulos a los sitios potenciales de restauración, mientras que la selección basada en medidas ecológicas y socioeconómicas capturó el 46% de los manglares funcionales. Desarrollamos nuestra estrategia como parte de una colaboración entre organizaciones no gubernamentales, el gobierno local y académicos sujetos a una fecha pronta de entrega debido a los compromisos preexistentes para la restauración de manglares. El proceso de decisión sistemática que usamos integró las consideraciones ecológicas y socioeconómicas incluso con plazos cortos de entrega. Nuestra estrategia puede adaptarse para apoyar en la selección de sitios de restauración de manglares en otros sitios.

From swamp to field: how genes from mangroves and its associates can enhance crop salinity tolerance.

Salinity stress is a critical challenge in crop production and requires innovative strategies to enhance the salt tolerance of plants. Insights from mangrove species, which are renowned for their adaptability to high-salinity environments, provides valuable genetic targets and resources for improving crops. A significant hurdle in salinity stress is the excessive uptake of sodium ions (Na+) by plant roots, causing disruptions in cellular balance, nutrient deficiencies, and hampered growth. Specific ion transporters and channels play crucial roles in maintaining a low Na+/K+ ratio in root cells which is pivotal for salt tolerance. The family of high-affinity potassium transporters, recently characterized in Avicennia officinalis, contributes to K+ homeostasis in transgenic Arabidopsis plants even under high-salt conditions. The salt overly sensitive pathway and genes related to vacuolar-type H+-ATPases hold promise for expelling cytosolic Na+ and sequestering Na+ in transgenic plants, respectively. Aquaporins contribute to mangroves' adaptation to saline environments by regulating water uptake, transpiration, and osmotic balance. Antioxidant enzymes mitigate oxidative damage, whereas genes regulating osmolytes, such as glycine betaine and proline, provide osmoprotection. Mangroves exhibit increased expression of stress-responsive transcription factors such as MYB, NAC, and CBFs under high salinity. Moreover, genes involved in various metabolic pathways, including jasmonate synthesis, triterpenoid production, and protein stability under salt stress, have been identified. This review highlights the potential of mangrove genes to enhance salt tolerance of crops. Further research is imperative to fully comprehend and apply these genes to crop breeding to improve salinity resilience.

How do soil processes control the provision of ecosystem services in coastal wetlands?

Coastal wetlands are known for their diverse ecosystems, yet their soil characteristics are often misunderstood and thought to be monotonous. These soils are frequently subjected to saline water saturation, leading to unique soil processes. However, the combination and intensity of these processes can vary considerably across different ecosystems. In this study, we hypothesize that these diverse soil processes not only govern the geochemical conditions in coastal ecosystems but also influence their ability to deliver ecosystem services. To test this hypothesis, we conducted soil analyses in mangroves, seagrass meadows, and hypersaline tidal flats along the Brazilian coast. We used key soil properties as indicators of soil processes and developed a conceptual model linking soil processes and soil-related ecosystem services in these environments. Under more anoxic conditions, the intense soil organic matter accumulation and sulfidization processes in mangroves evidence their significance in terms of climate regulation through organic carbon sequestration and contaminants immobilization. Similarly, pronounced sulfidization in seagrasses underscores their ability to immobilize contaminants. In contrast, hypersaline tidal flats soils exhibit increased intensities of salinization and calcification processes, leading to a high capacity for accumulating inorganic carbon as secondary carbonates (CaCO3), underscoring their role in climate regulation through inorganic carbon sequestration. Our findings show that contrary to previously thought coastal wetlands are far from monotonous, exhibiting significant variations in the types and intensities of soil processes, which in turn influence their capacity to deliver ecosystem services. This understanding is pivotal for guiding effective management strategies to enhance ecosystem services in coastal wetlands.

Benthic jellyfish dominate water mixing in mangrove ecosystems.

Water mixing is a critical mechanism in marine habitats that governs many important processes, including nutrient transport. Physical mechanisms, such as winds or tides, are primarily responsible for mixing effects in shallow coastal systems, but the sheltered habitats adjacent to mangroves experience very low turbulence and vertical mixing. The significance of biogenic mixing in pelagic habitats has been investigated but remains unclear. In this study, we show that the upside-down jellyfish Cassiopea sp. plays a significant role with respect to biogenic contributions to water column mixing within its shallow natural habitat ([Formula: see text] m deep). The mixing contribution was determined by high-resolution flow velocimetry methods in both the laboratory and the natural environment. We demonstrate that Cassiopea sp. continuously pump water from the benthos upward in a vertical jet with flow velocities on the scale of centimeters per second. The volumetric flow rate was calculated to be 212 L⋅h-1 for average-sized animals (8.6 cm bell diameter), which translates to turnover of the entire water column every 15 min for a median population density (29 animals per m2). In addition, we found Cassiopea sp. are capable of releasing porewater into the water column at an average rate of 2.64 mL⋅h-1 per individual. The release of nutrient-rich benthic porewater combined with strong contributions to water column mixing suggests a role for Cassiopea sp. as an ecosystem engineer in mangrove habitats.

Integrated physiological, biochemical, and transcriptomic analyses of Bruguiera gymnorhiza leaves under long-term copper stress: Stomatal size, wax crystals and composition.

Copper (Cu) is a necessary mineral nutrient for plant growth and development and is involved in several morphological, physiological, and biochemical processes; however, high concentrations of Cu can negatively impact these processes. The role of stomata in responding to various biotic and abiotic stimuli has not been studied in Bruguiera gymnorhiza, particularly in terms of their coordinated interactions at the molecular, physiological, and biochemical levels. Moreover, numerous plants employ strategies such as the presence of thick waxy cuticles on their leaf epidermis and the closing of stomata to reduce water loss. Thus, this study investigates the accumulation of Cu in B. gymnorhiza and its effect on leaf morphology and the molecular response under different Cu treatments (0, 200, and 400 mg L⁻¹, Cu0, Cu200, and Cu400, respectively) during a two years stress period. The results show that Cu stress affected accumulation and transport, increased the activities of peroxidase and ascorbate peroxidase, concentrations of soluble sugar, proline, and H2O2, and decreased the activity of catalase and content of malondialdehyde. Also, Cu-induced stress decreased the uptake of phosphorus and nitrogen and inhibited plant photosynthesis, which consequently led to reduced plant growth. Scanning electron microscopy combined with gas chromatography-mass spectrometry showed that B. gymnorhiza leaves had higher wax crystals and compositions under increased Cu stress, which forced the leaf's stomata to be closed. Also, the contents of alkanes, alcohols, primary alcohol levels (C26:0, C28:0, C30:0, and C32:0), n-Alkanes (C29 and C30), and other wax loads were significantly higher, while fatty acid (C12, C16, and C18) was lower in Cu200 and Cu400 compared to Cu0. Furthermore, the transcriptomic analyses revealed 1240 (771 up- and 469 downregulated), 1000 (723 up- and 277 down-regulated), and 1476 (808 up- and 668 downregulated) differentially expressed genes in Cu0 vs Cu200, Cu0 vs Cu400, and Cu200 vs Cu400, respectively. RNA-seq analyses showed that Cu mainly affected eight pathways, including photosynthesis, cutin, suberin, and wax biosynthesis. This study provides a reference for understanding mangrove response to heavy metal stress and developing novel management practices.

Characterization of oil exposure parameters affecting impact, recovery, and reestablishment of mangrove forests: Lessons learned.

The recovery and reestablishment times of mangrove forests exposed to oil are highly dependent on the oil type and oil-related contaminant levels in water and sediments, spill magnitude, oil exposure duration and frequency, duration of the oil contamination remaining in water and sediments, and post-spill events and clean up actions. Estimating the adverse effects of oil exposure and recovery times of mangrove forests is often done by referencing other spills in different geographical regions or locations with different coastal and environmental characteristics. As a result, these projections may not provide reliable estimates for recovery times and the success of the recovery efforts. A systematic methodology is needed to categorize the prespill conditions and oil exposure vulnerability of mangrove forests. The objectives of this review are to: 1) emphasize the need for a systematic process to document the pre- and post-spill characteristics of mangrove forests, 2) identify key factors that influence the vulnerability of mangrove forests to oil exposure, 3) highlight the differences in mangrove forest characteristics and types of spilled oil to develop effective recovery strategies, 4) emphasize the importance of developing a recovery estimation tool to project the adverse effects of oil spills and recovery times, considering geographical features, mangrove characteristics, and the nature of the spilled oil, and 5) stress the necessity for using appropriate monitoring tools for systematically tracking the recovery of mangrove forests after exposure to oil.

Ecotourism and mangrove conservation in Southeast Asia: Current trends and perspectives.

Mangroves in Southeast Asia provide numerous supporting, provisioning, regulating, and cultural services that are crucial to the environment and local livelihoods since they support biodiversity conservation and climate change resilience. However, Southeast Asia mangroves face deforestation threats from the expansion of commercial aquaculture, agriculture, and urban development, along with climate change-related natural processes. Ecotourism has gained prominence as a financial incentive tool to support mangrove conservation and restoration. Through a systematic literature review approach, we examined the relationships between ecotourism and mangrove conservation in Southeast Asia based on scientific papers published from 2010 to 2022. Most of the studies were reported in Indonesia, Malaysia, Philippines, Thailand, and Vietnam, respectively, which were associated with the highest number of vibrant mangrove ecotourism sites and largest mangrove areas compared to the other countries of Southeast Asia. Mangrove-related ecotourism activities in the above countries mainly include boat tours, bird and wildlife watching, mangrove planting, kayaking, eating seafood, and snorkeling. The economic benefits, such as an increase in income associated with mangrove ecotourism, have stimulated infrastructural development in ecotourism destinations. Local communities benefited from increased access to social amenities such as clean water, electricity, transportation networks, schools, and health services that are intended to make destinations more attractive to tourists. Economic benefits from mangrove ecotourism motivated the implementation of several community-based mangrove conservation and restoration initiatives, which attracted international financial incentives and public-private partnerships. Since mangroves are mostly located on the land occupied by indigenous people and local communities, ensuring respect for their land rights and equity in economic benefit sharing may increase their intrinsic motivation and participation in mangrove restoration and conservation initiatives. Remote sensing tools for mangrove monitoring, evaluation, and reporting, and integrated education and awareness campaigns can ensure the long-term conservation of mangroves while sustaining ecotourism's economic infrastructure and social amenities benefits.

Transformation of coastal wetlands in the Sundarban Delta (1999-2020).

Spanning across Bangladesh and India, the Sundarban Delta consists of over a thousand islands, the majority of which are protected. These islands are important for the rich biodiversity and unique species found here. However, these islands are also at the forefront of climate change due to the impact of rising sea levels and extreme weather events. Therefore, we analyzed the long-term transformations in the land use land cover (LULC) between 1999 and 2020. We used a variety of geostatistical methods, including optimized hot spots cold spots and join count statistics, to examine the spatial patterns of changes in LULC across the study area. The results of our analysis revealed substantial changes in the spatial patterns of mangroves and pond aquaculture. The changes revealed a distinct north-south demarcation in spatial patterns, in the form of clustering of mangroves in the uninhabited islands located in the south and pond aquaculture clustered in the northern inhabited islands. The loss of area under mangroves was concentrated in the southern edges of the islands, which were most exposed to erosion in the open ocean. Nevertheless, we observed an increase in the area under mangroves in some of the northern riverine islands (17 km2). In the case of pond aquaculture, it was mostly concentrated in inhabited islands in the north. Most of the expansions were concentrated in the Indian part of the delta (631 km2). It is noteworthy that because of effective conservation measures, there was very limited overlap between mangroves and pond aquaculture, denoting the conversion of agricultural land to pond aquaculture instead of mangroves. Thus, the results of our study revealed the importance of local level conservation policies and anthropogenic activities, such as deforestation and local level disturbance like over-extraction of water and pollution, on the changing patterns of LULC across this unique, fragile ecosystem. Future studies may incorporate a finer resolution time series of LULC changes over time and space to enable more detailed analysis.

Role of Nitrifiers Associated with Mangrove clam Polymesoda Erosa in Bioremediation.

Polymesoda erosa is a mangrove clam known for its water filtration ability. This clam was investigated for its bioremediation potential and growth in synthetic wastewater during 40 days of incubation. Variation in the nutrient composition of water, biochemical composition of the clams, and metagenomic analysis of the microorganisms associated with clam tissue were carried out. Significant differences in the concentration of ammonia (p ≤ 0.01), nitrite (p ≤ 0.001), and nitrate (p ≤ 0.05) in the wastewater were observed between day 0 and day 40. A reduction of approximately 89% in ammonia concentration at the end of the experiment was recorded indicating nitrification activity. However, biochemical parameters showed negligible differences before and after the incubation experiment. Thus suggesting that the chemosynthetic-based nutrition aids in the survival of the clam as no organic matter was added to the medium. The substantial decline in levels of ammonia in the presence of clams as compared to its absence suggests the significant role of clams in improving the water quality. Furthermore, the metagenomic analysis of the gill tissue of P. erosa revealed ~ 50% of the microbial population to consist of nitrifiers. The study highlights the contribution by the nitrifers associated with the clams not only to its growth and resilience but also to bioremediation.

Condensed tannin accretions specifically distributed in mesophyll cells of non-salt secretor mangroves help in salt tolerance.

MAIN CONCLUSION: Auto-fluorescent condensed tannins specifically accumulated in mesophyll cells of non-salt secretor mangroves are involved in the compartmentation of Na+ and osmotic regulation, contributing to their salt tolerance. Salinity is a major abiotic stress affecting the distribution and growth of mangrove plants. The salt exclusion mechanism from salt secretor mangrove leaves is quite known; however, salt management strategies in non-salt secretor leaves remain unclear. In this study, we reported the auto-fluorescent inclusions (AFIs) specifically accumulated in mesophyll cells (MCs) of four non-salt secretor mangroves but absent in three salt secretors. The AFIs increased with the leaf development under natural condition, and applied NaCl concentrations applied in the lab. The AFIs in MCs were isolated and identified as condensed tannin accretions (CTAs) using the dye dimethyl-amino-cinnamaldehyde (DMACA), specific for condensed tannin (CT), both in situ leaf cross sections and in the purified AFIs. Fluorescence microscopy and transmission electron microscope (TEM) analysis indicated that the CTAs originated from the inflated chloroplasts. The CTAs had an obvious membrane and could induce changes in shape and fluorescence intensity in hypotonic and hypertonic NaCl solutions, suggesting CTAs might have osmotic regulation ability and play an important role in the osmotic regulation in MCs. The purified CTAs were labeled by the fluorescent sodium-binding benzofuran isophthalate acetoxymethyl ester (SBFI-AM), confirming they were involved in the compartmentation of excess Na+ in MCs. This study provided a new view on the salt resistance-associated strategies in mangroves.

Modeling strategies and data needs for representing coastal wetland vegetation in land surface models.

Vegetated coastal ecosystems sequester carbon rapidly relative to terrestrial ecosystems. Coastal wetlands are poorly represented in land surface models, but work is underway to improve process-based, predictive modeling of these ecosystems. Here, we identify guiding questions, potential simulations, and data needs to make progress in improving representation of vegetation in terrestrial-aquatic interfaces, with a focus on coastal and estuarine ecosystems. We synthesize relevant plant traits and environmental controls on vegetation that influence carbon cycling in coastal ecosystems. We propose that models include separate plant functional types (PFTs) for mangroves, graminoid salt marshes, and succulent salt marshes to adequately represent the variation in aboveground and belowground productivity between common coastal wetland vegetation types. We also discuss the drivers and carbon storage consequences of shifts in dominant PFTs. We suggest several potential approaches to represent the diversity in vegetation tolerance and adaptations to fluctuations in salinity and water level, which drive key gradients in coastal wetland ecosystems. Finally, we discuss data needs for parameterizing and evaluating model implementations of coastal wetland vegetation types and function.

Thermal acclimation of leaf respiration is consistent in tropical and subtropical populations of two mangrove species.

Populations from different climates often show unique growth responses to temperature, reflecting temperature adaptation. Yet, whether populations from different climates differ in physiological temperature acclimation remains unclear. Here, we test whether populations from differing thermal environments exhibit different growth responses to temperature and differences in temperature acclimation of leaf respiration. We grew tropical and subtropical populations of two mangrove species (Avicennia germinans and Rhizophora mangle) under ambient and experimentally warmed conditions in a common garden at the species' northern range limit. We quantified growth and temperature responses of leaf respiration (R) at seven time points over ~10 months. Warming increased productivity of tropical populations more than subtropical populations, reflecting a higher temperature optimum for growth. In both species, R measured at 25 °C declined as seasonal temperatures increased, demonstrating thermal acclimation. Contrary to our expectations, acclimation of R was consistent across populations and temperature treatments. However, populations differed in adjusting the temperature sensitivity of R (Q10) to seasonal temperatures. Following a freeze event, tropical Avicennia showed greater freeze damage than subtropical Avicennia, while both Rhizophora populations appeared equally susceptible. We found evidence of temperature adaptation at the whole-plant scale but little evidence for population differences in thermal acclimation of leaf physiology. Studies that examine potential costs and benefits of thermal acclimation in an evolutionary context may provide new insights into limits of thermal acclimation.

Global mangrove root production, its controls and roles in the blue carbon budget of mangroves.

Mangroves are among the most carbon-dense ecosystems worldwide. Most of the carbon in mangroves is found belowground, and root production might be an important control of carbon accumulation, but has been rarely quantified and understood at the global scale. Here, we determined the global mangrove root production rate and its controls using a systematic review and a recently formalised, spatially explicit mangrove typology framework based on geomorphological settings. We found that global mangrove root production averaged ~770 ± 202 g of dry biomass m-2 year-1 globally, which is much higher than previously reported and close to the root production of the most productive tropical forests. Geomorphological settings exerted marked control over root production together with air temperature and precipitation (r2 ≈ 30%, p < .001). Our review shows that individual global changes (e.g. warming, eutrophication, drought) have antagonist effects on root production, but they have rarely been studied in combination. Based on this newly established root production rate, root-derived carbon might account for most of the total carbon buried in mangroves, and 19 Tg C lost in mangroves each year (e.g. as CO2 ). Inclusion of root production measurements in understudied geomorphological settings (i.e. deltas), regions (Indonesia, South America and Africa) and soil depth (>40 cm), as well as the creation of a mangrove root trait database will push forward our understanding of the global mangrove carbon cycle for now and the future. Overall, this review presents a comprehensive analysis of root production in mangroves, and highlights the central role of root production in the global mangrove carbon budget.

Response of macrophyte litter decomposition in global blue carbon ecosystems to climate change.

Blue carbon ecosystems (BCEs) are important nature-based solutions for climate change-mitigation. However, current debates question the reliability and contribution of BCEs under future climatic-scenarios. The answer to this question depends on ecosystem processes driving carbon-sequestration and -storage, such as primary production and decomposition, and their future rates. We performed a global meta-analysis on litter decomposition rate constants (k) in BCEs and predicted changes in carbon release from 309 studies. The relationships between k and climatic factors were examined by extracting remote-sensing data on air temperature, sea-surface temperature, and precipitation aligning to the decomposition time of each experiment. We constructed global numerical models of litter decomposition to forecast k and carbon release under different scenarios. The current k averages at 27 ± 3 × 10-2 day-1 for macroalgae were higher than for seagrasses (1.7 ± 0.2 × 10-2 day-1 ), mangroves (1.6 ± 0.1 × 10-2 day-1 ) and tidal marshes (5.9 ± 0.5 × 10-3 day-1 ). Macrophyte k increased with both air temperature and precipitation in intertidal BCEs and with sea surface temperature for subtidal seagrasses. Above a temperature threshold for vascular plant litter at ~25°C and ~20°C for macroalgae, k drastically increased with increasing temperature. However, the direct effect of high temperatures on k are obscured by other factors in field experiments compared with laboratory experiments. We defined "fundamental" and "realized" temperature response to explain this effect. Based on relationships for realized temperature response, we predict that proportions of decomposed litter will increase by 0.9%-5% and 4.7%-28.8% by 2100 under low- (2°C) and high-warming conditions (4°C) compared to 2020, respectively. Net litter carbon sinks in BCEs will increase due to higher increase in litter C production than in decomposition by 2100 compared to 2020 under RCP 8.5. We highlight that BCEs will play an increasingly important role in future climate change-mitigation. Our findings can be leveraged for blue carbon accounting under future climate change scenarios.

Sustained mangrove reproduction despite major turnover in pollinator community composition at expanding range edge.

BACKGROUND AND AIMS: How well plants reproduce near their geographic range edge can determine whether distributions will shift in response to changing climate. Reproduction at the range edge can be limiting if pollinator scarcity leads to pollen limitation, or if abiotic stressors affect allocation to reproduction. For many animal-pollinated plants with expanding ranges, the mechanisms by which they have overcome these barriers are poorly understood. METHODS: In this study, we examined plant-pollinator interactions hypothesized to impact reproduction of the black mangrove, Avicennia germinans, which is expanding northward in coastal Florida, USA. We monitored insects visiting A. germinans populations varying in proximity to the geographic range edge, measured the pollen loads of the most common insect taxa and pollen receipt by A. germinans stigmas, and quantified flower and propagule production. KEY RESULTS: We found that despite an 84 % decline in median floral visits by insects at northernmost versus southernmost sites, range-edge pollen receipt remained high. Notably, local floral visitor assemblages exhibited substantial turnover along the study's latitudinal gradient, with large-bodied bees and hover flies increasingly common at northern sites. We also observed elevated flower production in northern populations and higher per capita reproductive output at the range edge. Furthermore, mean propagule mass in northern populations was 18 % larger than that from the southernmost populations. CONCLUSIONS: These findings reveal no erosion of fecundity in A. germinans populations at range limits, allowing rapid expansion of mangrove cover in the region. These results also illustrate that substantial turnover in the assemblage of flower-visiting insects can occur at an expanding range edge without altering pollen receipt.

Pseudodonghicola flavimaris sp. nov. and Sedimentitalea xiamensis sp. nov., two novel species belonging to the family Roseobacteraceae.

Two Gram-stain-negative, chemoheterotrophic, aerobic bacteria, designated IC7T and JM2-8T, were isolated from seawater of the Yellow Sea of China and rhizosphere soil of mangroves in Xiamen, Fujian, respectively. Phylogenetic analyses based on 16S rRNA gene and genome sequences showed that these two novel strains belonged to the family Roseobacteraceae. Strain IC7T formed a coherent lineage within the genus Pseudodonghicola, showing 98.05 % 16S rRNA gene sequence similarity to Pseudodonghicola xiamenensis Y-2T. Strain JM2-8T was most closely related to members of the genus Sedimentitalea, showing 96.51 and 96.73 % 16S rRNA gene sequence similarities to Sedimentitalea nanhaiensis NH52FT and Sedimentitalea todarodis KHS03T, respectively. The two novel strains contained Q-10 as the major quinone, and phosphatidylethanolamine, aminophospholipid, phosphatidylglycerol and phosphatidylcholine as the principal polar lipids. The main fatty acid of strain IC7T was C19 : 0 cyclo ω8c, while the fatty acid profile JM2-8T was dominated by summed feature 8 containing C18 : 1 ω7c and/or C18 : 1 ω6c. The average nucleotide identity and digital DNA-DNA hybridization values between these two novel isolates and their closely related species were below the cut-off values of 95-96 and 70 %, respectively. The combined genotypic and phenotypic data show that strain IC7T represents a novel species of the genus Pseudodonghicola, for which the name Pseudodonghicola flavimaris sp. nov. is proposed, with the type strain IC7T (=MCCC 1A02763T=KCTC 82844T), and strain JM2-8T represents a novel species of the genus Sedimentitalea, for which the name Sedimentitalea xiamensis sp. nov. is proposed, with the type strain JM2-8T (=MCCC 1A17756T=KCTC 82846T).

Spatiotemporal response of water quality in fragmented mangroves to anthropogenic activities and recommendations for restoration.

Mangroves have received substantial attention for their pivotal role as ecological barriers between land and sea, owing to their capacity to effectively capture considerable quantities of terrestrial pollutants. Mangrove fragmentation has been a widespread global trend. There is limited information on the water quality status of these small scattered mangrove patches in coastal sub-developed areas, coupled with a paucity of efficient and intuitive assessment methodologies. To address this gap, the Water Quality Index (WQI) was introduced to evaluate the spatiotemporal characteristics of mangrove water quality. The major sources of pollution and anthropogenic activities that affect mangrove water quality were identified. The results revealed an average WQI value of 44.1 ± 13.3 for mangrove patches, consistently indicating a "low" water quality classification throughout all seasons. Both the size and natural conditions impact the water quality of mangroves. The large artificial patch (WQI: 56.4 ± 7.61) and the natural patch (WQI: 46.6 ± 13.6) exhibited relatively superior water quality, while the WQI value of a size-equivalent artificial patch compared with the natural patch is 38.6 ± 11.8. Aquaculture was the primary human activity that adversely affected the water quality of mangroves, and the potential sources of pollution were rainfall runoff and river discharge. These findings elucidate the unfavorable water quality characteristics and dominant pollution of fragmented mangroves, and validate the applicability of the WQI method for long-term evaluation of the water quality in mangrove patches. This study provides a basis for decision-making in water quality assessment and management of coastal wetlands and marine ecosystems. Scientific guidance to the management for mangrove protection and restoration was offered, such as regulating aquaculture activities, controlling non-point source pollution, implementing mangrove reforestation by using native species in historical mangrove sites.