Search Results (262)

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. Full article

Heavy metal pollution threatens coastal ecosystems. Mangrove sediments, as transitional zones, are prone to contaminant accumulation. This study investigated eight heavy metals (Cu, Pb, Ni, As, Cr, Zn, Cd, Co) in Liusha Bay (Leizhou Peninsula, China). Field sampling, lab analysis, and multivariate statistics were used to assess pollution sources and ecological risks. The results show Al and Fe dominate sediment composition, with elevated P, Mn, and Sr. Arsenic (As) exhibiting the highest pollution severity (50% sites moderately contaminated by I_geo). Enrichment factors (EF) indicate anthropogenic contributions to As, Cu, Ni, and Co, while Cd and Pb originate mainly from natural sources. Ecological risk assessments highlight moderate risks for As and Cd at some sites. Source analysis identifies three dominant pathways: (1) lithogenic inputs (volcanic rock weathering) contributing Fe, Zn, Cr, and Ni; (2) biogenic materials (calcium carbonate-secreting organisms) influencing Cu, Mn, and Cd; and (3) anthropogenic activities (aquaculture, maritime traffic) linked to Cu and Pb. This study emphasizes localized monitoring of As and Cd in mangroves and calls for the integrated management of natural and anthropogenic drivers to mitigate pollution risks. Full article

Mangrove forests provide critical ecosystem services, including carbon sequestration, shoreline protection, and serving as a food resource for coastal communities. However, these ecosystems face increasing environmental risks due to industrial and urban pollution, particularly contamination by heavy metals. This study assessed environmental quality in mangrove areas of Babitonga Bay, southern Brazil, using biomonitoring with the oyster Crassostrea rhizophorae and the mangrove tree Laguncularia racemosa. Sediment analyses revealed significantly elevated concentrations of copper, nickel, aluminum, and iron in Vila da Glória compared to Espinheiros, exceeding Brazilian environmental guidelines for copper and zinc. Biomonitoring results indicated high accumulation of arsenic and zinc in L. racemosa leaves, while oysters from Espinheiros exhibited higher concentrations of multiple heavy metals and smaller anatomical dimensions compared to those from Vila da Glória. Strong negative correlations were found between metal concentrations in oyster tissues and sediments, suggesting complex bioavailability dynamics. The study demonstrates the applicability of C. rhizophorae and L. racemosa as possible bioindicators of metal contamination in mangrove ecosystems. These findings underscore the importance of integrating biomonitoring approaches into coastal environmental health assessments to inform public health policies and conservation strategies aimed at promoting balanced ecosystem and human health. Full article

Fungi of the genus Parengyodontium (Ascomycota, Hypocreales, Cordycipitaceae) are emerging as promising sources of secondary metabolites with significant biotechnological potential. While traditionally understudied, species such as Parengyodontium album, Parengyodontium torokii and Parengyodontium americanum have been isolated from diverse and sometimes extreme environments—including deep-sea sediments, mangroves, and NASA clean rooms—suggesting remarkable ecological adaptability. This review presents a comprehensive synthesis of current knowledge on the chemical diversity, biological activities, and potential industrial applications of secondary metabolites produced by fungi belonging to the genus. A wide variety of compounds have been identified, including polyketides (e.g., engyodontiumones, alternaphenol B2), terpenoids (e.g., cytochalasin K), alkaloids, and torrubielline derivatives. These metabolites exhibit cytotoxic, antibacterial, and antifouling properties, with promising anticancer and antimicrobial activities. In addition, recent evidence points to the genus’s role in bioremediation, particularly through the degradation of polyethylene by P. album. Despite the advances highlighted here, challenges remain in scaling production, elucidating biosynthetic pathways, and confirming in vivo efficacy. This review underscores the value of integrating chemical, genomic, and metabolomic approaches to fully unlock the biotechnological potential of Parengyodontium species. Additionally, we broaden the perspective by comparing trends in secondary metabolites among Cordycipitaceae, highlighting lifestyle-related chemical compounds that serve as a reference for the Parengyodontium profile. Full article

Antimicrobial resistance (AMR) poses a major global threat to human health. Among multidrug-resistant pathogens, MRSA is a leading cause of severe nosocomial infections, urgently demanding the discovery of novel antimicrobial agents. Nature, particularly Actinomycetota, remains a prolific source of potent bioactive compounds to combat pathogens. This review analyzes recent advancements in anti-MRSA compounds from Actinomycetota. We highlight the most promising bioactive metabolites, their sources, mechanisms of action, and current limitations. Our analysis identified numerous compounds with potent activity against MRSA, including chromomycins, actinomycins, diperamycin, lunaemycin A, lactoquinomycin A, and weddellamycin, which exhibit submicromolar minimal inhibitory concentrations (MICs). The renewed interest in exploring Actinomycetota de novo is directly driven by the AMR crisis. Furthermore, bioprospecting efforts in underexplored ecological niches, such as mangroves and marine sediments, have proven highly promising, as these habitats often harbour unique microbial communities producing novel metabolites. These findings underscore the critical importance of ecology-driven drug discovery in expanding the antimicrobial arsenal and effectively addressing the global health challenge of MRSA and other resistant pathogens. Full article

Pakistan’s coastline encompasses the Indus Delta, a critical ecosystem that sustains biodiversity, fisheries, and local livelihoods, yet it is increasingly threatened by both natural and anthropogenic pressures. This study quantifies multi-decadal shoreline changes in the Indus Delta and examines how changes in climatic factors (precipitation and wind) affect these changes, using the Digital Shoreline Analysis System (DSAS v5.1) and multi-temporal Landsat imagery (TM, ETM+, OLI) to quantify long-term shoreline dynamics from 1990 to 2020 (30-year period). Key metrics, including End Point Rate (EPR), Net Shoreline Movement (NSM), and Linear Regression Rate (LRR), indicated an overall retreat, with a mean NSM of −1810 m and a mean LRR of −173 m·year across the 30-year period. Shoreline change rates exhibited a significant relationship with climatic variables, particularly wind speed and precipitation, with dynamics shifting from erosion-dominated to localized accretion in areas where mangrove rehabilitation programs were implemented after 2005. Seasonal variability further influenced shoreline behavior: low-rainfall years intensified erosion due to reduced sediment availability, while high-rainfall years enhanced accretion through increased sediment input. These findings underscore the urgent need for integrated coastal management strategies, including mangrove conservation, sustainable sediment management, and climate-adaptive planning, to strengthen the resilience of the Indus Delta. Full article

Marine Aspergillus fungi, adapted to extreme marine environments (e.g., sediments, corals, mangroves), are prolific producers of structurally diverse secondary metabolites with significant bioactivities. This review comprehensively analyzes 340 novel natural products reported from 81 marine-derived Aspergillus strains over the past three years, classifying them into six major categories: alkaloids (31.2%), polyketides (29.4%), terpenoids, lignans, cyclopeptides, and others. Bioactivity assessments reveal broad therapeutic potential, including antitumor, antimicrobial, anti-inflammatory, and antiviral effects. Notably, marine sediments constitute the primary source (25.9% of strains), followed by sponges and corals. The predominance of alkaloids and polyketides underscores their pharmacological relevance. These findings highlight marine Aspergillus as a critical resource for drug discovery, offering promising scaffolds for developing treatments against human diseases and agricultural pathogens. Full article

Background: Mangrove ecosystems are critical coastal environments providing ecological services and acting as buffers between terrestrial and marine systems. Rising antibiotic use in aquaculture and coastal agriculture has led to the dissemination of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in these habitats. Aim: This narrative review aims to synthesize current knowledge on the prevalence, diversity, and environmental drivers of ARGs in mangrove ecosystems, highlighting their role as reservoirs and the potential for horizontal gene transfer. Methods: Studies published up to September 2024 were identified through PubMed, Scopus, Web of Science, and Google Scholar. Inclusion criteria focused on ARGs and ARB in mangrove sediments, water, and associated biota. Data on ARG prevalence, microbial community composition, detection methods, and environmental factors were extracted and narratively synthesized. Results: Seventeen studies from Asia, South America, and Africa were included. ARGs conferring resistance to tetracyclines, sulfonamides, β-lactams, and multidrug resistance were found to be widespread, particularly near aquaculture and urban-influenced areas. Metagenomic analyses revealed diverse resistomes with frequent mobile genetic elements, indicating high potential for horizontal gene transfer. Environmental factors, including sediment type, organic matter, and salinity, influenced ARG abundance and distribution. Conclusions: Mangrove ecosystems act as both reservoirs and natural buffers for ARGs. Sustainable aquaculture practices, continuous environmental monitoring, and integrated One Health approaches are essential to mitigate ARG dissemination in these sensitive coastal habitats. Full article

Modern agriculture faces critical challenges from soil degradation and excessive use of chemical fertilizers, threatening sustainable seed germination and crop establishment. The main objective of this research was to evaluate the feasibility of using Pseudomonas spp. isolated from Colombian mangrove sediments as biofertilizers to enhance crop productivity, with an emphasis on Lactuca sativa (lettuce) seed-to-seedling transition. Fifty-eight isolates were characterized and screened for their ability to improve the germination of the lettuce seeds, but only nine strains showed promising activity. The strains were identified at the species level and screened for Plant growth-promoting rhizobacteria (PGPR) traits such as indole-3-acetic acid (IAA) production, phosphate solubilization, organic acid production, and salt tolerance (5%). Four different species were identified, namely Pseudomonas putida (one strain), Pseudomonas monteiilli (two strains), Pseudomonas taiwanensis (one strain), and Pseudomonas aeruginosa (four strains). P. aeruginosa strains P8 and P9 demonstrated exceptional performance, significantly improving root elongation, seedling biomass, and antioxidant activity compared with the uninoculated plants in vitro. These strains showed dual agrobiotechnological value: (i) enhancing early seedling vigor through hormonal stimulation and (ii) improving nutrient availability via phosphate solubilization. Our findings highlight the biotechnological potential of mangrove-associated Pseudomonas spp. as a sustainable alternative to chemical fertilizers, particularly for seed priming and seedling establishment systems in stress-prone soils. Full article

Glycerol Dialkyl Glycerol Tetraethers (GDGTs) are microbial membrane lipids that can provide crucial information for identifying organic carbon sources and understanding paleoenvironments. Despite numerous studies reporting the presence of GDGTs in various terrestrial and marine environments, there is a paucity of reports concerning GDGTs in mangrove wetlands that are characterized by unique hydrological conditions and disproportionately high accumulation rates of blue carbon (i.e., carbon sequestered in coastal ecosystems, where tidal flooding and anaerobic sediments facilitate exceptional long-term carbon storage). This study investigates GDGTs in 81 sediment samples from 5 sediment cores collected from three Asian mangrove wetlands in Bangladesh, Hong Kong, and Guangxi Province, China. The Hong Kong mangrove sediments had the highest GDGT concentration (370.18 ± 58.00 ng·g⁻¹ dws), followed by Bangladesh mangrove sediments (136.70 ± 41.70 ng·g⁻¹ dws), while Guangxi mangrove sediments had the lowest (100.80 ± 28.71 ng·g⁻¹ dws). All samples demonstrated high BIT index values (>0.8), low IIIa/IIa index values (0.09–0.19) and the predominance of tetramethylated brGDGTs (70.38 ± 2.21%), indicating that terrestrial inputs are the primary source of organic carbon. Despite overall low methylation index (MI) values (0.15–0.35) and GDGT-0/Cren ratios, deeper sediment samples in the lower part of HK exhibited GDGT-0/Cren > 2, likely reflecting enhanced contributions of methanogenic archaea under distinct redox conditions compared to upper sediments. This in situ production may complicate the application of GDGT-based paleo-proxies, as indicated by the substantial deviations between CBT’-pH (MBT’_5ME-temperature) and measured pH (instrumental temperature). The dominant bacterial phyla in the mangrove sediments of Guangxi and Bangladesh were Proteobacteria, Actinobacteriota, Chloroflexi, Acidobacteriota, and Firmicutes (>70% relative abundance). However, correlations between microbial community compositions and brGDGT isomers are different among sampling sites. Our study emphasizes that site- and depth-specific microbial activity may significantly contribute to organic matter cycling and the in situ production of GDGTs in mangrove sediments. These factors should be taken into account for organic carbon sequestration and the validity of GDGT-based paleo-proxies in mangrove wetlands. Full article

Mangrove ecosystems play a critical role in climate regulation, carbon sequestration, and pollution mitigation. However, their long-term resilience to accelerating sea-level rise (SLR) under global climate change scenarios remains uncertain. Vertical soil accretion is a critical factor in determining the vulnerability of mangrove wetlands to SLR. In this study, vertical soil accretion rates in a mangrove wetland in the Beilun estuary were measured using a ²¹⁰Pbex dating method. Based on recently acquired data and previously available data, we conducted the first systematic assessment of SLR risk in mangrove wetlands in the Guangxi coastal zone in the context of increasing global climate change and extreme weather. The results show that the vertical soil accretion rate of 6.72 ± 1.91 (4.22–10.54) mm/a in the Beilun estuary is slightly higher than SLR rate in the Guangxi coastal zone. Concurrently, our results indicate that mangroves with thriving root systems enhance soil accretion through biotic controls in the Beilun estuary, while significant changes in soil sources and hydrodynamic forces during the 1980s and 2000s contributed to adaptation to SLR. Additionally, by linking sedimentation dynamics with SLR projections, we reveal that current accretion rates in some mangrove areas in the Guangxi coastal zone are insufficient to offset the projected SLR by the end of 2050 and 2100. This finding offers a new perspective on the traditional assumption of inherent resilience in mangroves while revealing the adaptive capacity of mangroves in the Beilun estuary and Guangxi coastal zone under projected SLR scenarios. It underscores the need for integrated management strategies that balance sediment supply maintenance and ecological restoration, which are critical to ensuring the long-term resilience of mangrove ecosystems, in line with sustainability principles. Full article

MPs are pervasive pollutants in marine ecosystems, posing risks to aquatic organisms due to their small size and bioaccumulation potential. This study investigated the intestinal toxicity of MP particles extracted from mangrove sediments in zebrafish, comparing the effects before and after microbial degradation. Zebrafish were exposed to either undegraded MPs or microbially degraded MP extracts at concentrations of 0 (control), 2, 10, and 50 mg/L for 21 days in 10 L tanks (stocking density: 10 fish/L), with three replicate tanks per concentration. MPs were dispersed ultrasonically before addition to the water. Intestinal samples were collected on 7, 14, and 21 days for the analysis of immune response (tumor necrosis factor-alpha, TNF-α; interleukin-1 beta, IL-1β; interleukin-6, IL-6; interleukin-8, IL-8) and antioxidant activity (superoxide dismutase, SOD; catalase, CAT). Histopathological analysis revealed intestinal wall thinning, villus damage, and epithelial cell detachment in zebrafish exposed to both undegraded and degraded MP extracts; however, undegraded MPs induced more severe intestinal damage. Results indicated dynamic changes in cytokine expression: TNF-α decreased initially before increasing, while IL-1β and IL-8 first rose then declined. IL-6 peaked on day 7, dropped by day 14, and increased again on day 21. CAT expression decreased, whereas SOD increased only in the pre-degradation group. Microbial degradation reduced intestinal damage severity, with effects intensifying at higher MP exposure levels. These findings demonstrate that MPs can impair zebrafish digestive systems, but microbial degradation mitigates their toxicity. This study underscores the importance of biodegradation as a potential environmental remediation strategy and provides experimental evidence on MPs’ impact on aquatic organisms. Full article

This study characterized the spatial distribution and assessed the ecological risks of carbon, nitrogen, and phosphorus in sediments of the Dongzhai Harbor mangrove wetland, Hainan, China. Analysis of key environmental indicators (grain size, pH, TOC, TN, TP) across twenty-seven sediment cores (0–100 cm depth) revealed distinct decreasing land–sea gradients and vertical stratification of nutrient concentrations. Mangrove plant debris was identified as the primary source of sedimentary organic matter. Elemental ratio analysis indicated terrestrial inputs as the dominant phosphorus source. Significant positive correlations between TOC, TN, and TP in surface sediments suggested coupled nutrient dynamics. Vertical distribution of C/N to C/P ratios increased with depth, which may be related to increased nitrogen and phosphorus inputs due to regional human activities. Pollution assessment showed significantly higher ecological risks in surface sediments (0–50 cm), particularly near inland areas and dense mangroves, indicating co-regulation by vegetation processes and human impacts. These findings highlight significant spatial heterogeneity in ecological risks, underscoring the need for enhanced monitoring and targeted management strategies in critical land–sea transition zones. Full article

A new trinor-sesterterpenoid penitalarin D (1), with a 3,6-dioxabicyclo[3.1.0]hexane moiety, as well as two known compounds, penitalarin C (2) and nafuredin A (3), were obtained from the mangrove sediment-derived Talaromyces sp. SCSIO 41412. Their structures were determined by detailed NMR, MS spectroscopic analyses, and ECD calculations. Penitalarin D (1) and nafuredin A (3) showed toxicity or no toxicity against HepG2 cells at a concentration of 200 μM. The transcriptome sequencing and bioinformatics analysis revealed that 3 could be effective by regulating ferroptosis pathways in HepG2 cells, which was subsequently validated by RT-qPCR, demonstrating significant upregulation of ferroptosis-related genes. Pre-treatment with 3 could mitigate hypoxia-reoxygenation-induced damage in the oxygen glucose deprivation/reperfusion (OGD/R) cell model. Given the structural similarity of compounds 1, 2, and 3, we also screened compounds 1 and 2 in an AML12 OGD/R model. As no significant activity was observed, compound 3 was selected for subsequent in vivo studies. Subsequently, in vivo experiments demonstrated that 3 could significantly decrease pro-inflammatory cytokines and display the hepatoprotective effects against hepatic ischemia-reperfusion injury (HIRI). These findings identified nafuredin A (3) as a promising hepatoprotective agent for new drug development. Full article

The present study quantifies mercury (Hg) concentrations in mangrove oysters (Crassostrea rhizophorae) and assesses their potential as biomonitors of Hg contamination in the Parnaíba River Delta (PRD), located on the equatorial coast of Brazil (ECB). The highest Hg concentrations occurred in the smallest individuals’ size class (20–40 mm) from the main channel of the Parnaíba River (52.1 to 195.4 ng g⁻¹ w.w.), whereas the largest individuals’ size class (larger than 60 mm) exhibited the lowest Hg concentrations (35.2–114 ng g⁻¹ w.w.). There was a significant correlation between Hg concentrations and shell sizes, either when considering all size classes or when considering only individuals of size classes smaller than 40 mm. Oysters larger than 40 mm did not present any significant correlation between Hg concentrations and size. In addition to size, higher concentrations were observed at the freshwater–seawater transition in the main channel sites. These maximum suspended particulate zones, with bottom sediment resuspension, can favor Hg adsorption to fine particles, increasing the bioavailability of Hg. A regional comparison of Hg concentrations in mangrove oysters from the ECB suggests they are efficient biomonitors at a regional level. In contrast, the environmental dynamics of the PRD, with high variability within sites, hampered its use at the local level. Mangrove oysters from the PRD are shown to be safe for human consumption, as far as Hg exposure is concerned, and the presented risk assessment shows no excessive exposure, even at high-frequency consumption rates. Full article