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A spatiotemporal framework to assess the bio-geomorphic interplay of saltmarsh vegetation and tidal emergence (Western Scheldt estuary)
No full textSea level changes will significantly drive hydrodynamic, morphological, and ecological development of estuaries. However, the interplay of geomorphology and vegetation at estuary scales remains unclear. To better understand this process, we take the Western Scheldt estuary in the Netherlands as an example to reveal the link between changes in emersion duration and vegetation dynamics in the period 1993–2016. We found that tidal flats in the Western Scheldt become steeper—higher intertidal areas increased in elevation and emersion duration, whereas the low-lying edges of tidal flats experienced a decrease in elevation and emersion duration. We found that longer emersion duration was associated with increased plant diversity and cover. Furthermore, we detected the unique spatiotemporal response patterns of four abundant plant species to geomorphological variations. Our study suggests that on a large estuary scale, geomorphological changes are coupled to the richness and cover of plant communities, and that potential changes in relative sea level can induce structural modifications of the plant communities. It also emphasizes the importance of assessing the potential effects of localized relative sea level changes while considering all aspects of natural processes and direct and indirect human influences. Our study provides a framework to assess the bio-geomorphic processes in a spatially explicit way.</span
Large-scale sampling of potential breeding sites in male ruffs
No full textThe traditional narrative of the life cycle of migratory birds is that individuals perform long-distance movements between a breeding and a wintering site, but are largely resident at those sites. Although this pattern may apply to socially monogamous species with biparental care, in polygamous systems, the sex that only provides gametes may benefit from continuing to move and sample several potential breeding sites during a single breeding season. Such behaviour would blur the distinction between migration and breeding. We used satellite telemetry to study movements during the breeding season of males of the ruff Calidris pugnax, a lekking wader with a polygynous mating system and female-only parental care. Ruffs have a unique life-history, with three distinct genetically determined male mating strategies: aggressive ‘independents’, submissive ‘satellites’, and female-mimicking ‘faeders’. Within the breeding season, ruff males visited up to 23 sites (median: 11) and travelled up to 9029 km (median: 4435 km) covering a considerable part of their known breeding range. All three male morphs displayed breeding site sampling, indicating that they might gain similar benefits from this behaviour. Our findings suggest that large-scale breeding range sampling may be a common feature of migratory species with female-only care and strong male-male competition.</span
Biofilm formation, modulation, and transcriptomic regulation under stress conditions in halomicronema sp.
No full textIn nature, bacteria often form heterogeneous communities enclosed in a complex matrix known as biofilms. This extracellular matrix, produced by the microorganisms themselves, serves as the first barrier between the cells and the environment. It is composed mainly of water, extracellular polymeric substances (EPS), lipids, proteins, and DNA. Cyanobacteria form biofilms and have unique characteristics such as oxygenic photosynthesis, nitrogen fixation, excellent adaptability to various abiotic stress conditions, and the ability to secrete a variety of metabolites and hormones. This work focused on the characterization of the cyanobacterium Halomicronema sp. strain isolated from a brackish environment. This study included microscopic imaging, determination of phenolic content and antioxidant capacity, identification of chemicals interfering with biofilm formation, and transcriptomic analysis by RNA sequencing and real-time PCR. Gene expression analysis was centered on genes related to the production of EPS and biofilm-related transcription factors. This study led to the identification of wza1 and wzt as EPS biomarkers and luxR-05665, along with genes belonging to the TetR/AcrR and LysR families, as potential biomarkers useful for studying and monitoring biofilm formation under different environmental conditions. Moreover, this work revealed that Halomicronema sp. can grow even in the presence of strong abiotic stresses, such as high salt, and has good antioxidant properties.</span
Assessing the success of marine ecosystem restoration using meta-analysis
No full textMarine ecosystem restoration success stories are needed to incentivize society and private enterprises to build capacity and stimulate investments. Yet, we still must demonstrate that restoration efforts can effectively contribute to achieving the targets set by the UN Decade on Ecosystem Restoration. Here, we conduct a meta-analysis on 764 active restoration interventions across a wide range of marine habitats worldwide. We show that marine ecosystem restorations have an average success of ~64% and that they are: viable for a large variety of marine habitats, including deep-sea ecosystems; highly successful for saltmarshes, tropical coral reefs and habitat-forming species such as animal forests; successful at all spatial scales, so that restoration over large spatial scales can be done using multiple interventions at small-spatial scales that better represent the natural variability, and scalable through dedicated policies, regulations, and financing instruments. Restoration interventions were surprisingly effective even in areas where human impacts persisted, demonstrating that successful restorations can be initiated before all stressors have been removed. These results demonstrate the immediate feasibility of a global ‘blue restoration’ plan even for deep-sea ecosystems, enabled by increasing availability of new and cost-effective technologies
Discovering hidden archaeal and bacterial lipid producers in a euxinic marine system
No full textBacterial membrane lipids are typically characterised by fatty acid bilayers linked through ester bonds, whereas those of Archaea are characterised by ether-linked isoprenoids forming bilayers or monolayers of membrane-spanning lipids known as isopre?noidal glycerol dialkyl glycerol tetraethers (isoGDGTs). However, this understanding has been reconsidered with the identifica?tion of branched GDGTs (brGDGTs), which are membrane-spanning ether-bound branched alkyl fatty acids of bacterial origin, though their producers are often unidentified. The limited availability of microbial cultures constrains the understanding of the biological sources of these membrane lipids, thus limiting their use as biomarkers. To address this issue, we identified membrane lipids in the Black Sea using high-resolution accurate mass/mass spectrometry and inferred their potential producers by targeting lipid biosynthetic pathways encoded on the metagenome, in metagenome-assembled genomes and unbinned scaffolds. We also identified brGDGTs and highly branched GDGTs in the suboxic and euxinic waters, potentially attributed to Planctomycetota, Cloacimonadota, Desulfobacterota, Chloroflexota, Actinobacteria and Myxococcota—based on their lipid biosynthetic genomic potential. These findings introduce new possibilities for using specific brGDGTs as biomarkers of anoxic conditions in marine environments and highlight the role of these membrane lipids in microbial adaptation
Marine fungal enzymes as potential degraders of the diverse seaweed cell-walls
No full textMarine fungi play a critical yet understudied role in marine ecosystems, contributing to microbial diversity and ecological balance through their interactions with seaweed and other organisms. These interactions are essential for nutrient cycling and maintaining ecosystem health. While the carbohydrate-active enzymes (CAZymes) of terrestrial fungi are well-documented for plant biomass degradation, the enzymatic capabilities of marine fungi, specifically for degrading seaweed biomass, remain less explored. The distinct sugar composition of seaweed has likely shaped the CAZome of marine fungi, specifically in activities targeting seaweed cell wall polysaccharides. This review focuses on the potential of marine fungal CAZymes as biocatalysts for the degradation of seaweed cell wall polysaccharides. We provide a detailed examination of the unique sugar composition of seaweed cell walls, such as alginates, fucoidans, and carrageenans, and analyze the putative CAZy abilities of marine fungi to target these structures. A better understanding of marine fungal enzymatic processes could unlock sustainable strategies for extracting valuable compounds, such as proteins and nutraceuticals, from seaweed biomass, while enabling the comprehensive valorization of all biomass fractions within a biorefinery framework. By summarizing current knowledge and identifying research gaps, this review highlights the untapped potential of marine fungi as key agents in the development of efficient, integrated seaweed biorefineries.</span
Unravelling mangrove storm damage resistance for sustainable flood defense safety using 3D-printed mimics
No full textMangrove forests are vital for flood reduction, yet their failure mechanisms during storms are poorly known, hampering their integration into engineered coastal protection. In this paper, we aimed to unravel the relationship between the resistance of mangrove trees to overturning and root distribution and the properties of the soil, while avoiding damage to natural mangrove forests. We therefore (i) tested the stability of 3D-printed tree mimics that imitate typical shallow mangrove root systems, mimicking both damaged and intact root systems, in sediments representing the soil properties of contrasting mangrove sites, and subsequently (ii) tested if the existing stability models for terrestrial trees are applicable for mangrove tree species, which have unique shallow root systems to survive waterlogged soils. Root systems of different complexities were modeled after Avicennia alba, Avicennia germinans, and Rhizophora stylosa, and printed at a 1:100 scale using material densities matching those of natural tree roots, to ensure the geometric scaling of overturning moments. The mimic stability increased with the soil shear strength and root plate surface area. The optimal root configuration for mimic stability depended on the sediment properties: spreading root systems performed better in softer sediments, while concentrating root biomass near the trunk improved stability in stronger sediments. An adapted terrestrial tree resistance model reproduced our measurements well, suggesting that such models could be adapted to predict the stability of shallow-rooted mangroves living in waterlogged soils. Field tree-pulling experiments are needed to further confirm our conclusions with real-world data, examine complicating factors like root intertwining, and consider mangrove tree properties like aerial roots. Overall, this work establishes a foundation for incorporating mangrove storm damage into hybrid coastal protection systems.</span
Effect of upscaling nature‐based coastal protection on estuarine biodiversity using foreshores and transitional polders
No full textNature-based solutions (NbS), integrating ecosystems and natural processes, offer a promising approach to deliver benefits to both ecosystems and human society. In estuarine and coastal regions, highly vulnerable to storm surges and large wave exposures, NbS schemes are often primarily evaluated for flood risk. Comprehensive assessments of their broader impacts on biodiversity are frequently overlooked.This study presents an integrated modelling approach to compare the long-term estuarine biodiversity outcomes of two nature-based coastal protection schemes: (i) a seaward foreshore and (ii) a landward transitional polder (i.e. a temporary de-embankment). These schemes involve the creation of coastal wetlands, each subjected to different environmental and landscape settings. We also assess the influence of sea-level rise (SLR), sediment availability (i.e. suspended sediment concentration; SSC) and initial elevation on the temporal development of intertidal biodiversity, focusing on macrozoobenthos and tidal marsh vegetation.The findings demonstrate that the effectiveness of different NbS schemes in enhancing biodiversity is strongly dependent on the initial environmental conditions and, consequently, on how the NbS is integrated into the landscape. In accreting environments, existing sloped foreshores facilitate rapid vegetation establishment and development, while initially flatter, lower-elevation transitional polders better support benthic biodiversity. However, flat transitional polders initiated at elevations above mean sea level rapidly become dominated by vegetation, reducing their benefits to benthos.Over time, biodiversity outcomes in two schemes gradually converge as accretion progresses. SLR and SSC are key factors influencing the temporal development of biodiversity and scheme comparison. Higher SSC levels accelerate convergence, while SLR decelerates it.Synthesis and applications. Our study provides a critical toolset for designing, comparing and planning nature-based solutions with respect to biodiversity effects, supporting coastal management strategies that integrate flood safety with optimal biodiversity outcomes. By considering the distinct biodiversity trajectories of different nature-based solutions schemes—shaped by sea-level rise and suspended sediment concentration—we highlight time-sensitive trade-offs and long-term ecosystem developments. These insights are particularly relevant given practical constraints, such as hydrodynamic challenges for seaward foreshores and societal resistance to land-use changes for transitional polders. This study facilitates informed decision-making for sustainable and adaptive coastal management.</ol
Warming alters non-trophic interactions in soft bottom habitats
No full textThough there is mounting evidence that climate warming is altering trophic interactions between organisms, its effects on non-trophic interactions remain relatively undocumented. In seagrass systems, the bioturbating activity of infauna influences annual seagrass patch development by influencing seed burial depth and germination success as well as sediment properties. If bioturbation is altered by warming, consequences on seagrass may result. Here, we assessed how heatwaves alter seagrass seed burial depth and germination rates when no bioturbators (control), single bioturbators and mixtures of bioturbators of contrasting feeding activities are present. The three bioturbators manipulated were surface (top 1-2 cm of sediment) biodiffusor, the brown shrimp (Crangon crangon), the shallow (top 3–8 cm) diffusor, the common cockle, (Cerastoderma edule) and the upward (5–15 cm) conveyor, the polychaete, Cappitellidae spp. We applied two temperature treatments: (1) a present-day scenario set at the average summer temperature of seagrass habitat (17ºC); and (2) a heatwave scenario modelled on the maximum recorded temperature (26.6ºC). Under present-day conditions, seed burial was greater in the presence of bioturbators than the control where no infauna was added (42–74% vs. 33 ± 7%, respectively). Cockles had the greatest impact on seed burial amongst all the bioturbators. Under the heatwave scenario, seed burial in the mixed bioturbator treatment increased to match that of the cockle treatment. Cockles and polychaetes elevated the germination rates of buried seeds under present-day temperature, but not under the heatwave scenario. Overall, these results indicate that heatwaves have the potential both to amplify and disrupt non-trophic interactions, with implications for seagrass seed germination.</span
There and back again; on dinoflagellate cyst index events of the Eocene - Oligocene Transition in the (Para)Tethyan Realm
No full textA recent biochronostratigraphic (coccolithophorids, dinoflagellate cysts) and paleoenvironmental analysis of the hemipelagic deposits of the İhsaniye Formation, exposed along the cliffs in the Karaburun area (Black Sea coast, NW Turkey) provided new insights into the paleoceanographic and paleoclimatic evolution of the central (Para)Tethyan region across the Eocene–Oligocene Transition (EOT). Among others, the study identified the Earliest Oligocene Stable Isotope Step (EOIS) marking the inception of Antarctica\u27s first continental-scale ice sheets since the mid-Permian and coinciding with a major eustatic lowering, followed by the Early Oligocene Glacial Maximum (EOGM) period with its peak δ18O values. The study showed apparent (quasi) continuity of the EOT succession at Karaburun, a notion that is not a 100% obvious from the organic walled dinoflagellate cyst (or dinocyst) record. This is mainly because the iconic Eocene – earliest Oligocene taxon Areosphaeridium diktyoplokum, in coeval sections in the region quite abundant near the end of the Eocene, is virtually absent. Here, we focus on obtaining a more detailed picture of correlative secondary dinocyst and other EOT bioevents allowing an even more robust chronostratigraphic assessment of the succession, including correlation to the Italian type sections. Particularly the ranges of the (herein taxonomically revised) species Explodinium priabonensis gen. and comb. nov. and the new species Glaphyrocysta peterbijlii sp. nov. may be regarded as additional criteria to correlate EOT strata within the (Para)Tethyan realm. Combined evidence now suggests that the Karaburun section may not be as complete as previously assumed and that a small part of the succession correlative to the base of the EOGM, representing a portion of the Adi dinocyst Zone may be missing. This aspect does not affect the overall outcome and significance of the studies at Karaburun. In fact, a brief hiatus may well be driven by the major EOT sea level lowering. </ul