Search Results (55)

Madagascar’s expanding blue economy is largely underpinned by seaweed aquaculture, particularly Kappaphycus alvarezii (Cottonii), which offers an alternative to declining small-scale fisheries and strengthens the resilience of coastal socio-ecosystems. Ensuring the sustainability of this economic activity requires effective ecological monitoring of aquaculture sites and surrounding habitats. This study examines and compares the performance of two imaging configurations—an RGB composite derived from a subset of multispectral images capturing red (650 nm), green (560 nm), and blue (450 nm) bands; and a five-band multispectral (MS) image encompassing blue, green, red, red-edge (730 nm), and near-infrared (840 nm) bands—combined with a Random Forest (RF) classification model, for benthic habitat mapping in a seaweed cultivation context. High-resolution orthomosaics (2 cm/pixel) enabled the discrimination of Kappaphycus cultivation plots from three shallow-water habitats: (i) ‘benthic macrophytes’, which comprise: seagrass meadows and benthic macroalgal; (ii) ‘sandy bottom’ and (iii) ‘green algae’. The RF classification achieved an overall accuracy of 87% (Kappa = 0.82) across ~10 hectares. Producer’s accuracy exceeded 80% for Kappaphycus cultivation, green algae, and sandy bottom for both the RGB and MS datasets, indicating strong classification performance. However, early-stage seaweed was occasionally misclassified as benthic macrophytes, likely due to its low biomass and weak spectral signature. This UAS-based approach provided a robust and cost-effective framework for monitoring off-bottom seaweed farms and associated natural habitats. This approach supports sustainable aquaculture development and integrated coastal management in Madagascar and comparable tropical reef socio-ecosystems. Full article

Abiotic stresses severely constrain crop productivity by disrupting cellular redox homeostasis and hormone signaling. Although individual stresses differ in origin, plant responses converge on a conserved regulatory system centered on reactive oxygen species (ROS) and phytohormone crosstalk. Controlled ROS production in chloroplasts, mitochondria and the apoplast functions as a signaling mechanism that interacts dynamically with abscisic acid, auxin, ethylene, jasmonate and cytokinin pathways through shared regulatory nodes, including nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and redox-sensitive transcriptional cascades. Endogenous metabolites, including phenolics, terpenoids, carotenoids, alkaloids, polyamines, glutathione and signaling peptides, are embedded within this network and modulate its amplitude and sensitivity. In parallel, non-microbial biostimulants derived from seaweeds, higher plants, protein hydrolysates and humic substances have been widely reported to enhance crop performance under abiotic stress. However, mechanistic integration between biostimulant research and plant stress signaling remains limited. In this review, we propose that terrestrial plant- and algal-derived biostimulants act not as external substitutes for hormones or antioxidants but as modulators of endogenous ROS–hormone signaling hubs. We first synthesize the current understanding of redox–hormone integration under abiotic stress, then examine endogenous metabolites as intrinsic regulators of this network, followed by an analysis of biostimulants in relation to shared regulatory nodes. By positioning biostimulant action within the established redox–hormone network, we provide a mechanistic framework that links stress biology with agronomic application and supports rational strategies to enhance crop resilience. Full article

As the global demand for seaweed products increases, resource managers, conservation groups, and other stakeholders strive to protect wild seaweed populations and the ecosystem services they provide from the damaging effects of over-harvesting. Ascophyllum nodosum (rockweed) is a slow-growing, intertidal brown alga of the North Atlantic that is commercially harvested for crop biostimulants, soil conditioners, and other products. Rockweed is considered a foundation species due to its high abundance, tall canopy, habitat characteristics, and role in detrital food webs. Rockweed shoots survive after harvesting if the holdfast remains intact, but rates of canopy and biomass recovery depend on the intensity of harvesting. In Maine, USA, and eastern Canada, little is known about how harvesting rockweed at various intensities affects recovery rates of algal height or biomass. Herein, we evaluate published studies and suggest improved experimental designs. Most experimental studies focus on a single harvest event, often with incomplete data on control plots, amount of biomass removed, or previous harvesting history at study sites. Much has been learned from previous work, but more rigorous studies are needed to develop harvest recommendations that address both commercial and conservation-related goals. Importantly, experimental studies of the effects of repeated harvesting on rockweed beds are lacking. Full article

Herbaria, originally books of medicinal plants, became collections of dried plants after 1500, later extending to seaweeds and supporting taxonomy and systematics. Digitalization has made herbaria accessible, and advances in DNA sequencing have transformed them into valuable resources for genetic research. Label data, which include place and date of collection, make exsiccata essential tools for biogeographic studies and conservation strategies, helping map biodiversity and protect endangered species. The historical Pierpaoli herbarium (MBMP) houses 584 seaweed specimens collected from the Ionian and Adriatic seas between 1920 and 1965. It has been digitized within the NPRR Project ITINERIS and the DiSSCo infrastructure. Floristic changes in the Mar Piccolo over three periods (1920–2024) and the Mar Grande (1920–1992) were compared using herbarium specimens, papers, and recent data. Mar Piccolo’s flora over a century revealed significant changes. Many historical species disappeared, while new ones appeared, including 14 non-indigenous species. The biogeographical composition also shifted, with Cosmopolitan and Indo-Pacific elements increasing. In the Mar Grande, less than half the species were found again in 1992. Evidently, phytobenthic communities underwent noticeable changes over a century, highlighting the impact of environmental shifts. This confirms that Natural Science Collections are invaluable resources for understanding our planet’s biodiversity and history. Full article

Coastal zones are critical areas of marine ecosystems, where biodiversity is a key ecological element for maintaining ecosystem stability and ensuring the sustainability of fishery resources. The Shengsi Ma’an Archipelago Marine Special Reserve features heterogeneous habitats such as rocky reefs, seaweed beds, and artificial aquaculture areas, which are significantly affected by human activities. This study focused on the nearshore waters of Lvhua Island within the reserve. Based on the degree of human disturbance, the study area was divided into five typical habitat types: cage culture area (A), intertidal seaweed bed (B), marine platform area (C), open waters (D), and mussel culture area (E). Environmental DNA (eDNA) technology was employed to analyze the characteristics of eukaryotic community structures across these habitats and their coupling mechanisms with environmental factors. The results showed that a total of 767,360 valid sequences were obtained from 15 seawater samples. Clustering into operational taxonomic units (OTUs) yielded 811 OTUs, taxonomically covering 50 phyla, 104 classes, 220 orders, 334 families, 435 genera, and 530 species. The number of OTUs shared across all habitats was 387. The intertidal seaweed bed (B) had the highest proportion of unique OTUs (4.8%) and showed significant differences (0.01 < p < 0.05) in OTU composition compared to the marine platform area (C) and the mussel culture area (E). Among the major dominant phyla, the abundance of Dinoflagellata across sites was A (74.56%) > E (68.32%) > B (62.15%) > C (58.74%) > D (55.21%). The abundance of Arthropoda across sites was D (27.34%) > C (19.98%) > B (17.89%) > E (9.17%) > A (8.25%). Each of the other sites had 1-2 dominant phyla. Among the major dominant genera, the abundance of an unclassified genus of Dinophyceae was B (41.39%) > C (23.31%) > D (22.03%) > E (19.27%) > A (18.56%). The genus Noctiluca was endemic to Site A, with an abundance of 39.98%. The genus Calanus was dominant in site D (26.17%). The genus Meganyctiphanes was unique to sites C (12.12%) and D (8.76%). The genus Ectopleura was unique to site A. The genus Botrylloides was unique to site E. The remaining genera were evenly distributed across sites without significant habitat specificity. Alpha diversity analysis revealed that the marine platform area (C) had the highest Shannon index (3.32 ± 0.22) and Pielou index (0.54 ± 0.04), while the mussel culture area (E) had the highest Chao1 index (578.96 ± 10.25). All diversity indices were lowest in the cage culture area (A). Principal coordinate analysis (PCoA) and ANOSIM tests indicated significant differences (p < 0.05) in eukaryotic community structures among different habitats. Samples from the seaweed bed clustered separately and were distant from other habitats. Redundancy analysis (RDA) showed that pH was the key environmental factor driving the differentiation of eukaryotic community structure. Temperature was negatively correlated with dissolved oxygen, while salinity was positively correlated with pH. The combined differences in environmental factors were the main drivers of eukaryotic community structure differentiation. In conclusion, this study clarifies the regulatory role of habitat type on the eukaryotic community structure in the nearshore waters of Ma’an Archipelago, confirming a negative correlation between human activity intensity and biodiversity, and a positive correlation between natural habitat complexity and biodiversity. The research findings provide scientific support for assessing the health of the marine ecosystem and formulating ecological conservation and management strategies in this region. Full article

The global increase in life expectancy underscores the need to promote healthy aging, particularly by addressing age-related leaky gut syndrome, which contributes to systemic inflammation and chronic disease. This study focused on the sustainable production and functional development of Ulva meridionalis, a fast-growing seaweed, to improve gut health and mitigate the effects of aging. Using land-based aquaculture, a scalable cultivation system for U. meridionalis was established, and its polysaccharide, ulvan, was extracted. Ion exchange treatment enhanced the functionality of ulvan to produce ulvan-Na, which contains high levels of Na⁺ and conveys superior anti-aging properties. Ulvan-Na restored intestinal barrier integrity in aged mice by reducing serum LPS levels and increasing claudin-1 expression. Ulvan-Na modulated the gut microbiota, increasing beneficial bacteria such as Clostridiales vadin BB60 and suppressing inflammatory bacteria such as Turicibacter. The mechanism was clarified whereby ulvan-Na activates β-catenin to enhance claudin-1 expression. These findings highlight ulvan-Na as a bioactive compound that ameliorates age-related intestinal dysfunction while demonstrating the feasibility of sustainable U. meridionalis production for functional food innovation and environmental conservation. Full article

Over the past twenty years, significant efforts have been made to digitize natural collections. This process represents a crucial step in preserving and enhancing biodiversity data. In this context, the phycology team from the Institute for Water Research (CNR-IRSA) in Taranto (southern Italy), as a partner of the NRRP Project ITINERIS, and within the nascent European Research Infrastructure “Distributed System of Scientific Collections” (DiSSCo), answered to the challenge of digitizing and sharing the extensive biodiversity data preserved in the marine macrophyte collection Herbarium TAR. This herbarium includes over 500 species collected between 1982 and 2025. Digitization was carried out in accordance with international standards for imaging and in compliance with FAIR principles for metadata curation. A total of 353 digital specimens were produced, including 152 species of seaweeds (76 Rhodophyta, 47 Heterokontophyta, and 29 Chlorophyta) and 3 species of Spermatophyta. Notably, 15 non-indigenous species were documented. Part of the metadata, structured using the Darwin Core standard, has been published on GBIF. This initiative, carried out within the ITINERIS framework, highlights the value of both long-term biodiversity monitoring and digital data in supporting research on climate change, biological invasions, and the conservation of marine ecosystems. Full article

Excessive nitrogen (N) fertilizer usage in agriculture has prompted the exploration of sustainable strategies to enhance nitrogen use efficiency (NUE) while maintaining crop yield and quality. Processed tomatoes (Solanum lycopersicum L.) were grown for two years (2023 and 2024) following a two-way factorial randomized complete block (RCBD) design, considering three biostimulants and three N regimes as two factors, to assess their morphophysiological, biochemical, anatomical and yield performances. Nitrogen application significantly influenced biomass accumulation, the leaf area index (LAI), nitrogen uptake and yield with notable comparable values between reduced and optimal nitrogen dose, indicating improved nitrogen use efficiency. Biostimulants showed limited effects alone but enhanced plant performance under reduced nitrogen conditions, particularly improving chlorophyll content, crop growth, N uptake, yield and anatomical adaptations. Moreover, compared to 2024, biostimulant application enhanced tomato growth more evidently in 2023 due to environmental variations, likely due to the occurrence of stress conditions. Importantly, biostimulants, together with N regimes, i.e., optimal and reduced doses, showed improved anatomical traits, especially regarding leaf thickness and thickness between the two epidermises, indicating adaptive responses that may support sustained productivity under N-limited conditions. Among the biostimulants used, the processed tomatoes responded better to protein hydrolysate and endophytic N-fixing bacteria than to seaweed extract. These findings suggest that although biostimulants alone were not affected, integrating them with reduced N fertilization provides a viable strategy for optimizing tomato production, conserving resources and minimizing the environmental impact without compromising yield or quality. Full article

The aquaculture sector is essential for meeting seafood demand while ensuring sustainability. It involves farming fish, mollusks, crustaceans, other invertebrates, and algae in controlled environments, helping to conserve marine resources and reduce ecological pressures. Sustainable practices, such as an integrated multitrophic recirculating aquaculture system (IMTA-RAS) with fish and seaweed, can minimize the environmental impact of fish aquaculture. However, the impact of the introduction of macroalgae on the fish muscle metabolism has not been studied. This research examines the impact of growing Senegalese sole (Solea senegalensis) together with sea lettuce (Ulva ohnoi) on fish metabolism using high-resolution ¹H-NMR-based metabolomics. Three farming systems were compared. These were E₁, a recirculating aquaculture system (RAS); E₂, an IMTA-RAS integrating U. ohnoi for biofiltration; and E₃, an IMTA-RAS with U. ohnoi and Phaeobacter sp. strain 4UAC3, a probiotic bacterium isolated from wild U. australis known to counteract fish pathogens. A metabolomic analysis revealed that energy metabolism was enhanced in IMTA-RAS and even more in IMTA-RAS-Phaeobacter–grown fish, increasing overall metabolic activity. These results indicate that the presence of the algae with the probiotic had a clear impact on the physiological state of the fish, and this deserves further investigation. This study contributes to the understanding of the physiological responses of fish to innovative aquaculture practices, supporting the development of more sustainable and efficient management that reduces the environmental impact and increases fish health and welfare. Full article

Sargassum thunbergii is a dominant seaweed species in the intertidal zone along the coast of China. It provides various ecological services, such as primary productivity, marine carbon sequestration, and water purification. To investigate the population structure characteristics of Sargassum thunbergii, the Hegyi competition model was employed to quantify intraspecific competition within populations in the intertidal zone of Luhua Island, China. The results showed that the competition intensity decreased as a power function (y = 1.93x^−0.89, R² = 0.28) with increasing seaweed height. Intraspecific competition had minimal effects on seaweeds taller than 50 cm. Seaweeds at lower population levels exhibited more stable competition indices. Therefore, the model can reliably predict intraspecific competition intensity in Sargassum thunbergii. The sample circle method was applied to identify an optimal intraspecific competitive range of 50 cm for intertidal populations of Sargassum thunbergii. This study provides scientific guidance for seaweed spacing and rational harvesting during ecological restoration. Moreover, it offers valuable insight for conserving other macroalgae, such as Sargassum fusiforme, and restoring seaweed beds ecologically. Full article

Background/Objectives: Desiccation profoundly influences the distribution and abundance of intertidal seaweeds, necessitating robust molecular adaptations. Sargassum muticum is a brown seaweed inhabiting intertidal rocky substrates. During low tides, this species undergoes periodic aerial exposure. Such environmental conditions necessitate robust physiological mechanisms to mitigate desiccation stress. Yet, the molecular basis of this adaptation remains poorly understood. Methods: To investigate desiccation-responsive genes and elucidate the underlying mechanisms of adaptation, we exposed S. muticum to 6 h of controlled desiccation stress in sterilized ceramic trays, simulating natural tidal conditions, and performed comparative transcriptome analysis using RNA-seq on the Illumina NovaSeq 6000 platform. Results: High-quality sequencing identified 66,192 unigenes, with 1990 differentially expressed genes (1399 upregulated and 591 downregulated). These differentially expressed genes (DEGs) were categorized into regulatory genes—including mitogen-activated protein kinase (MAPK), calmodulin, elongation factor, and serine/threonine-protein kinase—and functional genes, such as heat shock protein family members (HSP20, HSP40, and HSP70), tubulin (TUBA and TUBB), and endoplasmic reticulum homeostasis-related genes (protein disulfide-isomerase A6, calreticulin, and calnexin). Gene Ontology (GO) enrichment highlighted upregulated DEGs in metabolic processes like glutathione metabolism, critical for oxidative stress mitigation, while downregulated genes were linked to transport functions, such as ammonium transport, suggesting reduced nutrient uptake during dehydration. KEGG pathway analysis revealed significant enrichment in “protein processing in endoplasmic reticulum” and “MAPK signaling pathway-plant”, implicating endoplasmic reticulum stress response and conserved signaling cascades in desiccation adaptation. Validation via qRT-PCR confirmed consistent expression trends for key genes, reinforcing the reliability of transcriptomic data. Conclusions: These findings suggest that S. muticum undergoes extensive biological adjustments to mitigate desiccation stress, highlighting candidate pathways for future investigations into recovery and tolerance mechanisms. Full article

Understanding population genetic connectivity is crucial for the sustainability and persistence of marine biodiversity. As a fundamental reef-building macroalga of the coastal ecosystem, Halimeda macroloba Decaisne is one of the dominant intertidal seaweeds in the Indo-Pacific region. However, its genetic structure and population connectivity have been poorly recognized. Here, we explored the population genetic structure and genetic connectivity of H. macroloba using chloroplast tufA, rps3-rpl14, and rbcL. Our results indicated low genetic diversity and shallow population genetic structure at the intraspecific level, uncovering five genetic groups with six subdivided lineages in tufA and two genetic clusters in rps3-rpl14. We detected demographic expansion in the last glacial period of the Pleistocene and significantly asymmetric gene flow among different geographical units. We suggest that the southwestward ocean currents under the influence of northeast monsoon in the Indo-Pacific region are the main factor in shaping the present genetic structure, and the asexual reproduction of H. macroloba also plays an important role of the low genetic diversity pattern; in addition, the divergence between genetic clusters might be related to the historical isolation led by the paleoclimate oscillation in the Pleistocene. The Xisha Islands in the northern South China Sea might serve as a potential refugium of H. macroloba, which needs extra attention to conservation management. Given the limitation of sample size, we need to conduct more field work and carry out further research at a larger scale in the future. Our study provided new insights into the theory of population connectivity in the Indo-Pacific region and provided scientific basis for tropical costal seaweed conservation. Full article

The possible regulatory effects of C2H2 zinc finger proteins, which are important transcription factors, on intertidal seaweed responses to abiotic stress are unclear. This study was conducted to comprehensively analyze the C2H2 gene family of a representative intertidal seaweed species (Pyropia haitanensis) and clarify its genomic characteristics and biological functions. A total of 107 PhC2H2 zinc finger protein-encoding genes distributed on five P. haitanensis chromosomes were identified and divided into three subgroups. The expression levels of 85, 61, 58, 45, and 41 PhC2H2 genes responded in the maturation of filaments, high-temperature, salt, low-irradiance, and dehydration stress, respectively. The PhC2H2 gene family was conserved during Porphyra evolution, with no indications of large-scale genome-wide replication events. On average, PhC2H2 genes had more transposable element (TE) insertions than Pyropia yezoensis and Porphyra umbilicalisC2H2 genes, suggesting that TE insertions may have been the main driver of PhC2H2 gene family expansion. A key gene (PhC2H2.94) screened following a quantitative trait locus analysis was significantly responsive to high-temperature stress and was associated with photosynthesis, peroxisomes, the ubiquitin proteasome pathway, and the endoplasmic reticulum-related protein processing pathway, which contribute to the stress tolerance of P. haitanensis. Additionally, PhC2H2.94 transgenic Chlamydomonas reinhardtii exhibited increased tolerance to heat stress. This study provides new insights and genetic resources for characterizing the molecular mechanism underlying intertidal seaweed responses to abiotic stresses and breeding stress-resistant macroalgae. Full article

Sargassum hemiphyllum var. chinense is a common brown seaweed along the southeastern coast of China, playing a significant ecological role and possessing considerable resource utilization value. However, its genetic diversity and phylogeographic patterns remain poorly understood. In this study, we employed multiple molecular markers, including the nuclear ITS sequence (ribosomal internal transcribed spacer), the plastid rbcL gene (encoding the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase), and the mitochondrial cox3 and cox1 genes (encoding cytochrome c oxidase subunits III and I, respectively), to elucidate the genetic and phylogeographic structure of S. hemiphyllum var. chinense. Our findings demonstrate that the combined use of plastid and mitochondrial gene sequences is suitable for phylogeographic studies of this species. Genetic structure difference was observed among 15 populations which localities covering most of its distribution range, likely resulting from colonization by ancestors of different origins and limited gene flow among populations. The study revealed two distinct lineages of S. hemiphyllum var. chinense, exhibiting a north–south geographical distribution with a mixed zone in the southern Fujian–eastern Guangdong coastal region. These lineages are inferred to have diverged during the Middle to Late Pleistocene due to the isolation of the East China Sea and South China Sea during glacial periods. Sub-lineage differentiation was also detected within the northern lineage. The southern lineage experienced demographic expansion following the end of the Last Glacial Maximum, while the northern lineage remained stable. The southern Fujian–eastern Guangdong region, characterized by high genetic diversity, may have served as a glacial refugium or a contact zone for the post-glacial recolonization of the two lineages. Global warming may lead to range contraction and reduced genetic diversity in this species. The high genetic diversity area should be prioritized for conservation efforts. Overall, these findings provide insights into the genetic structure status and causes of S. hemiphyllum var. chinense and offer a scientific basis for proposing reasonable measures for its resource management. Full article

Surf zones are important nursery grounds for fish larvae and juveniles. However, little is known about fish larvae and juveniles in the surf zone along the coast of Jiangsu Province. To describe the species composition of fish larvae and juveniles, monthly collections were conducted at eight stations during the spring tide from February 2024 to January 2025. The fish larvae and juveniles were sampled using a seine net (1m × 4m; 1 mm mesh aperture), with sampling repeated three times at each station per month. A total of 1435 fish larvae and juveniles were collected, belonging to 42 species and 37 genera in 21 families. Almost half of them were postflexion larvae. Gobiidae, with 14 species, was the most diverse family. Based on the index of relative importance (IRI) result, the dominant species was Amoya pflaumi, accounting for 35.33% of the total number of individuals collected. Common species were Mugil cephalus, Amblychaeturichthys hexanema, Tridentiger trigonocephalus, Acanthogobius ommaturus, Mugilogobius abei, Thryssa mystax, Periophthalmus modestus, Sillago sihama, and Mugilogobius myxodermus. All other species were classified as rare. No fish larvae or juveniles were collected in February 2024 and January 2025. The species number, catch per unit effort (CPUE), Margalef’s richness index, Pielou’s evenness index, and Shannon–Wiener diversity index showed similar trends, and significant differences could be found for each parameter among sampling months. The cluster analysis from the ten months (excluding February 2024 and January 2025) indicated a significant seasonal change in the community structure of fish larvae and juveniles. Fish larvae and juveniles were abundant and diverse at one station near an aquaculture tidal flat for seaweed. This study provides essential basic data to support the management and conservation of fishery resources in the surf zone along the coast of Jiangsu Province. Full article