Search Results (477)

Marine biofouling remains a major challenge for maritime industries, affecting submerged structures and vessels worldwide. The long-standing reliance on biocidal coatings, together with their documented environmental impacts, has led to increasingly restrictive regulations and an urgent demand for environmentally compatible antifouling (AF) solutions. This study evaluates the AF potential and toxicological profile of two nucleoside analogues, hypoxanthine arabinoside (1′) and 2′-deoxyinosine (2′), selected based on the previously reported non-lethal AF activity of the naturally occurring nucleosides adenosine and 2′-deoxyadenosine from cyanobacteria. Both analogues inhibited the growth of Navicula sp. by approximately 60% without inducing mortality and significantly reduced settlement of Mytilus galloprovincialis plantigrades, with EC₅₀ values of 5.50 µM (1′) and 8.54 µM (2′), and no lethality detected (LC₅₀ > 200 µM). At near-EC₅₀ concentrations, both compounds increased acetylcholinesterase and tyrosinase activities, supported by molecular docking results, suggesting involvement of neurotransmission- and byssal formation-related pathways. Proteomic analysis revealed compound-specific molecular responses. No lethal effects were observed in non-target organisms (LC₅₀ > 32 µM for A. amphitrite and LC₅₀ > 50 µM for A. salina), and environmental fate modelling predicted low bioaccumulation and rapid degradation. Overall, substitution of the amino group by a carbonyl group preserved AF efficacy without increasing toxicity, highlighting nucleosides as promising low-toxicity AF agents. Full article

Polysaccharides derived from cyanobacteria and microalgae have attracted increasing interest as natural virucidal agents. Among them, polysaccharides from the cyanobacterium Arthrospira platensis (A. platensis), and the green microalgae Dunaliella salina (D. salina) have shown virucidal activities, mainly against enveloped viruses, while evidence on non-enveloped viruses is still limited. In this study, the virucidal activity of purified polysaccharides extracted from A. platensis (APPs) and from D. salina (DSPs) was evaluated in vitro against human adenovirus type 5 (HAdV5), a non-enveloped pathogenic virus with high persistence in the environment and resistance to disinfection. The in vitro assays were carried out at concentrations previously verified as non-toxic by morphological evaluation of A549 cells after 24 and 48 h of incubation, testing two viral loads, namely, 10³ and 10⁴ tissue culture infectious dose 50% per milliliter (TCID₅₀/mL). For APPs, a possible time-dependent effect was also assessed at different contact times (15, 30 and 60 min). DSPs showed a limited virucidal effect related to the starting viral concentration, while APPs induced a consistent viral reduction (up to 98.8%) at both viral concentrations. The virucidal effect of APPs occurred rapidly and was not significantly influenced by contact time, thus suggesting that prolonged exposure is not a determining factor for polysaccharide virucidal activity. These findings demonstrate the virucidal activity of APPs against a highly resistant non-enveloped virus and provide preliminary in vitro evidence of their potential application as natural virucidal agents, particularly for environmental disinfection purposes. Further investigations are warranted to elucidate the underlying mechanisms of action and to optimize their practical use. Full article

Due to their exceptional nutritional benefits, microalgae and cyanobacteria are recognized as sustainable food sources and key contributors to the circular bioeconomy. Arthrospira sp. has garnered significant attention as one of the most promising cyanobacteria for a wide range of applications. The purpose of this study is to systematically analyze and synthesize global research trends in Arthrospira sp. applications. In this context, a “systematic review” refers to an integrated bibliometric and thematic analysis encompassing publication trends, geographical distribution of research outputs, leading journals, key application sectors, market development, and associated challenges and future prospects. Consequently, extensive research has been conducted on this species, leading to diverse areas of interest and application. This review article is the first of its kind, offering a comprehensive summary of trends in Arthrospira sp. applications over the past 15 years. It presents a bibliometric analysis of publications from 2010 to 2024 in journals indexed by Scopus. The analysis revealed that Bioresource Technology is the leading journal in publishing related research, with China producing the highest number of studies. Furthermore, phycocyanin extraction emerged as the most frequently studied application. Recently explored applications include its use as a biofertilizer, in bioplastic production, and in cosmetics. The Arthrospira sp. market is currently valued at an estimated $619 million in 2024, positioning it as a dominant player in the global industry. However, challenges persist, including safety concerns related to potential allergies and toxicity, as well as regulatory hurdles that may affect commercialization and market expansion. Full article

Fluorescent dyes are commonly used as tracers in hydrological investigations to quantify transport pathways, residence times, mixing behavior, and connectivity in surface water, groundwater, and coastal systems. Despite their long history of application, the ecological implications of deliberate dye releases are not well understood. This review synthesizes current knowledge on the physico-chemical characteristics, environmental behavior, and ecotoxicological effects of major dye classes, with emphasis on rhodamines, fluorescein derivatives, and sulfonated xanthene dyes commonly used in water tracing studies. Toxicity data for algae, cyanobacteria, invertebrates, and fish show large inter-specific variability. Some dyes, particularly rhodamine B and eosin Y, show acute or sub-lethal effects at concentrations detected during poorly controlled applications. By contrast, dyes with high polarity and extensive sulfonation (e.g., rhodamine WT, sulforhodamine B, pyranine, and fluorescein) show consistently low toxicity and minimal bioaccumulation potential. Environmental fate processes, including photolysis, sorption, and transformation into potentially more reactive products, influence exposure dynamics, especially in clear, shallow, or slow-moving systems. This review also evaluates regulatory frameworks and operational guidance for safe use, identifies gaps in toxicological and fate data, and proposes recommendations for minimizing environmental impact through dye selection, mass optimization, injection design, and monitoring. The findings support the continued use of fluorescent dyes but highlight the need for more systematic assessment of transformation products, chronic and sub-lethal responses, and cumulative exposure in sensitive environments. Full article

Cyanobacteria of the genus Phormidesmis are recognized as a promising source of biologically active secondary metabolites with anticancer and immunomodulatory properties. In the present study, we investigated both the cytotoxic and immunological effects of an extract obtained from Phormidesmis molle PACC (Plovdiv Algal Culture Collection) 8140 as well as its chemical composition. The extract was profiled by LC-ESI-MS/MS (Liquid chromatography—electrospray ionization—tandem mass spectrometry), and selected compounds were evaluated with in silico ADMET (Absorption, distribution, metabolism, excretion and toxicity) modeling. The cytotoxic potential of the extract was evaluated in vitro using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay on human colorectal adenocarcinoma cell lines (Caco-2, HT-29, and LS-180). The immunological impact of the extract was assessed on human peripheral blood mononuclear cells (PBMCs) isolated from healthy donors. PBMCs were treated with 100 µg/mL extract for 48 h, followed by flow cytometric immunophenotyping and ELISA (Enzyme-linked immunosorbent assay)-based cytokine quantification. The extract induced a concentration- and time-dependent decrease in cancer cell viability after 24, 48, and 72 h of exposure. At 72 h, treatment with the highest concentration (200 µg/mL) reduced cell viability to 74% in Caco-2 cells, 69–70% in HT-29 cells, and 59–61% in LS-180 cells. Morphological changes observed after treatment with Phormidesmis extract showed pronounced cytotoxic and apoptosis-related effects in the colorectal cancer cell lines tested. Immunophenotyping revealed a pronounced expansion of natural killer (NK) cells (CD56⁺ and/or CD16⁺). CD3⁻CD56⁻CD16⁺ NK population was markedly increased (from 67.7 ± 0.95% in non-treated PBMCs to 94.66 ± 0.90% in extract-treated PBMCs, p < 0.001). In contrast, the proportions of CD8⁺ T cells, CD19⁺ B cells, and CD11b⁺ monocytes were significantly reduced (from 21.5 ± 4.50% to 7.22 ± 0.41%, from 11.9 ± 1.70% to 6.06 ± 0.42%, and from 66.4 ± 0.60% to 34.4 ± 0.87%, respectively). Cytokine analysis demonstrated strong suppression of Th1-associated cytokines, with significantly reduced interferon gamma (IFN-γ, 461 ng/mL in controls vs. 84 ng/mL in extract-treated cultures) and tumor necrosis factor alpha (TNF-α) levels (169 ng/mL in controls vs. 32 ng/mL in extract-treated cultures), whereas nterleukin-6 (IL-6) was moderately elevated (from 158 ng/mL in controls to 234 ng/mL in extract-treated cultures) and IL-10 remained low. These findings demonstrate that P. molle extract combines cytotoxic activity against cancer cells with potent immunomodulatory effects, highlighting its potential as a source of bioactive compounds for immune-based therapeutic strategies. Full article

Artificial water bodies in post-mining landscapes often remain chemically altered and ecologically degraded, yet their ecological risk is frequently underestimated by conventional water quality assessments. Persistent toxicity in mining-impacted waters is a global challenge, as acidity alone often fails to explain the adverse biological effects observed. This study assessed the ecological condition of three artificial ponds in a former gold–antimony mining area (Midões, northern Portugal), using an integrated framework that combined physicochemical and biological (phytoplankton and macroinvertebrates) elements with ecotoxicological assays. Ecotoxicity was evaluated using Lemna minor (growth inhibition) and Daphnia magna (acute toxicity, survival, and feeding rate) under untreated water and pH-adjusted conditions to disentangle acidity-driven effects from other chemical stressors. According to Water Framework Directive metrics, all ponds were classified as having moderate ecological potential, driven by persistent acidic conditions and elevated heavy metal concentrations (e.g., zinc and cadmium). Biological communities showed marked temporal/spatial variability, reflecting physicochemical differences among ponds. Phytoplankton showed summer blooms of cyanobacteria, while macroinvertebrates were generally dominated by tolerant taxa (exhibiting low taxonomic richness/diversity). Ecotoxicological assays showed consistent toxicity across all sampling periods, with high mortality and reduced feeding rates in D. magna and growth inhibition in L. minor. Notably, toxicity often persisted even after pH adjustment, indicating that the observed biological effects were not driven by acidity but were largely attributable to residual metal contamination. These findings highlight the ecological vulnerability of mining-impacted water bodies and underscore the need for management and remediation strategies that address metal removal in addition to pH correction. Full article

Phytoplankton are key indicators of water quality and low-cost tools for freshwater monitoring, yet their diversity and ecological drivers remain poorly documented in the Tropical Andes. This study provides the first national-scale, multi-ecosystem assessment of net phytoplanktonic communities (including microalgae and cyanobacteria), across Ecuador, integrating physicochemical, multivariate, and geospatial analyses. Eighteen lakes and rivers from three biogeographic regions and a wide altitudinal gradient were surveyed, yielding 129 taxa, 77 identified at species level, the most comprehensive checklist reported to date for Ecuador. Community structure showed a clear lentic–lotic differentiation driven by hydrodynamic contrasts, while the absence of distance–decay patterns indicated high dispersal and environmental filtering pattern rather than spatial structuring. Anthropogenic pressure acted as a secondary gradient: pristine high-Andean lakes were dominated by desmids and diatoms, whereas agricultural and urban basins showed chlorophyte and potentially toxic cyanobacterial assemblages. Palmer’s Index detected organic pollution but underestimated eutrophication in endorheic, geochemically enriched lakes. Land-use effects presented strong basin-scale signals in lakes but weak correlations in rivers due to overriding hydromorphological constraints. These findings establish a robust spatial baseline for freshwater bioassessment in the Andes, demonstrating the value of phytoplankton as effective, low-cost indicators readily applicable to national water-quality assessment programs. Full article

The progressive degradation of surface waters should become one of the most important problems requiring an urgent solution. One of the methods developed is filtering water through loose, degraded sediments, blooms of cyanobacteria or algae, or a bed of hemp (Cannabis sativa L.) waste or hemp fibers. The conducted tests on the percolation of water samples and/or water with sediment from surface waters at sites with different ecological statuses indicate the possibility of using hemp waste for the reclamation of water reservoirs and rivers. The effect of filtration is a rapid improvement in water quality and, consequently, an improvement in the ecological status. The best result was achieved for a small freshwater reservoir with a large number of algae and loose degraded sediment. The initial turbidity value was at the limit of the device’s measurement capability, reaching 9991 NTU. After filtration through the hemp waste bed, the turbidity dropped to 42.52 NTU, a 99.57% decrease. The remaining parameters, C, TDS, and pH, were not subject to significant variability as a result of filtering. Excessive amounts of organic matter, which create a problem for surface waters, are removed. Due to the carrier (hemp waste), which is organic waste, any possible release of small amounts into the aquatic environment will not pose a threat. After applying filtration, a decision can be made on further actions regarding the water reservoir or river: Self-renewal of the reservoir or further percolation using, for example, mill gauze or cleaning the reservoir with other, non-invasive methods. After the filtering procedure, the hemp waste, enriched with organic matter and water remaining in the waste, can be used for composting or directly for soil mulching (preliminary tests have yielded positive results). A hemp waste filter effectively removes Chronomus aprilinus larvae (Chrinomidae) from water. This result indicates the possibility of removing mosquito larvae in malaria-affected areas. The use of hemp filters would reduce the amount of toxic chemicals used to reduce mosquito larvae. Improving the ecological status of surface waters by filtering contaminants with hemp waste filters can reduce the need for chemical treatment. The use of natural, biological filters enables sustainable surface water management. This is crucial in today’s rapidly increasing chemical pollution of surface waters. Full article

Microcystin-LR (MC-LR), produced by Cyanobacteria, is being detected in many types of waters, posing a universal threat to aquatic animals. However, there have been few comprehensive endpoints assessed, including oxidative stress, transcriptome changes, intestinal microbiota, and histopathology, in anurans exposed to MC-LR. In this study, all these effects of MC-LR on Chinese brown frog (Rana chensinensis David, 1875) tadpoles were investigated by exposing the tadpoles to MC-LR at different concentrations (0, 0.1, 1.0, 5.0, and 10.0 μg/L) for 7 days. Our results revealed that treatment of tadpoles with the high MC-LR dosage (10.0 μg/L) induced a significant increase in malondialdehyde (MDA) content and decreases in superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, and total antioxidant capacity (TAC). RNA-seq analysis of the liver showed that the number of differentially expressed genes (DEGs) was 2361 under lower MC-LR stress (1.0 μg/L), while the number of DEGs increased to 3185 under higher MC-LR stress (10.0 μg/L). Gene Ontology analysis showed that several biological processes and molecular functions related to digestion were enriched in both MC-LR treated groups, such as digestion, serine-type endopeptidase activity, and serine-type peptidase activity. KEGG enrichment analysis also indicated that the digestion for pancreatic secretion, protein digestion and absorption, and fat digestion and absorption pathways were significantly enriched in the treatment groups. Additionally, the bacterial richness was elevated by MC-LR exposure. At the phylum level, treatment with MC-LR changed the relative abundances of Desulfobacterota, Fusobacteriota, and Actinobacteriota. At the genus level, MC-LR caused significant alterations in the abundances of 23 genera. Furthermore, examination of sections obtained from the livers and intestines of tadpoles in the treatment groups showed damaged histological structure. The knowledge from this study will have potential value for understanding the mechanisms related to MC-LR toxicity in anurans. Full article

Taganrog Bay is part of the Azov Sea, which has significant environmental value. However, in recent years, anthropogenic activity and climate change have increasingly impacted this coastal system. These factors have led to increased sea salinity. These factors also contribute to abundant blooms of potentially toxic cyanobacteria. One additional method for preventing the abundant growth of cyanobacteria may be the introduction of green algae into the bay. The aim of this study was to conduct a computational experiment on the biological rehabilitation of Taganrog Bay using mathematical modeling methods. For this purpose, the authors developed and analyzed a mathematical model of phytoplankton populations. A software model was developed based on modern mathematical modeling methods. The input data for the software module included grid points for advective transport velocities, salinity, and temperature, as well as phytoplankton population and nutrient concentrations. The software module outputs three-dimensional distributions of green algae and cyanobacteria concentrations. A computational experiment on biological rehabilitation of the Taganrog Bay by introducing a suspension of green algae was conducted. Green algae and cyanobacteria concentrations were obtained over 15 and 30-day time intervals. The concentration and volume of introduced suspension were empirically determined to prevent harmful cyanobacteria growth without leading to eutrophication of the bay by green algae. Full article

Eutrophication of water bodies and the bloom of toxin-producing cyanoprokaryotes raise health concerns. Various cyanoprokaryotes species, including Microcystis, Raphidiopsis, Nodularia, and Chrysosporum, release toxins into the aquatic environment, which can reach concentrations toxic to humans and animals. Rising temperatures and human activities are primary drivers behind the increasing frequency of toxic cyanobacterial blooms. The Word Health Organization (WHO) has established provisional guideline values for cyanotoxins in drinking water and water used for other purposes in daily human activities, and has published guidance for identifying hazards and managing risks posed by cyanobacteria and their toxins. There are currently no acceptable limit values for cyanotoxins. To address monitoring needs, contemporary strategies now incorporate molecular genetics, immunoassays, biochemical profiling, and emerging machine-learning frameworks. This paper reviews current early detection methods for harmful cyanobacterial blooms, highlighting their practical advantages and drawbacks. Full article

Saxitoxin (STX) is one of the most potent marine neurotoxins, produced by several species of freshwater cyanobacteria and marine dinoflagellates. Although omics-based approaches have advanced our understanding of STX biosynthesis in recent decades, the origin, regulation, and ecological drivers of STX in dinoflagellates remain poorly resolved. Specifically, dinoflagellate STX biosynthetic genes (sxt) are extremely fragmented, inconsistently expressed, and unevenly distributed between toxic and non-toxic taxa. Environmental studies further report inconsistent relationships between abiotic factors and STX production, suggesting regulation across multiple genomic, transcriptional, post-transcriptional, and epigenetic levels. These gaps prevent a comprehensive understanding of STX biosynthesis in dinoflagellates and limit the development of accurate predictive models for harmful algal blooms (HABs) and paralytic shellfish poisoning (PSP). Artificial intelligence (AI), including machine learning and deep learning, offers new opportunities in ecological pattern recognition, molecular annotation, and data-driven prediction. This review explores the current state of knowledge and persistent knowledge gaps in dinoflagellate STX research and proposes an AI-integrated multi-omics framework highlighting recommended models for sxt gene identification (e.g., DeepFRI, ProtTrans, ESM-2), evolutionary reconstruction (e.g., PhyloGAN, GNN, PhyloVAE, NeuralNJ), molecular regulation (e.g., MOFA+, LSTM, GRU, DeepMF), and toxin prediction (e.g., XGBoost, LightGBM, LSTM, ConvLSTM). By integrating AI with diverse biological datasets, this novel framework outlines how AI can advance fundamental understanding of STX biosynthesis and inform future applications in HAB monitoring, seafood safety, and PSP risk management in aquaculture and fisheries. Full article

Cyanobacterial blooms are an escalating ecological concern driven by eutrophication and climate warming. Bloom-forming cyanobacteria can produce a broad spectrum of bioactive secondary metabolites. Among these, microcystins (MCs) are the most recognised hepatotoxins; however, natural populations of Planktothrix agardhii also synthesise numerous non-ribosomal peptides (NRPs) with poorly understood ecological roles and combined toxic effects. This review demonstrated the role of mixtures of P. agardhii cyanometabolites (oligopeptides and biogenic compounds) in cyanobacterial proliferation, emphasising the rapid evolution of chemotypes. The role of P. agardhii oligopeptides other than MCs in the cyanobacterial toxicity to duckweeds is also discussed. Laboratory experiments indicated that crude extracts containing complex peptide mixtures may inhibit Spirodela polyrhiza growth more strongly than pure MC-LR, suggesting synergistic effects within natural metabolite assemblages. Particular attention is given to variant-specific degradation pathways of MCs within duckweed-associated microbiota. By integrating biochemical, ecological, and microbiological perspectives, this synthesis outlines emerging directions in the study of mixtures of cyanobacterial peptides and other compounds, microbial degraders, and macrophyte-associated bioremediation strategies aimed at mitigating cyanotoxin risks in aquatic environments. Full article

Fluoxetine (FLX) is an antidepressant pertaining to the class of selective serotonin reuptake inhibitors. FLX use has increased in the past decade culminating in its discharge to surface waters. Owing to the limited knowledge about the toxicity of this drug to aquatic biota, this study aimed to evaluate potential toxic effects of FLX on green algae Chlorella vulgaris, cyanobacteria Microcystis novacekii, marine bacteria Aliivibrio fischeri, and mollusk Biomphalaria glabrata. Assays with C. vulgaris and M. novacekii followed OECD protocol 201 (2011) and NBR 12648 standard (2018), respectively. The assay with A. fischeri was carried out according to ISO/OIN 11348-3 (2007). Toxicity assays with B. glabrata were performed by exposing these organisms (newborn and embryos) in 24-well culture plates for 3 and 7 days, respectively. All test-organisms were exposed to at least 6 different concentrations of FLX, ranging from 0.1 to 20,000 µg/L, in triplicates. Effect concentrations (EC50) obtained for these assays showed that FLX is more toxic to M. novacekii (10.71 ± 1.67 µg/L), followed by C. vulgaris (13.01 ± 2.01 µg/L) and A. fischeri (3140 ± 1050 µg/L). Regarding B. glabrata, the 50% lethal concentration for newborns was 1770 ± 260 µg/L, while for embryos it was equivalent to 34.98 ± 3.66 µg/L. Considering recent reports of FLX occurrence in environmental matrices in the µg/L range, results reported in this study and the toxicity classification criteria by the Globally Harmonized System, FLX poses high risk to aquatic environments, its biodiversity, and ecosystems. Therefore, measures must be taken to prevent the disposal of waste containing FLX into the environment, especially in region lacking basic sanitation infrastructure. Full article

Clear Lake in Lake County, CA, USA has experienced highly toxic cyanobacterial blooms for more than a decade, with multiple cyanobacterial taxa and cyanotoxins appearing sporadically, typically throughout much of the early-spring to late-fall seasons. Recurring blooms have been attributed to high internal nutrient loads within the lake, with hydrography and hydrology playing important but still poorly documented roles in controlling the availability of growth-limiting elements to the phytoplankton community. The lake is approximately 180 km² in areal extent and composed of three somewhat disjointed lobes, or ‘Arms’. The large size of the lake presents a formidable task for synoptic lakewide surveys and for understanding the specific features that stimulate the development and magnitude of harmful blooms. We conducted a study in August of 2020 that involved the use of an autonomous underwater vehicle and deployment of a hand-held water column profiler to describe the lakewide status of various biological, chemical, and physical features. Discrete water samples were also collected from ten stations located throughout the lake to produce a near-synoptic depiction of lake status. Additionally, a mechanically driven, continuously monitoring water-column profiler was deployed at a central lake location to document short-term temporal (minutes to months) changes in water-column structure and chemistry. Wind was a dominant feature affecting the lake’s chemistry and biology during the study, resulting in massive concentrations and dramatic spatial heterogeneity of phytoplankton biomass and cyanotoxins in the eastern and southeastern Arms of the lake, and confirmed by the analysis of discrete water samples. Unique insight into the processes leading to or prolonging blooms was revealed by the water column profiler, which demonstrated rapid development (within a few hours) of suboxic conditions during periods of calm winds. We speculate that these quiescent periods are fundamental events in the lake’s ecology, resulting in episodic ‘pulses’ of nutrient release from the sediments, which can stimulate or refuel blooms of cyanobacteria in the water column. Full article