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Simple Summary: The life cycle of marine benthic invertebrates includes a planktonic larval stage and a benthic adult stage, with larval settlement being the critical transition from a planktonic to a benthic lifestyle. Since adult mobility is limited or completely lost in the benthic environment, larval settlement directly affects population distribution, growth, and reproduction. Although larval settlement induced by natural chemical cues is widespread among marine invertebrates, the molecular mechanisms underlying this process remain unclear. Mytilopsis sallei, a typical marine fouling mussel, releases three purine compounds—adenosine, inosine, and hypoxanthine—that synergistically induce larval settlement. In this study, transcriptomic sequencing was employed to identify differentially expressed genes and signaling pathways associated with purine-compound-induced larval settlement. This research not only provides new insights into the molecular mechanisms of larval settlement in marine benthic invertebrates, but also offers a scientific basis and theoretical foundation for the ecological control of marine fouling organisms. The settlement of marine benthic invertebrate larvae is a crucial stage in their life cycle, directly influencing their population distribution, growth, and reproduction. It is generally believed that multiple chemical inducers in the environment synergistically affect larval settlement, though the underlying molecular mechanisms remain unclear. Our previous study has established that three purine compounds (adenosine, inosine, and hypoxanthine) released by adults of the mussel Mytilopsis sallei synergistically induced larval settlement. In this study, we performed transcriptomic sequencing analysis on larvae exposed to individual purine compounds and those exposed to a combination of three purine compounds. A total of 21,850 differentially expressed genes (DEGs) were identified. KEGG enrichment analysis of these DEGs revealed that the AMPK signaling pathway, FoxO signaling pathway, extracellular matrix (ECM)-receptor interaction, focal adhesion, and the thyroid hormone signaling pathway play key roles in the settlement of M. sallei larvae. Moreover, in larvae exposed to the combined action of three purines, the expression of relevant signaling pathways and metabolic processes was more significant. This research provides important information for understanding the molecular mechanisms underlying the induction of larval settlement in M. sallei by purine compounds in natural environments. [ABSTRACT FROM AUTHOR]

Marine ranching is a fishery model that can improve the ecological environment of sea areas, increase and conserve fishery resources, and realize the sustainable utilization of fishery resources. It is widely used worldwide. In Shandong Province, marine ranching is divided into the following types: Reef casting, game fishing, bottom seeding, pastoral, and equipment, based on the production mode. Among them, pastoral marine ranching refers to marine ranching dominated by three-dimensional ecological aspects such as raft culture facilities.Raft culture facilities are a culture framework that must be constructed for the culture of bivalves such as oysters, scallops, and mussels in China's coastal waters. These facilities include six parts: a wooden pile, pursed rope, float, suspended cage, suspended rope, and floating rope. In the process of bivalve culture, the construction of a raft culture facility provides a good adhesion substrate for other organisms in the ocean, and a large number of fouling organisms will inhabit and survive on the culture facility. The activity of these fouling organisms will soften the raft culture facility and shorten the service life of the raft culture facility. Furthermore, the fouling organisms can plug the mesh, leading to the death of the farmed shellfish due to lack of oxygen, causing economic losses. However, relevant studies have also shown that the presence of fouling organisms can accelerate the rate of nutrient salt exchange between suspended organisms and aquaculture waters, which can promote the growth of phytoplankton, improve primary productivity, provide more bait for bivalve culture, and increase the fertility of bivalve culture, which is beneficial to bivalve culture. There are differences in the relationship between the fouling organisms' species number and biomass and environmental factors across different raft aquaculture areas. Therefore, basic research must be conducted on fouling organisms in raft culture areas to provide reference for healthy bivalve culture and further provide basic data for exploring the impact of fouling organisms on the ecological environment in raft culture facilities.To explore the seasonal changes of fouling organisms in raft culture facilities of pastoral marine ranching and their relationship with environmental factors, a 4-quarter survey was performed in the pastoral marine ranching area of Rushan Huaxin Foodstuffs Co., Ltd., from July 2022 to April 2023. A total of four fixed stations were set up in the raft culture area of oysters for each survey. The fouling organisms were investigated at each station. An area of 10 cm × 10 cm in the float, a length of 30 cm of the floating rope, and an area of 20 cm × 20 cm in the suspended cage were sampled. The collected samples were bottled and numbered; then, the sample was fixed and stored in 5% formaldehyde solution, and returned to the laboratory for species identification and counting. The species, biomass, diversity, dominant species, and community structure of the fouling organisms at three different sampling sites were analyzed, and the relationship between environmental factors and dominant species was determined by redundancy analysis (RDA) and Spearman analysis.The results showed that 35 species of fouling organisms were found in eight categories, including 13 species of Crustacea, 8 species of Mollusca, 4 species of Polychaeta, 3 species of Chordate, 2 species of Cnidaria and Phaeophyta, and 1 species each of Rhodophyta, Chlorophycophyta, and Echinodermata. There were significant seasonal variations in the community structure of fouling organisms. Furthermore, there were significant differences in the community structures of fouling organisms in suspended cages, floating ropes, and floats, and the biomass varied in the ranges of 31.48~1 645.82 g/m2, 23.22~580.76 g/m2, and 5.76~30.12 g/m2, respectively. The maximum biomass of fouling organisms appeared in summer. The richness index, evenness index, and diversity index of the fouling organisms ranged from 1.38 to 3.61, 0.33 to 0.92, and 0.88 to 2.58, respectively. The lowest richness index was observed on the summer float, the lowest evenness index and diversity index were observed on the summer suspended cage, and the three indexes reached the highest values on the spring suspended cage. The dominant species of fouling organisms belonged to the phyla Crustacea and Mollusca. Mytilus edulis was the dominant species on the floating ropes and suspended cages, and Caprella aino was the dominant species on the floats. The dominant species of fouling organisms in the float showed obvious seasonal changes. The dominant species on the float in summer was Perinereis aibuhitensis, and that in autumn was Crassostrea gigas. Gracilaria vermiculophylla was the dominant species on the float in winter and spring. The RDA results of dominant species and environmental factors showed that transparency, temperature, silicate levels, and chlorophyll were the main environmental factors affecting the community structure of fouling organisms, and the correlation between different species and environmental factors was also different. In this study, the seasonal variation of fouling organisms and their relationship with environmental factors were investigated in the Rushan oyster raft culture facility, and our results can provide reference for healthy oyster culture in this area.

Ultrasonic technology has drawn extensive interests for its great potential in marine antifouling applications. However, its effects on the adhesion behavior of marine fouling organisms on marine structures remain underexplored. This work investigated how ultrasonic treatment impacted the adhesion of Pseudoalteromonas on a gel-like marine epoxy primer. And the process parameters for ultrasonic treatment were optimized using response surface analysis with Design-Expert software 11. The results revealed that ultrasonic treatment disrupted the cellular structure of Pseudoalteromonas, causing the deformation and fragmentation of the cell membrane, leading to bacterial death. Additionally, ultrasonic treatment reduced the particle size and Zeta potential value of Pseudoalteromonas, which disrupted the stability of bacterial suspensions. It also increased the relative surface hydrophobicity of Pseudoalteromonas cells, resulting in a reduction in adhesion to the gel-like marine epoxy primer. This study demonstrated that ultrasonic treatment significantly disturbed the adhesion behavior of microorganisms like Pseudoalteromonas on the gel-like marine epoxy primer, which provided an effective approach for controlling marine biofouling. [ABSTRACT FROM AUTHOR]

Herein, inspired by the macrophage's defensive behavior of releasing free radicals to kill bacteria and viruses, a marine antifouling coating with dynamic surfaces is prepared by precise regulation of dynamic covalent bonds. Alkyl radical (R·) derived from oxime-urethane structure attracts and disrupts microbe cell membrane and pili between intimate cells, resulting in excellent anti-biofouling effect. Moreover, the newly exposed coating then continues to break, which ultimately results in the peeling of the layers, thus making barnacles, mussels and other fouling organisms less likely to adhere. [Display omitted] • Macrophage-inspired marine antifouling coating with dynamic surfaces is prepared. • Alkyl radical (R·) derived from oxime-urethane structure offers excellent anti-fouling performance. • The newly exposed coating continues to break making it less likely that fouling organisms will adhere to it. • This study presents a novel methodology for fulfilling the technological gap of marine coatings with dynamic surface. Macrophages can kill bacteria and viruses by releasing free radicals, which provides a possible approach to construct antifouling coatings with dynamic surfaces that release free radicals if the breaking of dynamic covalent bonds is precisely regulated. Herein, inspired by the defensive behavior of macrophages of releasing free radicals to kill bacteria and viruses, a marine antifouling coating composed of polyurethane incorporating dimethylglyoxime (PU x -DMG) is prepared by precise regulation of dynamic oxime-urethane covalent bonds. The obtained alkyl radical (R·) derived from the cleavage of the oxime-urethane bonds manages to effectively suppress the attachment of marine biofouling. Moreover, the intrinsic dynamic surface makes it difficult for biofouling to adhere and ultimately achieves sustainable antifouling property. Notably, the PU 50 -DMG coating not only presents efficient antibacterial and antialgae properties, but also prevents macroorganisms from settling in the sea for up to 4 months. This provides a pioneer broad-spectrum strategy to explore the marine antifouling coatings. [ABSTRACT FROM AUTHOR]

Ultrasound waves have been employed to control marine biofouling but their effects on fouling organisms remain poorly understood. This study investigated the influence of ultrasound waves on barnacle (Tetraclita stalactifera cyprid larvae) pre-settlement behavior. Substrate inspection constituted most of the larval time budget, with a focus on the bottom surface rather than lateral or air–water interfaces. The frequency of substrate inspection decreased at 10 kPa when compared to higher acoustic pressures, while the time spent in the water column had an opposite trend. Various larval swimming modes were observed, including rotating, sinking, walking, and cruising, with rotating being dominant. Barnacle larvae exhibited higher speeds and less complex trajectories when subjected to ultrasound in comparison to controls. The impact of ultrasound waves on barnacle cyprid larvae behavior had a non-linear pattern, with lower acoustic pressure (10 kPa) inducing more effective substrate rejection than higher (15 and 20 kPa) intensities. [ABSTRACT FROM AUTHOR]

Simple Summary: Marine biofouling is the undesirable accumulation of marine organisms onto man-made surfaces, which causes severe economical and environmental consequences. In recent years, using natural products as environmentally friendly antifouling agents to combat foulers has been a promising approach. However, the search for effective antifouling agents is hampered by the lack of well-defined conserved molecular targets responsible for regulating the larval settlement in fouling organisms. In this study, an in silico approach was used to screen the natural compounds' libraries against silk gland factor 1 (SGF1), which is responsible for the larval settlement of the fouling mussel Mytilopsis sallei. It was found that the targeted binding compounds against SGF1 could significantly affect the larval settlement, foot proteins' gene expression, and byssus secretion of adults in M. sallei. The laboratory bioassay results are promising, even though field trials are necessary to confirm the in silico results. Hence, this study paves the way for new experimental studies to be carried out for finding environmentally friendly antifouling agents by using SGF1-targeted compounds. Most fouling organisms have planktonic larval and benthic adult stages. Larval settlement, the planktonic–benthic transition, is the critical point when biofouling begins. However, our understanding of the molecular mechanisms of larval settlement is limited. In our previous studies, we identified that the AMP-activated protein kinase-silk gland factor 1 (AMPK-SGF1) pathway was involved in triggering the larval settlement in the fouling mussel M. sallei. In this study, to further confirm the pivotal role of SGF1, multiple targeted binding compounds of SGF1 were obtained using high-throughput virtual screening. It was found that the targeted binding compounds, such as NAD+ and atorvastatin, could significantly induce and inhibit the larval settlement, respectively. Furthermore, the qRT-PCR showed that the expression of the foot proteins' genes was significantly increased after the exposure to 10 μM NAD+, while the gene expression was significantly suppressed after the exposure to 10 μM atorvastatin. Additionally, the production of the byssus threads of the adults was significantly increased after the exposure to 10–20 μM of NAD+, while the production of the byssus threads was significantly decreased after the exposure to 10–50 μM of atorvastatin. This work will deepen our understanding of SGF1 in triggering the larval settlement in mussels and will provide insights into the potential targets for developing novel antifouling agents. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are insidious plastic particles with sizes ranging from 1 to 5000 µm. Their presence has been reported all over the world. Recently, bioremediation to remove MPs from water columns using filter feeders as biofilters has been proposed. In a previous lab experiment, the MP bioremediation potential of four fouling organisms from a mariculture facility (Mytilus galloprovincialis, Sabella spallanzanii, Phallusia mammillata, Paraleucilla magna) was separately assessed in single-species experiment. Herein, a follow-up of the work is presented using a multi-species approach. The four organisms were placed together in the same 5 L beaker and fed with a concentration of 250 p/L 6 µm red polystyrene discernible particles. After digesting the organisms and counting the MPs in both the water and the organisms, the results of the two experiments were compared. In the previous experiment, S. spallanzanii had the highest particle retention (PR) value (PR = 88.01%), while in this experiment, P. mammillata has the lowest PR value (PR = 31%). The multi-species approach resulted in a higher number of plastics being removed from the water (88%) compared to the single-species experiments. These fouling organisms naturally exist as a community, acting as an efficient filter with complex morphologies and hydrodynamic features. Here, this simple marine animal forest is re-evaluated by exploiting the ecosystem services provided by these organisms as a solution to MP pollution problem in a mariculture environment. [ABSTRACT FROM AUTHOR]

The port fouling fauna from Mexico has received greater study in the last 15 years. By improving our knowledge of fouling invertebrates on artificial substrates on the Southern Pacific coast of Mexico, we can better understand their distribution and prevent bioinvasions. The specimens listed in this present study come from PVC plates that were placed between June 2019 to June 2020 submerged at 1 m depth, on four docks of the Chahué Marina, Oaxaca, Mexico. Forty-four taxa, representing nine phyla were identi-fied: Sipuncula (1 species), Entoprocta (1), Bryozoa (3), Arthropoda (3), Porifera (4), Cnidaria (5), Chordata (6), Mollusca (10) and Annelida (11). Thirty taxa were identified to species, with two still requiring confirmation. Five were identified to genus, two to family, and five to class level. From the 30 identified species, 18 were non-native species: one entoproct, one mollusk, two bryozoans, three hydrozoans, three barnacles, four polychaetes, and four ascidians. These results include seven new records from the state of Oaxaca: one entoproct, one barnacle, two bryozoans, and three hydrozoans. [ABSTRACT FROM AUTHOR]

Many female squids and cuttlefishes have a symbiotic reproductive organ called the accessory nidamental gland (ANG) that hosts a bacterial consortium involved with egg defense against pathogens and fouling organisms. While the ANG is found in multiple cephalopod families, little is known about the global microbial diversity of these ANG bacterial symbionts. We used 16S rRNA gene community analysis to characterize the ANG microbiome from different cephalopod species and assess the relationship between host and symbiont phylogenies. The ANG microbiome of 11 species of cephalopods from four families (superorder: Decapodiformes) that span seven geographic locations was characterized. Bacteria of class Alphaproteobacteria, Gammaproteobacteria, and Flavobacteriia were found in all species, yet analysis of amplicon sequence variants by multiple distance metrics revealed a significant difference between ANG microbiomes of cephalopod families (weighted/unweighted UniFrac, Bray–Curtis, P = 0.001). Despite being collected from widely disparate geographic locations, members of the family Sepiolidae (bobtail squid) shared many bacterial taxa including (~50%) Opitutae (Verrucomicrobia) and Ruegeria (Alphaproteobacteria) species. Furthermore, we tested for phylosymbiosis and found a positive correlation between host phylogenetic distance and bacterial community dissimilarity (Mantel test r = 0.7). These data suggest that closely related sepiolids select for distinct symbionts from similar bacterial taxa. Overall, the ANGs of different cephalopod species harbor distinct microbiomes and thus offer a diverse symbiont community to explore antimicrobial activity and other functional roles in host fitness. IMPORTANCE Many aquatic organisms recruit microbial symbionts from the environment that provide a variety of functions, including defense from pathogens. Some female cephalopods (squids, bobtail squids, and cuttlefish) have a reproductive organ called the accessory nidamental gland (ANG) that contains a bacterial consortium that protects eggs from pathogens. Despite the wide distribution of these cephalopods, whether they share similar microbiomes is unknown. Here, we studied the microbial diversity of the ANG in 11 species of cephalopods distributed over a broad geographic range and representing 15–120 million years of host divergence. The ANG microbiomes shared some bacterial taxa, but each cephalopod species had unique symbiotic members. Additionally, analysis of host–symbiont phylogenies suggests that the evolutionary histories of the partners have been important in shaping the ANG microbiome. This study advances our knowledge of cephalopod–bacteria relationships and provides a foundation to explore defensive symbionts in other systems. [ABSTRACT FROM AUTHOR]

Surface biofouling, corrosion, and wettability are important parameters to understand and characterize aluminum alloys to prevent the failure in marine environments. Antifouling technologies predominantly encompass chemical and biocidal approaches with negative environmental consequences. Therefore, this study focuses on a new method of producing non‐toxic and effective antifouling and corrosion‐resistant surfaces. In this study, ultrafast laser texturing is used to modify the surface of an aluminum alloy using a femtosecond laser system. Five different unique texture patterns are designed and fabricated using 3 W laser power, 100 kHz pulse repetition rate, and 4 mm s−1 scanning speed in order to make the aluminum surface antifouling and corrosion resistant. The non‐textured sample has a contact angle of 85° while the textured samples have contact angles of up to 157°. The contact angle increased with time up to 90 days of aging. Biofouling assessment is conducted using marine algae Nitzschia ovalis as a marine fouling test organism. A reduction of biofilm coverage of 79% is recorded from the laser‐produced star pattern texture. This study demonstrates that laser‐textured surfaces have the potential to mitigate the formation of biofilms on the surfaces while also providing a mechanism to control the relative level of corrosion. [ABSTRACT FROM AUTHOR]

This study reported the composition of the macrobenthic assemblage living on the shell of the pectinid scallop Mimachlamys sanguinea inhabiting the Suez Canal Expansion Channel. Nine epibiont groups were observed encrusting the valves of the scallop primarily serpulids, barnacles and tunicates (20.9, 15.5, and 14.8%, respectively). The upper valve was significantly more fouled than the lower one. A positive correlation was observed between the percent cover of fouling material and the shell size, with maximum percent cover and size occurring during the spring. The relationship between the scallop and its fouling organisms was discussed. The importance of M. sanguinea shells as a natural substratum for various epibiotic groups was highlighted in this study. [ABSTRACT FROM AUTHOR]

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The purpose of this study is to describe fishermen's and managers' current awareness of International Maritime Organization (IMO) biofouling guidelines to improve biofouling management on all fishing vessel types in the northern Persian Gulf. A total of 234 in-depth and semi-structured interviews were conducted face-to-face with fishermen and managers using a random sampling technique from February to November 2021. Analyses of data indicated that the majority of industrial fishermen (87%) and all of managers were aware of the IMO biofouling guidelines, but traditional fishermen had a low level of awareness (38%) and they had also many problems such as increased cost, lack of training courses, lack of sufficient facilities for implementation of IMO biofouling guidelines. For industrial fishermen, literacy was a most effective variable on awareness of IMO guidelines (p ˂ 0.05, r = 1.62). As regulations to prevent invasions and the accumulation of biofouling in fishing gear and fleets, biofouling should be managed and evaluated, and also training should be provided to fishermen to clean the biofouling of fishing gear and fleets in accordance with IMO guidelines, as well as more monitoring by managers, environmentalists, the government, and policymakers. [ABSTRACT FROM AUTHOR]

This research aimed to reduce reliance on chemical antifouling agents; it was conducted at depths of 0.5 and 1.5 meters in the Eastern Harbor, at Alexandria, Mediterranean Sea. This study delves into the realm of environmentally sustainable antifouling solutions by exploring the efficacy of natural crude extracts from two Red Sea sponge species, Acanthella acuta (Extract A) and Carteriospongia sp. (Extract B). The results revealed a rich diversity of fouling organisms, encompassing six phyla, seven classes, eleven orders, twenty-two families, and thirty-three species. Noteworthy absences were noted at specific depths, indicating depth-dependent variations in fouling communities . The application of extract A at 0.5 meters depth demonstrated significant reductions in fouling biomass and shifts in dominant species. Treatment 3 stood out with the lowest biomass (9.69 ± 2.83 g/m² ) and the fewest species (only 2 species). At 1.5 meters depth, extract B exhibited consistent trends with treatment 6 displaying the lowest biomass (20.85 ± 23.35 g/m2 ) and also species diversity (only 2 species). Meanwhile, Extract B showcased compelling antifouling potential. At 0.5 meters depth, treatment 4 exhibited notable reductions in fouling biomass, dominated by Balanus amphitrite, Balanus eburneus, and Balanus sp. At 1.5 meters depth, treatment 6 emerged as the most effective, with the lowest biomass (249.3 ± 120.4 g/m² ) and a streamlined species composition. This study underscores the promise of natural crude extracts from the Red Sea sponges as potent alternatives for environmentally friendly antifouling strategies. The observed variations in fouling biomass and species composition offer critical insights for the development and application of these extracts in combating fouling organisms, presenting a significant stride toward sustainable marine ecosystem conservation. [ABSTRACT FROM AUTHOR]

Marine biofouling, undesirable growth of organisms on submerged surfaces, poses significant challenges in various industries and marine applications. The development of environmentally safe antifouling coatings employing nano-MnO2/cellulose nanofiber (CNF) composite with bisphenol A epoxy diacrylate/glycidyl methacrylate (BED/GMA) irradiated by electron beam (T1) has been achieved in the current work. The physico-chemical characteristics of the fabricated coatings have been studied using Fourier transforms infrared spectroscopy, scanning electron microscope, water contact angle, and X-ray diffraction. The efficacy of T1 formulation and pure BED/GMA polymer (T2) in inhibiting biofouling formation was investigated in seawater of Alexandria Eastern Harbour by examining biofilm development morphologically and biochemically. In addition, regular analyses of seawater physicochemical parameters were conducted monthly throughout study. Results provide valuable information on coating performance as well as the complex interactions between coatings, biofilms, and environmental factors. The T1 formulation exhibited strong anti-fouling and anticorrosion properties over 2 months. However, after four months of immersion, all coated steel surfaces, including T1, T2, and T0, were heavily covered with macro-fouling, including tubeworms, barnacles, and algae. Biochemical analysis of extracellular polymeric substances (EPS) showed statistically significant variations in carbohydrates content between the coated surfaces. The T1 formulation showed decreased protein and carbohydrate content in EPS fractions after 14 days of immersion indicating less biofouling. Moreover, elemental analysis showed that carbon, oxygen, and iron were the predominant elements in the biofilm. Other elements such as sodium, silicon, chloride, and calcium were in lower concentrations. T2 and T0 surfaces revealed higher calcium levels and the appearance of sulphur peaks if compared with T1 surface. Diatoms and bacteria were detected on T1, T2, and T0 surfaces. The observed warming of seawater and nutrient-rich conditions were found to promote the growth of fouling organisms, emphasizing the importance of considering environmental factors in biofouling management strategies. [ABSTRACT FROM AUTHOR]

This is a phylogeographical study of Juxtacribrilina mutabilis, a recently described bryozoan from Japan with sightings in Sweden, Norway, and Maine (US), to test how fast and far it has expanded across Europe in recent years. J. mutabilis settles easily on ship hulls, making it a useful model organism for studying long-distance invasion pathways. The study was conducted using Autonomous Reef Monitoring Structures (ARMS) to monitor the entire European coastline and Svalbard for J. mutabilis using DNA metabarcoding. During the time between its first sighting in Europe 2008 and the last ARMS retrieval 2020, the data shows how J. mutabilis has gained a pan-European distribution, being genetically identified in 14 new distinct locations. Presence/absence of barcodes were confirmed by image-based identification in 74% of the samples. Fourteen haplotypes never reported before were discovered in a 264 bp region of the cytochrome oxidase I gene. Two haplotypes (HP1 and HP3) occurred frequently and geographically widely dispersed, indicating intercontinental connectivity. Two locations, Koster and Getxo showed particularly high genetic diversity with similar haplotype networks suggesting continuous gene flow across oceanographically unlinked regions. Given the recent description of J. mutabilis and the relatively few historical encounters, the genetic diversity described here suggests an unusually fast range expansion within the last two decades. Such global spreading events of fouling organisms may become more common in the future as a result of more frequent and interconnected ship traffic. [ABSTRACT FROM AUTHOR]

Marine habitats are being targeted for the extraction of offshore renewable energy (ORE) as part of the drive to decarbonise electricity generation. Unmanaged biofouling impacts ORE devices and infrastructure by elevating drag forces, increasing weight, and accelerating corrosion, leading to decreased performance and survivability, and extending costly periods of maintenance. ORE deployments in high tidal flow locations are providing opportunities to study the biofouling unique to these habitats. In this study, surveys of numerous devices and associated infrastructure deployed at the European Marine Energy Centre in Scotland identified high tidal flow fouling assemblages. Substrate orientation relative to tidal flow appears to affect the abundance of key fouling species, including the massive barnacle Chirona hameri. This species is shown to recruit to a wide range of artificial substrates, over a prolonged period from mid-spring to mid-summer, and in maximum current speeds from 0.4–4.0 m/s. For the first time, C. hameri is reported in near-surface depths, on uncoated components of a floating tidal device. The highly gregarious settlement behaviour and rapid growth exhibited by this species may have important implications for managing fouling in the ORE industry, especially in 'niche' areas. Anti-fouling strategies and maintenance scheduling applicable to ORE and other marine industries are discussed. [ABSTRACT FROM AUTHOR]

The adhesion of marine-fouling organisms to ships significantly increases the hull surface resistance and expedites hull material corrosion. This review delves into the marine biofouling mechanism on marine material surfaces, analyzing the fouling organism adhesion process on hull surfaces and common desorption methods. It highlights the crucial role played by surface energy in antifouling and drag reduction on hulls. The paper primarily concentrates on low-surface-energy antifouling coatings, such as organic silicon and organic fluorine, for ship hull antifouling and drag reduction. Furthermore, it explores the antifouling mechanisms of silicon-based and fluorine-based low-surface-energy antifouling coatings, elucidating their respective advantages and limitations in real-world applications. This review also investigates the antifouling effectiveness of bionic microstructures based on the self-cleaning abilities of natural organisms. It provides a thorough analysis of antifouling and drag reduction theories and preparation methods linked to marine organism surface microstructures, while also clarifying the relationship between microstructure surface antifouling and surface hydrophobicity. Furthermore, it reviews the impact of antibacterial agents, especially antibacterial peptides, on fouling organisms' adhesion to substrate surfaces and compares the differing effects of surface structure and substances on ship surface antifouling. The paper outlines the potential applications and future directions for low-surface-energy antifouling coating technology. [ABSTRACT FROM AUTHOR]

Carbon steels are widely used in ocean engineering due to their cost effectiveness, ease of manufacture, and excellent weldability. However, the attachment of macro-fouling organisms in seawater poses a serious threat to the integrity of carbon steel structures. In this experiment, carbon steel plates were immersed in the Dalian Sea area from January to October to investigate the effects of macro-fouling on corrosion propagation. The electrochemical measurement indicated that the propensity for the corrosion of Q235B is ranked as ascidians > mussels > barnacles. The characterization results indicated that various marine organisms significantly influenced the corrosion behavior of Q235B carbon steel immersed in natural seawater. The colonization of barnacles inhibited corrosion at the barnacle central area, and the presence of barnacle covering caused crevice corrosion at the edges of the barnacle due to oxygen concentration cells. The presence of ascidians resulted in general corrosion due to the locally high conductivity and ion diffusion rate. A relatively compact rust layer, which exhibited localized defects, was observed beneath the mussels. Seawater had the ability to penetrate the rust layer through these defects, leading to the formation of pitting corrosion on the metal substrate. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a method for assessing the growth of photoautotrophs on plaster coatings, which will be used to reliably assess the resistance of these materials to photoautotrophic growth in the simulation of long-term exposure. In the course of the study, mineral and silicone plaster substrates were inoculated with a mixture of Stichococcus bacillaris, Nostoc commune, Pseudochlorella signiensis, and Coenochloris signiensis, and incubated for 28 days in model conditions. At 14 and 28 days after inoculation, the degree of photoautotrophic growth was determined using hemocytometer cell counting, a HY-LiTE 2 ATP measuring system, chlorophyll a concentration quantification, CIE L*a*b spectrophotometric color change evaluation, and visual assessment. The acquired results allowed us to select visual assessment and spectrophotometric color change evaluation as quick-to-perform and reliable techniques for further laboratory studies. The impact of minor changes introduced in the inoculation and incubation procedures on the rate of biofilm formation and severity of microbial fouling was studied. Differences in inoculation and incubation procedures strongly affected the results of the performed tests. Both methods have shown high potential and should be further expanded upon in environmental studies. [ABSTRACT FROM AUTHOR]

This study aimed to study the settlement of fouling organisms in the Eastern Harbor of Alexandria during the period from 2019 to 2020. Seasonal samples of marine fouling invertebrate species had been collected using white roughened wood test panels. Some environmental parameters (temperature, transparency, salinity, pH, and dissolved oxygen) were studied. The fouling invertebrate species and taxa were identified and classified. Statistical analysis was conducted using primer and paste software. The results of this study showed that some environmental parameters such as dissolved oxygen and water temperature of marine water in Eastern Harbor, Alexandria can significantly affect the settlement of fouling organisms. The results showed also that the fouling was composed of 37 invertebrate species, belonging to 23 families, within 12 orders, 7 classes, and 6 phyla. The highest diversity phyla were Crustacea (20 species from 11 families), followed by Bryozoa (7 species from 7 families) and Annelida (6 species from 2 families). The biomass of fouling invertebrate families and their species varied in different depths. The most heavy families were Serpulidae and Balanidae. At 0.5 m depth, Hydroides elegans had the mostly heavy biomass (2720.2±1716.3 g/m2); followed by Balanus amphitrite (889.3±687.4 g/m2). At 1.5 m depth, also Hydroides elegans had the heavy biomass (2264.6±2506.7 g/m2); followed byBalanus perforates (1691.3±3198.3 g/m2). Seasonal variation in fouling invertebrate biomass showed that Hydroides eleganes represented the heaviest recorded biomass during spring, summer and autumn, while Balanus amphitrite was the heaviest biomass observed during winter. [ABSTRACT FROM AUTHOR]

Non-indigenous species tend to colonize aquaculture installations, especially when they are near international ports. In addition to the local environmental hazard that colonizing non-indigenous species pose, they can also take advantage of local transport opportunities to spread elsewhere. In this study, we examined the risk of the spread of eight invasive fouling species that are found in mussel farms in southern Brazil. We used ensemble niche models based on worldwide occurrences of these species, and environmental variables (ocean temperature and salinity) to predict suitable areas for each species with three algorithms (Maxent, Random Forest, and Support Vector Machine). As a proxy for propagule pressure, we used the tonnage transported by container ships from Santa Catarina (the main mariculture region) that travel to other Brazilian ports. We found that ports in the tropical states of Pernambuco, Ceará, and Bahia received the largest tonnage, although far from Santa Catarina and in a different ecoregion. The ascidians Aplidium accarense and Didemnum perlucidum are known from Bahia, with a high risk of invasion in the other states. The bryozoan Watersipora subtorquata also has a high risk of establishment in Pernambuco, while the ascidian Botrylloides giganteus has a medium risk in Bahia. Paraná, a state in the same ecoregion as Santa Catarina is likely to be invaded by all species. A second state in this region, Rio Grande do Sul, is vulnerable to A. accarense, the barnacle Megabalanus coccopoma, and the mussel Mytilus galloprovincialis. Climate change is changing species latitudinal distributions and most species will gain rather than lose area in near future (by 2050). As an ideal habitat for fouling organisms and invasive species, aquaculture farms can increase propagule pressure and thus the probability that species will expand their distributions, especially if they are close to ports. Therefore, an integrated approach of the risks of both aquaculture and nautical transport equipment present in a region is necessary to better inform decision-making procedures aiming at the expansion or establishment of new aquaculture farms. The risk maps provided will allow authorities and regional stakeholders to prioritize areas of concern for mitigating the present and future spread of fouling species. [ABSTRACT FROM AUTHOR]

Biofouling is a significant means for introducing non-indigenous marine species internationally, which can alter habitats and disturb marine ecosystems. This study estimated the flux of ships' wetted surface area (WSA) to Korea in 2020 to assess the risks of biological invasion via biofouling on ships' hulls. The annual total WSA flux entering Korea was estimated to be 418.26 km2, with short-stay vessels (<3 weeks) contributing to 99.7% of the total WSA flux. Busan and Ulsan ports were identified as the main sources of high-risk flux, with container ships being a major vector in Busan and tankers in Ulsan. Gwangyang port had the third-highest total WSA flux, with nearly half of the flux driven from coastwise voyages, making it particularly vulnerable to the spread of hull fouling organisms. These findings could help enhance the management and inspection of hull fouling organisms in Korea. [ABSTRACT FROM AUTHOR]

Implantable electrochemical sensors that enable the real-time detection of significant biomarkers offer huge potential for the enhancement and personalisation of therapies; however, biofouling is a key challenge encountered by any implantable system. This is particularly an issue immediately after implantation, when the foreign body response and associated biofouling processes are at their most active in passivating a foreign object. Here, we present the development of a sensor protection and activation strategy against biofouling, based on coatings consisting of a pH-triggered, dissolvable polymer, that covered a functionalised electrode surface. We demonstrate that reproducible delayed sensor activation can be achieved, and that the length of this delay can be controlled by the optimisation of coating thickness, homogeneity and density through tuning of the coating method and temperature. Comparative evaluation of the polymer-coated and uncoated probe-modified electrodes in biological media revealed significant improvements in their anti-biofouling characteristics, demonstrating that this offers a promising approach to the design of enhanced sensing devices. [ABSTRACT FROM AUTHOR]

Fouling organisms reduce a ship's fuel efficiency and disturb the ecosystem. Therefore, the International Maritime Organization (IMO) and many nations have enacted laws that mandate periodic hull cleaning for removing fouling organisms. However, cleaning niche areas of the ship hull is extremely difficult. Due to their complex shape, applying antifouling paint and cleaning with hull cleaning robots is difficult, but about 80% of fouling organisms are concentrated in the niche areas. To resolve this issue, this research proposes the use of an autonomous cleaning robot with a hydraulic polyarticular robot arm to clean niche areas of the ship hull. This robot can approach niche areas of the ship hull with complex shapes using its polyarticular arm. It was designed to be able to scan the cleaning area, establish a cleaning plan, and clean accordingly. This robot autonomously cleaned a propeller blade, which is a typical niche area of the ship hull, to verify the applicability of this system. The experiment results show that approximately 80% of the biofouling was removed from the hull crevices and 81% of the cleaned biofouling was recovered. [ABSTRACT FROM AUTHOR]

With increasing numbers of antimicrobial‐resistant (AMR) bacteria strains, it becomes essential that new and effective routes to minimizing bacterial infection rates are produced. Superhydrophobic materials show to be effective in reducing the attachment of bacteria due to their unique wetting properties which can minimize the points at which bacteria can initially adhere. Here, the impact of surface design on the anti‐biofouling capabilities of superhydrophobic pillared arrays prepared via photolithography is investigated. By systematically varying pillar spacing, insight is gained into the complex nature of superhydrophobic fouling as well as allowing for optimization of the antifouling performance. The optimal material within is achieved at a pillar spacing of 87.5 µm, which shows over a 3‐log (and gt; 99.9%) reduction in bacterial attachment. [ABSTRACT FROM AUTHOR]

A new species belonging to the genus Parathalestris Brady & Robertson, 1873 was identified and described here based on samples recently collected from a survey on fouling organisms at the Zhonggang wharf in Qingdao, China. The new species differs from its congeners in the following characteristics: caudal rami 2.0 times longer than wide, with bulbous setae II and setae III of caudal ramus issuing terminally and laterodistally, respectively; exopod of antenna two-segmented, with two setae on first segment and four setae on second one;maxilla with two bipinnate setae on proximal endite, and three spinulose setae on middle and distal endites; basis of maxilliped with concave inner edge; P1 exopod and endopod approximately same length, enp-1 about 6.7 times as long as greatest width, with inner seta reaching proximal 2/3 of segment; baseoendopod and exopod of female P5 with transversal rows of spinules on its surface, exopod bearing six marginal setae; male P1 carrying an inner curved spine on basis; exopod of male P5 bearing six elements. The DNA barcode (COI) sequence of the new species was obtained and submitted to GenBank. This is the first report of Parathalestris from the China Seas. [ABSTRACT FROM AUTHOR]

Organic compounds, including antimicrobial agents azithromycin and hydrous allicin extracts, were sequestered in a silicate sol–gel matrix to function as a biofouling-resistant window for oceanographic instrumentation. The windows fabricated in this manner resisted the formation of microbial biofilms (the precursor to settlement of larger macro-fouling organisms) for up to a week and maintained low levels of fouling for 3 weeks, whereas bare glass substrates form biofilms within hours of seawater submersion. The technique shows promise for the construction of additional translucent solids and coatings using other environmentally friendly biocides. [ABSTRACT FROM AUTHOR]

Many marine invertebrates have planktonic larval and benthic juvenile/adult stages. When the planktonic larvae are fully developed, they must find a favorable site to settle and metamorphose into benthic juveniles. This transition from a planktonic to a benthic mode of life is a complex behavioral process involving substrate searching and exploration. Although the mechanosensitive receptor in the tactile sensor has been implicated in sensing and responding to surfaces of the substrates, few have been unambiguously identified. Recently, we identified that the mechanosensitive transient receptor potential melastatin-subfamily member 7 (TRPM7) channel, highly expressed in the larval foot of the mussel Mytilospsis sallei, was involved in substrate exploration for settlement. Here, we show that the TRPM7-mediated Ca2+ signal was involved in triggering the larval settlement of M. sallei through the calmodulin-dependent protein kinase kinase β/AMP-activated protein kinase/silk gland factor 1 (CaMKKβ-AMPK-SGF1) pathway. It was found that M. sallei larvae preferred the stiff surfaces for settlement, on which TRPM7, CaMKKβ, AMPK, and SGF1 were highly expressed. These findings will help us to better understand the molecular mechanisms of larval settlement in marine invertebrates, and will provide insights into the potential targets for developing environmentally friendly antifouling coatings for fouling organisms. [ABSTRACT FROM AUTHOR]

Ship hull fouling is recognized as an important vector for the introduction of nonindigenous species (NIS), which has been studied globally but no empirical works exist in the Southeast Pacific. The present study examined fouling organisms on the hulls of three ships in one international Chilean port, and compared them with those on settling plates and natural substrates. Also, genetic analyses were perfomed on the most common NIS recorded in order to explore number and potential origin of the genetic linages found. The highest number of total taxa and NIS were found on ship hulls, with three species identified as NIS in ship samplings. Settling plates displayed the largest number of taxa, with a large abundance of the invasive tunicate Ciona robusta, which also showed high mitochondrial genetic diversity. This study showed that Chilean coasts are subjected to both NIS colonization and propagule pressure through ship hulls. Biosecurity measures should urgently be taken on ship hulls along these coasts. [ABSTRACT FROM AUTHOR]

In the last few years, the endemic Mediterranean bivalve Pinna nobilis has been exposed to dramatic mortality in its entire area, which could lead to the extinction of the species. Throughout the Mediterranean, a lot of effort is being put into finding ways of preserving it. One of the methods used to monitor recruitment and juveniles' survival is the installation of collectors for bivalve larvae. We installed collectors at two locations: in Brijuni National Park (North Adriatic) and Luka Cove (central Adriatic). Our aim was to compare the fouling community on the collectors in two consecutive years (2019 and 2020), especially because the installation of collectors in 2020 coincided with mass mortality events of P. nobilis in the area. The number and size of juvenile P. nobilis and the qualitative and quantitative composition of the fouling communities were determined. The results show a reduction in the number and size of juvenile P. nobilis and an explosion of the invasive bivalve Anadara transversa population on collectors in the second year. In Luka Cove, another invasive species—the ascidian Styela plicata—also seriously affected other organisms on the collectors to the point of preventing analysis of the fouling community. [ABSTRACT FROM AUTHOR]

Marine resources such as marine invertebrates and mangrove plants favor the production of secondary metabolites that exhibit antifouling properties. These natural-derived compounds are considered environmentally friendly compared to synthetic compounds with similar activity and technological applications. The current study was conducted to determine the antifouling properties of Diadema setosum (DS) and Sonneratia lanceolata (SL) crude extracts and their incorporated paints, in addition to the identification of the metabolites involved. Both crude extracts were tested against Pseudomonas aeruginosa via a crystal violet assay, while the incorporated paints with 5% (SL5% and DS5%) and 10% (SL10% and DS10%) weight per volume (w/v) were tested in an aquarium and submerged in the seawater at Kemaman and Pulau Redang (Malaysia) for field testing. The identification of the bioactive compounds from the crude extracts was carried out using Liquid Chromatography-Mass Spectrometry (LC-MS). The results of the crystal violet assay showed that both of the crude extracts reduced the biofilm formed by Pseudomonas aeruginosa. The marine bacteria growths contained in natural seawater were inhibited the most by SL5%, followed by DS5%, DS10%, and SL10% in the aquarium testing. Based on the photographic observation, all of the paints incorporated with the crude extracts successfully reduced the settlement of fouling organisms compared to the blank paint, as lesser macroalgae were found growing on the SL5%, DS5%, and DS10%. The LC-MS results showed 3-Methyloxiranyl phosphonic acid; (2RS,3SR)-form from the SL crude extract, while the 8-Decene-1,3,5-triol, 3-Hydroxyundecanoic acid, and 1-O-(6-Deoxy-6-sulfoglucopyranosyl)glycerol; α-D-form, 3-Hexadecanoyl from the DS crude extract were involved in the antifouling properties. In conclusion, both crude extracts have the potential to be developed as antifouling agents. [ABSTRACT FROM AUTHOR]

As permanently attached organism, soft corals can prevent fouling organisms from attaching to them through its anti-fouling mechanisms. In this paper, the antifouling mechanism of soft coral tentacles was revealed through the combination of numerical simulation and laboratory experiment. The results indicated that the interaction between tentacle structures and fluid medium affects the distribution and adhesion of bacteria. At the microscopic level, the boundary layer of low normal flow velocity forms a "water film" near the tentacles, preventing bacteria from approaching the tentacle surface. From the macro perspective, coral tentacles can disrupt the flow field through vortex streets, disrupt water flow stability, and make it difficult for bacteria to attach. The new discovery of bacterial movement and attachment behavior in the flow around a circular cylinder provides theoretical guidance for the design of antifouling surfaces. [Display omitted] [ABSTRACT FROM AUTHOR]

Biofouling is the major factor that limits long-term monitoring studies with automated optical instruments. Protection of the sensing areas, surfaces, and structural housing of the sensors must be considered to deliver reliable data without the need for cleaning or maintenance. In this work, we present the design and field validation of different techniques for biofouling protection based on different housing materials, biocides, and transparent coatings. Six optical turbidity probes were built using polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), PLA with copper filament, ABS coated with PDMS, ABS coated with epoxy and ABS assembled with a system for in situ chlorine production. The probes were deployed in the sea for 48 days and their anti-biofouling efficiency was evaluated using the results of the field experiment, visual inspections, and calibration signal loss after the tests. The PLA and ABS were used as samplers without fouling protection. The probe with chlorine production outperformed the other techniques, providing reliable data during the in situ experiment. The copper probe had lower performance but still retarded the biological growth. The techniques based on transparent coatings, epoxy, and PDMS did not prevent biofilm formation and suffered mostly from micro-biofouling. [ABSTRACT FROM AUTHOR]

Although it is well known that microbes play a significant role in marine corrosion, few studies have systematically studied the relationship between microorganisms and corrosion products under long-term immersion. In this study, the corrosion characteristics of the rust layer formed on carbon steel immersed in the South China Sea for 5.5 years were investigated using various surface analysis and microbial community analysis techniques. Magnetite (Fe3O4), iron sulfide, and green rust were identified in the inner rust layer. The middle rust layer was composed of maghemite (γ-Fe2O3), and some Fe3O4 and mackinamite were also detected. The outer rust layer contained several Fe(III)-oxyhydroxides, and it had a large number of fouling organisms attached to it. In all of the rust layers, anaerobic sulfate-reducing bacteria (SRB) were the dominant bacteria, and they may have played a key role in the formation of the corrosion products. One SRB strain (Desulfovibrio bizertensis SY-1) with a highly corrosivity (13.561 mg/cm2) was isolated from these rust layers, and its physiological and metabolic characteristics were studied. These results expand the membership of corrosive SRB and establish a better understanding of marine microbiologically influenced corrosion (MIC). [ABSTRACT FROM AUTHOR]

Aquatic ecosystems are under threat from nonindigenous species invasion. Fouling organisms on ship hulls are constantly in transit, posing a threat to recipient communities by reducing biodiversity and causing severe economic and public health impact. In the south of Iraq, a range expansion for the nonindigenous barnacle Amphibalanus subalbidus was recorded. On a West Asian scale, Shatt Al-Arab could be a hotspot for biological invasions in Iraq, since this river connects the Persian Gulf to inland waterbodies. Amphibalanus subalbidus could establish settlements in a variety of habitats due to its highly oligohaline distribution, which can withstand prolonged exposure to fresh water. Thus, a morphological consideration and their related distribution in the south of Iraq are discussed for this invasive species. [ABSTRACT FROM AUTHOR]

Carbon steels are widely used in ocean engineering due to their cost effectiveness, ease of manufacture, and excellent weldability. However, the attachment of macro-fouling organisms in seawater poses a serious threat to the integrity of carbon steel structures. In this experiment, carbon steel plates were immersed in the Dalian Sea area from January to October to investigate the effects of macro-fouling on corrosion propagation. The electrochemical measurement indicated that the propensity for the corrosion of Q235B is ranked as ascidians > mussels > barnacles. The characterization results indicated that various marine organisms significantly influenced the corrosion behavior of Q235B carbon steel immersed in natural seawater. The colonization of barnacles inhibited corrosion at the barnacle central area, and the presence of barnacle covering caused crevice corrosion at the edges of the barnacle due to oxygen concentration cells. The presence of ascidians resulted in general corrosion due to the locally high conductivity and ion diffusion rate. A relatively compact rust layer, which exhibited localized defects, was observed beneath the mussels. Seawater had the ability to penetrate the rust layer through these defects, leading to the formation of pitting corrosion on the metal substrate.

Biofouling of marine surfaces such as ship hulls is a major industrial problem. Antifouling (AF) paints delay the onset of biofouling by releasing biocidal chemicals. We present a computational model for microbial colonization of a biocide-releasing AF surface. Our model accounts for random arrival from the ocean of microorganisms with different biocide resistance levels, biocide-dependent proliferation or killing, and a transition to a biofilm state. Our computer simulations support a picture in which biocide-resistant microorganisms initially form a loosely attached layer that eventually transitions to a growing biofilm. Once the growing biofilm is established, immigrating microorganisms are shielded from the biocide, allowing more biocide-susceptible strains to proliferate. In our model, colonization of the AF surface is highly stochastic. The waiting time before the biofilm establishes is exponentially distributed, suggesting a Poisson process. The waiting time depends exponentially on both the concentration of biocide at the surface and the rate of arrival of resistant microorganisms from the ocean. Taken together our results suggest that biofouling of AF surfaces may be intrinsically stochastic and hence unpredictable, but immigration of more biocide-resistant species, as well as the biological transition to biofilm physiology, may be important factors controlling the time to biofilm establishment. [ABSTRACT FROM AUTHOR]

In the early stages after larval settlement, coral spat can be rapidly overgrown and outcompeted by algae, reducing overall survival for coral reef replenishment and supply for restoration programs. Here we investigated three antifouling (AF) coatings for their ability to inhibit algal fouling on coral settlement plugs, a commonly-used restoration substrate. Plugs were either fully or partially coated with the AF coatings and incubated in mesocosm systems with partial recirculation for 37 days to track fouling succession. In addition, settlement of Acropora tenuis larvae was measured to determine whether AF coatings were a settlement deterrent. Uncoated control plugs became heavily fouled, yielding only 4–8% bare substrate on upper surfaces after 37 days. During this period, an encapsulated dichlorooctylisothiazolinone (DCOIT)-coating was most effective in reducing fouling, yielding 61–63% bare substrate. Antiadhesive and cerium dioxide (CeO2−x) nanoparticle (NP) coatings were less effective, yielding 11–17% and 2% bare substrate, respectively. Average settlement of A. tenuis larvae on the three types of AF-coated plugs did not statistically differ from settlement on uncoated controls. However, settlement on the NP-coating was generally the highest and was significantly higher than settlement found on the antiadhesive- and DCOIT-coating. Furthermore, on plugs only partially-covered with AF coatings, larval settlement on coated NP- areas was significantly higher than settlement on coated antiadhesive- and DCOIT-areas. These results demonstrate that AF coatings can reduce fouling intensity on biologically-relevant timescales while preserving robust levels of coral settlement. This represents an important step towards reducing fine-scale competition with benthic fouling organisms in coral breeding and propagation. [ABSTRACT FROM AUTHOR]

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Although carbon materials are widely used in surface engineering, particularly graphene (GP) and carbon nanotubes (CNTs), the application of these nanocomposites for the development of antibiofilm marine surfaces is still poorly documented. The aim of this study was, thus, to gather and discuss the relevant literature concerning the antifouling performance of carbon-based coatings against marine micro- and macrofoulers. For this purpose, a PRISMA-oriented systematic review was conducted based on predefined criteria, which resulted in the selection of thirty studies for a qualitative synthesis. In addition, the retrieved publications were subjected to a quality assessment process based on an adapted Methodological Index for Non-Randomized Studies (MINORS) scale. In general, this review demonstrated the promising antifouling performance of these carbon nanomaterials in marine environments. Further, results from the revised studies suggested that functionalized GP- and CNTs-based marine coatings exhibited improved antifouling performance compared to these materials in pristine forms. Thanks to their high self-cleaning and enhanced antimicrobial properties, as well as durability, these functionalized composites showed outstanding results in protecting submerged surfaces from the settlement of fouling organisms in marine settings. Overall, these findings can pave the way for the development of new carbon-engineered surfaces capable of preventing marine biofouling. [ABSTRACT FROM AUTHOR]

• Hemp fiber with optimal adsorption capacity and optimal fouling resistance of amidoxime-quaternized polyethyleneimine (HFAO-QPEI) were prepared using simple fiber surface modification grafting. • HFAO-QPEI exhibits excellent uranium selectivity and recyclability. • Quaternization gives HFAO-QPEI significant biofouling resistance, especially inhibiting the adhesion of mussels. • DFT calculation results indicate that the HFAO-QPEI-U mode exhibits the most stable structure. Nuclear energy plays a key role in the global energy supply. The adsorption and extraction of uranium from seawater is key to the rapid development of nuclear energy. In this paper, quaternary aminated polyethyleneimine/amidoxime-modified hemp fiber (HFAO-QPEI) with high adsorption capacity and anti-biofouling properties were successfully synthesized by immersion and hydrothermal methods. Upon systematic evaluation, HFAO-QPEI possessed high adsorption capacity and good reusability with fast adsorption kinetics, as well as good adsorption selectivity and affinity for uranyl ions. Furthermore, HFAO-QPEI not only reached a maximum adsorption capacity of 364.7 mg/g but also demonstrated a short adsorption equilibrium time of 200 min. In contrast, HFAO-QPEI demonstrated high selectivity for uranyl ions, removing up to 95.1 % of uranium with K d value of 4.69 × 104 mL/g, which was 256.3 times greater than that of hemp fiber (HF). After the fifth adsorption–desorption cycle, the recovery of U(VI) was 91.38 %. DFT calculations proved that HFAO-QPEI-U was the most stable model. The quaternary ammonium salt functionalization not only makes HFAO-QPEI have excellent anti-biofouling ability (anti-diatom rate up to 87.22 %, anti-bacterial rate up to 97 % or more, anti-adhesion of large fouling organisms mussels with a certain effect), but also modifies its surface charge, making it more suitable for the marine environment. In addition, HFAO-QPEI showed a high adsorption capacity of 2.45 mg/g in natural seawater. The results suggest that the HFAO-QPEI adsorbent holds great promise for extracting uranium from seawater. [ABSTRACT FROM AUTHOR]

We experimentally evaluated the biofouling reduction by on-site heat treatment in enhancing oyster aquaculture production and mitigating its environmental impacts. Specifically, we compared oyster growth, settling flux of particulate organic matter (POM), and its oxygen consumption rate (OCR) between heat-treated (HT) and non-treated (N) sections within suspension oyster farms in a temperate bay. HT demonstrated a substantial reduction of 81–99% in fouling mussel biomass and approximately 20–30% increases in cultivated oysters' growth and condition index. The settling flux of POM was 10–57% smaller in HT mainly due to the reduction in biodeposition from fouling mussels. However, OCR of settling POM at a unit mass was 6–62% higher in HT than in N; overall, the short-term oxygen consumption by settling POM did not significantly differ between HT and N. The increase in OCR of settling POM in HT may be attributable to the decrease in biodeposits from fouling organisms and increase in the relative contribution of fresh POM entering from unfarmed areas. Meanwhile, from the longer-term perspective, the substantial reduction in settling POM by the heat treatment lower the potential for oxygen consumption in the bottom layers over the half-year farming operation by 31%. In conclusion, on-site heat treatment is a simple tactic for controlling nutrient and POM flows at production sites, simultaneously enhancing oyster production and mitigating the local environmental impact of non-fed oyster aquaculture. Furthermore, this approach exemplifies an effective tactic to enhance the sustainability of primary food production processes. [Display omitted] • Tested benefits from on-site heat treatment (HT) in non-fed oyster aquaculture. • HT reduced biofouling organisms and increased food allocation to oysters. • HT oysters were 20–30% higher in biomass and condition index than non-HT oysters. • HT reduced settling POM and its potential O 2 consumption by 31% over 5 months. • HT exemplifies a simple, effective tactic to enhance primary food production. [ABSTRACT FROM AUTHOR]

Põldma, M; Põllumäe, A., Jaanus, A., Kotta, I., Reisalu, G., Taevere, T., and Teeveer, K., 2024. Monitoring non-indigenous species in port habitats in the Gulf of Finland, Baltic Sea. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 392-395. Charlotte (North Carolina), ISSN 0749-0208. Role of commercial harbours and recreational marinas in the spread of non-indigenous species (NIS) has been increased globally. Harbour monitoring is important to assess NIS introduction and spread. The 1-year survey (2022) for species composition, abundance and biomass of mobile epifauna and fish, fouling organisms, benthic infauna, and plankton was conducted in 10 different sites in three harbours of southern Gulf of Finland (Baltic Sea): Tallinn's Old City Harbour, Paldiski South Harbour and Muuga Harbour. The study was carried out in accordance with the HELCOM and OSPAR port survey protocol. A total of 70 taxa were identified, including 9 NIS. In comparison with previous surveys, one new NIS arrival was observed: cumacean Nippoleucon hinumensis. [ABSTRACT FROM AUTHOR]

To mitigate the attachment of fouling organisms, Slippery Liquid-Infused Porous Surfaces (SLIPS) hold tremendous potential as a green and broad-spectrum antifouling solution, capable of replacing traditional antifouling coatings. However, the complexity of current preparation methods and the limited lifespan of lubricating oils constrain their widespread application in marine antifouling for vessels. In this study, melamine sponge (MS) was used as a substrate, and modifications were made by introducing superhydrophobic silica nanoparticles (SiO 2 NPs), a biocompatible adhesive (ethyl cyanoacrylate, ECA), and a highly stretchable polymer (poly-ε-caprolactone, PCL). By combining natural surface microstructures with additional nanomaterials, we successfully obtained a superoleophilic surface, effectively capturing liquid lubricants and maintaining their long-term stability. The sponge substrate possesses distinctive contractility, with the lubricant stored in the grid spontaneously compensating for the loss of surface lubricant, thereby effectively enhancing its durability. This study provides a straightforward fabrication method with reduced manufacturing costs for environmentally friendly marine anti-fouling coatings. The approach demonstrates a prolonged cyclic anti-fouling effect, effectively advancing the development of SLIPS for anti-fouling applications in shallow marine environments. [Display omitted] • Hydrophobic surface with 3D interconnected net-like structures were achieved through a simple immersion process, effectively capturing liquid lubricants and maintaining long-term stability. • Changing the surface energy of the mixed coating effectively enhances the adsorption capacity for non-polar liquids(oil). • Prolonged anti-fouling effects by altering the viscosity of injected lubricating oil. [ABSTRACT FROM AUTHOR]

This study developed a new protocol to prepare feed spacers in the membrane module, by combining the optimization of spacers' geometrical parameters with subsequent chemical modification of the spacers' surface, to enhance filtration performance comprehensively. Geometrical parameters of columnar spacers were optimized using an object-oriented and automatic optimization method based on computational fluid dynamics (CFD) simulation coupled with response surface optimization. In chemical modification, polydopamine was firstly used to provide anti-adhesive properties, followed by the even integration of silver nanoparticles (AgNPs) to exhibit antimicrobial activity. Anti-biofouling experiments involving Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria demonstrated that the combined structurally optimized and chemically modified spacers resulted in over 10 % improvement in permeate flux and a 27 % reduction in feed channel pressure (FCP) drop. Chemical modification enhanced the structural optimization resistance to flux attenuation and FCP drop increase by over 220 % and 200 %, respectively. Analysis of the anti-biofouling behavior indicated that the primary mechanism of the integrated, optimized spacers lies in the increased wall shear, bactericidal activity of AgNPs, and improved interfacial interaction energy between the spacers and foulants. This study not only developed a novel modification method for anti-biofouling spacers, but also provides in-depth understanding of the roles of modified spacers, all of which are important for their practical applications in improving membrane filtration performance. [Display omitted] • Membrane spacers were structurally optimized and chemically modified simultaneously. • Dual-functional anti-adhesive and antibacterial spacers were successfully prepared. • The spacers exhibit high antimicrobial efficacy against Gram-negative and Gram-positive bacteria. • The modified spacers synergistically control biofouling and improve membrane permeability. [ABSTRACT FROM AUTHOR]

Marine biofouling caused huge economic losses of maritime industries. We aim to develop high-efficient, less-toxic, and cost-effective antifoulants to solve the problems of biofouling. In this study, we described the antifouling compounds albofungin and its derivatives (albofungin A, chrestoxanthone A, and chloroalbofungin) isolated from the metabolites of bacterium Streptomyces chrestomyceticus BCC 24770, the construction of high-yield strains for albofungin production, and application of albofungin-based antifouling coatings. Results showed that these albofungins have potent antibiofilm activities against Gram-positive and Gram-negative bacteria and antimacrofouling activities against larval settlement of major fouling organisms with low cytotoxicity. With the best antifouling activity and highest yield in bacterial culture, albofungin was subsequently incorporated with hydrolyzable and degradable copolymer to form antifouling coatings, which altered biofilm structures and prevented the settlement of macrofouling organisms in marine environments. Our results suggested that albofungins were promising antifouling compounds with potential application in marine environments. [ABSTRACT FROM AUTHOR]

The number of scientists and tourists visiting Antarctica is on the rise and, despite the management framework for environmental protection, some coastal areas, particularly in the Antarctic Peninsula region, are affected by plastic contamination. The few data available on the occurrence of microplastics (<5 mm) are difficult to compare, due to the different methodologies used in monitoring studies. However, indications are emerging to guide future research and to implement environmental protocols. In the surface and subsurface waters of the Southern Ocean, plastic debris >300 µm appears to be scarce and far less abundant than paint chips released from research vessels. Yet, near some coastal scientific stations, the fragmentation and degradation of larger plastic items, as well as microbeads and microfibers released into wastewater from personal care products and laundry, could potentially affect marine organisms. Some studies indicate that, through long-range atmospheric transport, plastic fibers produced on other continents can be deposited in Antarctica. Drifting plastic debris can also cross the Polar Front, with the potential to carry alien fouling organisms into the Southern Ocean. Sea ice dynamics appear to favor the uptake of microplastics by ice algae and Antarctic krill, the key species in the Antarctic marine food web. Euphausia superba apparently has the ability to fragment and expel ingested plastic particles at the nanoscale. However, most Antarctic organisms are endemic species, with unique ecophysiological adaptations to extreme environmental conditions and are likely highly sensitive to cumulative stresses caused by climate change, microplastics and other anthropogenic disturbances. Although there is limited evidence to date that micro- and nanoplastics have direct biological effects, our review aims at raising awareness of the problem and, in order to assess the real potential impact of microplastics in Antarctica, underlines the urgency to fill the methodological gaps for their detection in all environmental matrices, and to equip scientific stations and ships with adequate wastewater treatment plants to reduce the release of microfibers. [ABSTRACT FROM AUTHOR]

Membrane bioreactors (MBRs) are widely used to treat wastewater, mainly due to the production of high-quality effluent. However, biofilm forming on the surface of membranes can cause many problems, which remains one of the major limitations of this technique. Bacterial quorum quenching (QQ) has been proven to be a successful strategy to control biofouling in MBRs. However, for many QQ bacterial isolates, the detailed degradation rates of acyl homoserine lactones (AHLs) have rarely been reported. Therefore, this study aimed to isolate potential QQ bacteria and investigate their degradation rates against eight different AHLs. Results showed that four isolates (A9, A12, B11, and D3) exhibited consistent C8-HSL–(N-octanoyl-L-homoserine lactone) removal capabilities. These four isolates removed at least 70% of all AHLs tested within 180 min. They might have different QQ enzymes, based on our observation that the locations of enzyme activities differed. The bacteria most closely related to A9, A12, and B11 were Brucella anthropic, Bacillus cereus, and Bacillus toyonensis, respectively. Bacillus species have shown QQ activity in many studies, but AHL-reducing Brucella species have not been previously reported. Overall, this study extends our current knowledge of QQ bacteria that could be used to mitigate biofilm formation on MBR membranes. [ABSTRACT FROM AUTHOR]