Marine Fouling Research Articles

Environmentally Friendly Protective Coatings for Transport

Using examples developed in Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, the methods of protection of various objects, first and foremost, transportation means and transport infrastructure, from adverse climatic conditions, corrosion, icing, radiation, marine fouling, and destruction under the influence of biodestructors are analyzed. The physicochemical fundamentals of the technology of preparation of organosilicate coatings for their high performance are considered. New methods and approaches used in the formulation of environmentally friendly protective coatings are characterized, in particular, the future of superhydrofobic coatings is discussed.

Superhydrophobic Silicone/TiO2–SiO2 Nanorod‐like Composites for Marine Fouling Release Coatings

AbstractFor the first time, a superhydrophobic series of silicone/nanorod‐like TiO2–SiO2 core–shell composites was fabricated by solution casting for marine fouling release (FR) coatings. Hydrothermal technique was used to prepare single crystal TiO2 nanorods as a core structure in the diameter regime of 20 nm and preferentially grown in {101} direction. Hybrid nanorod‐like TiO2–SiO2 core–shell nanofillers were synthesized by sol–gel technique with silica shell thickness of 2–5 nm. The structure‐property relationship was investigated by dispersing various nanofiller concentrations in the silicone matrix. Surface non‐wettability properties were investigated using water contact angle (WCA), surface free energy (SFE), and atomic force microscopy. Coating′s photocatalytic degradation of organic pollutants and microorganisms was also investigated. Selected micro‐ and macro‐fouling strains were used for antifouling assessments in laboratory. The fabricated models were subjected to a rigorous field trial in natural seawater for 6 months in a tropical area. Well‐distributed nanorod‐like TiO2–SiO2 core–shell (0.5 wt.%) exhibited the preferable FR self‐cleaning with WCA of 154° and SFE of 10.45 mN/m.

Superhydrophobic coating of silicone/β–MnO2 nanorod composite for marine antifouling

A novel superhydrophobic series of silicone/β–MnO2 nanorod composite was successfully fabricated for marine fouling release (FR) coatings. We studied how the self-cleaning and antifouling features were affected by controlling the β–MnO2 nanorod preparation and distribution in the silicone matrix. The nanorods exhibited a single crystal structure, a mean diameter of 20–30 nm and a length of 0.5–1 μm, and they had a wurtzite structure that preferentially grew in the [100] direction which has the most stable surface, high antimicrobial, and low free energy. Nanorod fillers of different concentrations were distributed in the silicone matrix for enhancing the surface roughness, water repellency and FR features. Surface characteristics were evaluated by using the contact angle of water experiments, atomic force microscope and scanning electron microscope for studying the superhydrophobicity and antifouling attributes. Well-dispersed nanorods exhibited a particular increase in the coating roughness, superhydrophobicity, and low surface energy properties. Thermal and mechanical properties, as well as stability in different pH solutions, were tested as durability parameters. For assessing the biological and fouling repellency effects of the coating systems, chosen micro-fouling organisms were used in the laboratory for one month. Also, a field experiment was carried out by immersing the coated samples in natural seawater up to 90 days and the screening method and image analysis were used to test the FR behavior. The well-dispersed nanorods (0.5 wt.%) presented the most profound superhydrophobic FR nanostructured coating; which demonstrated a 158° and 12.65 mN/m for the surface contact angle and free energy.

Superhydrophobic silicone/SiC nanowire composite as a fouling release coating material

A ceramic superhydrophobic series of polydimethylsiloxane/silicon carbide nanowire (SiC NW) composites was designed for marine fouling release (FR) coatings of the ship hull. Single-crystal SiC NWs with 50–80 nm diameters were grown in {111} crystal plane and employed as nanofillers. Ex situ silicone nanocomposites were facilely developed and cured by a mechanism of hydrosilation. The effects of incorporating different nanofiller concentrations on the surface, mechanical, and FR properties of silicone nanocomposites were extensively studied. Surface properties were studied by nonwettability and free energy and characterized via scanning electron and atomic force microscopes. Nanocomposites’ mechanical features were tested as durability factors. Selected microfoulants of fungi and bacterial progenies were used for biological assessments in the laboratory. A field test was performed on the developed coating samples in natural seawater for 3 months in a tropical area. Excellent distributed SiC NWs (0.5 wt%) showed outstanding hydrophobicity with 153° contact angle, 11.25 mN/m free energy of the surface, micro-/nanoscale roughness, and FR properties.

"Safe" Chitosan/Zinc Oxide Nanocomposite Has Minimal Organ-Specific Toxicity in Early Stages of Zebrafish Development.

Marine biofouling is considered to be one of the most challenging issues affecting maritime industries worldwide. In this regard, traditional biocides, being used to combat biofouling, have high toxicity toward aquatic systems. Recently, a new chitosan/zinc oxide nanoparticle (CZNC) composite has been used as a promising "green" biocide. It is thought that because of the ecofriendly nature of chitosan, CZNCs may pave the way to developing less toxic surfaces for combating marine fouling. Zebrafish has become one of the most employed models for ecotoxicology studies. Therefore, this study aims to comprehensively evaluate any potential acute, cardio, neuro, or hepatotoxic effect of CZNCs using zebrafish embryos. As evidenced by the acute toxicity assays, exposing zebrafish embryos to CZNCs (25-200 mg/L) did not elicit any signs of acute toxicity or mortality, suggesting a hypothetical LC50 higher than the maximum dose employed. CZNCs, at a concentration of 250 mg/L, also showed no cardiotoxic or neurotoxic effects. At the same dosage, a minor hepatotoxic effect was observed in zebrafish embryos exposed to CZNCs. However, the observed hepatotoxicity had no effect on embryo survival even after long-term (10-days) exposure to CZNCs. We believe our results add valuable information to the potential toxicity of chitosan/metal oxide nanocomposites, which may provide new insights into the synthesis of ecofriendly coatings with improved antifouling performance and a low adverse impact on the marine environment.

Ultimate bending capacity of aged fixed platform by considering the effect of marine fouling

Abstract For offshore structures, especially jacket supported structure such as fixed platform and offshore wind turbine, the underwater area provides an ideal site for corrosion formation and marine fouling. In this marine environment, the structures are exposed to particularly aggressive corrosion and colonized by marine organisms involving a diversity of species. In this paper, a number of cases are conducted where an existing fixed platform is subjected to uniform corrosion. Furthermore, the platform is also subjected to marine fouling. The platform is assessed to investigate the effects of corrosion and marine fouling on its structural strength by determining the Reserve Strength Ratio (RSR) value. It is found the platform is limited to at least 50 years of service life when subjected to average corrosion. However, the platform is no longer considered as safe after 37 years when subjected to severe corrosion. Moreover, there is an RSR loss of 38% when marine fouling is introduced at the first 5 years which is detrimental to the overall safety of the platform. On the other hand, there is minimum RSR loss of only 5% for most cases when marine fouling is introduced but still detrimental to the overall safety of the platform. The obtained outcomes were documented and will be useful information to conduct condition assessment (or structural health monitoring) of aged fixed jacket structures.

SEAR JIP: the value of sharing of lessons learned on subsea integrity and reliability

The award-winning Subsea Equipment Australian Reliability (SEAR) Joint Industry Project (JIP) is a partnership led by Wood and has participation of a group of OGAS Operators namely Chevron Australia, ConocoPhillips, Inpex, Quadrant, Shell Australia and Woodside. Now delivering Phase 6, the JIP is focused on collaboration and knowledge sharing, so as to improve the competitiveness of Australia’s oil and gas sector by addressing critical challenges associated with equipment that is failing prematurely subsea. The SEAR JIP was initiated in 2014 and has since developed a reliability database to collect failure information from SEAR members with Australian offshore operations. The SEAR database provides a low cost–high value method of capturing and sharing failures and lessons learnt for Australia. Over the years, the JIP has focused on different but common industry challenges, such as the impact of marine fouling affecting operability during interventions. To address this challenge, the JIP is deploying ‘living laboratories’ at different geographical locations and water depths across various Australian waters, in collaboration with suppliers and local universities to identify game-changing technology. The ability to better understand failures and intervention requirements has the potential to offer operators significant cost savings, by optimising equipment reliability and availability. This paper will provide an overview of SEAR JIP and outlines lessons learned and value created, and discusses how a similar collaborative approach can create value in other parts of the Australian LNG value chain.

Hydroids (Cnidaria, Hydrozoa) from marine fouling assemblages in the Galápagos Islands, Ecuador

An account is given of hydroids collected in 2015 and 2016 from port and harbor fouling communities in the Galapagos Islands. Also included is the hydroid of Ectopleura media, discovered on the wreck of the tanker Jessica near Isla San Cristobal in 2001. Among 20 species reported herein were six anthoathecates and 14 leptothecates. Most common in the samples were the kirchenpaueriid Ventromma halecioides and the halopteridid Halopteris alternata. Eight species (Bougainvillia muscus, Bimeria vestita, Clytia elongata, C. obliqua, C. thornelyi, Obelia oxydentata, Eucheilota sp., and Halecium labiatum) are reported for the first time from the Galapagos archipelago. Three of them (Clytia elongata, C. thornelyi, and Halecium labiatum) are also new to the eastern Pacific. Seven species treated here are considered introduced by shipping to the islands, bringing to eight the number of introduced hydroids. In addition, we treat four species as cryptogenic, bringing to five the total number of the latter in the Galapagos. The binomena Obelia thornelyi Nutting, 1927, Clytia stolonifera Blackburn, 1938, and C. latitheca Millard and Bouillon, 1973 are regarded as synonyms, with the first of these having nomenclatural priority. Meanwhile, the senior synonym O. thornelyi is reassigned to the genus Clytia Lamouroux, 1812 as C. thornelyi. Another species in the samples, Dynamena distans Lamouroux, 1816 (also widely known as Sertularia distans and Tridentata distans), is combined for the first time with the genus Amphisbetia L. Agassiz, 1862, as A. distans.

Marine Fouling Panel Survey and Assessment of Marine Alien Invasive Species in Myanmar

A survey on fouling using PVC panels was carried out for a period of one year in Yangon River. Additional observations on fouling of man-made structures elsewhere in Myanmar were also made in an effort to find marine alien invasive species. The Myanmar ports at Yangon, Sittway and Myeik have a long history of overseas trading with Europe since the 17th century. In addition, though the Yangon port and jetties are located upstream some 12 miles from the mouth of Yangon River, it experiences regular tidal action with seasonal brackish water conditions. Its catchment area is only 100 miles from the mouth and hence the river and its tributaries are short and small. Moreover, there are several weirs and small dams on the tributaries, which result in reduced sediment influx at the mouth and thus less turbidity. Therefore, the physiochemical conditions at Yangon port may not pose a limitation on the distribution of nuisance species that are able to survive brackish water conditions. Elsewhere, Sittway port at the mouth of the Kispanadi River also experiences regular tidal action and is directly connected to the Bay of Bengal, conditions which are favourable for the intrusion of marine nuisance species. Myeik port is located along the open shore of the Myeik, which is located near the Myeik Archipelago. The waters around the archipelago are clear and the shelf is characterized by high biodiversity. Therefore, the environment also appears to be highly favourable for alien invasive species. However, these ports have no record of the occurrence of alien invasive species in particular the Caribbean bivalve Mytilopsis sallei.

Delamination of a rigid punch from an elastic substrate under normal and shear forces

Delamination of rigid objects from an elastic substrate with finite thickness is a fundamental problem underlying applications such as marine fouling release coatings or anti-icing coatings. Most existing theoretical studies assume that delamination is driven by forces normal to the substrate surface, while in practice the delamination force may also include shear components that are parallel to the substrate surface. In this work, we consider a model system where a rigid cylindrical punch is detached from an elastic substrate under normal force, shear force or both. Our focus is to determine the pull-off force and to reveal the delamination mechanics under various geometrical and loading conditions, specifically the substrate thickness and the position and angle of the delamination force. To gain theoretical insights, we first study a plane strain model where a long rigid strip is adhered to an elastic half-space, and obtain an analytical solution revealing how the pull-off force depends on the loading position and angle. Moreover, we develop a three-dimensional finite element model to simulate the delamination of a rigid cylindrical punch from an elastic substrate with finite thickness. Three delamination modes are identified from finite element results: Mode-I crack propagation, Mode-II crack propagation, and interface cavitation. For the first two modes, we obtain empirical formulas to calculate the pull-off force using adhesion energy, substrate modulus, contact radius and substrate thickness. We also find that the analytical solution derived from the plan strain model can serve as a qualitative guide to estimate the effect of loading position and angle on the pull-off force.

MOLLUSKS ON RECRUITMENT PANELS PLACED IN AN OFFSHORE HARBOR IN TROPICAL NORTHEASTERN BRAZIL

Como o objetivo de contribuir para o conhecimento das comunidades marinhas incrustantes, o presente estudo analisou a variação temporal em comunidades de moluscos encontradas em placas de recrutamento trimestrais e anuais instaladas em uma região portuária no nordeste do Brasil. Um conjunto de 30 placas artificiais foi submerso entre os pilares do píer a uma profundidade aproximada de 6 m. A cada três meses, um subconjunto de 15 placas era removido para o exame da biota presente. O segundo subconjunto de 15 placas foi deixado submerso por um ano, e depois removido para análise. No mesmo dia em que as placas eram removidas, elas eram substituídas por novas placas. Doze remoções/reposições de placas foram realizadas de outubro de 2009 a novembro de 2012. Duas classes de Mollusca foram encontradas nos painéis de recrutamento: Gastropoda e Bivalvia. Trinta táxons foram encontrados nas placas trimestrais e 23 táxons nas placas anuais. Duas espécies nãonativas da costa brasileira foram encontradas: Isognomon bicolor e Eualetes tulipa. Nas placas trimestrais, a espécie mais comum e abundante foi a ostra Crassostrea brasiliana e a espécie mais abundante nas placas anuais foi o bivalve Musculus lateralis.

Effect of Marine Fouling Organisms Adhesion on Formation of Calcareous Deposits Formed by Cathodic Protection on Surface of Q235 Carbon Steel

Effect of Marine Fouling Organisms Adhesion on Formation of Calcareous Deposits Formed by Cathodic Protection on Surface of Q235 Carbon Steel

Plasma biomarkers in juvenile marine fish provide evidence for endocrine modulation potential of organotin compounds

Organotin compounds, such as tributyltin (TBT) and triphenyltin (TPT), have been widely used to control marine fouling. Here, we show that organotin stimulation reduces the hormone levels in the plasma of two economically important aquaculture fish. Blood plasma samples were collected from juvenile red seabream and black rockfish exposed to environmentally realistic concentrations of TBT and TPT for 14 days. The levels of two plasma biomarkers, namely the yolk protein precursor vitellogenin (VTG) and the sex steroid 17β-estradiol (E2), were measured to determine the endocrine disrupting potential of the organotin compounds. Both organotin compounds were dose-dependently accumulated in the blood of two fish. Exposure to waterborne TBT and TBT significantly decreased the plasma VTG levels in both the juvenile fish in a dose-dependent manner. In contrast, the treatment with E2, a well-known VTG inducer, significantly increased the plasma VTG levels in both the fish. In addition, the mRNA levels of vtg were also downregulated in the liver tissues of both the fish at 100 and/or 1000 ng L−1 of TBT or TPT exposure. The plasma E2 titers were significantly suppressed at 100 and/or 1000 ng L−1 of TBT or TPT exposure for 14 days compared to their titer in the control. Since estrogen directly regulates vtg gene expression and VTG synthesis, our results reveal the endocrine disrupting potential of organotin compounds, and subsequently the endocrine modulation at early stage of fish can trigger further fluctuations in sexual differentiation, maturation, sex ration or egg production. In addition, the results demonstrate their effects on non-target organisms, particularly on animals reared in aquaculture and fisheries.

Settlement and Corrosion Behaviour of Marine Fouling Organisms

Settlement and Corrosion Behaviour of Marine Fouling Organisms

Flexible Hydrophobic Antifouling Coating with Oriented Nanotopography and Nonleaking Capsaicin

Incorporating natural product antifoulants (NPAs) into coatings with controlled surface topography is considered a promising way to suppress marine fouling. However, the rapid leakage of NPAs and the relatively complicated process of constructing well-patterned topography remain unresolved problems for practical applications. In this work, capsaicin bonded to CoFe2O4/gelatin magnetic nanoparticles was mixed with a polydimethylsiloxane (PDMS)-based block copolymer. When applied together by a simple spray-coating method, these materials formed a film. The leakage of capsaicin was restrained by the chemical bonds with the CoFe2O4/gelatin nanospheres. The primary nanorough structure was constructed by the phase separation of the PDMS-based copolymer. The secondary nanorough structure was formed by the incorporation of capsaicin-loaded CoFe2O4/gelatin nanospheres, which were demonstrated to improve the orientation of the PDMS-based block copolymer chains. The combination of oriented nanotopography and nonleaking capsaicin endows the coating with enhanced, long-lasting antifouling ability.

Adsorption of Aluminum, Arsenic and Sulphate Ions from Synthetic and Real Underground Water by Marine Fouling

The removal of Al3+, As3+ and SO42- ions from aqueous solution was investigated by using marine fouling. The effect of removal of adsorbent was studied in batch technique under various operating parameters such as pH, contact time, adsorbent dose, adsorbent particle size and metal ions concentration at 500 rpm and 25oC. The maximum removal of Al3+, As3+ and SO42- was 100% at pH 5 for Al3+, pH 8 for As3+ and pH 3 for SO42- using 0.7 g for 120 min. and 45 μm of adsorbent particle size. The Langmuir and Freundlich adsorption isotherm models were under taken to analyse the equilibrium data. Langmuir isotherm showed the best fit to the equilibrium data, which gave maximum adsorption capacity for Al3+, As3+ and SO42- was 28.81, 23.58 and 34.48 mg/g, respectively. The adsorption process follows the pseudo-second-order model. This study recommended that marine fouling can be used for removal of toxic metal ions due to highly efficiently and low cost.

An Investigation Into The Drag Increase on Roughen Surface due to Marine Fouling Growth

Marine biofouling attached to underwater ship hull has caused problems for many years to ship operators. It has been reported to increase the total drag thus can reduce the speed of ship and disturb the overall operation of marine vehicles. Changes laminar to turbulent flow becomes fast when passing through rough ships surface. The current study models the growth of marine fouling for one year periods basis on general cargo vessel. The methods have been used in this studied was model scale 1 : 53. The use of smooth model is also included in order to analyses the difference between the two conditions. Two models of the hull roughness are regular and irregular roughness. The modeling of roughness using sand with a specific size and have been scaled. The results show that an increase in skin friction drag of about 41% per year for biofouling spread not evenly at wetted surface area (WSA).

Towards an understanding of marine fouling effects on VIV of circular cylinders: Aggregation effects

The current study is aimed at getting a further insight into the changes the fouling brings to the Vortex Induced Vibration (VIV) of circular cylinders. Instead of regular patterns considered in previous studies, using the Poisson Cluster Process, an aggregated spatial distribution was considered for the artificial marine fouling. This is believed to better simulate the natural settlement of the marine biofouling. Different coverage ratios and fouling shapes plus regular and aggregated distributions were considered. The towing tank VIV tests were conducted on elastically mounted rigid cylinders. The Reynolds number ranged from around 7.8 × 103 to 4.9 × 104.On the whole, the maximum oscillation amplitude and the maximum lift force coefficient were meaningfully smaller in cylinders with either aggregated or regular fouling, as compared to those from the corresponding clean cylinder. Both aggregated and regular fouling were, thus, acting as VIV suppression devices. The suppression effectiveness increased by reduction in the coverage ratio of the artificial fouling. The effectiveness, however, reduced by the aggregation as compared to that with regular distribution. In general, the maximum VIV oscillations and the force coefficients appeared to be sensitive, in descending order, to coverage ratio, aggregation, flow incidence and the fouling shape.

Macrofouling communities and the degradation of plastic bags in the sea: an insitu experiment.

The increasing amount of plastic littered into the sea may provide a new substratum for benthic organisms. These marine fouling communities on plastic have not received much scientific attention. We present, to our knowledge, the first comprehensive analysis of their macroscopic community composition, their primary production and the polymer degradation comparing conventional polyethylene (PE) and a biodegradable starch-based plastic blend in coastal benthic and pelagic habitats in the Mediterranean Sea. The biomass of the fouling layer increased significantly over time and all samples became heavy enough to sink to the seafloor. The fouling communities, consisting of 21 families, were distinct between habitats, but not between polymer types. Positive primary production was measured in the pelagic, but not in the benthic habitat, suggesting that large accumulations of floating plastic could pose a source of oxygen for local ecosystems, as well as a carbon sink. Contrary to PE, the biodegradable plastic showed a significant loss of tensile strength and disintegrated over time in both habitats. These results indicate that in the marine environment, biodegradable polymers may disintegrate at higher rates than conventional polymers. This should be considered for the development of new materials, environmental risk assessment and waste management strategies.

Electroactive Polyhydroquinone Coatings for Marine Fouling Prevention-A Rejected Dynamic pH Hypothesis and a Deceiving Artifact in Electrochemical Antifouling Testing.

Nanometer-thin coatings of polyhydroquinone (PHQ), which release and absorb protons upon oxidation and reduction, respectively, were tested for electrochemically induced anti-biofouling activity under the hypothesis that a dynamic pH environment would discourage fouling. Antifouling tests in artificial seawater using the marine, biofilm-forming bacterium Vibrio alginolyticus proved the coatings to be ineffective in fouling prevention but revealed a deceiving artifact from the reactive species generated at the counter electrode (CE), even for electrochemical bias potentials as low as |400| mV versus Ag|AgCl. These findings provide valuable information on the preparation of nanothin PHQ coatings and their electrochemical behavior in artificial seawater. The results further demonstrate that it is critical to isolate the CE in electrochemical anti-biofouling testing.