Rolland, JP; DeSimone, JM

Polymeric Materials Science and Engineering (USA), vol. 88, pp. 606-607, Spring 2003

Minimally adhesive coatings are currently being investigated for use as fouling release coatings on naval vessels. The attachment of organisms to the ship hull can dramatically increase drag and therefore fuel consumption. A mechanically stable, non-toxic coating is desired to prevent the adhesion of foulants. Modulus has been correlated to adhesion with lower modulus materials resulting in lower adhesion. We are investigating perfluoropolyethers (PFPEs) as low surface energy components in these coatings. PFPEs are remarkable materials typically used as high performance lubricants. They exhibit incredibly low surface energy (15-20 mN m exp -1 ), very low Tg (-120 to -70 deg C), and excellent chemical and thermal stability. Ongoing work involves the systematic variation of surface and bulk properties including Tg, fluorine content, and crosslinking density. A study of how these properties affect biofouling is greatly desired. A series of graft terpolymers containing various acrylic monomers, a crosslinkable hydroxyethylacrylate(HEA) moiety, and a perfluoropolyether macromonomer has been synthesized for this purpose.

Brady, RF,Jr

Journal of Protective Coatings & Linings; Vol 17; No 6; pp 42-46; June 2000

The problem of marine organisms adhering to structures in the sea is as old as time. The problem is acute for ships, especially warships. A layer of marine organisms on a ship's hull decreases speed, manoeuvrability, and range, and it raises propulsive fuel consumption by as much as 30%. To prevent the formation of a fouling layer, antifouling paints typically incorporate compounds such as cuprous oxide or organotins, which are toxic at low concentrations to most forms of fouling. These compounds persist in the water, but organotins cause deformations in some kinds of sea life. Consequently, the Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) has approved a resolution to phase out and eventually prohibit the use of toxic organotin derivatives in antifouling paint. Thus, there is a compelling need to develop, test, and market environmentally acceptable hull coatings that effectively keep ships free of fouling. The replacement for tin coatings will likely be low-toxicity, copper-based paints and various toxin-free fouling-release coatings. This article reviews the composition and action mechanism of these coatings. It also presents their strengths and weaknesses, with the aim of clarifying the impact these coatings will have on the operation of vessels. (Article followed by a sidebar describing 11 commercially available tin-free antifouling coatings, with tradename and producer identified.)

Younqlood, JP; Andruzzi, L; Senaratne, W; Ober, CK; Callow, JA; Finlay, JA; Callow, ME

Polymeric Materials Science and Engineering (USA), vol. 88, pp. 608-609, Spring 2003

Marine fouling is a major problem in the transport of materials worldwide. The biofouling slimes that form on ship hulls raise fuel consumption by as much as 30%. Traditionally, marine coatings contain metals such as copper and triorganotin compounds, but application of coatings containing the latter will be prohibited from January 2003 and the former are undesirable due to concerns that they are toxic and accumulative in non-target organisms. It is now hoped that minimizing adhesion between biofoulants and the target surfaces will provide for eco-friendly coatings that decrease fouling as well as providing for easy removal. It would be desirable to engineer self-cleaning materials where the shear force on a ship hull moving through water at moderate speeds (10-15 knots) is enough to remove fouling material. Barnacles do start to detach from some silicones at these speeds, but even the best commercial fouling release silicone elastomers need hull speeds around 30 knots to completely self-clean. The many fouling organisms and environmental conditions world-wide makes the task of developing a novel non-toxic coating that resists fouling and /or self-cleans very challenging. This paper reports the preparation of poly(styrene)-based surface active block copolymers (SABCs) modified with either pendent hydrophilic poly(ethylene glycol) for biocompatibility or non-polar liquid crystalline semifluorinated groups for minimal adhesion. A novel bilayer structure that optimizes mechanical properties through use of an elastomer (SEBS) primer layer and provides target surface chemistry through use of the SABCs has been developed. The preparation and testing of both sets of bilayers as marine fouling resistant/release coatings is also reported.

Anderson, C

Corrosion Management (Australia), vol. 40, pp. 21-24, Nov.-Dec. 2002

Moving a heavy object (a ship) through a dense fluid (sea water) requires energy, and the rougher the surface of the ship the greater the energy required. Marine biofouling increases the roughness of underwater hulls, resulting in greater fuel consumption and increased emission of greenhouse gases, and it is the minimizing of these effects which antifouling coatings are primarily designed to achieve.

Brizzolara, RA

Surface and Interface Analysis (UK), vol. 33, no. 4, pp. 351-360, Apr. 2002

Biological fouling (biofouling) is a chronic and costly problem in the maritime industry. Alginic acid is a major component of bacterial extracellular polysaccharides and titanium is a commonly used material in shipboard heat exchangers. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) have been used to characterize the adsorption of alginic acid to titanium as a function of alginic acid solution pH. It was found that alginic acid adsorbs in greater quantity at acidic pH than at basic pH. The results provide evidence for an anion-exchange adsorption mechanism at weakly acidic pH. Addition of calcium chloride to the alginic acid solution results in a reduction of alginic acid adsorption at acidic pH and an increase at basic pH. This behavior can be explained by inhibition of anion exchange by the calcium cation at acidic pH and mediation of a bond between alginic acid and the titanium surface at basic pH. Elucidation of the adsorption chemistry of biofilm components to the surfaces of engineering materials is a prerequisite to developing surface modification strategies to reduce biofouling adhesion. Data presented herein can be used in the future as a baseline for comparison with data for such modified surfaces.

Nair, KVK

Journal of the Indian Institute of Science (India), vol. 79, no. 6, pp. 497-511, Nov.-Dec. 2000

Biofouling has been a major problem to ships, offshore platforms, marine intakes, data buoys and to almost all marine-technology ventures. With the emergence of multi-megawatt power plants during the last three decades more and more nuclear and thermal power stations are turning to the sea to meet their cooling water needs. The use of sea water for condenser cooling has brought the problem of marine biofouling into power-plant intake and discharge conduits as well as heat exchangers. The problem is particularly severe in tropics and even more so in ocean thermal energy conversion (OTEC) plants wherein the sea water flows through evaporators as well as condensers. While many approaches are followed for control of biofouling involving chemicals, antifouling paints, foul-release coatings, electric charges, velocity and heat, there is no method which can totally prevent it. The paper reviews the state of the art in this area largely based on experience from a power station at Kalpakkam, south of Chennai.

De Rincon, OT; Morris, E; De Romero, M; Andrade, S

NACE International, Corrosion/2001 (USA), pp. 15, Mar. 2001

Exotic marine organisms Garveia franciscana, called 'pelo de oso' by the locals, were detected in Lake Maracaibo after the lake was opened to the sea in 1959. These organisms adapt and maintain a favorable ecological growth in this environment. 'Pelo de oso' constitutes one of the three components of the metal/biota /solution system that interact in Lake Maracaibo, producing biofouling and promoting microbiological corrosion. The latter generate great economic problems, mainly: water-pump failures, increase in cleaning frequency at inlet, decreasing efficiency of deoxygenating towers, increase in facility- maintenance costs due to unscheduled shutdowns, and so on. The main objective of this study is to determine: The preference of 'Pelo de Oso' for metal or non-metal materials immersed in lake water and Electrochemical, Chemical and physical factors that might lead to an understanding of how to control 'Pelo de Oso' development and growth on equipment that uses lake water.

Anderson, J M; Cima, M J; Langer, R; Shawgo, R S; Shive, M S; von Recum, H; Voskerician, G

Biomaterials; 24 (11) May 2003, p.1959-67

The biocompatibility and biofouling of the microfabrication materials for a MEMS drug delivery device were evaluated. Metallic gold, silicon nitride, silicon dioxide, silicon and SU-8 photoresist were evaluated, using the cage implant system in a rodent model. Overall, the inflammatory responses elicited by these materials were not significantly different from those for the empty cage controls over 21 days. Also, the adherent cellular density (biofouling) of gold, silicon nitride, silicon oxide and SU-8 were comparable and statistically less than silicon. These analyses identified the MEMS component materials gold, silicon nitride, silicon dioxide, SU-8 and silicon as biocompatible, with gold, silicon nitride, silicon dioxide and SU-8 showing reduced biofouling. (Original abstract - amended)

Kolari, M

Dissertationes Biocentri Viikki Universitatis Helsingiensis 12 /2003, Helsinki, Finland: University of Helsinki, 2003, 129pp (ISBN 9521003448) (K)

An investigation into the tendency of bacterial biofilms to impair the operation of paper machines, where the biofilms detach from surfaces, cause holes or spots in the paper products and can cause the paper web to break was conducted. The results indicated that only a small proportion of the wide range of microflora living in the warm paper machine waters is capable of initiating the biofilm formation on clean surfaces. Five taxonomic groups of such primary biofilm formers were recognised: Deinococcus geothermalis, Meiothermus silvanus, members of a novel genus of Rhodobacter-like, alpha-Proteobacteria, the genus Thermomonas, and the Burkholderia cepacia complex. Many of the bacteria were able to form biofilms in the presence of biocide concentrations that were inhibitory to free swimming cells. Several of the biofilm isolates responded to the biocide by increased transition to the biofilm mode of growth, suggesting that if the dose of biocide was too low to prevent the surface attached growth, this may actually cause the planktonic bacteria to seek protection by shifting to growth in biofilms and thus increase biofouling of the process.

Lewis, D P; Piontkowski, J M; Straney, R W; Knowlton, J J

Fire Technology; 33 (4) Dec 97, p.356-71

Zebra mussels, first discovered in the Great Lakes in 1988, have frequently been detected in fire protection systems. However, the potential for large-scale infestations has not been established. It is clear that even small numbers of mussels can cause problems in areas that have small-diameter piping or in sprinkler system nozzles, if shells are flushed downstream during emergency use. This paper discusses the development of a method of mussel control that limited interference with normal system operations at the Dunkirk station. Because oxygen is often depressed in these systems and limits mussel survival and growth, it was established that by monitoring oxygen alone, or in combination with veliger or mussel larval monitoring, high-risk areas for mussel infestation could be determined. In previous laboratory research, it had already been determined that concentrations of potassium in excess of 100 mg/L would lead to quick mortality in adult mussels. These results, along with a biofouling risk assessment, were used to to develop and implement successful treatment of the plant's fire protection water systems using potassium in the form of potash as the controlling agent. (Original abstract - amended)

Panchal, CB; et al

DE84-014643; CONF-840930-1, 6 pp, 1984

The rate and characteristics of biofouling and corrosion were investigated as part of the ocean thermal energy conversion research program. No detectable biofouling from cold water in smooth tubes was observed. Intermittent, low-level chlorination appears to control biofouling from warm water in smooth tubes. Uniform corrosion of 5052 Al alloy is low, with less pitting found with warm water than with cold water over the same period. Although the testing of waterside enhancements just began, results indicate that low-level chlorination may be effective in preventing biofouling buildup on such enhancements. Corrosion data indicate that Al-based materials may achieve long service lives in marine environments.--STAR.

Gehrke, T; Sand, W

NACE International, Corrosion/2003 (USA), pp. 8, 2003

A 3-year study of steel pilings in German marine harbours with and without corrosion was performed to quantify the relevant corrosion causing bacteria (SRB and thiobacilli) in the biofouling layers on the pilings at, above, and below the low-water. These organisms occurred at the low-water level jointly, although specially separated in the layers (closed sulfur cycle = sulfuretum), and caused the accelerated corrosion once the layer became sufficiently thick in the course of its ageing. At low tide the layer was thoroughly aerated, whereas at high tide partially anaerobic zones, especially near to the metal must have occurred. Consequently, this type of corrosion needs years to develop. The experimental data clearly indicate that the increased amount of corrosion products (mainly iron) at strongly corroded areas is correlated with enhanced contents of sulfur and sulfate, high cell counts, and (microbial and chemical) activities. Additionally, iron sulfide and pyrite are detectable at the low-water level. These sulfur compounds as well as elemental sulfur are known to be highly corrosive.

Griebe, T; Flemming, HC

Invest. Tec. Pap., vol. 37, no. 146, Oct. 2000, pp 676-677 (C, K, P, S)

Biofilm growth is limited by the amounts of nutrients available, therefore the growth of biofilms in the controlled biofilter will occur at the expense of the nutrients and this means that, downstream of the reactor, the nutrient concentration (biodegradable dissolved organic carbon (BDOC)) is reduced and less biofilm develops on the membrane. Membrane fouling was characterised by measurements of protein, total organic carbon, humic substances, uronic acid as a parameter for EPS. Furthermore the thickness of biofilms on RO-membranes were measured using a cryosectioning technique. The biofiltration step was sufficient to keep the biofilm accumulation on the membrane below the threshold of interference. The structure and composition of the biofilms on the RO-membranes before and after the biofilter were found to be different. The content of protein, total organic carbon, humic substances and uronic acid decreased significantly after the biofiltration step. The antifouling strategy, which was investigated in a cooling water system, proved to be feasible and offers the promise of a reduction in the need for biocides.

Brown, Malcom, Jr

NASA no. 19990027847

We developed new approaches with high resolution transmission electron microscopy in order to image beam-labile molecular structures which are important to the Navy in biofouling. In particular, we studied the adhesive components of two important marine biofoulers, Achnanthes and Stauronesis. We found interesting molecular structures which may contribute to the attachment of these diatoms to substrates such as ship and submarine surfaces. We produced a dichotomous key to help assess and describe in an objective way the complex molecular structures observed. We studied the effects of electron beam irradiation of the samples and learned that the uranyl acetate negative stain "protects" the samples from degradation during irradiation. These studies will augment x-ray crystallographic investigations in understanding the structural basis for unwanted molecular adhesion which is so common in the marine environment.

Lewis, RJ; Johnson, LM; Hoagland, KD

Journal of Phycology [J. Phycol.]. Vol. 38, no. 6, pp. 1125-1131. Dec 2002.

Achnanthes longipes Ag. is a marine stalk-forming diatom that grows in dense biofilms. The effects of cell density, temperature, and light on growth and stalk production were examined in the laboratory to determine how they affected the ability of this diatom to form a biofilm. Stalk production abruptly increased when A. longipes was cultured at a density of 5.4 x 10 super(3) cells.mL super(-), with a lag before stalk production occurring in cultures initiated at lower densities. Growth occurred at all temperatures from 8 to 32 degree C, with maximum growth at 26 degree C. Growth rate was light saturated at 60 mu mol photons.m super(-) super(2).s super(-). Stalk production was determined as the proportion of cells producing stalks and stalk length in response to various temperatures and light intensities at high (5000 cells.mL super(-)) and low (500 cells.mL super(-)) densities. More cells formed stalks at high density, with no difference in stalk length. The proportion of cells producing stalks was maximal at 20 degree C, with little change at 17-32 degree C. Stalk length was at a maximum between 14 and 26 degree C. Stalk production showed little change in response to varying light intensity. The results of an earlier investigation on the effects of bromide concentration on stalk formation were expressed as the proportion of cells forming stalks and the lengths of the stalks. Both measures of stalk production varied with bromide concentration, with maximum values at 30 mM bromide. The increased stalk production at higher densities may be a means of elevating cells above the substrate to avoid competition in the dense biofilm.

Gomez de Saravia, SG; Guiamet, PS; Videla, HA

Institute of Corrosion, Corrosion Odyssey 2001 (UK), pp. 9, 2001

Biocorrosion and biodeterioration processes are directly related to the presence of biofouling deposits on the surfaces of the structural materials. These deposits are the result of a surface accumulation process not uniform in time or space that starts with the formation of biofilms. There is a direct relationship between biocorrosion and the environment. The growth of the microorganisms capable to induce biocorrosion is conditioned by favourable environmental conditions (pH, available nutrients, humidity, etc.). Conversely, the chemical agents generally used to prevent or protect metallic structures from biocorrosion are highly toxic and their use can have a negative impact on the environment. Four different strategies developed in our laboratory to prevent and control biocorrosion minimizing the environmental impact, are successively presented in this paper: a) the use of dissolved ozone as an environmentally friendly biocide for cooling water systems; b) the use of innovative substances such as mixtures of immunoglobulins to prevent bacterial adhesion and biofilm formation; c) the potential use of film forming corrosion inhibitors to simultaneously prevent biofouling and corrosion and d) the assessment of the effectiveness of natural biocides on planktonic and sessile bacteria. (Example materials include stainless steel.)

Dobrevsky, I; Tsvetanova, Z; Varbanov, P; Dimitrov, D; Savcheva, G

European Federation of Corrosion Publications (UK), vol. 29, pp. 202-212, 2000

A method based on the classical approach of biofilm collection by removal from a defined test area and subsequent laboratory analysis was used to assess the characteristics of slime adhesion on test coupons. The influences of the size and nature of the material (carbon steel and stainless steel) on the biofilm mass and microbial composition were assessed in a recirculating cooling water system (RCWS) of the Bulgarian Petroleum Refinery Plant 'Plama'-Ltd. The physicochemical and microbiological characteristics of the biofilms formed on carbon steel and stainless steel collector coupons were compared and the possibility of microbially induced corrosion on the carbon steel surfaces was also assessed. It was found that the biofilm consortia on both types of steel surfaces were composed of the same physiological groups and species of microorganisms, including the main groups of corrosion-related bacteria. The bacteria quantities in the biofilm samples developed on the carbon steel coupons were larger, probably because the porous corrosion products available on the surface provide more favourable conditions for bacterial growth. It was found that the qualitative microbiological composition of the biofilm consortia formed on 'small' and 'large' coupon surfaces was similar, but the bacteria quantities of the great mass of the studied physiological groups were larger in the majority of the biofilm samples formed on the 'small' size coupons. The study confirmed that the biofilm monitoring method used is applicable in the case of working RCWS and provides the information needed for management and limitation of the biofouling formation. The choice of the biofilm test coupons used for RCWS monitoring must be considered with respect to the purposes of the exercise and the type of the construction materials in the RCWS equipment.

Dobrevsky, I; Tsvetanova, Z; Varbanov, P; Dimitrov, D; Savcheva, G

European Federation of Corrosion Publications (UK), vol. 29, pp. 263-273, 2000

Monitoring and field studies of the biofouling problems in a recirculating cooling water system (RCWS) of the Bulgarian Petroleum Refinery Plant, Plama Ltd. were carried out. Chemical and microbiological characteristics of the biofilms developed on different surfaces in contact with the cooling water (heat exchanger surfaces, carbon steel and stainless steel biofilm collector coupons) were made. The microbial compositions of the biofilm consortia formed on the heat exchanger surfaces and biofilm collector tests were the same, including the diverse corrosion-related bacteria. The biofilms on the surfaces of both types of steel were of complex composition but of the the same microbial content, i.e. they contained the same physiological groups of bacteria or bacterial species. The quantities of the diverse microorganisms in the biofilm samples developed on the carbon steel surfaces were larger than on the stainless steel. The experimental results offered new specific information, concerning the problems in the operation of this RCWS. They showed the important role microbial activity in biofouling and corrosion of the metal surfaces in contact with the cooling water.

Muralidharan, J; Jayachandran, S

Process Biochemistry [Process Biochem.]. Vol. 38, no. 6, pp. 841-847. Jan 2003.

Growth and exopolysaccharide (EPS) production by Vibrio alginolyticus, a marine fouling bacterium was studied in sea water nutrient broth in vitro. Fourier transformed infrared spectral analysis of the purified EPS revealed prominent characteristic groups corresponding to polyhydric alcohols. When the derivatized alditol acetates from EPS were separated by gas chromatography five peaks corresponding to glucose tetraacetate, xylopyranose tetraacetate, aminoarabinose tetraacetate, aminoribose tetraacetate and glucose pentaacetate, were observed. Mass spectrophotometric analysis of derivatized EPS revealed the presence of glucose, aminoarabinose, aminoribose and xylose in the molar ratio of 2:1:9:1. Viscometric studies suggested that the molecular weight of EPS was ~6.39x10 Da. Rheological studies of aqueous EPS showed good shearing property. However, the EPS was unstable at high temperatures and high pH.

Jelvestam, M; Edrud, S; Petronis, S; Gatenholm, P

Surface and Interface Analysis (UK), vol. 35, no. 2, pp. 168-173, Feb. 2003

Toxic coatings are now banned all over the world, owing to the negative effects on the marine ecosystem. The invention of new coatings that prevent biofouling but are non-toxic is very high priority. The long-term goal of this study has been to prepare materials with a designed surface micro-architecture that is able to prevent marine fouling by barnacles. Rows of steep microstructures with an elevation of a few micrometres separated from each other by 60 mu m were manufactured using a biomimetic approach based on crystallization of calcite on surfaces of chemically patterned templates with carboxylate functionality. Templates were produced by the microcontact printing process using microfabricated silicone stamps with a surface micro-architecture that has been shown to prevent barnacle settling. Electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectrometry (SIMS) imaging and observations of wetting behaviour were used to examine the surfaces. The templates were used to grow surface microstructures by controlled crystallization of calcium carbonate by immersion in calcium chloride solution. Crystals grow randomly on the acidic areas of surfaces with 60/40 mu m lines, whereas they grow in a regular fashion on a surface stamped with tiny (3-6 mu m) 16-mercaptohexadecanoic acid lines. This study showed that it is possible to prepare stable surface microstructures of a size up to 50 mu m in a regular arrangement of lines.

Stein, J; Truby, K; Wood, CD; Wiebe, D; Montemarano, J; Holm, E; Wendt, D; Smith, C; Meyer, A; Swain, G

Polymer Preprints (USA), vol. 42, no. 1, pp. 236-237, Spring 2001

Biofouling is ubiquitous in the marine environment. There are two main categories of fouling: noncalcareous (soft) and calcareous (hard). Algae, slime and hydroids exemplify noncalcareous foulers. Examples of calcareous foulers, which form shells comprised of calcium carbonate, are barnacles, encrusting bryozoans, molluscs, tubeworms and zebra mussels. Attachment of all of these organisms to the hulls of ships and other underwater structures has negative consequences on their performance. Biofouling of ships increases fuel consumption, increases drag resistance, decreases maximum attainable speed and promotes corrosion. Fouling of power plant intake bays necessitates frequent shut downs and measures such as chlorination. Fouling by calcareous organisms contributes the greatest penalty because of their profile, and their tenacious adhesion to surfaces. Each of the calcareous organisms attaches in a slightly different way using different glues. The most common method of prevention of fouling on ship hulls and other underwater structures uses copper or organotin containing paints. Although organotin containing coatings are highly effective, they are also dangerous to the marine environment in which they are used because the tin leachates can poison non-target organisms such as fish, vegetation, and marine mammals. Because of the increased evidence of ecosystem damage in areas close to concentrated use of tin-containing paints, application of these antifouling paints is being restricted and in some cases prohibited. Fouling release coating technologies are currently under development in response to the need for a nontoxic coating alternative to antifouling paints. Fouling organisms may grow on the surfaces of these coatings but adhere poorly and can be removed by light brushing, water spray or by hydrodynamic self-cleaning. Silicone polymers have show better fouling release capability than fluoropolymers and other coatings. This has been attributed to their being within an optimum range of critical surface tension, which is related (but not equal) to surface energy. Other factors thought to contribute to silicones' superior fouling release ability are their surface structure, extremely low glass transition temperature and low modulus. All of the current coating technology employs condensation cure chemistry. The coatings are prepared by the reaction of a crosslinker with a silanol polymer in the presence of a condensation cure catalyst such as dibutyltindiacetate. We and others have previously shown that oil incorporation may benefit fouling release properties. In this paper, we expand upon the relationship between oil incorporation and foul release properties.

Klassen, RD; Roberge, PR; Porter, J; Pelletier, G; Zwicker, B

NACE International, Corrosion/2001 (USA), pp. 11, Mar. 2001

Biofouling within the cooling water systems of ships can be serious enough to cause immobilization. Marine growth on pipes also promotes crevice corrosion. In seawater, blue mussels are the predominate species that cause biofouling. A biofouling test system was constructed at the Dockyard Laboratory in Halifax, Nova Scotia by the Defense Research Establishment Atlantic. Seawater from the Halifax harbor continuously flowed through pipe networks that were designed to simulate the cooling water piping on a ship. Three commercial chemical injection systems were tested simultaneously, namely copper, iodine and hypochlorite. Personnel from the Bedford Institute of Oceanography assessed the biological effectiveness of each system by observing adult mussels one at a time in a beaker of treated water. These tests revealed a wide range of effectiveness between these chemicals in preventing mussel attachment. Each injection system was better than no treatment at all. As designed and operated, the copper and iodine release systems were only modestly effective whereas the hypochlorite system was completely effective in preventing mussel attachment. Observations of the piping after several months of flow-through operation were consistent with the biological tests with treated water. The process engineering for installing a hypochlorite system on a ship is described.

Gunasingh Masilamoni, J; Jesudoss, KS; Nandakumar, K; Satapathy, KK; Azariah, J; Nair, KVK

Marine Environmental Research [Mar. Environ. Res.]. Vol. 53, no. 1, pp. 65-76. 2002.

Continuous chlorination is a widely followed cooling water treatment practice used in the power industry to combat biofouling. The green mussel Perna viridis is one of the dominant fouling organisms (> 70%) in the Madras Atomic Power Station. Mortality pattern as well as physiological responses such as oxygen consumption, filtration rate, byssus thread production and faecal matter production of three different size groups of this mussel were studied at different chlorination concentrations. At 0.7 mg 1 super(-1) residual chlorine, 3-4 cm size mussels showed 100% mortality in 553.3 h while 8-9 cm size group mussels died within 588 h. At a relatively high level of residual chlorine (9.1 mg 1 super(-1)), 100% mortality in 3-4 cm and 8-9 cm size groups took 94 and 114 h, respectively.. All physiological activities studied showed a progressive reduction as chlorine residuals were increased from 0 to 0.55 mg 1 super(-1). The data indicated that the green mussel can sense a residual chlorine level as low as < 0.15 mg 1 super(-1) and complete valve closure occurs only at 0.55 mg 1 super(-1). The paper also shows that the sub-lethal physiological responses are better indices than lethal responses in planning chlorination strategies.

Burton, Dennis T; Fisher, Daniel J

RECON no. 20020068075

The use of chlorine by electric utilities and other surface water users to inhibit biofouling and the chlorination of wastewater by POTWs to eliminate the discharge of pathogenic organisms are widespread practices. A number of surface water users in the Great Lakes region recently expressed an interest in using chlorine to control the zebra mussel (Dreissena polymorpha) which was introduced from Europe in the mid-1980s. It is well known, however, that chlorine-produced oxidants may be toxic to aquatic life when discharged into receiving waters. In addition, chlorine reacts with ammonia and chlorinated hydrocarbons to form various chloramines and trihalomethanes, which have long half-lives and similar toxicities relative to free chlorine (Fisher et al. 1999).

Faille, C; Dennin, L; Bellon-Fontaine, MN; Benezech, T., -

Biofouling (USA), vol. 14, no. 2, pp. 143-151, Sept. 1999

Adhesion of Bacillus thuringiensis spores on stainless steel surfaces has been investigated under various fouling conditions (static and dynamic). The number of adhering spores as well as the removal of adherent spores following a standard cleaning in place (CIP) procedure were analysed. The number of adhering spores was demonstrated to depend on the fouling conditions, with a significant lower level adhering under static conditions (up to 0.6 log). Under dynamic conditions, the initial rate of contamination was found to be more than twice as high as in the turbulent conditions tested, but then appeared to slow down with time. Cleanability assessment of these surfaces revealed a weak attachment of spores adhering under static conditions as well as in turbulent conditions (removal up to 93% compared to 68% under some laminar fouling conditions). Fouling conditions should thus be taken into account as a major concern in risk assessment procedures. (Authors note the importance of bacterial spore biofouling of food processing equipment.)

Bott, TR; Miller, PC

J. Chem. Technol. Biotechnol., 33B, (3), 177-184, Sept. 1983

The development of biofilms in contact with flowing liquids was monitored in a biofouling culture apparatus which contained Al tubes and which was inoculated with Pseudomonas fluorescens . Tests were carried out in which, alternately, the nutrient feed or the bacterial supply was stopped. Results showed that once the surface is colonized, the predominant mechanism for biofilm development was growth within the film. Maximum biofilm development occurred at liquid flow velocities approx 1 m/sec. Rapid development occurred even in the presence of very small amounts of nutrient. 17 ref.--AA/MS.

Mater Performance; Vol 36; No 3; pp 57-58; 1997, March

Experience with the 110,000-pound mixed-metal (stainless-aluminum bronze) roller gate chain at the Robert C. Byrd Locks and Dam near Apple Grove, West Virginia has shown that zebra mussels which have been troublesome to the dam operators by fouling the previous carbon steel chains find 'the aluminum bronze components in the chain distasteful'. The two metals were very compatible.

Mathiyarasu, J; Palaniswamy, N; Muralidharan, VS

Bulletin of Electrochemistry (India), vol. 18, no. 11, pp. 489-495, Nov. 2002

The electrochemical behaviour of the dissolution of cupronickel in aqueous sodium chloride solutions was investigated through cyclic voltammetric and X-ray diffraction studies. This investigation analyses the discrepancies existing in the ideas related to cupronickel dissolution whether selective dissolution/ simultaneous dissolution. Anodic dissolution of cupronickel alloys is found to be potential dependent. Selective dissolution takes place at lower potentials and simultaneous dissolution at higher potentials. The rate of simultaneous dissolution of the alloy is lower than that of the anodic dissolution of pure copper. [Cupronickels are being extensively employed in marine environments because of their excellent corrosion and biofouling resistance.]

Boulton, LH; Powell, CA; Hudson, WB

10th International Congress on Marine Corrosion and Fouling, University of Melbourne, February 1999, Additional Papers (Australia), pp. 73-87, 2001

Copper-nickels are alloys which possess a combination of excellent corrosion resistance and a high natural resistance to biofouling in seawater. They have a proven performance record over many years in applications such as seawater piping, intake screens, water boxes, and for cladding of offshore structures. The property combination also makes copper-nickel an attractive material for boat hulls, either as the hull material itself or applied as a sheathing. A more recent innovation has been the application of 90-10 copper-nickel sheathing as an adhesive-backed thin foil. This paper principally describes trials and evaluation of 90-10 copper-nickel sheathing on the hulls of two commercial passenger ferries, in service on the Auckland harbour, Auckland, New Zealand. One vessel is a slow ferry (10 knots), constructed of fibreglass reinforced polymer (FRP), which was retrofitted with copper-nickel sheathing in 1993. The other vessel is a fast catamaran ferry (22 knots) with a FRP hull, which was sheathed during construction in 1994. The older monohull vessel MV Koru is kept in reserve most of the time, whereas the catamaran MV Osprey has been in service for about 30,000 nautical miles since construction. In addition, biofouling results of parallel testing programmes exposing test panels in harbour environments in New Zealand, Singapore and the United Kingdom are described.

Powell, CA; Michels, HT

NACE International, Corrosion 2000 (USA), pp. 00627.1-00627.17, Mar. 2000

This review describes the behaviour of the 90-10 (C70600) and 70-30 (C71500) copper-nickel alloys, which were developed for and have been used extensively in seawater applications for over half a century. It provides an assessment of the corrosion resisting characteristics and also the inherent biofouling resistance of the alloys with the aim of learning from past experiences and ensuring good commissioning and operational practices for future use.

KME Europa Metal Aktiengesellschaft, The Behavior of CuNi 90/10 vs 6Mo Superaustenitic and Superduplex Steels in Marine Environments (Germany), pp. 17, 2000

This paper highlights the properties of copper-nickel alloy Cu Ni 90/10 versus high alloy steels (superduplex and 6Mo), and the metals' respective behaviours in seawater environments. Recent reports about corrosion-related failures in these steels and, on the other hand, the excellent long-time performance record of CuNi 90/10 show that CuNi 90/10 is eminently suitable for offshore applications, its advantages being in particular: Good availability of all the pipe system components; greater ease of jointing and field erection; favourable material and installation costs; good resistance to corrosion, also in crevices; good resistance to biofouling/no chlorination; and excellent long-time performance experience.

Stein, J; Wood, CD; Harblin, O; Resue, J

Performer: General Electric Corporate Research and Development, Schenectady, NY. 31 Oct 2001. 352p.

Biofouling on ship hulls presents a significant challenge for the U. S. Navy. Fouling on the hulls of marine vessels has been shown to reduce maximum speed and increase propulsive fuel consumption1. Historically, marine antifouling paints have utilized compounds toxic to marine organisms, such as triorganotin, as a means of combating the fouling problem2. In recent years, the environmental impact of these coatings has come under scrutiny3,4. The application of triorganotin-based paints has been prohibited on smaller vessels (< 25 m) and the U.S. Navy has discontinued its use.

Murugan, A; Ramasamy, MS

Indian journal of marine sciences [Indian J. Mar. Sci.]. Vol. 32, no. 2, pp. 162-164. 2003.

Growth of marine sedentary organisms causes notable damage to ship-hull, harbour structures and industrial cooling and filtration systems. TBT based antifouling paints are widely used worldwide and is to be phased out by the year 2008 because of its adverse effect on non-target organisms. Efforts are therefore being made to develop alternative eco-friendly antifoulant paints. The crude methanol: water extract of the ascidian, Distaplia nathensis showed antimicrobial activity against 12 out of 14 bacteria screened in the present study. At a concentration of 0.1 mg/ml, the crude extract completely inhibited the byssal production and attachment in the mussel Perna indica. The EC sub(50) and LC sub(50) were found to be 50 plus or minus 6.45 mg/ml and 150 plus or minus 19.2 mu g/ml respectively. The gradient partition showed high polar nature of the active component. The indication of non-toxic nature of the extract in the toxicity assay and the broad spectral antimicrobial activity has revealed that it could be a potential source of the antifouling compound.

Advanced Materials & Processes (USA), vol. 158, no. 4, pp. 16, Oct. 2000

Copper has demonstrated significant antibacterial advantages in pipes that carry drinking water, according to a study funded by the International Copper Association, New York, NY, USA. A research team found that in soft water systems at 10 deg C (50 deg F), the concentration of toxic E. coli 0157 was over 100 times lower on Cu substrates than on steel or plastic substrates. At temperatures of 20 deg C (70 deg F) in soft water, the antibacterial effect is more than ten times greater than plastic or stainless steel. The study also found that Cu has strong biofouling prevention characteristics in 10 deg C (50 deg F) soft water, whereas biofouling was very significant on plastic and steel. Contact: Ken Geremia, International Copper Association, 260 Madison Ave, New York, NY 10016, USA; tel 212/251-7200, email: kgeremia@cda.copper.org, website: www.copper.org.

Douglas-Helders, GM*; Tan, C; Carson, J; Nowak, BF

Aquaculture [Aquaculture]. Vol. 221, no. 1-4, pp. 13-22. 1 May 2003.

Amoebic gill disease (AGD) is the main disease affecting the salmon industry in Australia. Little information is available on the epidemiology of AGD and the biology of Neoparamoeba pemaquidensis [Page, 1987], the disease-causing organism of AGD. In previous studies, N. pemaquidensis was found on biofouled netting of sea cages, and a reduction in AGD prevalence was achieved with increasing number of net changes. Presently, it is not known if N. pemaquidensis on netting is able to induce AGD. To reduce biofouling on nets, antifouling paints are commonly used on Tasmanian salmon farms. This study investigated the effects of a copper-based antifouling paint on the N. pemaquidensis densities on nets and the AGD prevalence of Atlantic salmon reared in these nets. Four sea cages stocked with 5-9 kg/m super(3) Atlantic salmon were used in this study. Two nets were coated with a copper-based antifouling paint and two nets were not treated and used as a control. Fish were sampled every 2 weeks for 10 weeks. A gross gill score was determined and gill mucus samples were taken for dot blot analysis to determine the presence of N. pemaquidensis for each fish. Biofouling samples from netting were inoculated onto 75% malt yeast agar culture plates, and presence of N. pemaquidensis assessed using conventional culture techniques, followed by indirect immunofluorescent antibody test (IFAT). The presence of N. pemaquidensis was confirmed from culture-enriched biofouling samples from weeks 2 and 8 were tested using nested PCR. Results suggest that copper paint treated cages had significantly higher paramoebae (P=0.002) and AGD (P=0.014) prevalence compared to the control cages. No treatment effect was found on the intensity of infection, determined by gross gill scores (P=0.243). At the end of the study, the paramoebae prevalence of net samples was 58.5% (S.E. 1.5) and AGD prevalence was 42.5% (S.E. 2.5) for copper treated nets, while no paramoebae were found on control nets and AGD prevalence was 35.0% (S.E. 5.0). Nets could be the source of N. pemaquidensis infection of fish with AGD, and therefore copper paint treated nets could be a risk factor for AGD.

Marine Engineers Review (UK), pp. 12-13, 15, Feb. 2002

Concern that copper-based antifoulings may in time become restricted, has been the driving force behind the formation of the Copper Antifouling Environmental Programme, and with it, calls for a greater understanding of copper in the marine environment. The adoption by IMO of the Convention of the Control of Harmful Antifouling Paints and the impending ban of TBT has resulted in a shift back to the use of copper as the main biocidal ingredient in antifouling systems, but in years to come copper too could become an outlawed substance. Indeed, the IMO TBT Resolution does include provision for the restriction of other substances if deemed detrimental to the ecosystem. There are already voices of concern and the European Commission has proposed to give copper an R50/R53 classification. If this is adopted, an R50/R53 classification would render copper as toxic, persistent and bio-accumulative in the environment and would necessitate certain approvals and conditions for its continued use as an antifoulant. Yet rumbles of dissent can be heard around the passageways and gangways of the industry, particularly in the marine coatings sector, arguing that there has been no hard evidence to suggest that any marine organism population or ecosystem is being adversely affected by the use of copper in antifouling. So concerned in fact at the supposed lack of understanding and research into copper in the marine environment that last year a group of companies formed the Copper Antifouling and Environment Programme (CAEP), a voluntary body established to generate, collate and distribute accurate information regarding the effective use of and environmental fate of copper in antifouling.

Rajagopal, S; Van der Velde, G; Van der Gaag, M; Jenner, HA

Water Research [Water Res.]. Vol. 37, no. 2, pp. 329-338. Jan 2003.

Mussel control in cooling water systems is generally achieved by means of chlorination. Chlorine is applied continuously or intermittently, depending on cost and discharge criteria. In this paper, we examined whether mussels will be able to survive intermittent chlorination because of their ability to close their valves during periods of chlorination. Experiments were carried out using three common species of mussels: a freshwater mussel, Dreissena polymorpha, a brackish water mussel, Mytilopsis leucophaeata and a marine mussel, Mytilus edulis. The mussels were subjected to continuous or intermittent (4 h chlorination followed by 4 h no chlorination) chlorination at concentrations varying from 1 to 3 mg l super(-1) and their responses (lethal and sublethal) were compared to those of control mussels. In addition, shell valve activity of mussels was monitored using a Mussel-monitor registered . Data clearly indicate that mussels shut their valves as soon as chlorine is detected in the environment and open only after chlorine dosing is stopped. However, under continuous chlorination mussels are constrained to keep the shell valves shut continuously. The mussels subjected to continuous chlorination at 1 mg l super(-1) showed 100% mortality after 588 h (D. polymorpha), 966 h (Mytilus edulis) and 1104 h (Mytilopsis leucophaeata), while those subjected to intermittent chlorination at 1 mg l super(-1) showed very little or no mortality during the same periods. Filtration rate, foot activity index and shell valve movement of D. polymorpha, Mytilopsis leucophaeata and Mytilus edulis decreased more than 90% at 1 mg l super(-1) chlorine residual when compared to control. However, mussels subjected to intermittent chlorination showed a similar reduction (about 90%) in filtration rate, foot activity index and shell valve movement during chlorination and 3% during breaks in chlorination. The data indicate that intermittent chlorination between 1 and 3 mg l super(-1) applied at 4 h on and 4 h off cycle is unlikely to control biofouling if mussels are the dominant fouling organisms.

Brady, RF Jr

Journal of Protective Coatings & Linings (USA), vol. 20, no. 1, pp. 33,34,37, Jan. 2003

Alternatives for organotin-based antifouling coatings are most likely to come from one of three technologies: copper-based coatings, coatings containing organic biocides, or nontoxic fouling release coatings. These topics, among many others, were prominently featured at the Eleventh International Congress on Marine Corrosion and Fouling, held in July 2002 at the University of San Diego. The following reports on some of the most interesting work in this area presented at the Congress. Many of these studies will be published in the journal Biofouling early in 2003. [Application: aluminum ship hulls.]

Tsibouklis J; Stone M; Thorpe AA; Graaham P; Barbu E; Eaton PJ; Smith JR; Nevell TG; Ewen RJ

Surface Coatings International Part B; 85, No.B4, Nov.2002, p.301-8

The utilisation of non-toxic polymeric coating materials onto which colonising organisms will not adhere presents an attractive means of preventing the fouling of surfaces. The molecular design requirements for the fabrication of materials which, if applied as coatings, can remove the ability of fouling micro-organisms to form a permanent bond with the coated surface, are examined. 8 refs.

BLIDBERG, DR

Sea Technology, vol. 38, no. 12, pp. 45-51, December, 1997

Advances in the technology of autonomous underwater vehicles (AUVs) has brought about solar power as a means of overcoming obstacles that include navigation and communication, as well as energy. The Autonomous Undersea Systems Institute in New Hampshire and the Institute for Marine Technology Problems in Vladivostok, Russia, are examining the potential of solar energy to power long-endurance AUV ocean monitoring missions. A prototype vehicle is being used to assess system components and their integration with charging and power management systems for an endurance run exceeding 1 year. With a need to surface on a regular basis for recharging, the AUV provides the opportunity for researchers to receive data and transmit mission commands via satellite-based communications. Research in the use of AUVs for monitoring ocean environments must address a number of technological limitations. Many scientific sensors require too much power for operation aboard solar-powered AUVs, although some have substantially reduced power requirements as a result of recent technological advances. Sensors must also be capable of maintaining calibration over the extended sampling periods. Biofouling of the solar arrays and sensors is also a problem, especially in the photic zone and at latitudes where the annual mean daily total horizontal solar radiation is less than what is required to power the AUV systems. Easy-release array surfaces, such as those coated with ethyl vinyl acetate, provide a low surface tension to water with antifouling qualities. A mechanical removal of biological growth is also being investigated as a means of maintaining the arrays. The range of a solar-powered AUV can be calculated for low insolation and high insolation areas. A photovoltaic array of 0.5 square meters and a 10% conversion efficiency provide an output of about 75 watt-hours per day in a low insolation region of 1.5 kilowatt-hours per square meter per day. A high insolation area of about 6.0 kilowatt-hours per square meter per day can provide an output of 300 watt-hour per day from the same photovoltaic array. Test runs off the New Hampshire coast indicate that wave motions do not significantly affect the efficiency of the array when its angular orientation is limited to within 25 degrees from the direction of the sun. The array is also effective when slightly submerged in water less than 20-30 centimeters below the surface. With a 420 watt-hours battery capacity, the AUV prototype is expected to have a range of about 24 kilometers per day in areas where the solar insolation level is about 2,000 watt-hours per square meter per day.

Stein, J; Truby, K; Wood, CD; Takemori, M; Vallance, M; Swain, G; Kavanagh, C; Kovach, B; Schultz, M; Wiebe, D

Biofouling (UK), 19, (2), 87-94, Apr. 2003

Model silicone foul-release coatings with controlled molecular architecture were evaluated to determine the effect of compositional variables such as filler loading and crosslink density on pseudobarnacle attachment strength. Pseudobarnacle adhesion values correlated with filler loadings in both condensation and hydrosilylation-cured silicones. Variation of crosslink density of hydrosilylation-cured silicones had an insignificant effect on attachment strength. X-ray photoelectron spectroscopy (XPS) indicated that the mode of failure upon detachment of the pseudobarnacle was dependent upon the corsslink density; samples with high crosslink density failed cohesively within the silicone. Silicone polymers, Karstedt's catalyst, dibutyltinbis (acetylacetonate), fumed silica, tetraethylorthosilicate, calcium carbonate, and SS4155 were obtained from GE Silicones. Aluminum panels were obtained from the Q Panel Company. Applications: seafaring vessels.

Nandakumar, K; Obika, H; Shinozaki, T; Ooie, T; Utsumi, A; Yano, T

Water Research [Water Res.]. Vol. 37, no. 10, pp. 2311-2316. May 2003.

The ability of pulsed laser irradiations to cause damage on the biofouling organisms is recently being investigated. If this technique is employed in industries such as power generation wherein a large quantity of water is being used for the cooling purpose, many organisms other than the targeted would get affected. In this study, we have investigated the damage caused by the pulsed laser irradiations from an Nd:YAG laser (fluence 0.1 J/cm super(2)) for varying durations such as 2, 5, 10, 30, 60 and 300 s on two marine diatom species namely Skeletonema costatum and Chaetoceros gracilis. Upon exposure to low power laser irradiations, these diatom species showed mortalities between 52.6+/-9.3% to 97.7+/-3.1% in the case of S. costatum and 57.8+/-2.5% to 98.9+/-0.6% in the case of C. gracilis for 2 and 300 s of irradiations, respectively. The mortality increased with the increase in the duration of laser irradiation. The estimation of the chlorophyll a concentration in the irradiated samples showed a considerable reduction varying between 9.8% and 57% in C. gracilis and 3% and 70.3% in S. costatum for 2 and 300 s of irradiations, respectively. The laser-survived cells grew as the non-irradiated (control) samples. C. gracilis frustules were broken by the laser whilst, the cell materials were drained out of the frustules in the case of S. costatum. The study therefore showed that the low power pulsed laser irradiations could cause significant damage on the two species of planktonic diatoms.

Mackie, GL; Lowery, P; Cooper, C

Performer: Army Engineer Waterways Experiment Station, Vicksburg, MS. Engineer Research and Development Center. Dec 2000. 13p. Report: ERDC-TN-ZMR-2-22

A plasma sparker has been developed by Sparktec Environmental Inc. to control settlement of zebra and quagga mussels. Plasma pulse technology is a physical, nonchemical, nonthermal process for introducing energy directly into an aqueous solution. This patented system is made up of three separate components, a power supply to control the power management, a capacitor storage bank to store the required energy, and a submersible assembly where this energy is released to the water. When the plasma sparker is activated, electrical energy stored by capacitors is released between two submerged electrodes in microseconds. A plasma channel is formed because of this high current/high voltage electrical discharge. The discharge process consists of at least three primary events, an intense shockwave, a steam bubble which may lead to a supercritical water phase where oxidation of organic substrates will occur, and ultraviolet light. The technology is currently in use in several utilities and industries in Canada and the United States. These experiments, most of which are now completed, are designed to show what mechanisms are being employed to control zebra mussel biofouling in pipelines. Mechanisms being evaluated are: (1) indirect control through continuous application of pulsed power to limit biofilm biomass and composition; (2) direct control through continuous application of pulsed power to (a) kill the zebra mussels, (b) detach mussels already settled, (c) prevent settlement of new recruits and reattachment of translocators; and (3) control by application of pulsed power for short durations to sustain permanent damage to shells or weaken the mussels sufficiently that they eventually die.

Walch, M; Mazzola, M; Grothaus, M

Performer: Naval Surface Warfare Center Carderock Div., Bethesda, MD. Feb 2000. 37p. Report: NSWCCD-TR-2000/04

This report describes a preliminary field test of a new biofouling control device designed for seawater piping and cooling systems. This technology uses a pulsed, underwater electrical discharge to generate an acoustic wave in pipes. The test was conducted during February 1994 in a seawater test loop, constructed of clear PVC piping, located at the Naval Surface Warfare Centers' Corrosion Test Facility in Dania, Florida. It included an untreated, control pipe and another identical pipe which was treated with an acoustic pulse every two seconds, ten hours per day, for 10 days. Results of visual observations, microbial counts, environmental electron microscopy (ESEM) and energy-dispersive x-ray analysis (EDS) demonstrated a significant reduction in the rate of biofouling in the pipe treated with the pulsed acoustic device compared to the control.

Kem, WR; Soti, F; Rittschof, D

Biomolecular Engineering [Biomol. Eng.]. Vol. 20, no. 4-6, pp. 355-361. Jul 2003.

Hoplonemertines are carnivorous marine worms, which prey upon crustaceans and annelids. They paralyze their prey by injecting alkaloids with a stylet- bearing proboscis. The dermis of these animals also secretes alkaloids to repel predators. Besides affecting central and peripheral nervous system nicotinic receptors, some pyridyl alkaloids also activate certain chemoreceptor neurons in crustacean walking legs, which sense environmental chemicals. Anabaseine (2-[3- pyridyl]-3, 4, 5, 6-tetrahydropyridyl) and 2, 3'-bipyridyl (2, 3'-BP) are two nemertine alkaloids, which potently paralyze crustaceans. Anabaseine is an agonist of vertebrate as well as invertebrate nicotinic receptors. While 2, 3'- BP is non-toxic to mice, it is toxic to crustaceans. We tested a variety of nemertine pyridyl alkaloids for inhibition of barnacle (Balanus amphitrite) larval settlement and for crustacean toxicity in order to determine whether toxicity could be dissociated from inhibition of larval settlement. We prepared eight C-methylated 2, 3'-BP isomers to determine where substitution is permitted without loss of activity. Anti-settlement and toxicity activities were not always related. For instance, 4'-methyl-2, 3'-BP displayed only 3% of the crayfish paralytic activity of 2, 3'-BP, but inhibited settlement almost 2-fold more effectively. Two other isomers displaying exceptional anti-settlement activity were the 4- and 5-methyl-2, 3'-BPs; these also displayed high crustacean toxicity. Nemertelline inhibited barnacle settlement at concentrations similar to 2, 3'-BP but was 136-fold less toxic when injected into crayfish. Thus, certain bipyridyls and tetrapyridyls may be useful anti-fouling additives.

Kelly, SR; Jensen, PR; Henkel, TP; Fenical, W; Pawlik, JR

Aquatic Microbial Ecology [Aquat. Microb. Ecol.]. Vol. 31, no. 2, pp. 175-182. 13 Mar 2003.

Attachment is one of the first steps in bacterial colonization. By inhibiting bacterial attachment on surface cells, sponges may not only prevent infection, but also the process of biofouling. Crude organic extracts from 26 species of Caribbean sponges were assayed for their ability to inhibit bacterial attachment. Bacterial attachment was tested using Vibrio harveyi, a motile marine bacterium, isolated from seawater collected above one of the reefs from which sponges were sampled. Extracts were incorporated into agar blocks at concentrations volumetrically equivalent to whole sponge tissue. Extracts from 21 of 26 species (81%) resulted in bacterial attachment on treated blocks that was <40% of attachment on controls. Of these extracts, 9 were particularly active, with mean levels of attachment <8% of controls (Agelas conifera, Ailochroia crassa, Aka coralliphagum, Amphimedon compressa, Aplysina fulva, Erylus formosus, Plakortis halichondrioides, Ptilocaulis spiculifera, Verongula gigantea). Extracts from 4 species (Ailochroia crassa, Chondrilla nucula, Ectyoplasia ferox, and Iotrochota birotulata) inhibited bacterial attachment in this assay but were not found to inhibit bacterial growth in a previous study. Purified compounds that deterred feeding of predatory fishes in a prior study were also tested for their effects on bacterial attachment; they were: oroidin, 4,5-dibromopyrrole-2-carboxylic acid and sceptrin from Agelas species, amphitoxin from A. compressa, aeroplysinin-1 and dibromocyclohexadienone from Aplysina species, steroidal glycosides from E. ferox, and formoside from E. formosus. Of these, all but the steroidal glycosides from E. ferox deterred bacterial attachment at natural concentrations, providing evidence that sponge secondary metabolites may have multiple ecological functions.

Holmstroem, C; Egan, S; Franks, A; McCloy, S; Kjelleberg, S

FEMS Microbiology Ecology [FEMS Microbiol. Ecol.]. Vol. 41, no. 1, pp. 47-58. Jul 2002.

Members of the marine bacterial genus Pseudoalteromonas have been found in association with living surfaces and are suggested to produce bioactive compounds against settlement of algal spores, invertebrate larvae, bacteria and fungi. To determine the extent by which these antifouling activities and the production of bioactive compounds are distributed amongst the members of the genus Pseudoalteromonas, 10 different Pseudoalteromonas species mostly derived from different host organisms were tested in a broad range of biofouling bioassays. These assays included the settlement of larvae of two ubiquitous invertebrates Hydroides elegans and Balanus amphitrite as well as the settlement of spores of the common fouling algae Ulva lactuca and Polysiphonia sp. The growth of bacteria and fungi, which are the initial fouling organisms on marine surfaces, was also assayed in the presence of each of the 10 Pseudoalteromonas species. It was found that most members of this genus produced a variety of bioactive compounds. The broadest range of inhibitory activities was expressed by Pseudoalteromonas tunicata which inhibited all target fouling organisms. Only two species, Pseudoalteromonas haloplanktis and Pseudoalteromonas nigrifaciens, displayed negligible activity in the bioassays. These were also the only two non-pigmented species tested in this study which indicates a correlation between production of bioactive compounds and expression of pigment. Three members, P. tunicata, Pseudoalteromonas citrea and Pseudoalteromonas rubra, were demonstrated to express autoinhibitory activity. It is suggested that most Pseudoalteromonas species are efficient producers of antifouling agents and that the production of inhibitory compounds by surface associated Pseudoalteromonas species may aid the host against colonisation of its surface.

Diggins, TP; Baier, RE; Meyer, AE; Forsberg, RL

Biofouling (UK), vol. 18, no. 1, pp. 29-36, Mar. 2002

Dreissenid mussels (Dreissena polymorpha and Dreissena bugensis) are typically cited as troublesome invasive biofoulers, but their high productivity and filtration capacity offer promise for water quality management. Described here is a design that has evaluated the potential for flow-through mussel filters to clear bioavailable contamination from effluents before discharge. Fine resuspended natural sediments (to which many pollutants readily adsorb) were intercepted by a cascading series of three 16 l filters with a residence time of less than 10 min tank exp -1 . The inexpensive design cleared up to 96% of suspended particles, and allowed removal of mussels and pseudofaeces as needed. More than 80% of particle interception resulted from mussel filtering, with little attributed to blockage by the apparatus and/or mussel shells. Scale-up, treatment and disposal of by-products, and practical filter applications are recommended. [Various metals are mentioned as contaminants.]

Yan, T; Yan, WX

Biofouling (UK), vol. 19, Suppl., pp. 133-138, Apr. 2003

Biofouling on ships' hulls and other man-made structures is a major economic and technical problem around the world. In recent decades, the development and growth of the offshore oil and gas industry has led to increased interest in, and studies on marine fouling in offshore regions. This paper reviews the effects of marine fouling on offshore structures, the development of offshore fouling studies in China, and the characteristics of marine fouling in relevant areas. Future research strategies are also proposed.

Matsunaga, H; Takagi, M; Kogiku, F

Tetsu-to-Hagane (Journal of the Iron and Steel Institute of Japan) (Japan), vol. 89, no. 4, pp. 454-460, Apr. 2003

Block without cement and natural aggregates has been developed from steel slag, and its applicability to marine structure has been investigated. The slag block has the following feature: (1) Similar-manufacturing process to conventional concrete can be used. (2) It has sufficient strength to adapt the standard of marine concrete. (3) It has excellent abrasion resistance characteristics. (4) The lower rate of dissolution of alkaline elements in soaking seawater. (5) The biofouling growth on slag block was significantly more than that on the concrete block in the intertidal area at Mizushima Port in the Inland Sea. This was true both with respect to the total biomass of biofouling organisms as well as the number of species.