WO1994008904A1

WO1994008904A1 - Antifouling coating composition and method

Info

Publication number: WO1994008904A1
Application number: PCT/US1993/009762
Authority: WO
Inventors: Donald John Gerhart; Daniel Rittschof; Irving R. Hooper; Anthony Simon Clare
Original assignee: Duke University
Priority date: 1992-10-15
Filing date: 1993-10-13
Publication date: 1994-04-28
Also published as: CA2146130C; KR950704197A; CA2146130A1; SG49287A1; AU5404394A; KR100314105B1

Abstract

Certain compounds are disclosed as being useful as marine or fresh water antifoulant compounds to be used in protective carrier compositions such as film forming polymer to protect fish nets, boats, pilings, and piers. The compounds are selected from those of formulae (1, 2, 3, 4, 5, 6, 7, 8, 9).

Description

Antifouling Coating Composition and Method

BACKGROUND OF THE INVENTION This invention relates generally to protection of underwater surfaces from fouling by aquatic organisms. This invention was made with government support awarded by the Office of Naval Research under contract No. N00014-86-K-0261. The government has certain rights in the invention.

DESCRIPTION OF THE PRIOR ART In marine, brackish, and freshwater environments, organisms collect, settle, attach, and grown on submerged structures. Organisms which do so can include algae, and aquatic animals, such as tunicates, hydroids, bivalves, bryozoans, polychaete worms, sponges, and barnacles. Submerged structures can include the underwater surfaces of ships, docks and piers, pilings, fishnets, heat exchangers, dams, piping structures, such as intake screens, and cooling towers. The presence of these organisms, known as the "fouling" of a structure, can be harmful in many respects. They can add to the weight of the structure, hamper its hydrodynamics, reduce its operating efficiency, increase susceptibility to corrosion, and degrade or even fracture the structure. The common method of controlling the attachment of fouling organisms is by protecting the structure to be protected with a paint or coating which contains an antifouling agent. Exemplary antifouling coatings and paints are described in U.S. Patent No. 4,596,724 to Lane, U.S. Patent No.4,410,642 to Layton, and U.S. Patent No. 4,788,302 to Costlow. Application of a coating of this type inhibits the attachment, or "settling", of the organism, by either disabling the organism or providing it with an unattractive environment upon which to settle.

Of the fouling organisms noted above, barnacles have proven to be among the most difficult to control. Typically, commercial antifouling coatings and paints include a toxic metal-containing compound such as tri-n-butyl tin (TBT), or cuprous oxide, which leaches from the coating. Although these compounds exhibit moderate success in inhibiting barnacle settlement, they degrade slowly in marine environments, and therefore are ecologically harmful. In fact, TBT is sufficiently toxic that its release rate is limited by legislation in some countries. Some experimental non-toxic compounds have been tested with limited success in barnacle settlement inhibition. See, e.g., Gerhart et al., J. Chem. Ecol. 14:1905-1917 (1988), which discloses the use of pukalide, epoxypukalide, and an extract produced by the octocoral Leptogorgia virgulata, to inhibit barnacle settlement, and Sears et al., J. Chem. Ecol. 16:791-799 (1990), which discloses the use of ethyl acetate extracts of the sponge Lissodendoryx isodictylais to inhibit settlement.

Japanese Patent Disclosure No. 54-44018A of April 7,1979 (Patent Application No. 52-109110 of September 10,1977, discloses gamma- methylenebutenolide lactone and alkyl gamma-methylenebutenolide lactone derivatives having the general structure

wherein Rl and R2 are hydrogen or saturated or unsaturated alkyl groups of 1-8 carbon atoms. The compounds are natural products from terrestrial plants.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide an antifouling composition which is effective in inhibiting the settlement of fouling organisms on an underwater surface.

Another object of the present invention is to provide an antifouling paint or coating composition which is effective in protecting underwater structures from fouling by barnacles, and other aquatic organisms.

A further object is to provide structures which are effectively protected against fouling by aquatic organisms.

These and other objects are accomplished by the present invention which in one aspect comprises a composition for use as a marine or freshwater antifoulant comprising a protective carrier component functioning to release antifouling agent and, as an antifouling agent, at least one compound selected from the group consisting of

(8) (9)

wherein R\_f R2, R3, and R4 are independently selected from -C(0)R5,- C(0)OR6, (Cι-Cδ)alkyl, phenyl, phenyl substituted with (Ci-C^alkyl, ( - C4)alkoxy, (C2-Cs)alkenyl, (C2-C8)alkynyl, halogen, and hydrogen, provided that at least one of Ri, R2, R3, and R4 is not hydrogen; wherein R5 is R6 or NR7R8; wherein R6 is (Cι-Cδ)alkyl, (C2-Cs)alkenyl, (C2-Cs)alkynyl, phenyl, phenyl substituted with (Cι-C4)alkyl, (Q-C4)alkoxy, or halogen; wherein R7 and Rs are independently selected from hydrogen or R& wherein R9, Rio, Rll, Rl2, Rl3/ Rl4/ Rl5,

Rl7/ Rl8, Rl9, R20/ and R21 are independently selected from the group consisting of hydrogen and (C1-C10) alkyl; and wherein R22_/ R23 ^and R24 are each independently selected from hydrogen, (C1-C3) alkyl groups, (C1-C3) alkoxy groups, halogens, and hydroxyl groups. A second aspect of the present invention comprises a method of protecting a marine or freshwater structure against fouling by marine or freshwater fouling organisms comprising applying at least one of the aforementioned compounds on and /or into said structure.

Another invention is a marine or freshwater structure protected against fouling organisms wherein said protection is afforded by at least one of the aforementioned compounds having been applied on and/ or into said structure.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph plotting settlement rate of untreated controls as a function of larval density. The least squares regression equation for the data is Y = 47.4 (log X) - 41.3, where Y represents settlement rate and X represents larval density.

Figure 2 is a graph plotting settlement rate of treated samples as a function of larval density. The least squares regression equation for the data is Y = -51.7 (log X) + 118.6, where Y represents settlement rate and X represents larval density). DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to controlling the attachment of unwanted organisms to submerged surfaces by contacting the organisms with one or more compounds having antifouling activity selected from the group consisting of those of formulae (1) through (9). It has been discovered that such compounds inhibit the settlement of fouling organisms, particularly barnacles. As used herein, "settlement" refers to the attachment of aquatic organisms to an underwater structure. Contacting an organism with a compound of the invention in the area adjacent a submerged surface prevents the settling of the organism on that submerged surface. In the practice of the method of the present invention, the antifouling compound may be contacted to the organism by coating the object to be protected with a coating containing the antifouling compound, which then releases the compound into the aquatic environment immediately adjacent the external surfaces of the article, by including the antifouling compound within material formed into an aquatic article which then releases the compound, by releasing the compound directly into the aquatic environment surrounding the protected object, or by any other method wherein the compound contacts the organism prior to its attachment to the surface. As used herein, the term "contacting" means that an amount of antifouling compound sufficient to inhibit settlement of the organism on the surface of interest physically contacts the organism, whether by direct external contact, inhalation, respiration, digestion, inhibition, or any other process.

Preferred compounds are selected from the group consisting of 2- ethylfuran; 2-methylfuran; methyl-2-furanoate; ethyl-3-furoate; 2-furyl-n-pentyl ketone; 2-acetylfuran; khellin; γ-decalactone; α-angelica lactone; α-santonin; α- methylene-γ-butyrolactone; coumaranone; alantolactone; and 3-methyl-2- cyclohexene-1-one.

The amount of compound to be used in the method will vary depending on a number of factors, including the identity of the antifouling compound, the identity of the organism to be inhibited, and the mode of contact. In addition, the rate at which the compound is released into the surrounding aquatic environment can be a major factor in determining both the effectiveness of the method and the duration of protection. If the compound is released too rapidly, it will be exhausted quickly, and the coating must be re-applied for the surface to be protected. If, on the other hand, the release rate of the antifouling compound is too slow, the concentration of the compound in the aquatic environment immediately surrounding the surface to be protected may be insufficient to inhibit settlement. Preferably, the antifouling compound is released into the environment adjacent the protected surface at the rate of between about 0.0001 and 1000 g/cm^-hr, and more preferably is released at a rate of between about 0 01 and 100 g/cm^-hr. Compositions of the invention preferably comprise one or more compounds of the invention in a concentration of about 0.01 weight percent to about 50 weight percent based on said composition, more preferably in a concentration of about 0.1 to 20 weight percent based on said composition.

The organisms against which a surface can be protected by the present method can be any organism which can attach to a submerged surface. Exemplary organisms include algae, including members of the phyla Chlorophyll and, fungi, microbes, tunicates, including members of the class Ascidiancea, such as Ciona intestinalis, Diplosoma listerianium, and Botryllus sclosseri, members of the class Hydrozoa, including Clava squamata, Hydractinia echinata, Obelia geniculata, and Tubularia larnyx, bivalves, including Mytilus edulis, Crassostrea virginica, Ostrea edulis, Ostrea chilensia, and Lasaea rubra, bryozoans, including Ectra pilosa, Bugula neritinia, and Bowerbankia gracilis, polychaete worms, including Hydroides norvegica, sponges, and members of the class Cirripedia (barnacles), such as Balanus amphitrite, Lepas anatifera, Balanus balanus, Balanus balanoides, Balanus hameri, Balanus crenatus, Balanus improvisus, Balanus galeatus, and Balanus eburneus. Organisms of the genus Balanus are particularly frequent foulers of aquatic structures. Specific fouling organisms to which this invention is especially directed include barnacles, zebra mussels, algae, bacteria, diatoms, hydroids, bryzoa, ascidians, tube worms, and asiatic clams.

In addition to the compounds of the invention, the composition can comprise additional antifouling agents which may act in combination or synergistically; said additional antifouling agent can be, for example: manganese ethylene bisdithiocarbamate; a coordination product of zinc ion and manganese ethylene bisdithiocarbamate; zinc ethylene bisdithiocarbamate; zinc dimethyl dithiocarbamate; 2, 4, 5, 6-tetrachloroisophthalonitrile; 2-methylthio-4-t- butylamino-6-cyclopropylamino-s-triazine; 3-(3,4-dichlorophenyl)-l,l-dimetl yl urea; N-(fluorodichloromethylthio)-phthalimide; N,N-dimethyl-N'-phenyl-(N- fluorodichloromethylthio)-svιlfamide; tetramethylthiuram disulfide; 2, 4, 6- trichlorophenyl maleimide; zinc 2-pyridinthiol-l— oxide; copper thiocyanate; Cu- 10% Ni alloy solid solution; and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one.

The protective carrier component functioning to release antifouling agent can be a film-forming component, an elastomeric component, vulcanized rubber, or a cementitious component. The protective carrier component can be any component or combination of components which is applied easily to the surface to be protected, adheres to the submerged surface to be protected, and permits the release of the antifouling compound into the water immediately surrounding the coated surface. Different components will be preferred depending on the material comprising the underwater surface, the operation requirements of the surface, the configuration of the surface, and the antifouling compound. Exemplary film- forming components include polymer resin solutions. Exemplary polymer resins include unsaturated polyester resins formed from (a) unsaturated acids and anhydrides, such as maleic anhydride, fumaric acid, and itaconic acid; (b) saturated acids and anhydrides, such as phthalic anhydride, isophthalic anhydride, terephthalic anhydride, tetrahydrophthalic anhydride, tetrahalophthalic anhydrides, chlorendic acid, adipic acid, and sebacic acid; (c) glycols, such as ethylene glycol, 1,2 propylene glycol, dibromoneopentyl glycol, Dianol 33®, and Dianol 22®; and (d) vinyl monomers, such as styrene, vinyl toluene, chlorostyrene, bromostyrene, methylmethacrylate, and ethylene glycol dimethacrylate. Other suitable resins include vinyl ester-, vinyl acetate-, and vinyl chloride-based resins, elastomeric components, vulcanized rubbers, and urethane- based resins. The cementitious compounds are used to protect certain types of underwater structures, as are the elastomeric materials and vulcanized rubber.

The percentage of the antifouling compound of the invention in the coating required for proper release of the compound into the aquatic environment surrounding the surface to be protected will vary depending on the identify of the antifouling compound, the identity of the film-forming component of the coating and other additives present in the coating which may affect release rate. As described above, the release rate of the antifouling compound can be a major factor in determining both the effectiveness of the method and the duration of protection. It is preferred that the coating be released into the surrounding water at a rate of between about 0.0001 and 1,000 μg/cm^-hr; more preferably, the compound comprises between about 0.01 and 100 μg/cm^-hr. Preferably, the antifouling compound comprises between about 0.001 and 80 percent of the coating by weight, and more preferably comprises between 0.01 and 20 percent of the coating. Those skilled in this art will appreciate that a coating of the present invention can comprise any number of forms, including a paint, a gelcoat, or varnish, and the like. The coating can include components in addition to the antifouling coating and film-forming component which confer a desirable property, such as hardness, strength, rigidity, reduced drag, impermeability, or water resistance.

The present invention encompasses any article which contains a surface coated with a coating containing at least one of the aforementioned compounds. Those articles which are particularly suitable for protection with the coating are those which, either intentionally or inadvertently, are submerged for a least the duration required for an organism to settle on a submerged object. Coated articles can comprise any material to which aquatic organisms are know to attach, such as metal, wood, concrete, polymer, and stone. Exemplary articles which may require antifouling protection include boats and boat hulls, fish nets, recreational equipment, such as surfboards, jet skis, and water skis, piers and pilings, buoys, offshore oil rigging equipment, and decorative or functional stone formations.

The composition of the invention can be a cementitious composition which includes at least one of said antifouling compounds and a cementitious matrix. Such a composition is suitable for use in submerged structures, such as piers, pilings, and offshore oil rigging equipment and scaffolding, upon which fouling organisms tend to settle. Exemplary cementitious matrix compositions include portland cement and calcium aluminate based compositions. As those skilled in this art will appreciate, the cementitious matrix should be able to release the antifouling compound, and the antifouling compound must be present in sufficient concentration that the release rate of the compound into the surrounding aquatic environment inhibits settling of organisms on the submerged surface of an article formed from the composition.

The invention is now described in more detail in the following examples which are provided to more completely disclose the information to those skilled in this art, but should not be considered as limiting the invention. EXAMPLES Collection and Culture of Experimental Specimens Adult individuals of the acorn barnacle Balanus amphitrite Darwin were collected from the Duke University Marine Laboratory seawall in Beaufort, North Carolina. Collected specimens were crushed, and the nauplius stage larvae released therefrom were cultured to cyprid stage for cyprid-stage assays according to the methods of Rittschof et al., 1. Exp. Mar. Biol. Ecol. 82:131-146 (1984).

Settlement Assays for Cyprid-Stage Larvae Settlement assays were performed as previously described by Rittschof et al. /. Chem. Ecol. 11: 551-563 (1985). Three-day old cyprid larvae were used.

All compounds were tested for their ability to inhibit settlement by cyprid larvae of the barnacle Balanus amphitrite. Larvae were added to 50 x 9 mm polystyrene Petri dishes containing 5 ml of aged seawater that had been passed through a 100 kDa cut-off filter and varying levels of test compound. Controls consisted of barnacle larvae and filtered seawater added to the dishes without test compound. Dishes were then incubated for 20-24 hrs at 28° C with light for approximately 15 hours and in darkness for approximately 9 hours. The dishes were then removed from the incubator, examined under a dissecting microscope to determine whether larvae were living or dead. Larvae were then killed by addition of several drops of 10% formalin solution. Settlement rate was quantified as number of larvae that had attached to the dish surface, expressed as a percentage of total larvae in the dish. Experiments were performed in duplicate. The lower the percent settlement, the more efficacious the test compound.

EXAMPLE 1 Ethyl-3-furoate (9.63 μl) was diluted to 20 ml with seawater. Aliquots of this stock solution were added to separate dishes containing seawater to provide the concentrations shown in Table 1. The larvae were added and the test conducted as described above.

TABLE 1 Control of Barnacle Settlement with Ethyl-3-furoate Concentration % Settlement

0 (Control) 53 500 μg/ml 0

50 μg/ml 11

5 μg/ml 18

500 ng/ml 52 EXAMPLE 2 Methyl-2-furoate (8.48 μl) was diluted to 20 ml with seawater. Aliquots of this stock solution were added to separate dishes containing seawater to provide the concentrations shown in Table 2. The larvae were added and the test conducted as described above.

TABLE 2 Control of Barnacle Settlement with Methyl-2-furoate

Concentration % Settlement 0 (Control) 53

500 μg/ml 2

50 μg/ml 46

5 μg/ml 53

EXAMPLE 3

2-Ethylfuran (6.94 μl) was diluted to 20 ml with seawater. Aliquots of this stock solution were added to separate dishes containing seawater to provide the concentrations shown in Table 3. The larvae were added and the test conducted as described above.

TABLE 3 Control of Barnacle Settlement with 2-Ethylfuran Concentration % Settlement 0 (Control) 53

500 μg/ml 41

50 μg/ml 54

EXAMPLE 4 2-Methylfuran (10.98 μl) was diluted to 20 ml with seawater. Aliquots of this stock solution were added to separate dishes containing seawater to provide the concentrations shown in Table 4. The larvae were added and the test conducted as described above. TABLE 4 Control of Barnacle Settlement with 2-Methylfuran

Concentration % Settlement

0 (Control) 53 50 μg/ml 39

5 μg/ml 61

EXAMPLE 5 2-Acetylfuran (9.11μl) was diluted to 20 ml with seawater. Aliquots of this stock solution were added to separate dishes containing seawater to provide the concentrations shown in Table 5. The larvae were added and the test conducted as described above.

TABLE 5 Control of Barnacle Settlement with 2-Acetylfuran

Concentration % Settlement

0 (Control) 53

500 μg/ml 54

EXAMPLE 6

2-Furyl-n-pentyl ketone (0.909 μl) was diluted to 20 ml with seawater. Aliquots of this stock solution were added to separate dishes containing seawater to provide the concentrations shown in Table 6. The larvae were added and the test conducted as described above.

TABLE 6 Control of Barnacle Settlement with 2-Furyl-n-pentyl ketone Concentration % Settlement

0 (Control) 42 500 μg/ml 0

50 μg/ml 1

5 μg/ml 2

500 ng/ml 14

50 ng/ml 26 5 ng/ml 20

500 ng/ml 22 EXAMPLE 7 2-Furyl-n-pentyl ketone (0.909 μl) 2-ethylfuran (6.94 μl) and 2-acetylfuran (9.11 μl) were each diluted to 20 ml with seawater. Aliquots of these stock solutions were added to separate dishes containing seawater to provide the respective test substances in concentrations of 500 μg/ml. The larvae were added and the test conducted as described above. These data are presented in Table 7.

TABLE 7 Control of Barnacle Settlement with Furan Compounds at 500 μg/ml Compound % Settlement

Control 61

2-Furyl-n-pentyl ketone 0

2-Ethylfuran 34

2-Acetylfuran 41

EXAMPLE 8

A number of lactones were tested for control of barnade settlement. All lactones were tested at a concentration of 3 x 10"^ M in dishes containing seawater. The larvae were added and the test conducted as described above. These data are presented in Table 8.

Solutions of α-methylene-γ-butyrolactone were prepared in seawater at the concentrations shown in the table below. Five ml of each solution were added to duplicate dishes. The larvae were then added to the dishes and the test conducted as described above. These data are presented in Table 9. TABLE 9

Control of Barnacle Settlement with α-Methylene-Υ-butyrolactone Concentration % Settlement

0 (Control) 62 500 μg/ml 0

50 μg/ml 0

5 μg/ml 36

500 ng/ml 58

50 ng/ml 62 5 ng/ml 61

EXAMPLE 10 A second test was performed with α-methylene-γ-butyrolactone. A series of solutions of α-methylene^ -butyrolactone in seawater at concentrations ranging from 500 μg/ml to 50 ng/ml were prepared. Aliquots of these solutions were taken and added to duplicate dishes. The actual concentrations tested appear in the table below. The larvae were then added to the dishes and the test conducted as described above. These data are presented in Table 10.

TABLE 10

Control of Barnacle Settlement with α-Methylene-γ-Butyrolactone

Concentration % Settlement

0 (Control) 66

500 μg/ml 5 50 μg/ml 29

5 μg/ml 47

500 ng/ml 53

50 ng/ml 49

EXAMPLE 11

Solutions of α-angelica lactone were prepared in seawater at the concentrations shown in the table below. Five ml of each solution were added to duphcate dishes. The larvae were then added to the dishes and the test conducted as described above. These data are presented in Table 11. TABLE 11

Control of Barnacle Settlement with α- Angelica lactone Concentration % Settlement

0 (Control) 62 500 μg/ml 0

50 μg/ml 39

5 μg/ml 54

500 ng/ml 60

50 ng/ml 65 5 ng/ml 62

EXAMPLE 12 A second test was performed with α-angelica lactone. A series of solutions of α-angelica lactone in seawater at concentrations ranging from 500 μg/ml to 5 ng/ml were prepared. Ahquots of these solutions were taken and added to duplicate dishes. The actual concentrations tested appear in the table below. The larvae were then added to the dishes and the test conducted as described above. These data are presented in Table 12.

TABLE 12

0 (Control) 66

500 μg/ml 0 50 μg/ml 3

5 μg/ml 33

500 ng/ml 33

50 ng/ml 53

5 ng/ml 41

EXAMPLE 13

A solution of 2-coumaranone (25 μg in 50 ml of filtered, aged seawater) was prepared. Aliquots of this solution were taken and added to duphcate dishes to provide the nominal concentrations shown in the table below. The larvae were then added to the dishes and the test conducted as described above. These data are presented in Table 13. TABLE 13 Control of Barnacle Settlement with 2-Coumaranone

A series of solutions of γ-decalactone in seawater at concentrations ranging from 500 μg/ml to 5 pg/ml were prepared. Aliquots of these solutions were taken and added to duphcate dishes. The actual concentrations tested appear in the table below. The larvae were then added to the dishes and the test conducted as described above. These data are presented in Table 14.

TABLE 14 Control of Barnacle Settlement with γ-Decalactone

Concentration % Settlement

0 (Control) 66

500 μg/ml 0

50 μg/ml 1 5 μg/ml 25

500 ng/ml 8

50 ng/ml 25

5 ng/ml 32

500 pg/ml 44 50 pg/ml 52

5 pg/ml 45

EXAMPLE 15 A series of solutions of γ-valerolactone in seawater at concentrations ranging from 500 μg/ml to 500 pg/ml were prepared. Aliquots of these solutions were taken and added to duplicate dishes. The actual concentrations tested appear in the table below. The larvae were then added to the dishes and the test conducted as described above. These data are presented in Table 15. TABLE 15

Control of Barnade Settlement with γ-Valerolactone Concentration % Settlement

0 (Control) 66 500 μg/ml 52

50 μg/ml 37

5 μg/ml 42

500 ng/ml 48

50 ng/ml 42 5 ng/ml 43

500 pg/ml 55

EXAMPLE 16 Toxiάty assays were conducted by adding nauplius stage larvae to 50 x 5 mm polystyrene Petri dishes or glass vials containing 5 ml of 100 kDa filtered seawater. Experimental dishes received doses of γ-decalactone, α-angelica lactone, α-methylene-γ-butyrolactone, α-santonin and alantolactone. Dishes or vials receiving no test compound served as controls. The dishes or vials were incubated at 28° C with a 15:9 light:dark cycle. After incubation, the dishes or vials were examined under a dissecting microscope to determine whether the larvae were alive or dead. Larvae which did not respond to an emission of visible light were considered dead. The number of living and dead larvae were then counted. Probit analysis was used to obtain concentrations corresponding to half-maximal inhibition (EC50 values). These data are summarized in Table 16. TABLE 16

Lactone Half-maximal Inhibition Values

Compound EC p γ-decalactone 4 ng/ml (plastic) α-angelica lactone 70 μg/ml (plastic) α-methylene-γ-butyrolactone 6 μg/ml (plastic) α-methylene-γ-butyrolactone 40 μg/ml (glass) α-santonin 14 μg/ml (glass) alantolactone 500 ng/ml (glass)

EXAMPLE 17

Settlement Assay Procedure

Laboratory experiments were performed with day 3 cyprid larvae of the acorn barnacle Balanus amphitrite cultured as described in Rittschof et al., /. Exp. Marine Biol. & Ecol. 82:131-146 (1984). Settlement experiments were performed using polystyrene dishes as described in Rittschof et al., /. Chem. Ecol. 11:551-563 (1985) and in Sears et al., /. Chem. Ecol. 16:791-799 (1990). Larvae were added to polystyrene dishes containing 5 ml of aged seawater that had been passed through a 100 kilo-Dalton cut-off filter and varying levels of 3-methyl-2-cyclohexene-l-one. Controls consisted of barnacle larvae and filtered seawater added to polystyrene dishes without 3-methyl-2-cyclohexene-l-one. After addition of larvae, the dishes were incubated for 20 to 24 hours at 28°C on a 15:9 light:dark cycle.

The dishes were then removed from the incubator, examined under a dissecting microscope to determine if larvae were living (moving) or dead (not moving). Larvae were then killed by addition of several drops of 10% formalin solution.

Settlement rate was quantified as number of larvae that had attached to the dish surface, expressed as a percentage of total larvae in the dish. Dishes were more than 200 larvae were excluded from subsequent analysis, since extremely high larval densities may inhibit settlement rates. Linear regressions were performed using percentage settlement as the dependent (Y) variable and log of larval density (larvae per dish) as the independent variable. Each dish was treated as a single replicate.

Settlement Assay Results Data were combined for all control dishes (n=65 for combined data set). In the controls, barnacle settlement increased as a Unear function of larval density (Figure 1). The least squares regression equation for the data is: Y=47.4 (log X) - 41.3, where Y represents settlement rate and X represents larval density. Data also were combined for treatments generated by addition of 3-methyl-2-cyclohexene-l- one at concentrations of 9, 90, and 900 picomolar (n=44 for combined data set). At these concentrations, barnacle settlement decreased as a linear function of barnacle density (Figure 2). The least squares regression equation for this data set is: Y= -51.7 (log X) + 118.6, where Y represents settlement rate and X represents larval density).

Data also were combined for all higher concentrations of 3-methyl-2- cyclohexene-1-one (n=107) for combined data set - data not shown). The regression line for these replicates was not significantly different from that of the untreated controls (regression equation: Y = 48.5 (log X) - 49.1, where Y represents settlement rate and X represents larval density). The decrease in effectiveness at higher concentrations is not atypical for anti-aggregative pheromones.

While the invention has been described with reference to specific examples and applications, other modifications and uses for the invention will be apparent to those skilled in the art without departing from the spirit and scope of the invention as defined in the following claims.

Claims

Claims:

1. A marine or freshwater antifoulant composition comprising a material selected from the group consisting of film-forming polymer, cementitious material, elastomeric material, and vulcanized rubber and an amount of an antifouUng agent admixed with said material and effective to be released from said material at an antifouling effective level, said antifouling agent selected from the group consisting of at least one compound selected from the group consisting of

(8) (9) wherein Rl, R2, R3, and R4 are independently selected from -C(0)R5,- C(0)OR6, (Cι-Cδ)alkyl, phenyl, phenyl substituted with (Cι-C4)alkyl, (Q- C4)alkoxy, (C2-Cs)alkenyl, (C2-Cs)alkynyl, halogen, and hydrogen, provided that at least one of Ri, R2, R3, and R4 is not hydrogen; wherein R5 is R6 or NR7R8; wherein R6 is (Cι-Cs)alkyl, (C2-Cs)alkenyl, (C2-Cs)alkynyl, phenyl, phenyl substituted with (Ci-C4)alkyl, (Cl-C4)alkoxy, or halogen; wherein R7 and Rs are independently selected from hydrogen or R6; wherein R9, RlO, Rll, Rl2, Rl3/ Rl4, Rl5, Rl6, Rl7, Rl8, Rl9, R20, and R21 are independently selected from the group consisting of hydrogen and (C1-C10) alkyl; and wherein R22 R23 and R24 are each independently selected from hydrogen,

(C1-C3) alkyl groups, (C1-C3) alkoxy groups, halogens, and hydroxyl groups.

2. Composition according to claim 1 wherein said compound is present in a concentration of about 0.01 weight percent to about 50 weight percent based on said composition.

3. Composition according to claim 2 wherein said compound is present in a concentration of about 0.1 to 20 weight percent based on said composition.

4. Composition according to claim 1 wherein said compound is selected from the group consisting of 2-furyl-methylketone; 2-ethyl furan; 2-methyl furan; methyl-2-furanoate; ethyl-3-furoate; 2-furyl-n-pentyl ketone; 2-acetylfuran; khelhn; γ-decalactone; α-angelica lactone; α-santonin; α-methylene-γ- butyrolactone; coumaranone; alantolactone; and 3-methyl-2-cyclohexene-l-one.

5. Composition according to claim 1 further including one or more additional antifouling agents.

6. Composition according to claim 5 wherein said additional antifouling agent is selected from the group consisting of manganese ethylene bisdithiocarbamate; a coordination product of zinc ion and manganese ethylene bisdithiocarbamate; zinc ethylene bisdithiocarbamate; zinc dimethyl dithiocarbamate; 2, 4, 5, 6-tetrachloro-isophthalonitrile; 2-methylthio-4-t- butylaιnino-6-cyclopropylarr no-s-triazine; 3- (3,4-dichlorophenyl)-l,l-dimethyl urea; N-(fluorodichloromethylthio)-phthalimide; N,N-dimethyl-N'-phenyl-(N- fluorodichloromethylthio)-sulfamide; tetramethylthiuram disulfide; 2, 4, 6- trichlorophenyl maleimide; zinc 2-pyridinthiol-l -oxide; copper thiocyanate; Cu- 10% Ni alloy soUd solution; and 4,5-dichloro-2-n-octyl-4-isothiazoUn-3-one.

7. Method of protecting a structure against fouling by marine or freshwater fouUng organisms comprising applying a composition according to claim 1 on and/or into said structure.

8. Method according to claim 7 wherein said marine or freshwater fouling organisms are selected from the group consisting of barnacles, zebra mussels, algae, bacteria, diatoms, hydroids, bryzoa, asάdians, tube worms, and asiatic clams.

9. Method according to claim 7 wherein said organisms are one or more members of the genus Balanus.

10. Method according to claim 7 wherein said compound is used in a composition comprising a film-forming polymeric binder.

11. Marine or freshwater structure protected against fouUng organisms wherein said protection is afforded by a method according to claim 7.

12. Marine or freshwater structure according to claim 11 wherein said protection is afforded by a composition comprising a film-forming polymeric binder comprising at least one of said furan compounds having been applied on and/or into said structure.

13. Marine or freshwater structure according to claim 11 wherein said structure is a fish net, boat, piUng, or pier, or cooling tower.