摘要:

The search for marine natural product antifoulants is being hampered by problems associated with conventional settlement assays. Yet it has been recognised that the study of how chemical cues are perceived by fouling organisms may offer clues to settlement inhibitors and may identify novel biochemical assays for antifoulants based on signal transduction pathways. Here the role of calcium in barnacle settlement is re‐examined. A requirement for calcium in settlement of the cypris larva ofBalanus amphitritehas been confirmed; settlement was inibited in low calcium, and calcium‐free, seawater. Although 10 mM (19.27 mM) excess calcium had no effect and higher concentrations were inhibitory, a 5 mM excess stimulated settlement. Stimulation is proposed to be effected by an increase in intracellular calcium. The release of calcium from intracellular pools with thapsigargin (but not cyclopiazonic acid) induced settlement and an antagonist of intracellular calcium, TMB‐8, generally inhibited settlement. Nevertheless, the calcium ionophore A23187 did not induce settlement at the concentrations tested. Consequently, the relative importance of external calcium and intracellular pools to increased intracellular calcium has yet to be determined. Pharmacological manipulations of calcium channels with organic and inorganic channel blockers strongly indicate calcium channel involvement in barnacle settlement. The data are summarised in an hypothetical scheme for signal transduction at settlement and are compared to those obtained for other marine invertebrate larvae.

ISSN:0892-7014    

DOI:10.1080/08927019609386276

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Using scanning electron microscopy (SEM), differential interference contrast microscopy (DICM) and cytochemical staining techniques, preliminary observations have been made on the mechanisms of attachment of some common, marine, benthic fouling blue‐green algae ("cyanobacteria") isolated into culture from various toxic and non‐toxic surfaces in Langstone Harbour, south coast of England. Blue‐green algae investigated included species ofCalothrix, Dermocarpa, Plectonema, PhormidiumandXenococcus. The blue‐green algae are rapid colonisers and can make an important contribution to the pioneering communities on both toxic and non‐toxic surfaces. A characteristic feature of the colonization process is the production of variable quantities of extracellular polymeric substances (EPS) which appear to function as adhesives. Cytochemical staining revealed the EPS to be an acidic polysaccharide and, therefore, chemically similar to the EPS produced by sessile diatoms. It is suggested that the EPS additionally assists in cell motility, acts as an antidesiccant and may influence the fouling process by combining with antifouling paint toxins and modifying the surface energy of substrata.

ISSN:0892-7014    

DOI:10.1080/08927019609386277

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A membrane perfusion device for determining minimum effective release rates (MERR) of antifouling agents is described. The technique is applied to known biocidal agents and to a new prospective natural antifouling agent. This method allows controlled and reproducible release rates to be achieved independent of water chemistry and flow near the immersed surface. Unlike constant concentration methods, the device acts similarly to a painted surface, allowing establishment of diffusion gradients, thereby allowing fouling organisms to exhibit natural chemotactic responses to the released toxin. The method was applied at four remote sites to natural populations of fouling organisms. The MERRs of known (tributyltin chloride, dibutyltin chloride, and cupric ion) and experimental (zosteric acid) AF agents were determined. The effective release rates of cupric ion and organotin were consistent with immersed panel data and field observation of ship hulls, while the effective rate of zosteric acid, determined at two test sites, was much higher. Such data provide coatings formulators with valuable information relating to the suitability of an agent for AF coating use.

ISSN:0892-7014    

DOI:10.1080/08927019609386278

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Field testing of non‐toxic antifouling coatings has required the development of test protocols that can quantify their performance. This includes the evaluation of the biofouling communities, the measurement of biofouling adhesion using a calibrated water jet and the measurement of barnacle adhesion in shear. Data are presented for several test surfaces, and the results are discussed with respect to the coating characteristics.

ISSN:0892-7014    

DOI:10.1080/08927019609386279

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The performances of some silicone elastomers as compliant coatings which are resistant to marine fouling have been assessed from a sea‐water exposure trial covering three fouling seasons. Measurements of contact angles (polar and non‐polar liquids, recently‐advanced and recently‐receded liquid drops and air bubbles) have been used to investigate the surface properties of materials and of coatings resistant to fouling after two years’ exposure. The unmodified poly (dimethyIsiloxane) elastomer General Electric (GE) 21 was still resistant to marine settlement after three seasons and the poly(dimethyldiphenylsiloxane) GE655 only became fouled during the third season. No other unmodified material showed resistance to fouling beyond two seasons. The addition of a low‐viscosity poly(dimethylsiloxane) oil to GE655 in a sufficient quantity (20 mass%)to cause blooming resulted in a material that remained free of fouling. Time‐dependent behaviour by drops of all liquids on freshly prepared samples was observed in recently‐advanced contact angles but not by recently‐receded contact angles. With polar liquids, hard clear elastomers showed stepwise changes and also gave considerable contact‐angle hysteresis effects. Immersion in water over a period of several weeks brought about a slow decrease in the hydrophobicity of all elastomers. GE21, after exposure in seawater for over two years, also showed a decrease as indicated by the contact angle of distilled water drops on its surface. The slow changes in the interfacial properties of silicones with polar liquids are attributed to rearrangements of polymer chains close to the surface, driven by the formation of hydrogen bonds between the solvent and oxygen atoms in the backbone. Penetration of the material by water gradually increases the surface energy and, sooner or later, the material becomes susceptible to fouling. For GE655, this may be delayed by incorporating with the formulation a relatively incompatible low‐viscosity silicone oil.

ISSN:0892-7014    

DOI:10.1080/08927019609386280

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Two major problems associated with biofouling studies are the lack of broad scale testing and failure to use consistent standards among different assays or studies. To address these issues the activity of two biologically active natural products, elatol and deschloroelatol, isolated from the marine red algaLaurencia rigida, and three commonly used biocides, Nopcocide N‐96™, Irgarol 1051™ and Sea‐Nine 211™, was compared, in a broad spectrum of bioassays. The activity of the different compounds varied substantially among different bioassay tests. Elatol and deschloroelatol had a narrow range of activity with strongest effects against invertebrate larvae. Both compounds were highly toxic. However, neither compound had strong activity against marine bacteria or the common epiphyteUlva lactuca. Irgarol 1051 also had a narrow range of activity, only affecting algal settlement strongly. Nopcocide N‐96 and Sea‐Nine 211 had moderate to strong activity across the spectrum of bioassays,viz.growth of marine bacteria(Vibrio fischeri, Serratiasp.), inhibition of settlement of macroalgae(Ulva lactuca), toxicity(Balanus amphitrite), and inhibition of settlement of invertebrate larvae(Balanus amphitrite, Bugula neritina). Based on the results it is proposed that Sea‐Nine 211, because of its broad spectrum activity, be used as a standard for comparative assessments of the antifouling activity of marine natural products and analogues.

ISSN:0892-7014    

DOI:10.1080/08927019609386281

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A computer‐based image analysis system that measures the behavioral response of the marine diatomAmphora coffeaeformisto potentially toxic challenges is described. At any one time the system is capable of measuring in a population of about 80 cells, changes in the number motile, their speed, direction, and if they are turning, their angular velocity and acceleration. Chemical compounds that interfere with the generation of energy, protein or glycoprotein synthesis, calcium homeostasis and cytoskeletal activity, change the motile behavior of the cell. A pre‐requisite of motility is that the cells be attached to a substratum. It is proposed that the system, which requires only a 1–2 minute data collection period per replicate, could be used to screen for potential antifouling activity in chemical agents, and it is speculated that it could be used also for measuring the physicochemical interaction between attached motile organisms and their substratum, as well as in environment toxicology measurements.

ISSN:0892-7014    

DOI:10.1080/08927019609386282

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The relative biodegradability in seawater of a number of compounds in current use in antifouling paints viz. Sea‐Nine™ 211 antifoulant (4,5‐dichloro‐2‐n‐octyl‐4‐isothiazolin‐3‐one), IrgarolR1051 (2‐methylthio‐4‐tert‐butylamino‐6‐cyclopropylamino‐s‐triazine), diuron (3‐(3,4‐dichlorophenyl)l‐l‐dimethylurea), chlorothalonil (tetrachloroisophthalonitrile) and TBTO (tributyltin oxide) was investigated. The disappearance of the each compound from seawater was monitored over 8 w by bioassay using the ship‐fouling diatomAmphora coffeaeformis. The results show, that under the test conditions employed, biodegradability ranges from very readily biodegradable (Sea‐Nine 211) to non‐biodegradable (diuron and Irgarol 1051). The results are discussed in relation to published data on biocide degradation.

ISSN:0892-7014    

DOI:10.1080/08927019609386283

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Two questions of relevance to the establishment of marine biofouling communities were addressed,viz(1) what is the frequency with which bacterial strains isolated from living and inanimate surfaces in the marine environment show inhibitory activity against the settlement of common fouling organisms, and (2) is the antifouling bacterium, D2, an inhabitant of different marine waters, and how unique is this bacterium, in its mode of action against different target organisms? With respect to the first question, ninety three marine bacteria isolated from various rock surfaces from the marine environment were tested against larvae ofBalanus amphitriteand spores ofUlva lactuca.Settlement assays against the diatomAmphorasp. were also performed on 10 of these strains. Nine bacterial isolates were shown to be inhibitory against larval settlement and eight of these strains were also inhibitory against algal spores. Altogether 16 strains were inhibitory against the settlement of algal spores while none of the bacterial strains inhibited diatom settlement. With respect to the second question, D2, a dark green pigmented bacterium, isolated from an adult tunicate off the Swedish west coast, has been found to be a very effective inhibitor against common fouling organisms. In order to see if this bacterium can be found in other marine waters, bacteria from living surfaces of marine plants and animals from waters around Sydney, Australia, were isolated and screened for inhibitory activity against barnacle larvae. Seventy four percent of the 23 plant isolates were shown to be inhibitory against larval settlement while only 30% of the 23 isolates from marine animals reduced settlement. Twenty two of the isolates from different seaweeds were dark pigmented and 20 of these strains inhibited settlement of barnacle larvae and algal spores. Three of the strains showed the same phenotypic expression as D2, and the results indicate that these strains may be D2 or closely related strains, suggesting that D2 may be a common inhabitant in the marine environment.

ISSN:0892-7014    

DOI:10.1080/08927019609386284

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Antifouling is a property of the epidermis in echinoderms. There is neither production of biocides that act at any distance from the surface nor is the sloughing rate of the entire surface capable of explaining the observed antifouling capability. As with many invertebrates, the epidermis in echinoderms is overlain by thin surface coats, often termed the cuticle. The outermost coat has attenuated fibrils radiating outwards from the underlying cuticle. As these fibrils are the “real”; surface of the echinoderm, this is the level at which any antifouling defense must operate. It is suggested that their function is primarily antifouling. The cuticle contains chondroitin sulphate proteoglycan molecules and is negatively charged. The cuticle appears to be a highly extended glycocalyx. It is suggested that the primitive function of cellular glycocalyces is to modulate adhesive interactions at the cell or organismal surface.

ISSN:0892-7014    

DOI:10.1080/08927019609386285

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor