The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Bernabe Santelices - One of the best experts on this subject based on the ideXlab platform.
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The fate of overgrown germlings in coalescing Rhodophyta
Phycologia, 2020Co-Authors: Bernabe Santelices, M. Hormazábal, Juan A. Correa, Verónica FloresAbstract:B. SANTELICES ,M. H ORMAZABAL ,J. C ORREA AND V. F LORES. 2004. The fate of overgrown germlings in coalescing Rhodo- phyta. Phycologia 43: 000-000. The overgrowth of young Sporelings by older and larger thalli is often assumed to result in death of the overgrown individual. However, if Sporelings and larger conspecifics are able to coalesce, the fate of the overgrown Sporeling may be different to the physical compression, starvation and mortality often assumed for them. Using cytological studies on laboratory-cultured individuals, as well as observations of recruitment in the field, we found that Sporelings of the red alga Mazzaella lami- narioides can be incorporated within the tissue of larger, overgrowing germlings or they may coalesce side-by-side with it, depending on Sporeling size before contact. Thus, young Sporelings do not necessarily die when overgrown by their older, conspecific competitors. Field observations suggest that these processes are common during natural recruitment; therefore, coalescence might be considered an alternative mechanism to intraspecific competition. Coalescing seaweeds should be included among the groups of sessile organisms that might be formed by genetically polymorphic thalli (chimeras).
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Coalescence increases abiotic stress tolerance in Sporelings of Mazzaella laminarioides (Gigartinales, Rhodophyta)
Journal of Applied Phycology, 2014Co-Authors: Francisco Javier Fernández Medina, Verónica Flores, Alejandra V. González, Bernabe SantelicesAbstract:Chimerism theoretically increases the genetic heterogeneity of coalescing organisms, which in turn may increase phenotypic variability in chimeras, allowing them greater tolerance to environmental changes when compared with non-coalescing individuals. In order to test this hypothesis, we compared abiotic stress tolerance between coalescing and non-coalescing organisms. The specific daily growth was compared using discs formed with 1, 5, and 20 Mazzaella laminarioides carpospores. These were cultivated under three different temperature (6, 12, and 25 °C) and salinity (10, 35, and 50 g L−1) conditions. Growth of the disc area was measured after 30 days of cultivation under controlled conditions. Sporeling survival similarly was calculated under each of these temperatures and salinities in order to record whether stress-resistant phenotypes were present. The results showed that, under stressful conditions, non-coalescing specimens experienced a significant reduction in the specific growth rate compared with those under non-stressful conditions. The reduction in growth falls off, however, as the number of coalescing spores increases. The cultivation of spore populations also indicates the presence of Sporelings with the capacity to survive alone in stressful situations. The results suggest that the coalescing discs exhibit higher tolerance to environmental stressors than non-coalescing discs, allowing them to survive and grow under these conditions. This can be explained by an increase in phenotypic plasticity, resulting from greater genetic heterogeneity due to somatic fusion of a larger number of spores.
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SIZE INCREMENTS DUE TO INTERINDIVIDUAL FUSIONS: HOW MUCH AND FOR HOW LONG?1
Journal of Phycology, 2010Co-Authors: Bernabe Santelices, Jorge L Alvarado, Verónica FloresAbstract:Size increments following interindividual fusions appear as a general benefit for organisms, such as coalescing seaweeds and modular invertebrates, with the capacity to fuse with conspecifics. Using Sporelings of the red algae Gracilaria chilensis C. J. Bird, McLachlan et E. C. Oliveira and Mazzaella laminarioides (Bory) Fredericq, we measured the growth patterns of Sporelings built with different numbers of spores, and the magnitude and persistence of the size increments gained by fusions. Then we studied three morphological processes that could help explain the observed growth patterns. Results indicate that in these algae, coalescence is followed by immediate increase in total size of the coalesced individual and that the increment is proportional to the number of individuals fusing. However, the size increments in Sporelings of both species do not last >60 d. Increasing reductions of marginal meristematic cells and increasing abundance of necrotic cells in Sporelings built with increasing numbers of initial spores are partial explanations for the above growth patterns. Since Sporelings formed by many spores differentiate erect axes earlier and in larger quantities than Sporelings formed by one or only a few spores, differentiation, emergence, and growth of erect axes appear as a more likely explanation for the slow radial growth of the multisporic Sporelings. Erect axis differentiation involves significant morphological and physiological changes and a shift from radial to axial growth. It is concluded that the growth pattern exhibited by these macroalgae after fusion differs from equivalent processes described for other organisms with the capacity to fuse, such as modular invertebrates.
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demographic consequences of coalescence in Sporeling populations of mazzaella laminarioides gigartinales rhodophyta 1
Journal of Phycology, 2008Co-Authors: Bernabe Santelices, Jorge L AlvaradoAbstract:: Coalescing macroalgae are ecologically important members of intertidal and shallow subtidal communities. However, we still lack quantitative information on the demographic consequences of coalescence. Using demographic models developed for modular invertebrates, we studied the demography of settlement and early recruitment in the coalescing macroalga Mazzaella laminarioides (Bory) Fredericq. Permanently marked microscopic fields on laboratory-incubated and field-incubated plates were monitored regularly (at 15, 30, 45, and 60 d) using image analysis techniques to evaluate the relative importance of settler abundance, mortality, coalescence (fusion), and fission on the changes in size and numbers of recruits. On the plates, spores settled individually or in groups. Over time, spores in close proximity may coalesce, resulting in a mixture of unisporic and multisporic crusts. When new spores arrive, they may or may not coalesce with previously settled crusts. Coalescence and mortality reduce the number of Sporelings, but coalescence increases the size of the Sporelings, thereby reducing further probability of Sporeling mortality. Crust fissions are negligible in frequency, while the frequency of coalescence increases from ∼25% after only 3 d, to ∼75% after 60 d. Thus, as a result of variable settlement, mortality, and coalescence, any area colonized by M. laminarioides would contain a mixture of crusts of different sizes, ages, and genetic constitution. The interactions between the above three processes create a more complex survivorship curve than the ones known for unitary organisms.
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Contact responses between spores and Sporelings of different species, karyological phases and cystocarps of coalescing Rhodophyta
Marine Biology, 2003Co-Authors: Bernabe Santelices, M. Hormazábal, Juan A. Correa, Verónica FloresAbstract:Coalescence is a well documented event in many red algal orders. However, it is as yet unknown if genetic compatibility and phylogenetic relationships could be factors limiting coalescence. Using controlled laboratory experiments complemented with cytological and ultrastructural analysis, in this study we test whether or not coalescence may occur between different seaweed species and between karyological phases of the same species. We also evaluate the effects of one species or karyological phase on the germination rates, germling survival and differentiation of erect axes of Sporelings of a second species or phase and whether the uni- or polycystocarpic origin of the coalesced germling may affect the germination and growth or the morphology of the resulting Sporeling. Results indicated that the process of coalescence is restricted to intraspecific partners only. A thick interphase with crushed cells and remains of cell walls developed in all the interspecific contacts studied. Results also indicated that coalescence may be expected between individuals of different karyological phases, as in the two cases tested (Mazzaella laminarioides and Sarcothalia crispata) the filaments of both phases grow intertwined in the new tissue of the coalesced crust. Germination rates, Sporeling survival and differentiation of erect axes were all affected by the different types of experimental cultures tested. However, results suggest that allorecognition among seaweeds seems to play a minor role in coalescence. The process appears as less sensitive to genetic recognition than the cell fusion processes described for other red algal species or than the colonial fusion described for colonial invertebrates and fungi.
Chaoyuan Wu - One of the best experts on this subject based on the ideXlab platform.
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mass culture of undaria gametophyte clones and their use in Sporeling culture
Hydrobiologia, 2004Co-Authors: Chaoyuan Wu, Dapeng Li, Guang PengAbstract:Undaria pinnatifida (Harv.) Sur. is one of the three main seaweed species under commercial cultivation in China. In the mid-1990s the annual production was about 20000 tons dry. The supply of healthy Sporelings is key to the success of commercial cultivation of Undaria. Previous studies demonstrated that instead of the zoospore collection method, Sporelings can be cultured through the use of gametophyte clones. This paper reports the experimental results on mass culture of clones and Sporeling raising in commercial scale. Light had an obvious effect on growth of gametophyte clones. Under an irradiance of 80 mumol m(-2) s(-1) and favorable temperature of 22-25degreesC, mean daily growth rate may reach as high as 37%. Several celled gametophyte fragments were sprayed onto the palm rope frame. Gametogenesis occurred after 4-6 days. Juvenile Sporeling growth experiments showed that nitrate and phosphate concentrations of 2.9 10(-4) mol 1(-1) and 1.7 10(-5) mol 1(-1) were sufficient to enable the Sporelings to maintain a high daily growth rate. Sporelings can reach a length of 1 cm in a month. Since 1997, extension of the clone technique has been carried out in Shandong Province. Large-scale production of Sporelings for commercial cultivation of 14 and 31 hectares in 1997 and 1998 had been conducted successfully.
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a new method of laminaria japonica strain selection and Sporeling raising by the use of gametophyte clones
Hydrobiologia, 1999Co-Authors: Dapeng Li, Zhigang Zhou, Chaoyuan WuAbstract:One-celled female and male gametophytes of three Laminaria japonica strains were isolated, cultured and gametophyte clones were formed. A technique combining strain selection with Sporeling raising by the use of these female and male gametophyte clones was studied. Experiments on 9 different crossing combinations was conducted in November of 1997 in Qingdao, P. R. China. The main economic characteristics, frond length and fresh weight, of sporophytes of different crossing combinations were measured. F-1 sporophytes of No. 2 showed a higher fresh weight and longer length, therefore, No. 2 (Wh860 + x Lid) was selected as a good combination. Its parental female and male gametophyte clones are being mass cultured for Sporeling production. By this method, the time needed for strain selection was shortened from 5-6 to 2 years. As compared with the routine method of Sporeling raising by the collection of zoospores, the time of Sporeling raising of this method decrease by 50%, and the production cost is also reduced by 50%. It is believed that this method will be labour and time saving and a more economic way for strain selection and Sporeling raising in L. japonica cultivation industry.
Barbara Azevedo De Oliveira - One of the best experts on this subject based on the ideXlab platform.
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spore germination and young gametophyte development of the endemic brazilian hornwort notothylas vitalii udar singh notothyladaceae anthocerotophyta with insights into Sporeling evolution
Acta Botanica Brasilica, 2017Co-Authors: Barbara Azevedo De Oliveira, Anna Flora De Novaes Pereira, Katia Cavalcanti Porto, Adaises Simone MacielsilvaAbstract:ABSTRACT Notothylas vitalii is an endemic Brazilian hornwort species, easily identifi ed by the absence of pseudoelaters and columella, and the presence of yellow spores. Plant material was collected in Recife, Brazil, and the spores were sown onto Knop’s medium, germinating after thirty days only with the presence of light. Germination occurred outside the exospore, and only after the walls had separated into three or four sections did a globose Sporeling initiate its development. Following longitudinal and transversal divisions, the initial loose mass of cells became a thalloid gametophyte, subsequently developing into a rosette-like juvenile thallus with fl attened lobes. Additional information concerning Sporeling types in key genera of hornworts, such as and FoliocerosPhymatoceros, will be crucial for inferring the possible ancestral type and the evolution of this trait among hornworts. Our study supports the necessity of supplementary studies on Sporeling development, combined with morphological and phylogenetic investigations, to help elucidate the evolution of the Anthocerotophyta and their distribution patterns.
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Spore germination and young gametophyte development of the endemic Brazilian hornwort Notothylas vitalii Udar & Singh (Notothyladaceae - Anthocerotophyta), with insights into Sporeling evolution
Acta Botanica Brasilica, 2017Co-Authors: Barbara Azevedo De Oliveira, Anna Flora De Novaes Pereira, Katia Cavalcanti Porto, Adaíses Simone Maciel-silvaAbstract:ABSTRACT Notothylas vitalii is an endemic Brazilian hornwort species, easily identifi ed by the absence of pseudoelaters and columella, and the presence of yellow spores. Plant material was collected in Recife, Brazil, and the spores were sown onto Knop’s medium, germinating after thirty days only with the presence of light. Germination occurred outside the exospore, and only after the walls had separated into three or four sections did a globose Sporeling initiate its development. Following longitudinal and transversal divisions, the initial loose mass of cells became a thalloid gametophyte, subsequently developing into a rosette-like juvenile thallus with fl attened lobes. Additional information concerning Sporeling types in key genera of hornworts, such as and FoliocerosPhymatoceros, will be crucial for inferring the possible ancestral type and the evolution of this trait among hornworts. Our study supports the necessity of supplementary studies on Sporeling development, combined with morphological and phylogenetic investigations, to help elucidate the evolution of the Anthocerotophyta and their distribution patterns.
Jorge L Alvarado - One of the best experts on this subject based on the ideXlab platform.
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SIZE INCREMENTS DUE TO INTERINDIVIDUAL FUSIONS: HOW MUCH AND FOR HOW LONG?1
Journal of Phycology, 2010Co-Authors: Bernabe Santelices, Jorge L Alvarado, Verónica FloresAbstract:Size increments following interindividual fusions appear as a general benefit for organisms, such as coalescing seaweeds and modular invertebrates, with the capacity to fuse with conspecifics. Using Sporelings of the red algae Gracilaria chilensis C. J. Bird, McLachlan et E. C. Oliveira and Mazzaella laminarioides (Bory) Fredericq, we measured the growth patterns of Sporelings built with different numbers of spores, and the magnitude and persistence of the size increments gained by fusions. Then we studied three morphological processes that could help explain the observed growth patterns. Results indicate that in these algae, coalescence is followed by immediate increase in total size of the coalesced individual and that the increment is proportional to the number of individuals fusing. However, the size increments in Sporelings of both species do not last >60 d. Increasing reductions of marginal meristematic cells and increasing abundance of necrotic cells in Sporelings built with increasing numbers of initial spores are partial explanations for the above growth patterns. Since Sporelings formed by many spores differentiate erect axes earlier and in larger quantities than Sporelings formed by one or only a few spores, differentiation, emergence, and growth of erect axes appear as a more likely explanation for the slow radial growth of the multisporic Sporelings. Erect axis differentiation involves significant morphological and physiological changes and a shift from radial to axial growth. It is concluded that the growth pattern exhibited by these macroalgae after fusion differs from equivalent processes described for other organisms with the capacity to fuse, such as modular invertebrates.
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demographic consequences of coalescence in Sporeling populations of mazzaella laminarioides gigartinales rhodophyta 1
Journal of Phycology, 2008Co-Authors: Bernabe Santelices, Jorge L AlvaradoAbstract:: Coalescing macroalgae are ecologically important members of intertidal and shallow subtidal communities. However, we still lack quantitative information on the demographic consequences of coalescence. Using demographic models developed for modular invertebrates, we studied the demography of settlement and early recruitment in the coalescing macroalga Mazzaella laminarioides (Bory) Fredericq. Permanently marked microscopic fields on laboratory-incubated and field-incubated plates were monitored regularly (at 15, 30, 45, and 60 d) using image analysis techniques to evaluate the relative importance of settler abundance, mortality, coalescence (fusion), and fission on the changes in size and numbers of recruits. On the plates, spores settled individually or in groups. Over time, spores in close proximity may coalesce, resulting in a mixture of unisporic and multisporic crusts. When new spores arrive, they may or may not coalesce with previously settled crusts. Coalescence and mortality reduce the number of Sporelings, but coalescence increases the size of the Sporelings, thereby reducing further probability of Sporeling mortality. Crust fissions are negligible in frequency, while the frequency of coalescence increases from ∼25% after only 3 d, to ∼75% after 60 d. Thus, as a result of variable settlement, mortality, and coalescence, any area colonized by M. laminarioides would contain a mixture of crusts of different sizes, ages, and genetic constitution. The interactions between the above three processes create a more complex survivorship curve than the ones known for unitary organisms.
Maureen E Callow - One of the best experts on this subject based on the ideXlab platform.
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The effect of formulation variables on fouling-release performance of stratified siloxane–polyurethane coatings
Journal of Coatings Technology and Research, 2012Co-Authors: Rajan B. Bodkhe, Maureen E Callow, James A Callow, Stephanie E. M. Thompson, Carolyn Yehle, Nicholas Cilz, Justin Daniels, Shane J. Stafslien, Dean C. WebsterAbstract:The effects of formulation variables, such as type of polyol, solvent type and solvent content, and coating application method, on the surface properties of siloxane–polyurethane fouling-release coatings were explored. Fouling-release coatings allow the easy removal of marine organisms from a ship’s hull via the application of a shear force to the surface. Self-stratified siloxane–polyurethane coatings are a new approach to a tough fouling-release coating system. Combinatorial High Throughput Experimentation was employed to formulate and characterize 24 different siloxane–polyurethane coatings applied using drawdown and drop-casting methods. The resulting coatings were tested for surface energy using contact angle measurements. The fouling-release performance of the coatings was tested using a number of diverse marine organisms including bacteria ( Halomonas pacifica and Cytophaga lytica ), Sporelings (young plants) of the green macroalga ( Ulva linza ), diatom ((microalga) Navicula incerta ), and barnacle ( Amphibalanus amphitrite ) . The performance of the majority of the coatings was found to be better than the silicone standards, Intersleek^® and Silastic^® T2. An increase in solvent content in the formulations increased the surface roughness of the coatings. Coatings made with polycaprolactone polyol appeared to be somewhat rougher compared to coatings made with the acrylic polyol. The adhesion strength of Sporelings of Ulva increased with an increase in solvent content and increase in surface roughness. The adhesion strengths of Ulva Sporelings, C. lytica, and N. incerta were independent of application method (cast or drawdown) in contrast to H. pacifica adhesion , which was dependent on the application method.
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Effect of contact angle hysteresis on the removal of the Sporelings of the green alga Ulva from the fouling-release coatings synthesized from polyolefin polymers
Biointerphases, 2010Co-Authors: Ikrime O. Ucar, Maureen E Callow, C. Elif Cansoy, H. Yildirim Erbil, Michala E. Pettitt, James A CallowAbstract:Wettability is one of the surface characteristics that is controlled by the chemical composition and roughness of a surface. A number of investigations have explored the relationship between water contact angle and surface free energy of polymeric coatings with the settlement (attachment) and adhesion strength of various marine organisms. However, the relationship between the contact angle hysteresis and fouling-release property is generally overlooked. In the present work, coatings were prepared by using commercial hydrophobic homopolymer and copolymer polyolefins, which have nearly the same surface free energy. The effects of contact angle hysteresis, wetting hysteresis, and surface free energy on the fouling-release properties for Sporelings of the green alga Ulva from substrates were then examined quantitatively under a defined shear stress in a water channel. The ease of removal of Sporelings under shear stress from the polymer surfaces was in the order of PP>HDPE>PPPE>EVA-12 and strongly and positively correlated with contact angle and wetting hysteresis; i.e., the higher the hysteresis, the greater the removal.
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the role of surface energy and water wettability in aminoalkyl fluorocarbon hydrocarbon modified xerogel surfaces in the control of marine biofouling
Biofouling, 2009Co-Authors: Stephanie M Bennett, John A Finlay, Nikhil Gunari, Gilbert C Walker, Maureen E Callow, David D Wells, James A Callow, Frank V Bright, Anne E. Meyer, Michael R DettyAbstract:Xerogel films with uniform surface topogrophy, as determined by scanning electron microscopy, atomic force microscopy (AFM), and time-of-flight secondary ion mass spectrometry, were prepared from aminopropylsilyl-, fluorocarbonsilyl-, and hydrocarbonsilyl- containing precursors. Young's modulus was determined from AFM indentation measurements. The xerogel coatings gave reduced settlement of zoospores of the marine fouling alga Ulva compared to a poly(dimethylsiloxane) elastomer (PDMSE) standard. Increased settlement correlated with decreased water wettability as measured by the static water contact angle, θWs, or with decreased polar contribution (γP) to the surface free energy (γS) as measured by comprehensive contact angle analysis. The strength of attachment of 7-day Sporelings (young plants) of Ulva on several of the xerogels was similar to that on PDMSE although no overall correlation was observed with either θWs or γS. For Sporelings attached to the fluorocarbon/hydrocarbon-modified xerogels, the st...
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Effect of background colour on growth and adhesion strength of Ulva Sporelings
Biofouling, 2008Co-Authors: John A Finlay, Maureen E Callow, Benjamin R. Fletcher, James A CallowAbstract:This study examined the effects of a range of black, grey and white substrata on the growth and attachment strength of Ulva Sporelings on glass and polydimethylsiloxane (Silastic®-T2) surfaces. The rate of development of Sporelings was strongly influenced by the colour of the substratum on which they grew. On black backgrounds, Sporelings grew slowly and germination was delayed. Laboratory screening methods for antifouling and fouling-release coatings that rely on the growth of Ulva Sporelings can be compromised if samples are of different colours. Hydrodynamic removal of Sporelings from coatings may also be affected by substratum colour, since smaller plants generate lower hydrodynamic forces making them more difficult to remove.
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The antifouling and fouling-release perfomance of hyperbranched fluoropolymer (HBFP)-poly(ethylene glycol) (PEG) composite coatings evaluated by adsorption of biomacromolecules and the green fouling alga ulva
Langmuir, 2005Co-Authors: James A Callow, Maureen E CallowAbstract:Cross-linked hyperbranched fluoropolymer (HBFP) and poly(ethylene glycol) (PEG) amphiphilic networks with PEG weight percentages of 14% (HBFP-PEG14), 29% (HBFP-PEG29), 45% (HBFP-PEG45), and 55% (HBFP-PEG55) were prepared on 3-aminopropyl)triethoxysilane (3-APS) functionalized microscope glass slides for marine antifouling and fouling-release applications. The surface-free energies (gamma(s)), polar (gamma(s)(p) and gamma(s)(AB)), and dispersion (gamma(s)(d) and gamma(s)(LW)) components were evaluated using advancing contact angles by two-liquid geometric-mean and three-liquid Lifshitz-van der Waals acid-base approaches. The HBFP coating exhibited a low surface energy of 22 mJ/m(2), while the gamma(s) and gamma(s)(p) of the cross-linked HBFP-PEG coatings increased proportionally with the PEG weight percentages in the networks. The adsorption of bovine serum albumin (BSA), lectin from Codium fragile (CFL), lipopolysaccharides from Escherichia coli (LPSE) and Salmonella minnesota (LPSS) upon glass, APS-glass, HBFP, PEG, and the cross-linked HBFP-PEG network coatings were investigated by fluorescence microscopy. The marine antifouling and fouling-release properties of the cross-linked HBFP-PEG coatings were evaluated by settlement and release assays involving zoospores of green fouling alga Ulva (syn. Enteromorpha; Hayden, H. S.; Blomster, J.; Maggs, C. A.; Silva, P. C.; Stanhope, M. J.; Waaland, J. R. Eur. J. Phycol. 2003, 38, 277). The growth and release of Ulva Sporelings were also investigated upon the HBFP-PEG45 coating in comparison to a poly(dimethylsiloxane) elastomer (PDMSE) standard material. Of the heterogeneous cross-linked network coatings, the maximum resistances to protein, lipopolysaccharide, and Ulva zoospore adhesion, as well as the best zoospore and Sporeling release properties, were recorded for the HBFP-PEG45 coating. This material also exhibited better performance than did a standard PDMSE coating, suggesting its unique applicability in fouling-resistance applications.