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Low light intensity habitats harbor unique sciophilous benthic communities and are a source of novel and unique sponge fauna. However, the community structure of these habitats is poorly studied to date. Thus, this study attempts to understand the composition and structure of sciophilous sponge populations in southeast Florida. Fifty limestone plates were placed on a shallow reef in Fort Lauderdale for two years (2010-2012). To identify the sponge community and their patterns over time, all plates were photographed at the end of each year. Then, samples were taken from each of the live sponge specimens observed on the plates and processed in the laboratory for taxonomical identification. A total of 45 different sponge species were found, the majority corresponding to the Poecilosclerida Order. Eighteen were identified to species level, twenty-two to genus, and five were undetermined. Eight sponges constitute new records to Florida, and four are potentially new species. The most dominant species include Oscarella sp.1, Dysidea etheria, Mycale sp.1, Halisarca caerula and Tedania ignis. Species richness significant varied among years, and species cover among sectors (inner and outer reef). However, sponge assemblages were similar between years with slightly variation between sectors. This study found a diverse and complex composition and structure of sponges that is quite distinct from the sponge assemblages on the open reefs. A guide of the biodiversity of cryptic sponge species was created to facilitate further studies in low light intensity habitats.

<p>To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn / 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn / 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association...</p>

<p>To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn / 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn / 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association...</p>

Magister Scientiae (Biodiversity and Conservation Biology) / To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn; 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn; 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association. / South Africa

Lors de la polymérisation en suspension du chlorure de vinyle, il se forme sur les parois un dépôt de polychlorure de vinyle (PVC). Ce phénomène, nommé encroûtement, génère des problèmes car il limite la production de PVC et affecte la qualité du produit final. Dans ce contexte, un projet FUI (Fond Unique Interministériel) intitulé «Ecoating», a été financé dans le cadre d’une collaboration entre plusieurs partenaires industriels et universitaires (INEOS ChlorVinyls, Mäder Research, Avenir Group, LPIM, ESPCI-ParisTech). Deux thèses ont vu le jour au LPIM, avec pour but de développer un revêtement (photo)polymère aux propriétés anti-encroûtement durables qui permettrait d’améliorer la qualité du PVC produit, d’augmenter les quantités produites et ainsi d’améliorer la compétitivité des usines de PVC. Cette thèse s’inscrit dans le développement d’un vernis photopolymère répondant au cahier des charges. Pour éviter l’encroûtement des réacteurs, il est nécessaire de stopper une étape du mécanisme d’encroûtement comme l'adsorption sur les parois du réacteur d’un copolymère nommé Acvagen Graft Copolymer (AGC). Ce copolymère est très actif dans le phénomène d’encroûtement (site de nucléation) et se trouve principalement dans la phase aqueuse du milieu réactionnel. La stratégie de recherche élaborée dans ce projet a été basée sur le développement d'un revêtement photopolymère présentant une faible affinité pour l'eau et devant adhérer à la surface des réacteurs pour éviter la formation de croûte. Les polymères à base de fluoroacrylates ont été les premiers candidats choisis dans cette étude du fait que leurs propriétés exceptionnelles (faible énergie de surface, stabilité chimique et haute hydrophobicité...) pouvaient éviter l'adsorption de l'AGC sur les parois du réacteur, et par conséquent le développement de la croûte. Une recherche bibliographique a été réalisée pour comprendre le comportement particulier de ces molécules qui migrent vers la surface du film et s’organisent en surface pour donner des surfaces hydrophobes. Des mélanges de résines fluoroacryliques modèles ont été testés pour évaluer le caractère hydrophobe du revêtement, comprendre la migration des molécules de fluor vers l’interface en fonction de la nature de substrat et aussi déterminer l’influence de l’ajout d’additifs fluorés au mélange sur les propriétés globales du film. Cette étude nous a permis de comprendre l’influence de l’additif fluoré sur les propriétés chimiques et physiques du film. À l’échelle du laboratoire des tests d’immersion de ces revêtements déposés sur l’acier inoxydable ont étés réalisés dans l’eau chaude (80°C) afin de caractériser leur caractère hydrophobe en fonction du vieillissement dans l’eau chaude ainsi que l’adhésion du film au substrat. Nous avons observé une diminution de l'hydrophobicité de la surface du film au cours du temps lors d’une immersion. [...] / Our scientific approach has explored different strategies to develop a durable UV-cured coating with antifouling properties to prevent the crust formation. Firstly, the potential of fluoroacrylate photocurable coatings was exhaustively investigated. Indeed, their outstanding properties (low surface energy, chemical stability and high hydrophobicity...) could limit the adsorption of the AGC on the reactor walls and further encrusting. A bibliographic research highlighted the behavior of fluorinated monomers on film surface and the parameters affecting the hydrophobic properties. Different fluorinated monomers were selected. At low concentration, they provide hydrophobic surfaces on 316L stainless steel, the reference substrate. However, a decrease of the films surface hydrophobicity in hot water was observed with time, and was attributed to a disorganization of the fluorinated chains on the coating surface. An optimization of the amount of fluoroacrylate monomer was performed by confocal Raman microscopy (CRM) to promote the fluorinated chains stability on the surface before and after immersion in hot water at 80°C. The beneficial effect was found maximal at a concentration ranging from 1 to 1.8 wt%. However, even after this optimization, a decrease of the film surface hydrophobicity was observed for increased immersion time in hot water. Therefore, optimized fluoroacrylate monomer concentration was combined with alternated thermal/immersion post-treatment and has conducted to more stable photocured films. This result was attributed to a rigidification of the fluorinated chains on the film surface limiting thus, the extent of their disorganization. After this study realized at a laboratory scale, we tested the photocured coating in the VCM pilot reactor. A surface cleaning, an increase of the stainless steel roughness by shot blasting and the use of alkoxysilanes as coupling agents were implemented in order to enhance the adhesion properties of the photopolymer film on stainless steel. In addition, the use of a fluorinated monomer containing a heteroatom improved the rigidification when associated with the alternated thermal/immersion post-treatment. The crust formation was limited during four successive polymerizations in the VCM pilot reactor. A durable anti-fouling UV-coating could be not obtained due to some swelling phenomena resulting from the lack of coating adhesion or some abrasion occurring from small PVC pellets during the PVC polymerization.A second part of this project was dedicated to superhydrophobic coatings. Indeed, reducing interaction with water should lead to a better protection of the substrate. A literature review on the superhydrophobic surfaces has shown that the contact with hot water generally strongly affects their antiwetting properties and induces a large contact angle decrease. [...]