Currently, zirconia is widely used in biomedical area as a material for prosthetic devices because of its good mechanical and chemical properties. Largely employed in clinical area for total hip replacement, zirconia ceramics (ZrO 2 ) are becoming a prevalent biomaterial in dentistry and dental implantology. Although titanium is used in dental implantology currently, there is a trend to develop new ceramic-based implants as an alternative to monolithic titanium. This article reviews the evolution and development of zirconia through data published between 1963 and January 2008 in English language. Articles were identified via a MEDLINE search using the following keywords: zirconia, zirconia/biocompatibility, zirconia/osseointegration, zirconia/periointegration, zirconia/review, and zirconia/bacterial adhesion or colonization. This review of the literature aims at highlighting and discussing zirconia properties in biological systems for their future use in dental implantology. In conclusion, zirconia with its interesting microstructural properties has been confirmed to be a material of choice for the ''new generation'' of implants, thanks to its biocompatibility, osseoconductivity, tendency to reduce plaque accumulation, and interaction with soft tissues, which leads to periointegration. However, scientific studies are promptly needed to fulfill gaps like long-term clinical evaluations of ''all zirconia implants,'' currently leading to propose an alternative use of ''hybrid systems'' (i.e., titanium screw with zirconia collar) and also bacterial colonization of zirconia. Moreover, there is a permanent need for consistent information about topography and chemistry of zirconia allowing easier cross-product comparisons of clinical devices. '

Marine biodiversity in French Guiana is strongly influenced by the amagon River waters of the river Amazon, which constitute a major structuring factor for the estuarine, coastal, and shelf marine ecosystems. Moreover, the marked seasonal and interannual variabilities play important roles in the stability or fluctuations in the environmental parameters that influence biodiversity at the ecological, population, and genetic levels. Previous and ongoing studies of the marine and littoral biota relate mostly to commercial marine species, protected species in danger of extinction and, specially, to the biodiversity and functioning of local coastal and littoral ecosystems such as estuaries, mudflats, sandy beaches and, particularly, littoral mangroves. A more integrated approach involving local, regional, and international scientific collaboration is needed for a better assessment and understanding of marine biodiversity. Such studies would benefit from international cooperation that would allow the gathering of new information and the comparison of previous data, the organization of common oceanographic surveys, the homogenisation of analytical protocols, and also favour the exchange of scientists and postgraduate students for a real transfer of ideas, techniques, and know-how. Moreover, research on the comparative biodiversity of analogous littoral and marine ecosystems in different parts of South America would allow a more accurate estimate of marine biodiversity on a continental scale.KEYWORDS: French Guiana, marine biodiversity, coastal systems, Amazon river waters, Intertropical Convergence Zone, ecological and conservation studies RESUMEN La biodiversidad marina en la Guyana Francesa está fuertemente influenciada por los aportes amazónicos, los cuales constituyen un factor estructurante de los ecosistemas estuarianos, costeros y de plataforma continental. Además, debido a las cambiantes condiciones meteorológicas y oceanográficas, la variabilidad estacional e inter-anual puede jugar un rol importante en la estabilidad o la modificación de los parámetros medio-ambientales que afectarían la biodiversidad ecológica, poblacional y genética de los ecosistemas locales. Los estudios llevados a cabo sobre la biología de las especies marinas y litorales se refieren principalmente a especies de interés comercial, especies protegidas en peligro de extinción, y sobre todo a las características del funcionamiento de ciertos ecosistemas costeros y litorales característicos como los estuarios, bancos de fango, playas de arena, y sobre todo los manglares. La idea de estudios o series de estudios mejor coordinados entre sí a nivel regional e internacional, emerge como una necesidad para una mejor estimación y comprensión de la biodiversidad marina. Estos estudios beneficiarían de una importante cooperación internacional que pemitiese comparar e integrar el conjunto de datos obtenidos en el pasado, llevar a cabo misiones oceanográficas conjuntas, mutualizar y homogeneizar los protocolos analíticos, y favorecer el interca...

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-Tropical shrimp fisheries are characterized by various interactions with their natural environment and with other fisheries. These latter interactions can be explained by the high quantity of bycatch taken by industrial trawler fleets, which has a significant impact on fish populations associated with shrimps and thus also on finfish fisheries. Bycatch also includes emblematic species, which are subject to strict conservation measures decided by the international community. It seems important to identify and assess the biological and economic consequences of different mitigation measures (increase of mesh size, turtle excluder devices and bycatch reducing devices). This communication is based on case studies undertaken on the Indian white prawn (Fenneropenaeus indicus) and speckled shrimp (Metapenaeus monoceros) fisheries in Madagascar and on the brown shrimp (Farfantepenaeus subtilis) and pink spotted shrimp (Farfantepenaeus brasiliensis) fishery in French Guiana. A review of the impacts of these fisheries on resources and ecosystems is made and some results of experiments on mitigation devices given. Finally, the results of simulations obtained using a multi-species, multi-fleet, age-structured bioeconomic model, including modifications of catchability and costs related to the adoption of these devices, is presented and discussed.

a b s t r a c tThe demersal trawl fishery of the north Tunisian coast primarily targets the deep-water rose shrimp, Parapenaeus longirostris, and secondarily a variety of demersal fish species. These fishes include hake (Merluccius merluccius), common pandora (Pagellus erythrinus), red mullet (Mullus barbatus), surmullet (Mullus surmuletus), Atlantic horse mackerel (Trachurus trachurus), bogue (Boops boops), picarel (Spicara smaris) and spotted flounder (Citharus linguatula). A bioeconomic model was used to test management measures through scenarios that ran over eleven years to estimate the viability of the fishery according to biological and economic results. The most beneficial scenario was the combination of several management measures including a temporal closure of two months, the replacement of the 40 mm diamond mesh codend with 40 mm square mesh, the removal of both the biological recovery tax and of fuel subsidies, and an 83% reduction in fishing capacity. This results in an annual private profit higher by 9.3 M TND (Tunisian Dinar) (6.9 M USD) that of 2008, and an economic rent that was higher by 13.3 M TND (9.9 M USD) than by the end of the projected period. Shrimp and fish biomasses have doubled compared with 2008, and trawling damages would be reduced to the equivalent of a five-fold reduction in fishing effort. This study shows that the objectives of improving demersal ecosystems and improving individual and collective wealth can be achieved through the synergistic effects of various regulatory measures.