Éditeur(s) : PSIC 11 - 11th Pacific Science Inter-Congress : Pacific Countries and their Ocean: Facing Local and Global Changes / 2nd Symposium on French Research in the Pacific. March 2 - 6, 2009 Tahiti, French Polynesia.
Résumé : Meiofauna is a functional group made of small benthic metazoans 45 to 500µm in size. Although protista, foraminifera living in this kind of environment are often put in to the meiofauna. Meiofauna has been studied in New Caledonia for its double role as biological indicator for monitoring pond health status and as shrimp forage. Suitability of EOM (easily oxidized material), SOD(sediment oxygen demand),as new biochemical tools for monitoring shrimp pond health was assessed in an environmental survey aiming to assess the role of the water/sediment interface in the occurrence of the summer syndrome vibriosis. EOM, SOD and redox were correlated with shrimp survivals. Lowest meiofauna biomass and abundance were concomitantly found in the most polluted station. Proportion of abnormal tests over exceeding the one found in areas subjected to natural ecological stress were collected and were positively related to EOM and SOD and negatively to redox. Shrimp pond dominant species are common to estuaries and lagoons. But foraminifera abnormal behaviour indicates specific shrimp pond conditions

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00198/30876/29244.pdf
http://archimer.ifremer.fr/doc/00198/30876/

Résumé : After a period of rapid development of the sites (an increase in both reared surface area and production), tropical shrimp aquaculture is currently being faced with critical problems due to economical and ecological constraints. In many countries with favourable conditions for shrimp aquaculture such as indonesia or Vietnam, sites are often badly selected and/or over-exploited. This conducts to sorne extent to decreases or collapses in the production due to the difficulty in predicting the maximum production capacity of the sites. Furthermore, it appears that production sustainability depends on many factors among which socio-economy and ecolo gy are of prime importance. The STD3 project titled « Assessment of tropical shrimp aquaculture impact on the environment in tropical countries using hydrobiology, ecology and remote sensing as helping tools for diagnosis )) was initiated in 1994, with the aim to study the sustainability of marine shrimp aquaculture in tropical areas, main! y Indonesia and Vietnam, through the following tasks: (i) improve site selection and study the impact of aquaculture on marine environments presenting a variable sensitivity to organic sewage, (ii) analyse the socio-economical aspects and profitability of the aquaculture industry and of common resources (iii) use remote sensing and geographical data bases for diagnosis and monitoring of site degradation (iv) reinforce the capacity of Asian scientists through training. Severa! aquaculture sites have been investigated in the Lampung region (South Sumatra, Indonesia), the Mekong delta (Vietnam) and on the West coast of New-Caledonia, providing a large range of typical ecosystems encountered in Asia and in the Pacifie, from coralline sites to coastal plains with mangrove and deltaic areas. The study concerned the spatial structure and seasonal influence of these ecosystems, the temporal variation during the course of the project (3 years) and the relation between the ecological structure and farm productions. Remote sensing provides a synoptic vision over large land expanses. Severa! scenes were processed for landuse mapping using conventional classification techniques. Concerning water quality assessment, a general relation for the Java sea was found between image and field data in terms of total suspended matter. Applying this relation to a new site in Sumatra has provided an initial approach to water type and, together with land use mapping, a preliminary assessment of the suitability of the area to shrimp aquaculture development. Socio-economic research has been focused on the identification ofneeds for collective action, including public policy, in the perspective of shrimp farming sustainability. The main concern is in the regulation of shrimp farming intensification and extensification at the scale of coastal ecosystemic entities in a common property resource management perspective. The common considered here is coastal water quality. Comparing the local development profiles and the institutional grounds for the design and implementation of collective management rules shows that variables such as land tenure system, farm owner socio-economic profile, social homogeneity or heterogeneity of the farmers are key factors to analyse the potential for sustainability. The defmition of water quality and the possible means to ensure its collective management are discussed. The main conclusion is that the economie incentives to farming development are strong but there is no significant difference among traditional, semi-intensive and intensive systems in terms of economie efficiency or wealth distribution. The description of the functioning of the different kinds of ecosystems make it possible to give an advice concerning the positioning of the activity inside the ecosystem, and furthermore to have a reference state in order to determine the impact of the activity on the coastal environnement. This impact can be summarized as an increase in the concentration of total suspended matt€?r, of particulate organic matter and of sulfate reducing bacterias. This organic ma~.er is either issued from rearing activities or from telluric origine, due to mangrove eradication when building the ponds. An evaluation of the relationship existing between productivity and characteristics of each ecosystem bas been conducted by correlating ecological indicators data (concentration of total suspended matter, particulate organic matter, chlorophyll, percentage of pheopigments in total pigments and cyanobacteria and sulfatereducing bacteria in water and sediments) with the average production of the farms. This comparison lead to the compilation of a scale of observed production integrating the range of these environmental parameters with shrimp production levels, bound to facilitate the positioning of shrimp farming in relation with the confmement leve! of each ecosystem. Lastly, ali geographie data originated from the various compartments of the study have been geo-referenced and loaded into a geographical information system. This allows to display any query made on spatial variables and their related statistical data, including the ir variations over the last few years and to reveal patterns and phenomena otherwise not obvious.
Le programme mis en oeuvre par la DRV (Paris, CREMA-L'Houmeau, DELIAO Brest, COP Tahiti, GIE/RA Nouvelle Calédonie), dans le cadre d'un projet européen STD3 «(Sciences et Technique au Service du Développement», en collaboration avec l'Université de Montpellier II, l'Ecole Nationale d'Agronomie de Rennes, l'ITC (Hollande), l'Institut Océanographique de Nha Trang (Vietnam), le BADC de Jepara et le BPPT de Jakarta (Indonésie), avait pour but la mise au point de méthodes permettant d'améliorer la sélection des sites ainsi que le suivi du développement et de l'impact de l'aquaculture des crevettes Péneides en milieu tropical pour éviter la surexploitation. Quatre axes de recherche ont été défmis : a) identifier la nature et quantifier les rejets de déchets issus de ce type d'aquaculture, b) définir les caractéristiques écologiques des écosystèmes susceptibles d'accueillir l'activité aquacole et suivre leur évolution sous l'influence des rejets, c) déterminer l'influence de la gestion des fermes et des ressources (aspects économiques) sur les performances de productivité, d) déterminer la capacité de la télédétection comme outil de diagnostic d'impact à l'échelle de la région, e) mener un programme de formation d'étudiants et jeunes chercheurs Vietnamiens et Indonésiens.

Droits : 1998 Ifremer
http://archimer.ifremer.fr/doc/00132/24357/22357.pdf
http://archimer.ifremer.fr/doc/00132/24357/

Éditeur(s) : Wiley-blackwell Publishing, Inc
Résumé : Aims: A description of bacterial pathogens in shrimp ponds is necessary to understand their pathogenesis. Vibrio nigripulchritudo was shown to contain saprophytic and pathogenic strains among New Caledonian isolates. We established a method to map the development of V. nigripulchritudo in pond sediments at three different genetic levels: the species level, then at the pathogenic cluster level and finally at the plasmid level, present only in all highly pathogenic isolates. Methods and Results: PCR methods were applied to shrimp pond sediments both before and after a mortality outbreak. Using crude samples, the species V. nigripulchritudo is not detected at first (0/42 samples at day 56 post stocking) but appears frequently in the sediments after the mortality event (30/42 at day 107). The distribution of strains from the pathogenic cluster of V. nigripulchritudo also follows this pattern. In contrast, the pSFn1 virulence-associated plasmid was detected in one sample at day 56 and none at day 107. An enrichment method was developed to lower the detection limits of our assays. After enrichment, the species V. nigripulchritudo was detected in all samples at both dates. The number of samples positive for pSFn1 was 42/42 samples at day 56 and 29/42 at day 107. Conclusions: These results show that the sediments contain V. nigripulchritudo, notably pathogenic strains. Surprisingly, the virulence-associated plasmid pSFn1 found in all V. nigripulchritudo isolated from moribund shrimp appears less frequently in sediments, possibly being useless or even detrimental to its recipient bacteria in this environment. Significance and Impact of the Study: This study confirms the presence of pathogenic V. nigripulchritudo strains in shrimp pond sediment before a mortality outbreak complying with a previous hypothesis that sediments could be the infecting reservoir. After the outbreak, both total V. nigripulchritudo and pathogenic strains populations have largely increased, possibly contributing to the recurrent mortality observed in this shrimp vibriosis.
Journal Of Applied Microbiology (1364-5072) (Wiley-blackwell Publishing, Inc), 2010-06 , Vol. 108 , N. 6 , P. 2003-2011

Droits : 2010 The Society for Applied Microbiology - Wiley-Blackwell
http://archimer.ifremer.fr/doc/00004/11484/8177.pdf
DOI:10.1111/j.1365-2672.2009.04601.x
http://archimer.ifremer.fr/doc/00004/11484/

Éditeur(s) : HAL CCSD Kluwer Academic Publishers
Résumé : International audience
The interlocking leaves of tank-forming bromeliads (Bromeliaceae) collect rainwater and detritus, thus creating a freshwater habitat for specialized organisms. Their abundance and the possibility of quantifying communities with accuracy give us unparalleled insight into how changes in local to regional environments influence community diversity in small water bodies. We sampled 365 bromeliads (365 invertebrate communities) along a southeastern to northwestern range in French Guiana. Geographic locality determined the species pool for bromeliad invertebrates, and local environments determined the abundance patterns through the selection of traits that are best adapted to the bromeliad habitats. Patterns in community structure mostly emerged from patterns of predator species occurrence and abundance across local-regional environments, while the set of detritivores remained constant. Water volume had a strong positive correlation with invertebrate diversity, making it a biologically relevant measure of the pools' carrying capacity. The significant effects of incoming detritus and incident light show that changes in local environments (e.g., the conversion of forest to cropping systems) strongly influence freshwater communities. Because changes in local environments do not affect detritivores and predators equally, one may expect functional shifts as sets of invertebrates with particular traits are replaced or complemented by other sets with different traits.
Hydrobiologia

hal-00845572
https://hal.archives-ouvertes.fr/hal-00845572

Éditeur(s) : Elsevier Science Bv
Résumé : The study was conducted to (1) estimate the effects of polyculture of blue shrimp Litopenaeus stylirostris with goldlined rabbitfish Siganus lineatus on production, environmental quality and water and sediment metabolism and (2) to determine if blue shrimp and goldlined rabbitfish polyculture is possible. The experiment was carried out for 12 weeks in a mesocosm system that consisted of 12 circular outdoor mesocosm fiberglass tanks (1.7 m2, 1275 L water volume). Shrimp (2.9 g) were randomly stocked at density of 15 shrimp.m− 2 without rabbitfish (control), with rabbitfish (25.5 g) at low density (1.2 fish.m− 2) (LDRB) and high density (2.4 fish.m− 2) (HDRB). Results indicated that goldlined rabbitfish S. lineatus did not affect shrimp growth performance. At the end of the experiment, the combined shrimp and rabbitfish yields in the LDRB (213 g.m− 2) treatment and the HDRB (295 g.m− 2) treatment were significantly greater (P < 0.05) than the shrimp yield in the control (143 g.m− 2). Most of the water and sediment parameters were similar among treatments. There was no significant difference (P > 0.05) in gross primary productivity and respiration between the HDRB treatment and the control. It was concluded that the polyculture of blue shrimp with goldlined rabbitfish is technically possible without degradation of the environment in the culture system.
Aquaculture (0044-8486) (Elsevier Science Bv), 2014-09 , Vol. 433 , P. 340-347

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00198/30968/29344.pdf
DOI:10.1016/j.aquaculture.2014.06.014
http://archimer.ifremer.fr/doc/00198/30968/