10 research outputs found
Evaluation de lâĂ©tat de santĂ© des habitats et peuplements de poissons de la zone de Voh-KonĂ©-Pouembout, Campagnes de stations vidĂ©o rotatives STAVIRO 2007-2013
âą Conducted within the AMBIO project, this work deals with coral reef fish communities and associated habitats, in the New Caledonian lagoons. It aims at assessing the status and trends of habitats and mobile macrofauna in the Voh-Kone-Pouembout lagoon, in the light of demographic and industrial developments and accounting for the existing customary reserve of Oundjo.
âą It relies on 280 stations collected in 2007 and 2013 using the remote unbaited underwater video STAVIRO rotating technique, which were analysed to characterize habitat, fish assemblages, turtles and sea snakes, from a list of 490 species (AMBIO/A/1).
âą 143 species (including one turtle species and one sea snake species), belonging to 23 families were observed. The most frequent and abundant families were surgeonfish and parrotfish, then goatfish, butterflyfish and emperors. Groupers and rabbitfish were rarely observed.
âą 27 indicators were computed, mapped (maps available on a Sextant server), and analysed using the PAMPA computing tool. Outcomes were organized in a dashboard for each management objective (biodiversity conservation and fisheries management).
âą Coral status is rather good and stable, and shows no impact from anthropogenic pressures, even close to the plant and shipping channel.
âą Frequency of sharks, rays and humphead wrasses clearly dropped between 2007 and 2013. Turtles were rarely observed in both years.
âą Fish community is moderately diversified, particularly in the Living Coral habitat. Herviores dominate species assemblage and piscivores are not abundant.
âą The abundance of several fished species distinctly declined between 2007 and 2013, but trends differed according to areas.âą Cette Ă©tude conduite dans le cadre du projet AMBIO concerne les communautĂ©s de poissons et habitats associĂ©s aux rĂ©cifs coralliens des lagons de Nouvelle-CalĂ©donie. Lâobjectif est dâĂ©valuer lâĂ©tat de santĂ© des habitats et de la macrofaune mobile de la zone de Voh-KonĂ©-Pouembout, au regard du dĂ©veloppement dĂ©mographique et industriel et en tenant compte de lâexistence de la RĂ©serve coutumiĂšre dâOundjo.
âą LâĂ©tude sâappuie sur 280 stations video STAVIRO collectĂ©es lors de deux campagnes rĂ©alisĂ©es en 2007 et 2013. Leur analyse a permis de caractĂ©riser lâhabitat environnant chaque station, ainsi que les communautĂ©s de poissons, tortues et serpents, sur la base dâune liste de 490 espĂšces (cf. AMBIO/A/1).
⹠143 espÚces de poissons, tortue et serpent, appartenant à 23 familles ont été observées. Les familles les plus fréquentes et les plus abondantes sont les chirurgiens et perroquets, suivis par les rougets-barbets, les poissons-papillons et les becs et bossus. Loches et picots sont assez peu observés.
âą 27 indicateurs ont Ă©tĂ© calculĂ©s, reprĂ©sentĂ©s sous forme de carte disponible sur un serveur Sextant, et analysĂ©s grĂące Ă lâoutil de calcul PAMPA. Les rĂ©sultats sont synthĂ©tisĂ©s sous forme de tableau de bord par objectif de gestion relatif Ă la conservation de la biodiversitĂ© et la gestion des ressources de la pĂȘche et sous forme de cartes avec des tendances pour les principaux indicateurs relatifs Ă la pĂȘche.
âą LâĂ©tat de santĂ© du corail est satisfaisant et stable ; il ne semble pas avoir souffert du dĂ©veloppement dĂ©mographique et Ă©conomique de la zone, mĂȘme Ă proximitĂ© de lâusine et du chenal.
âą La frĂ©quence dâobservation des requins, raies et poissons-napolĂ©ons a nettement diminuĂ© entre 2007 et 2013. Les tortues ont Ă©tĂ© peu observĂ©es les deux annĂ©es.
âą Le peuplement de poisson est moyennement diversifiĂ© et abondant, notamment sur lâhabitat Corail vivant. Les herbivores dominent lâassemblage, mais sont en diminution. Les piscivores sont peu abondants.
âą Lâabondance de plusieurs espĂšces pĂȘchĂ©es a nettement diminuĂ© entre 2007 et 2013, mais la tendance diffĂšre en fonction des zones
Influence of settings management and protection status on recreational uses and pressures in marine protected areas
International audienceCoastal populations and tourism are growing worldwide. Consequently outdoor recreational activity is increasing and diversifying. While Marine Protected Areas (MPAs) are valuable for mitigating anthropogenic impacts, recreational uses are rarely monitored and studied, resulting in a lack of knowledge on users' practices, motivation and impacts. Based on boat counts and interview data collected in New Caledonia, we i) explored factors affecting user practices and motivations, ii) constructed fine-scale pressure indices covering activities and associated behaviors, and iii) assessed the relationships between user practices and site selection. User practices were found to depend on protection status, boat type and user characteristics. Pressure indices were higher within no-take MPAs, except for fishing. We found significant relationships between user practices and settings characteristics. In the context of increasing recreational uses, these results highlight options for managing such uses through settings management without jeopardizing the social acceptance of MPAs or the attainment of conservation goals
Avantages et inconvénients de la stéréo vidéo : applicabilité au protocole pour STAVIRO
La stĂ©rĂ©o vidĂ©o repose sur lâutilisation synchronisĂ©e de 2 camĂ©ras permettant de produire une image en 3 dimensions. Elle permet par triangulation dâobtenir une estimation prĂ©cise de la taille de chaque individu et de mesurer les distances. En 2007 en Nouvelle CalĂ©donie lâ IFREMER a dĂ©veloppĂ© des systĂšmes mono-vidĂ©o autonomes et rotatifs (STAVIRO et MICADO). La camĂ©ra est dĂ©ployĂ©e 12 minutes depuis un bateau sans immersion de plongeurs, le temps dâeffectuer 3 rotations complĂštes. Lâobjectif de lâĂ©tude est de rĂ©aliser un bilan comparatif entre lâutilisation dâun systĂšme STAVIRO classique et lâutilisation dâun systĂšme Ă©quipĂ© en stĂ©rĂ©o vidĂ©o. 59 stations ont Ă©tĂ© rĂ©alisĂ©es entre le 2 et le 13 juin 2014 dans le lagon sud ouest de la Nouvelle CalĂ©donie
Hyehen 2012. Bilan de lâĂ©tat de santĂ© du rĂ©cif par stations vidĂ©o rotatives STAVIRO
This work deals with fish communities and associated habitats, in the context of New Caledonian coral reef ecosystems. It was conducted within the AMBIO project. The study relies on remote underwater video observations, using the STAVIRO rotating technique. The study takes place in the Hienghene area, an area (Eastern Coastal Area) part of the World Heritage site âNew Caledonian lagoonsâ. It encompasses two Marine Protected Areas, Do Himenand Yeega. The sampling design covers the entire area, and was stratified according to reef geomorphology and protection status. 105 stations were validated within 4,5 days. They were analyzed to characterize the habitat surrounding each station, and fish communities, based on a species list that includes fished species, emblematic species and functionally important species. 23 indicators were computed and corresponding maps were constructed (available on a Sextant server). Each indicator was plotted and analyzed using the PAMPA computing tool. Outcomes were organized in a dashboard for each management objective (biodiversity conservation and fisheries management).
Most stations were conducted on rocky substrate: 32% of stations in the living coral habitat and 47% on detritic substrate, and only 21% in soft bottoms habitats.
109 fish species, and one turtle species, belonging to 19families were observed.
Surgeonfishes and parrotfishes are the most frequently observed families (90% and 75% of stations) followed by butterflyfishes (54%), mullids (48%) and wrasses (45%). Nine families were observed in morethann20% of stations.
Seventeen species of butterflyfish were observed, several turtles, humphead wrasses and sharks, indicating an overall goodhealth of the reef ecosystem.
Herbivores and carnivores dominate the fish assemblage and are quite abundant in coral-rich habitats; carnivores are significantly more abundant in the both reserves, whereas this is only at Do-Himen(reserve on the barrier reef) for herbivores.
Species assemblage significantly differs between habitats and to a lesser extent on protection status. Most indicators display higher values inside reserves, these differences are significant for species richness (SR) in living coral habitat, and for the SR of surgeon fish and parrotfish. Indicator values are generally higher in the DO-Himen reserve than in Yeega which is closer to the shore.Cette Ă©tude conduite dans le cadre du projet AMBIO concerne les communautĂ©s de poissons et les habitats associĂ©s aux rĂ©cifs coralliens des lagons de Nouvelle-CalĂ©donie. Elle sâappuie sur des donnĂ©es collectĂ©es par STAVIRO, une technique vidĂ©o rotative. Cette campagne a Ă©tĂ© rĂ©alisĂ©e en 2012 dans la zone de HienghĂšne, comprise dans la Zone CĂŽtiĂšre Est, elle-mĂȘme situĂ©e dans le bien inscrit au Patrimoine Mondial de lâHumanitĂ©. La zone dâĂ©tude comprend Ă©galement les Aires Marines ProtĂ©gĂ©es (AMP) de Do Himen et de Yeega. Le plan d'Ă©chantillonnage couvre lâensemble de la zone et a Ă©tĂ© stratifiĂ© en fonction des trois structures rĂ©cifales (rĂ©cif frangeant, rĂ©cif dâĂźlot/intermĂ©diaire et rĂ©cif barriĂšre) et en tenant compte du statut de protection des AMP. En 4,5 jours 105stations vidĂ©o rotatives ont Ă©tĂ© validĂ©es. Leur analyse a permis de caractĂ©riser lâhabitat environnant chaque station, ainsi que les communautĂ©s de poissons sur la base dâune liste dâespĂšces dâintĂ©rĂȘt Ă©cologique, halieutique et emblĂ©matique. 31 indicateurs ont Ă©tĂ© calculĂ©s et reprĂ©sentĂ©s sous forme de cartes disponibles sur un serveur Sextant. 23 indicateurs ont Ă©tĂ© analysĂ©s grĂące Ă lâoutil de calcul PAMPA et ont fait lâobjet dâune fiche dĂ©taillĂ©e de rĂ©sultats en annexe du rapport. Ces rĂ©sultats sont repris et synthĂ©tisĂ©s sous forme de tableau de bord par objectif de gestion relatif Ă la conservation de la biodiversitĂ© et la gestion des ressources de la pĂȘche.
Les principaux habitats observés correspondent à des fonds durs : habitat riche en corail
vivant (32% des stations), et habitat détritique (47% des stations), et seulement 21% de stations sur fonds meubles.
109 espÚces de poissons et de tortue, appartenant à 19 familles ont été observées. Les familles les plus fréquentes sont les chirurgiens et les perroquets (90% et 75% des stations), suivis par les poissons-papillons (54%), les rougets-barbets (48%) et les labres (45%). Neuf familles sont observées sur plus de 20% des stations.
Dix-sept espĂšces de poissons-papillons, plusieurs tortues, napolĂ©ons et requins ont Ă©tĂ© observĂ©es, signes dâun bon Ă©tat de santĂ© dâensemble des rĂ©cifs observĂ©s.
Les herbivores et carnivores sont assez abondants sur les habitats coralliens ; les carnivores sont significativement plus abondants dans les deux réserves, tandis que les herbivores le sont seulement à Do-Himen, réserve située sur le récif barriÚre.
Lâassemblage spĂ©cifique diffĂšre significativement entre les habitats et marginalement en fonction du statut de protection. La plupart des indicateurs ont des valeurs plus Ă©levĂ©es en rĂ©serve, ces diffĂ©rences sont significatives pour la richesse spĂ©cifique (RS) sur lâhabitat Corail Vivant, la RS des chirurgiens et celle des perroquets.
Les indicateurs présentent en général des valeurs plus favorables dans la réserve de Do-Himen que dans celle de Yeega plus proche de la cÎte
Pweevo 2012. Bilan de lâĂ©tat de santĂ© du rĂ©cif par stations vidĂ©o rotatives STAVIRO
âą Conducted within the AMBIO project, this work deals with coral reef fish communities and associated habitats, in the New Caledonian lagoons. It relies on remote unbaited underwater video observations, using the STAVIRO rotating technique.
âą The study takes place in the Pouebo area, part of the New Caledonian World Heritage site, and encompassing three no-take marine reserves enclosed within a Locally Managed Area (LMA).
âą The sampling design covers the entire area, and was stratified according to reef geomorphology and protection status. 86 stations were validated within 4 days. They were analyzed to characterize the habitat surrounding each station, and fish communities, based on a species list that includes fished species, emblematic species and functionally important species.
âą 32 indicators were computed and mapped (Sextant server). 24 indicators were analysed using the PAMPA computing tool. Outcomes were organized in a dashboard per management objective (biodiversity conservation and fisheries management).
âą 131 fish and turtle species, belonging to 18 families were observed. Surgeonfish and parrotfish were most frequently observed (86% and 67% of stations), and then parrotfish (63%).
âą Twenty-two species of butterflyfish were observed, as well as several sharks, indicating an overall good ecological status of the reef, but turtles, humphead wrasses and rays were rarely seen.
âą There was no significant effect of protection upon the overall species assemblage, nor on the barrier reef. But on intermediate reefs, it differed between the Pewhane reserve and unprotected areas.
âą In Pewhane, coral cover and butterfly fish abundance were higher in reserve, and fished species, carnivore and herbivore species, surgeon fish and grouperswere more abundant in the living coral habitat. Target species were also abundant on the inner slope of the barrier reef, but with higher abundances outside reserves for surgeon fish, parrotfish and groupers. On the fringing reef, coral cover and fish-related indicatorswerehigher outside the LMA.
âą Finally, the ecological status in the area appears satisfactory with abundant key coral reef species and coral cover. Yet, the protection effects differ between the barrier reef, the intermediate reef and the fringing reef.
Biodiversity ; Fish ; Habitat ; Underwater video; STAVIRO ; Monitoring and assessment; Marine Protected Area ; MPA; World Heritage; Coral reefs; New Caledonia ; Indicator; Dashboard ; Map server ; Sextant ; PAMPACette Ă©tude conduite dans le cadre du projet AMBIO concerne les communautĂ©s de poissons et les habitats associĂ©s aux rĂ©cifs coralliens des lagons de Nouvelle-CalĂ©donie. Elle sâappuie sur des donnĂ©es collectĂ©es par STAVIRO, une technique vidĂ©o rotative. Cette campagne a Ă©tĂ© rĂ©alisĂ©e en 2012 dans la zone de PouĂ©bo, comprise dans la Zone CĂŽtiĂšre Nord Est, elle-mĂȘme situĂ©e dans le bien inscrit au Patrimoine Mondial de lâHumanitĂ©. La zone dâĂ©tude comprend Ă©galement les Aires Marines ProtĂ©gĂ©es (AMP) de Pewhane, Whan-DenecePouarape et WhangaLedane, incluses dans une Aire de Gestion Durable des Ressources (AGDR). Le plan d'Ă©chantillonnage couvre lâensemble de la zone et a Ă©tĂ© stratifiĂ© en fonction des trois structures rĂ©cifales (rĂ©cif frangeant, rĂ©cif dâĂźlot/intermĂ©diaire et rĂ©cif barriĂšre) et en tenant compte du statut de protection des AMP. 86 stations vidĂ©o rotatives ont Ă©tĂ© validĂ©es. Leur analyse a permis de caractĂ©riser lâhabitat environnant chaque station, ainsi que les communautĂ©s de poissons sur la base dâune liste dâespĂšces dâintĂ©rĂȘt Ă©cologique, halieutique et emblĂ©matique. 32 indicateurs ont Ă©tĂ© calculĂ©s et reprĂ©sentĂ©s sous forme de carte disponible sur un serveur Sextant. 24 indicateurs ont Ă©tĂ© analysĂ©s grĂące Ă lâoutil de calcul PAMPA et fait lâobjet dâune fiche dĂ©taillĂ©e de rĂ©sultats en annexe du rapport. Ces rĂ©sultats sont repris et synthĂ©tisĂ©s sous forme de tableau de bord par objectif de gestion relatif Ă la conservation de la biodiversitĂ© et la gestion des ressources de la pĂȘche.
Les principaux habitats observés correspondent à des fonds durs : habitat riche en corail vivant (48.5% des stations), et habitat détritique
(23.5% des stations), et seulement 28% de stations sur fonds meubles.
131 espÚces de poissons et de tortue, appartenant à 18 familles ont été observées.
Chirurgiens et papillons sont les familles les plus fréquentes (86% et 67% des stations), suivis par les perroquets (63%). Dix familles sont observées sur plus de 20% des stations.
Vingt-deux espĂšces de poissons-papillons ont Ă©tĂ© observĂ©es ainsi que plusieurs requins, signes dâun bon Ă©tat de santĂ© dâensemble des rĂ©cifs observĂ©s. En revanche, peu de tortues, de napolĂ©ons et de raies ont Ă©tĂ© vues.
A lâĂ©chelle de la zone, lâassemblage spĂ©cifique est nettement structurĂ© par lâhabitat mais ne diffĂšre pas significativement entre les statuts de protection. Par contre, sur les rĂ©cifs intermĂ©diaires dans lâhabitat Corail vivant, lâassemblage diffĂšre significativement entre la rĂ©serve Pewhane et les zones hors rĂ©serve, tandis que la situation nâest pas tranchĂ©e sur le rĂ©cif barriĂšre.Dans la RĂ©serve Pewhane, le recouvrement corallien et la richesse spĂ©cifique des poissons-papillons sont plus Ă©levĂ©s en rĂ©serve, et les indicateurs relatifs aux espĂšces commerciales, consommables, aux cibles de la chasse, aux carnivores et aux herbivores, ainsi quâaux chirurgiens et loches prĂ©sentent des valeurs significativement plus Ă©levĂ©es dans la rĂ©serve sur lâhabitat Corail vivant.Les espĂšces-cibles sont Ă©galement abondantes sur le tombant interne du rĂ©cif barriĂšre, mais avec des abondances plus Ă©levĂ©es en dehors des rĂ©serves pour les chirurgiens, les perroquets et les loches. Sur le rĂ©cif frangeant, la situation est plus favorable hors AGDR en terme de recouvrement corallien et dâindicateurs relatifs aux poissons, et ce du fait dâune frĂ©quentation et accessibilitĂ© moindres.
Au final, lâeffet de la protection se rĂ©vĂšle diffĂ©rent entre les rĂ©serves du rĂ©cif barriĂšre et la rĂ©serve Pewhane sur le rĂ©cif intermĂ©diaire
Local and landscape effects on the functional biodiversity in mango orchards on reunion island
International audienceMango production, which is an important part of tropical areas' economy, is at a phytosanitary and technical dead-end on Reunion Island. The use of chemical insecticides doesn't limit the losses in economy, caused by harmful insects (Diptera, Heteroptera, Homoptera and Thysanoptera). The inefficiency of these energizing and chemical inputs, dictate plant protection evolution towards agro-ecological practices. One of them is to create habitats in crops, in order to promote diversity and abundance of pests' natural enemies. Management of functional biodiversity requires the understanding of the ecological processes involved and the capacity to identify the factors governing predatory arthropod communities in agro-ecosystems. The integrative approach of this study is to characterize the richness and diversity of arthropod predators in mango orchards, depending on various factors: plant species richness in the crop, farming practices and landscape context. The study focuses on epigeal arthropod predators, which are involved in the cycle of several pest species, such as Cecidomyiidae and Tephritidae whose last instar is characterized by a fall to the ground, so as to achieve their pupal stage in the soil. Twenty-four plots were considered, divided into the mango production basins of Reunion Island. Characterization of the composition and properties (richness and diversity) of predatory arthropod communities was conducted by sampling, using pitfall traps. Vegetation adventitious inventory within the orchards permitted to quantify plant species richness. Plots were pooled (fuzzy partitioning) according to their agricultural practices and landscape context. The measures of 17 parameters, corresponding to the nature and frequency of the plant treatment, as well as the weed vegetation management, have identified four practices intensity regimes. The landscape has been mapped to a circle of 400 m radius around each plot; the 11 measured parameters, characterizing the landscape structure and heterogeneity, have distinguished three types of landscape contexts. Richness and evenness of predatory arthropod communities were correlated and compared to these three scales of factors. Trappings revealed that predator communities consisted mainly of ants (Hymenoptera: Formicinae) and of 11 spider families (Araneae). Analysis highlighted the fact that these communities had: (1) a diversity positively correlated with the richness of the vegetation, (2) a greater richness in more moderate cultural practices, (3) a species richness higher when landscape context is heterogeneous, with fragmented mango orchards. To our knowledge, this is the first simultaneous detection of local and landscape factors effects on terrestrial arthropod predators' diversity in a tropical agro-ecosystem. (Texte intégral
Field evaluation of the effectiveness of thermotherapy against cassava mosaic disease in Central African Republic
International audienceAim: The effectiveness of thermotherapy in managing cassava mosaic disease (CMD) was studied on a susceptible local cultivar in the field in the epidemiological conditions. Study Design: The field was laid out in randomized complete block design Place and Duration: Field experiment was conducted in forest zone at Kapou located in south west of Central African Republic according to University of Bangui during August 2010 and July 2011. Methodology: Diseased cassava cuttings were treated in a heated water bath at temperatures ranging from 43ÂșC to 51ÂșC for 30 min before being grown for 12 months in the field. Results: Temperatures from 43ÂșC to 49ÂșC were found to have no deleterious effect on either the survival of cuttings or on plant regeneration. One month after planting (MAP), up to 40% of the cuttings treated at 47ÂșC to 49ÂșC had regenerated a plant with no CMD symptoms compared to 7% of untreated cuttings. Between two and five MAP, cassava cuttings treated at 49ÂșC produced plants with a significantly lower incidence of CMD than plants produced from untreated cuttings. All plants grown from treated cuttings developed significantly less severe CMD symptoms than untreated cuttings between 8 and 12 months after planting. The highest tuberous root yield was obtained with diseased cuttings treated at 49ÂșC (4.7kg/plant), equivalent to the yield from untreated symptomless cuttings (4.6kg/plant). Conclusion: Our data clearly demonstrate the value of thermotherapy to maintain a high level of production using local cultivars under severe CMD epidemic conditions.(RĂ©sumĂ© d'auteur
Molecular epidemiology of cassava mosaic disease in Madagascar
International audienceCassava is the staple food for hundreds of millions of people in Africa but its cultivation is seriously constrained by cassava mosaic disease (CMD) in Madagascar, and in Africa in general. This study identified the cassava mosaic geminiviruses (CMGs) involved in CMD in Madagascar and their associated epidemiological characteristics from countrywide surveys. Molecular characterization of CMGs in Madagascar revealed an unprecedented diversity and co-occurrence of six viruses: African cassava mosaic virus (ACMV), East African cassava mosaic Cameroon virus (EACMCV), East African cassava mosaic Kenya virus (EACMKV), East African cassava mosaic virus (EACMV), South African cassava mosaic virus (SACMV) and the recently described Cassava mosaic Madagascar virus (CMMGV). Distinct geographical distributions were observed for the six viruses. While ACMV was more prevalent in the central highlands, EACMV and EACMKV were prevalent in lowlands and coastal regions. Both EACMCV and SACMV occurred in almost all the localities visited. PCR diagnosis revealed that mixed infection (up to four co-infected viruses) occurred in 21% of the samples and were associated with higher symptom severity scores. Pairwise comparisons of virus associations showed that EACMCV was found in mixed infections more often than expected while ACMV and SACMV were mostly found in single infections. A greater abundance of whiteflies was observed in lowland and coastal areas. Nevertheless, infected cuttings remain the primary source of CMD propagation (95%) in Madagascar. (Résumé d'auteur