Date (Publication)

2022-02-21

Citation identifier

https://portail.indigeo.fr/geonetwork/srv/metadata/f21d2508-5603-47a9-b19f-6bffbe06a09e

Status

Under development

Point of contact

Organisation name	Individual name	Electronic mail address	Role
IFREMER-LEMAR	POUVREAU Stéphane	stephane.pouvreau@ifremer.fr	Author

Maintenance and update frequency

Annually

GEMET - Concepts, version 2.4

• milieu marin

• mollusque

• coquillage

• écologie

• biosphère

• conservation des espèces

• conchyliculture

• invertébré

INSPIRE themes

• Habitats et biotopes

Continents, countries, sea regions of the world.

• France

Régions administratives de France

• Bretagne

Use limitation

Utilisation libre sous réserve de mentionner la source (a minima le nom du producteur) et la date de sa dernière mise à jour

Access constraints

Other restrictions

Use constraints

Intellectual property rights

Other constraints

Le fournisseur n’est pas en mesure de garantir l’exactitude, la mise à jour, l’intégrité, l’exhaustivité des données et en particulier qu'elles sont exemptes d'erreurs ou d'imprécisions, notamment de localisation, d’identification ou de qualification. Aucune garantie quant à l'aptitude des données à un usage particulier n'est apportée par le fournisseur. Les utilisateurs utilisent les données sous leur responsabilité pleine et entière, sans recours possible contre le fournisseur dont la responsabilité ne saurait être engagée du fait d’un dommage résultant directement ou indirectement de l’utilisation de ces données. En particulier, il appartient aux utilisateurs d’apprécier, sous leur seule responsabilité : l'opportunité d'utiliser les données; la compatibilité des fichiers avec leurs systèmes informatiques; l’adéquation des données à leurs besoins; qu’ils disposent de la compétence suffisante pour utiliser les données. Le fournisseur n’est en aucune façon responsable des éléments extérieurs aux données et notamment des outils d’analyse, matériels, logiciels, réseaux..., utilisés pour consulter et/ou traiter les données. L’utilisateur veille à vérifier que l’actualité des informations mises à disposition est compatible avec l’usage qu’il en fait.

Spatial representation type

Vector

Denominator

0

Language

fre

Character set

UTF8

Topic category

• Geoscientific information
• Oceans
• Biota

Description

France

Begin date

2008-01-01

End date

2030-12-31

Reference system identifier

EPSG / RGF93 / Lambert-93 (EPSG:2154) / 7.4

Distribution format

Name	Version
ESRI Shapefile	1.0

Distributor contact

Organisation name	Individual name	Electronic mail address	Role
UMR6554 LETG CNRS (INDIGEO)		contact@indigeo.fr	Publisher

OnLine resource

Protocol	Linkage	Name
WWW:LINK-1.0-http--link	https://wwz.ifremer.fr/velyger/	Réseau National Velyger
WWW:LINK-1.0-http--link	https://portail.indigeo.fr/geocms/maps/portail-kwnkswjg/share#project	visualisation et téléchargement

Hierarchy level

Dataset

Statement

Database content 1: Larval concentration (number of individuals per 1.5 m3) of Crassostrea gigas

The method used to monitor larval concentration is the following : An important volume of seawater (1.5 m3) is pumped twice a week, throughout the spawning season (june-september), at one meter below the surface at high tide (+/- 2h). Water is filtered trough plankton net fitted with 40 µm mesh. After a proper rinsing of the net, the retained material is transferred into a polyethylene bottle (1 liter) and fixed with alcohol. At laboratory, sample is then gently filtered and rinse again and transferred into eprouvette. Two sub-samples of 1 mL are then taken using a pipette and examined on a graticule slide for microscope. The microscopic examination is made with a conventional binocular optical microscope with micrometer stage at a magnification of 10 X (or above). During the counting, a special care is necessary as larvae of other bivalves are also collected and confusion is possible. Larvae of C. gigas are also classified into four stage of development:

Stage I = D-shaped straight hinge larvae (shell length <105 µm)

Stage II = Early umbo evolved larvae (shell length between 105 and 150 µm)

Stage III = Medium umbo larvae (shell length between 150 and 235 µm)

Stage IV = Large umbo eyed pediveliger larvae (shell length > 235 µm)

Database content 2: Recruitment Index (number of recruit per benthic collector) of Crassostrea gigas.

Recruitment is evaluated on benthic collectors (experimental or professional) deployed to catch larvae. The benthic collectors used must meet several physical criteria to be attractive for oyster larvae, including (1) being physically and chemically similar to adult calcareous shells; (2) offering a coarse surface with fine relief; and (3) having a white colour as shells. It has also been shown that multi-plates 3D-structure with a narrow space between plates (< 2cm) and without inclination constitute a satisfying frame, allowing the availability of replicates. Lastly, the benthic collectors should not be deployed directly onto the sediment (to avoid problems of hypoxia and sedimentation), but some centimetres above it.

To meet all those criteria, the standardised benthic collector’s method revised and proposed by Pouvreau et al. (2021) for monitoring recruitment of native oyster consist uses a series (n=6) of rugged plates of a known surface area made of plastic (collectors cups used in shellfish farming) or cement (aragonites tiles used for aquarium). Furthermore, the plates have to be fully covered by a fine limed coating (2mm thick), which is obtained through a standard procedure (1kg of lime, 800mL of seawater and 15 days of drying time at temperature fixed between 20°C and 25°C in a high air renewal place). This step of coating is very important because it standardises the surface of the substrate (in terms of composition, texture, roughness and colour).

The benthic collectors should be deployed in replicate (for instance n=2x6 plates) at the bottom of the seafloor near the native oyster habitat for a continuous period of time. The deployment of these benthic collectors can be made from a boat with a mooring, by SCUBA divers or on the shore in the low intertidal area at low tide. After exposure, collectors are removed, gently rinsed and dried at the laboratory. Newly settled recruits are identified and counted by visually inspecting the top and bottom sides of each plate under standard binocular microscopes or more advanced 3D microscopes (e.g. KEYENCE VHX 6000). Care should be taken to avoid misidentification of other bivalve species. For each deployment date, a minimum of three plates from each of the two collectors (i.e. six cups in total) should be analysed to get a reliable mean and standard error. Recruitment should be reported as the number of individuals settled per cm2 within 15 days of exposure (for biweekly recruitment) or per collector at the end of the reproductive period.

Metadata

File identifier

f21d2508-5603-47a9-b19f-6bffbe06a09e XML

Metadata language

fre

Character set

UTF8

Hierarchy level

Dataset

Date stamp

2022-03-15T15:53:24

Metadata standard name

ISO 19115

Metadata standard version

1.0

Metadata author

Organisation name	Individual name	Electronic mail address	Role
IFREMER LEMAR	POUVREAU Stéphane	stephane.pouvreau@ifremer.fr	Point of contact