Université de Bordeaux
LabEx COTECluster of Excellence
Cluster of excellence

MALABAR (BioGeCo / Ifremer / EPOC)

Metabarcoding Appliqué à LA Biodiversité des communautés microalgales du bassin d'ARcachon.

Project MALABAR aims at producing the first molecular inventories of some microalgae communities in Arcachon Bay (metabarcoding), especially of the nano and pico size fraction. These will lead in the project to quantify currenkty unknow resuspension of benthic flora in pelagos, according to seasons and tides. This is known to be a key process for shaping productivity of coastal bay ecosystems. The participants, altogether, have competences in microalgae biology and ecology, molecular biology, community ecology, bioinformatics, data analysis and numerical ecology. The innovative part is (i) checking whether patterns shown on routine optical inventories on an handful set of well-known genera are trustable surrogate for diversity patterns characterized over a wide taxonomic coverage (ii) using molecular-based diversity estimates to grasp microalgae communities dynamics at key periods like blooms with finer time scale than any previous study, and (iii) using molecular-based inventories to enable a first evaluation of the seasonal patterns of the relative contributions of benthos and pelagos diatoms in pelagic food webs of Arcachon Bay. The risk is that, whereas some markers are well established to discriminate and identify diatoms on a molecular basis (chloroplastic rbcL), the situation is more complex for non-diatoms microalgae. It has been established that rbcL gives false imprints in dinophyta (because of kleptoplasty, and presence of an ancestral form of Rubisco, type 2) and cannot be used. Only matching ribosomial DNA (18S, v9) on reference databases enables microalgae inventories, but microalgal part of existing plankton databases may be scarce. Therefore, OTUs reference databases will be developed, which is at the edge of current development of metabarcoding.

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