@article{7385, author = {Ana{\"\i}s Mass{\'e} and Aline Tribollet and Tarik Meziane and Marie-Lise Bourguet-Kondracki and Claude Y{\'e}pr{\'e}mian and Charlotte S{\`e}ve and Najet Thiney and Arlette Longeon and Alain Cout{\'e} and Isabelle Domart-Coulon}, title = {Functional diversity of microboring Ostreobium algae isolated from corals}, abstract = {The filamentous chlorophyte\ Ostreobium\ sp. dominates shallow marine carbonate microboring communities, and is one of the major agents of reef bioerosion. While its large genetic diversity has emerged, its physiology remains little known, with unexplored relationship between genotypes and phenotypes (endolithic\ versus\ free-living growth forms). Here, we isolated nine strains affiliated to two lineages of\ Ostreobium\ (\>8\% sequence divergence of the plastid gene\ rbcL), one of which was assigned to the family Odoaceae, from the fast-growing coral host\ Pocillopora acuta\ Lamarck 1816. Free-living isolates maintained their bioerosive potential, colonizing pre-bleached coral carbonate skeletons. We compared phenotypes, highlighting shifts in pigment and fatty acid compositions, carbon to nitrogen ratios and stable isotope compositions (δ13C and δ15N). Our data show a pattern of higher chlorophyll\ b\ and lower arachidonic acid (20:4ω6) content in endolithic\ versus\ free-living\ Ostreobium. Photosynthetic carbon fixation and nitrate uptake, quantified via 8 h pulse-labeling with\ 13C-bicarbonate and\ 15N-nitrate, showed lower isotopic enrichment in endolithic compared to free-living filaments. Our results highlight the functional plasticity of\ Ostreobium\ phenotypes. The isotope tracer approach opens the way to further study the biogeochemical cycling and trophic ecology of these cryptic algae at coral holobiont and reef scales.}, year = {2020}, journal = {Environmental Microbiology}, month = {Dec-10-2020}, issn = {1462-2912}, url = {https://onlinelibrary.wiley.com/doi/10.1111/1462-2920.15256}, doi = {10.1111/1462-2920.15256}, language = {eng}, }