Van Wynsberge S. auteur aut IRD Antypas F. auteur aut IRD Brisset M. auteur aut IRD Desnues Anne auteur aut IRD Jamet L. auteur aut IRD Lagourgue L. auteur aut IRD Payri Claude auteur aut IRD Jauffrais T. auteur aut IRD Lemonnier H. auteur aut IRD text journalArticle eng text/pdf born digital access Green tides occurrence has increased in coral reefs, yet few reference values have been documented to support bloom management in these ecosystems. Here, we took advantage of recent Ulva green tides that occurred in New Caledonia to (i) identify the elements limiting the growth of Ulva spp. during these blooms; and (ii) validate the use of isotopic markers for identifying sources of nutrients that generated blooms. N/P ratios highlighted a stronger limitation of algae by phosphorus than by nitrogen on sites under oceanic influence, while the proportions of N and P were optimal for algal growth at sites where green tides occurred. Macroalgae highly exposed to sewage water was characterized by higher delta 15N than macroalgae collected in areas exposed to synthetic inorganic fertilizers. From these results, we established a new set of threshold values for using delta 15N in Ulva species as an indicator of nitrogen source type in coral reefs. specialized Green tides Eutrophication Nitrogen Isotopy Elemental composition New Caledonia NOUVELLE CALEDONIE 036 038 082 200 116152 [10 p.] 2024 0025-326X https://www.documentation.ird.fr/hor/fdi:010089631 10.1016/j.marpolbul.2024.116152 0025-326X [F B010089631] https://www.documentation.ird.fr/hor/fdi:010089631 https://www.documentation.ird.fr/intranet/publi/2024-04/010089631.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2024-04-05 2026-06-12 fdi:010089631 fre