Villeger S. auteur aut IRD Fouilland E. auteur aut IRD Argenty J. auteur aut IRD Bouvier C. auteur aut IRD Carré Claire auteur aut IRD Bouvier T. auteur aut IRD text journalArticle eng The productivity of most marine ecosystems is limited by the availability of dissolved nitrogen (N) and phosphorus (P). Nutrient recycling is therefore a key process for ecosystem functioning. Fish recycle nutrients through the excretion of ammonia and phosphate and can influence the abundance and community structure of primary producers such as phytoplankton. However, the effect of fish on other plankton compartments, and whether all fish species have similar effects, is largely unknown. We used a tank experiment to test how 2 Mediterranean fish species, gilthead seabream Sparus aurata and golden mullet Chelon auratus, with distinctly different N and P excretion rates, can affect the abundance and community structure of 3 plankton compartments: phytoplankton, bacterioplankton, and microzooplankton. We found that the nutrients released by seabream (whose excreta had an N:P molar ratio greater than the Redfield ratio of 16:1) induced a substantial increase in the abundance of all plankton compartments. In addition, with seabream, the relative abundance of diatoms in the phytoplankton communities increased. However, no significant change was observed with mullet, which had a low excreta N:P molar ratio, suggesting that the growth of microbial plankton was limited by the availability of N. Our results demonstrate that nutrient excretion by fish affects the microbial food web through a species-specific bottom-up effect on the total abundance and community structure of the phytoplankton, bacterioplankton, and microzooplankton communities. specialized Marine fish Nutrient excretion Protozooplankton Phytoplankton Bacteria 036 82 3 289-298 2019 0948-3055 https://www.documentation.ird.fr/hor/PAR00019868 10.3354/ame01897 0948-3055 https://www.documentation.ird.fr/hor/PAR00019868 IRD - Base Horizon / Pleins textes 2019-11-05 2025-02-24 PAR00019868 fre