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A major challenge for ecologists is understanding ecosystem dynamics and function under environmental and anthropogenic stresses. An approach for addressing this challenge is the analysis of the different components contributing to secondary production (i.e., consumer incorporation of organic matter or energy per time unit) and how this production is influenced by external factors. Production studies have been recognized as a powerful tool in aquatic ecology, with applications in energy-biomass flow studies, trophic ecology, management of biological resources, as well as assessment of environmental stress. In this paper, we summarize ideas and techniques related to the estimation of secondary production and discuss how this approach may be used to evaluate ecological change in aquatic ecosystems. We include a critical review of classical methods and empirical models to estimate secondary production and provide several applications of production studies to current stresses affecting aquatic ecosystems, such as climate change, pollution, and the introduction of non-indigenous invasive species. Our goal is to illustrate the advantages of using secondary production as a more integrative tool for the assessment of the ecosystem function, in particular when subjected to strong anthropogenic and climatic stress. Un des grands defis auxquels sont confrontes les ecologistes est la comprehension de la dynamique et de la fonction des ecosystemes soumis a des stress environnementaux et anthropiques. Une approche permettant d'aborder cette question est l'analyse des differents elements qui participent a la production secondaire (c'est-a-dire l'incorporation par les consommateurs de matiere organique ou d'energie par unite de temps) et l'influence de facteurs externes sur cette production. Il est reconnu que les etudes de production constituent un puissant outil en ecologie aquatique, dont les applications touchent l'etude des flux d'energie--de biomasse, l'ecologie trophique, la gestion des ressources biologiques, ainsi que l'evaluation des stress environnementaux. L'article presente un survol des concepts et techniques touchant a l'estimation de la production secondaire et aborde l'utilite de cette approche pour l'evaluation des changements ecologiques dans les ecosystemes aquatiques. Il comprend un examen critique des methodes classiques et des modeles empiriques utilises pour estimer la production secondaire et presente plusieurs applications d'etudes de production a des stress affectant les ecosystemes aquatiques a l'heure actuelle, comme les changements climatiques, la pollution et l'introduction d'especes envahissantes non indigenes. L'article a ainsi pour but d'illustrer les avantages que presente l'utilisation de la production secondaire comme outil integratif pour evaluer la fonction des ecosystemes, plus particulierement ceux qui sont soumis a d'importants stress anthropiques et climatiques. [Traduit par la Redaction], Introduction Among major present-day concerns for ecologists and policymakers is the assessment of the status and integrity of ecosystems subject to environmental and anthropogenic stressors. Biodiversity, natural productivity, and stability [...]

Secondary production of a macrobenthic community at an intertidal mudflat was estimated for 33 successive months. Sampling was carried out along a eutrophication gradient, including non-eutrophied Zostera meadows, an intermediate muddy area, and a strongly eutrophied sand-muddy flat, where macroalgal blooms of Enteromorpha spp. usually occur. The Zostera meadows were always the most productive habitat (145-225 g ash-free dry weight [m.sup.-2] [year.sup.-1]). In the short term, the macroalgal bloom benefited the total estuarine production by enhancing the annual production in the eutrophied area. Nevertheless, our results show that this increase was short lived and in no way sufficient to match the production in the Zostera meadows. In the long term, the present study provides evidence that the disappearance of macrophyte beds, as a result of ongoing eutrophication, constitutes a major threat to the sustainability of the estuarine ecosystem.