LETTER LETTER Reply to Roopnarine: What is an apex predator?

Roopnarine (1) suggests that the significance required for food (4). However, these impacts be considered apex predators as they do not of the human trophic level (HTL) (2) is re- are not a result of our being apex preda- consume the total quantity of their catch? duced because it defines the position of tors, and we feel that the fact that we are a,1 a humans in the food web by diet and is not Anne-Elise Nieblas , Sylvain Bonhommeau , not apex predators is a useful observation b c representative of our functional role in the Olivier Le Pape , Emmanuel Chassot , with consequences for our ability to reduce c c ecosystem. He is concerned that humans are Laurent Dubroca ,JulienBarde,andDavid our impacts. c compared with low trophic level omnivores To consider humans as trophic compo- M. Kaplan a and asserts that we are apex predators because nents of ecosystems was the key objective of Institut Français de Recherche pour in marine systems, our extraction of wild fish our paper. Roopnarine’s (1) point regarding l’Exploitation de la MER, Unité Mixte de is linked to high trophic level species. marine systems is indeed interesting, and we Recherche (UMR) Exploited Marine Our report demonstrates that humans are believe that the exploration of the functional Ecosystems (EME-212), 34203 Sète Cedex, low trophic level omnivores because globally role of humans in specific food webs is an France; bEcologie et santé des écosystèmes we eat more plant than meat. This fact re- exciting topic for future research. For example, (UMR985 ESE) Agrocampus Ouest–Institut mains, regardless of the functional role of human impacts related to food production National de la Recherche Agronomique, humans in the ecosystem. Apex predators are vary widely between marine and terrestrial c most commonly defined by trophic dynam- F-35042 Rennes, France; and Institut de ecosystems, as Roopnarine notes (1). In gen- ics and are species that occupy the highest Recherche pour le Développement, UMR eral, resource exploitation in terrestrial systems trophic levels and are crucial in maintaining EME-212, Centre de Recherche Halieutique is caused by agricultural practices, leading to ecosystem health (3). Less commonly, apex Méditerranéenne et Tropicale, 34203 Sète a large harvest of plants and prey species with predators are defined as species that have no Cedex, France trophic levels close to 2, giving humans a con- predators themselves, in which case, we could be considered apex predators regardless of sequentlylowtrophiclevel.Inmarinesystems, what we eat. However, we assert that our eco- resource exploitation is primarily because of 1 Roopnarine PD (2014) Humans are apex predators. Proc Natl Acad wild harvest (including that of forage fish used Sci USA, 10.1073/pnas.1323645111. system function is more complex than that: 2 Bonhommeau S, et al. (2013) Eating up the world’s food web and the we have no predators, we are key in main- for fishmeal and oil), with minimal direct human trophic level. Proc Natl Acad Sci USA 110(51):20617–20620. extraction of primary productivity, and large 3 Elton C (1927) Animal Ecology (Sidgewick and Jackson, London). taining (or threatening) ecosystem health, 4 Imhoff ML, et al. (2004) Global patterns in human consumption of but we do not occupy the highest trophic extraction of high trophic level prey spe- net primary production. Nature 429(6994):870–873. ∼ – level. We fully agree that humans have sig- cies, 3.1 3.3 (5). If an HTL were calculated 5 Branch TA, et al. (2010) The trophic fingerprint of marine fisheries. as by Roopnarine (1), based on the trophic Nature 468(7322):431–435. nificant and wide-ranging ecosystem impacts 6 Heupel MR, et al. (2014) Sizing up the ecological role of sharks as because of our sheer numbers, which are ul- levels of extracted resources in marine eco- predators. Mar Ecol Prog Ser 495:291–298. timately linked to high levels of food con- systems rather than on direct food consump- tion, humans would indeed have a much sumption, and because of, e.g., pollution Author contributions: A.-E.N., S.B., O.L.P., E.C., L.D., J.B., and D.M.K. and land use change. For example, the total higher trophic level than 2.21. However, this wrote the paper.

nonfood-related primary production used by brings us back to the previous issue of pred- The authors declare no conflict of interest. humans (e.g., forestry, biofuels) presently rep- ator definitions. In general, predators ingest 1To whom correspondence should be addressed. E-mail: anne. resents three times the primary production what they kill (6); thus, can fishermen really [email protected].

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