RESEARCH ARTICLE Nutritional and toxicity constraints of phytoplankton from a Brazilian reservoir to the fitness of cladoceran species Aloysio da S. Ferrão-Filho 1 & Tatiane M. Dias 2 & Uanderson J. Pereira 3 & José Augusto A. dos Santos 1 & Betina Kozlowsky-Suzuki 4 Received: 13 November 2018 /Accepted: 12 March 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Camorim is a small, eutrophic reservoir in Rio de Janeiro, Brazil, with a phytoplankton community dominated most of the year by the filamentous diatom Aulacoseira spp. and the toxic cyanobacterium Cylindrospermopsis raciborskii. As filamentous species can be a poor food for grazers, we hypothesize that phytoplankton from this reservoir would constrain cladoceran fitness due to nutritional limitation and/or toxicity when animals fed mixtures of cultured green algae and natural seston. Clones of different cladoceran species were exposed either to seston from Camorim reservoir sampled in different seasons or to a C. raciborskii strain (CYLCAM-2) isolated from the reservoir. In short-term assays, cladocerans were exposed to either 100% seston or mixtures of 50% seston added to green algae (200 μgCL -1 ), and their survi- vorship and somatic growth were measured for 4 days. In life table assays, neonates were exposed to the same seston treatments over 14 days and age at first reproduction, survivorship, fecundity, total offspring, and the intrinsic rate of natural increase (r) were assessed. In general, seston negatively affected cladoceran survivorship and fitness (r), but this response was seasonally and species specific. Stronger effects of CYLCAM-2 than those caused by seston on survivor- ship, somatic growth, and r were found for all cladoceran species, especially when the proportion of CYLCAM-2 was higher than 50% in relation to green algae in a fixed total food concentration. Our results suggest that both nutritional (C/P and morphology) and toxicity factors can act to impair cladoceran fitness and help explain the absence of cladoc- erans in Camorim reservoir. Keywords Stoichiometry . Toxins . Tropical . Zooplankton . Daphnia . Ceriodaphnia . Moina Introduction Along with abiotic factors, competition and predation, food is one of the most important factors limiting zooplankton fitness in nature. Not only food quantity (Pietrzak et al. 2010), but food quality is of upmost importance. Food quality is gener- ally expressed in terms of elemental composition and stoichi- ometry (Elser et al. 2001; Sterner and Elser 2002), biochem- ical composition (Brett and Müller-Navarra 1997; von Elert 2004), shape and size of food particles (van Donk et al. 1997; Fileto et al. 2007), and toxicity (DeMott et al. 1991; Ferrão- Filho et al. 2000). Over the last two decades, there has been much debate on the primary or key factors governing food quality for zoo- plankton and much emphasis has been given to the mineral and biochemical hypotheses. The mineral hypothesis is based on the assumptions of the stoichiometric theory, which pre- dicts that above a certain carbon, nitrogen, and phosphorus Responsible editor: Boqiang Qin * Betina Kozlowsky-Suzuki betinaksuzuki@unirio.br 1 Laboratório de Avaliação e Promoção da Saúde Ambiental, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil, 4365—Manguinhos, Rio de Janeiro, RJ 21040-360, Brazil 2 Programa de Pós-Graduação em Ciências Biológicas (Biodiversidade Neotropical), Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Av. Pasteur 458, Urca, Rio de Janeiro, RJ 22290-040, Brazil 3 Programa de Pós-Graduação em Ciências Biológicas, Departamento de Botânica, Museu Nacional, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21940-590, Brazil 4 Departamento de Ecologia e Recursos Marinhos, Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Av. Pasteur 458, Urca, Rio de Janeiro, RJ 22290-040, Brazil Environmental Science and Pollution Research https://doi.org/10.1007/s11356-019-04851-6