title: Effects of dietary exposure to herbicide and of the nutritive quality of contaminated food on the reproductive output of Daphnia magna.
abstract: Risk assessment of pesticides has been based on direct toxic effects on aquatic organisms. Indirect effects data are taken into account but with limitations, as it is frequently difficult to predict their real impacts in the ecosystems. In this context the main aim of this work was to assess how the exposure to the herbicide pendimethalin (Prowl(®)), under environmentally relevant concentrations, may compromise the nutritional composition of food for a relevant group of primary consumers of freshwater food webs-the daphnids, thus affecting their reproduction performance and subsequently the long-term sustainability of active populations of this grazer. Therefore, Daphnia magna individuals were chronically exposed in a clean medium to a control diet (NCF - i.e., non-contaminated green algae Raphidocelis subcapitata) and to a contaminated diet (CF - i.e., the same monoalgal culture grown in a medium enriched with pendimethalin in a concentration equivalent to the EC20 for growth inhibition of algae), during which reproductive endpoints were assessed. The algae were analysed for protein, carbohydrate and fatty acid content. The chemical composition of R. subcapitata in the CF revealed a slight decrease on total fatty acid levels, with a particular decrease of essential ω9 monounsaturated fatty acids. In contrast, the protein content was high in the CF. D. magna exposed to CF experienced a 16% reduction in reproduction, measured as the total number of offspring produced per female. Additionally, an internal pendimethalin body burden of 4.226μgg(-1) was accumulated by daphnids fed with CF. Hence, although it is difficult to discriminate the contribution of the pesticide (as a toxic agent transferred through the food web) from that of the food with a poor quality-compromised by the same pesticide, there are no doubts that, under environmentally relevant concentrations of pesticides, both pathways may compromise the populations of freshwater grazers in the long term, with consequences in the control of the primary productivity of these systems.
authors.affiliation: Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: marciabessa@ua.pt.
authors.forename: M
authors.initials: M
authors.lastname: Bessa da Silva
authors.affiliation: Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: N
authors.initials: N
authors.lastname: Abrantes
authors.affiliation: CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; Departament of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: T A P
authors.initials: TA
authors.lastname: Rocha-Santos
authors.affiliation: CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; Departament of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: A C
authors.initials: AC
authors.lastname: Duarte
authors.affiliation: CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; Departament of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: A C
authors.initials: AC
authors.lastname: Freitas
authors.affiliation: Center of Biotechnology and Fine Chemistry, Portuguese Catholic University, Rua Arquiteto Lobão Vital, 2511, 4202-401 Porto, Portugal.
authors.forename: A M
authors.initials: AM
authors.lastname: Gomes
authors.affiliation: Instituto Superior de Engenharia do Porto, Porto Polytechnic Institute, REQUIMTE/LAQV, Rua Dr. António Bernardino de Almeida, 431, 4200-072 Porto, Portugal.
authors.forename: A P
authors.initials: AP
authors.lastname: Carvalho
authors.affiliation: MARE (Marine and Environmental Sciences Centre), Faculty of Science and Technology, University of Coimbra, 3004-517 Coimbra, Portugal.
authors.forename: J C
authors.initials: JC
authors.lastname: Marques
authors.affiliation: Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Gonçalves
authors.affiliation: CIIMAR (Interdisciplinary Centre of Marine and Environmental Research), University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; Departament of Biology & GreenUP/CITAB-UP, Faculty of Science, University of Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
authors.forename: R
authors.initials: R
authors.lastname: Pereira
mesh_terms: D000814:Aniline Compounds / Q000032:analysis; D000818:Animals; D018533:Biomass; D000460:Chlorophyta / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D003621:Daphnia / Q000187:drug effects* / Q000502:physiology; D004032:Diet; D005231:Fatty Acids, Unsaturated / Q000032:analysis; D005260:Female; D006540:Herbicides / Q000378:metabolism / Q000633:toxicity*; D009753:Nutritive Value; D012098:Reproduction / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000814:Aniline Compounds; D005231:Fatty Acids, Unsaturated; D006540:Herbicides; D014874:Water Pollutants, Chemical; C030856:pendimethalin
keywords: Freshwater trophic relations; Nutritional quality; Pendimethalin; Raphidocelis subcapitata