Effects of N-Heterocyclic Polyaromatic Hydrocarbons on Survival, Reproduction, and Biochemical Parameters in Daphnia magna M. Feldmannova ´ , K. Hilscherova ´ , B. Mars ˇa ´ lek, L. Bla ´ ha RECETOX—Research Centre for Environmental Chemistry and Ecotoxicology, Masaryk University, Kamenice 126/3, CZ 625 00 Brno, Czech Republic Centre for Cyanobacteria and Their Toxins, Institute of Botany, Czech Academy of Science, Kve ˇ tna ´ 8, CZ 603 65 Brno, Czech Republic Received 17 June 2005; accepted 30 March 2006 ABSTRACT: N-heterocyclic polycyclic aromatic hydrocarbons (N-PAHs) belong among newly identified classes of environmental pollutants with relatively high toxic potential. N-PAHs have been detected in air, soil, marine environments, and freshwater sediments. The N-PAHs are present at lower concentrations than their nonsubstituted analogues but their greater solubility would lead to greater bioavailibity and potential for toxic effects. Here we present results of acute and chronic toxicity in traditional aquatic inver- tebrate ecotoxicological model (Daphnia magna) along with assessment of biochemical responses. Stud- ied biomarkers in D. magna exposed to N-heterocyclic derivatives included glutathione levels and activ- ities of detoxication and antioxidative enzymes glutathione S-transferase and glutathione peroxidase. Phenanthrene and 1,10-phenathroline were the most toxic of all tested compounds (EC 50 < 6 M after 48 h exposure) and all tested N-PAHs suppressed reproduction of Daphnia magna. The data suggest that N-PAHs can induce oxidative stress in D. magna. The significant decline of glutathione content was found in animals treated with acridine, 1,10-phenanthroline, benzo(h)quinoline, phenantridine, and phenazine. Significant decrease of GPx activities relative to controls was found for all tested compounds except of phenanthrene and phenazine. Activities of GST increased after exposure to phenanthridine, phenazine, and benzo(h)quinoline, and declined in D. magna treated with phenanthrene (significant at one concentra- tion) or anthracene (not significant). Our results confirmed significant acute as well as chronic toxicities of N-PAHs as well as potential of biochemical parameters to be used as early warning signals of toxicity in Daphnia magna. # 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 425–431, 2006. Keywords: N-PAHs; Daphnia magna; biomarkers; glutathione; reproduction INTRODUCTION Polycyclic aromatic hydrocarbons (PAHs) represent a major class of organic contaminants in many industrial and urban regions worldwide. Besides the 16 traditionally monitored US EPA priority PAHs, there are many com- pounds that are currently overlooked in monitoring pro- grams. These include for example high molecular weight mutagenic PAHs, nitroderivatives and oxygenated PAHs, Correspondence to: M. Feldmannova ´; e-mail: feldmannova@recetox. muni.cz Contract grant sponsor: Grant Agency of the CR. Contract grant number: 525/03/0367. Contract grant sponsor: Czech Ministry of Education (INCHEM- BIOL). Contract grant number: MSM0021622412. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.20198  C 2006 Wiley Periodicals, Inc. 425