Bioaccumulation of secondary metabolites from cyanobacterial blooms in tilapia (Oreochromis niloticus)

Jessica A. Moretto1,2, Paloma N.N.Freitas 2,3, Vanessa Geraldes2,4, Fernanda Rios Jacinavicius4, H. Dail Laughinghouse IV1 and Ernani Pinto2. 1 University of Florida / IFAS, Fort Lauderdale Research and Education Center, Davie, Florida, United State of America. (e-mail: jessica.morettoa@ufl.edu; hlaughinghouse@ufl.edu) 2 Centre for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba-SP, Brazil (e-mail: ernani@usp.br; paloma.nathane@usp.br; vanessa.geraldes@outlook.com) 3 Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba-SP, Brazil (paloma.nathane@usp.br) 4 School of Pharmaceutical Sciences, University of São Paulo, São Paulo-SP, Brazil (vanessa.geraldes@outlook.com; fjacinavicius@usp.br) ABSTRACT Freshwater cyanobacteria can produce toxic and non-toxic secondary metabolites that accumulate in other organisms. These can negatively impact aquaculture, as different secondary metabolites can alter the quality of fish. The aim of this study was to evaluate the bioaccumulative effects of secondary metabolites from cyanobacterial blooms in tilapia fingerlings (Oreochromis niloticus). The experiments were carried out with 80 fish per aquarium of 58L, divided into negative control and different concentrations of the cyanobacteria biomass extract for 30 days. Cyanobacteria biomass and fish tissues were analyzed by LC/MS to detect secondary metabolites. The analysis showed different variants of microcystins, such as MC- LR (m/z 995) and MC-YR (m/z 1045) and mycosporines: palythine (m/z 245), shinorine (m/z 333), porphyra-334 (m/z 347) and mycosporine-glycine-alanine (m/z 317) in the cyanobacterial biomass. Microcystin was not found to accumulate in fish during the studied exposure time. Overall, the biomass concentrations used in the bioaccumulation experiment were not lethal to fish, as they remained alive until the end of the experiment. We found that mycosporines accumulated in muscle (palythine, shinorine and mycosporine-glycine-alanine) and liver (palythine and shinorine) of those fish exposed to higher concentrations of cyanobacterial biomass. Thus, these metabolites are capable of bioaccumulating in fish. KEYWORDS: MICROCYSTIN; MYCOSPORINE; LC/MS