Bioaccumulation and biochemical response in South American nativespecies exposed to zinc: Boosted regression trees as novel tool forbiomarkers selection

LIDWINA BERTRAND; RAMON ASIS; MARIA VALERIA AME; MAGDALENA VICTORIA MONFERRÁN

ECOLOGICAL INDICATORS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 67 p. 769 - 778

1470-160X

The aim of this study was to evaluate the response of a wide battery of biomarkers in two native species,the freshwater shrimp Palaemonetes argentinus and the macrophyte Potamogeton pusillus, experimen-tally exposed to zinc in order to establish the potential use of selected species as bioindicators of aquaticpollution. For this purpose, we propose the use of integrated biomarker index (IBR) with a previous selec-tion of biomarkers using boosted regression trees (BRTs) as a new tool in ecotoxicology. Organisms werecollected from a reference site, acclimated and exposed at relevant environmental zinc levels (control, 5,50 and 500 _g Zn L−1) for 96 h. Biomarkers were measured in cephalothorax and abdomen of shrimp aswell as in leaf, stem and root of plants.Significant zinc accumulation was observed in cephalothorax of P. argentinus from 50 _g Zn L−1andfrom 5 _g Zn L−1in stem and root of P. pusillus, when compared with control condition. Those effectbiomarkers with significant differences among treatments were pre-selected to run out the BRTs modelfor each species. In P. argentinus, microsomal acetylcholinesterase activity, metallothioneins and superox-ide dismutase activity measured in cephalothorax, as well as glutathione reductase activity in abdomen,showed the higher capacity to explain or predict the zinc exposure concentration. On the contrary, in P.pusillus, only chlorophyll a measured in leaf and H2O2measured in root were the more representative ofexposure concentrations, at least, within the biomarkers tested in the present study. Thereafter, IBR wascalculated with the selected biomarkers in P. argentinus and showed in a sole value the organism stress,which also correlates with zinc exposure and accumulation.Natives species tested displayed a sensitive response to metal exposure, which represents an importantcharacteristic for biomonitoring programs. Our findings suggest that the BRTs and IBR are useful androbust run tools to select the better biomarkers in toxicological studies and indicate the organism stress.