Toxin accumulation and biochemical alterations in the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura) after exposure to microcystins

Abstract

Neohelice granulata were collected during a bloom dominated by Microcystis sp. in Patos Lagoon (RS, Brazil) and then sacrificed at different times of depuration in laboratory in order to verify microcystin (MC) content and toxic effects in hepatopancreas of the estuarine crab. Biochemical measurements were: lipid peroxidation (LPO), activity of glutathione-S-transferase (GST), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). No variation of crab biochemical parameters and MC content mean value = 32 μg kg–1) was verified during the depuration period. MC content of the lyophilized bloom sample was determined by HPLC (0.129 μg mg–1). MC concentration in water at the sampling site was 1.92 μg L–1. Experimental assays were also performed via oral exposure (by gavage), in doses and time exposure varying between 0 and 55 μg kg–1 and 48 and 96 h. Analyzed variables were: GST activity (remained unaltered in all experimental conditions), LPO (augmented after 48 h in doses higher than 5.5 μg kg–1 but the opposite was observed after 96 h at the same doses) and oxygen consumption (increased in all doses and times of exposure). We conclude that (1) there is an absent or low depuration rate of MC; (2) oxidative damage should be attenuated by antioxidant defenses other than GST; (3) higher oxygen consumption should favor reactive oxygen species generation.