Abstract

Harmful algal blooms (HAB) on the coast of Chile are an ongoing problem and a challenge for producing seafood products from natural beds and from farming centers. Lipophilic marine biotoxins (LMB) are one of the groups of marine toxins, which in recent years, have been consistently identified in shellfish; its main characteristics are to have a latitudinal variability and species-specific assimilation/retention for each species. Shellfish in the aquatic environment represent the best bio-indicator model to allow establishing levels of toxicities related to LMB and also represent an important tool for the constant monitoring of water pollution on the coasts of Chile. Antioxidant enzymes play an important role in the cellular antioxidant defense systems of all organisms and whose main task is to protect against oxidative damage caused by reactive oxygen species (ROS). Bivalves from rocky strata, sandy bottoms and gastropods were extracted from areas exposed to lipophilic marine biotoxins (Aysén Region) and unpolluted areas (Los Ríos Region) to determine the levels of activity of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), lipid peroxidation (LP), glutathione peroxidase (GPx) and glutathione reductase (GR), and to relate it to the concentrations of LMB in the visceral (hepatopancreas) and non-visceral tissues (mantle, gills, adductor muscle and foot) in shellfish. Oxidative damage was detected in all evaluated species and significant differences were established with respect to those obtained from areas not polluted with LMBs. The species with the greatest oxidative damage were those related to the sandy bottom habitat (the Pacific clam and clam). LMB profiles detected in bivalves corresponded to okadaic acid (OA), dinophysistoxin-1 (DTX-1) and pectenotoxin-2 (PTX-2) in a ratio of 3:6:1, respectively. The variation of oxidative damage was related to decreased LMB toxicities in each species. This study shows that variations in the activity of antioxidant enzymes are directly related to the concentration levels of LMB in shellfish, which could be used to explain the levels of mortality of some species (bivalves) during HAB events in the coast of Chile.