Abstract
Saxitoxin (STX) group toxins consist of a set of analogues which are produced by harmful algal blooms (HABs). During a HAB, filter-feeding marine organisms accumulate the dinoflagellates and concentrate the toxins in the tissues. In this study, we analyze the changes in antioxidant enzymes and oxidative damage in the bivalves Mytilus chilensis and Ameghinomya antiqua, and the gastropod Concholepas concholepas during a bloom of Alexandrium pacificum. The results show that during the exponential phase of the bloom bivalves show an increase in toxicity and activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathinoe reductase, p < 0.05), while in the gastropods, increased activity of antioxidant enzymes was associated with the bioaccumulation of toxins through the diet. At the end of the bloom, decreased activity of antioxidant enzymes in the visceral and non-visceral tissues was detected in the bivalves, with an increase in oxidative damage (p < 0.05), in which the latter is correlated with the detection of the most toxic analogues of the STX-group (r = 0.988). In conclusion, in areas with high incidence of blooms, shellfish show a high activity of antioxidants, however, during the stages involving the distribution and bioconversion of toxins, there is decreased activity of antioxidant enzymes resulting in oxidative damage.
Highlights
Harmful algal blooms (HABs) are natural events that occur worldwide, which lead to significant economic, social, health, and tourism consequences, but due to their temporal variation in magnitude, the precise cost incurred by the affected countries is difficult to estimate [1,2]
Our objective was to correlate the responses of enzyme activities and oxidative damage with the level of assimilation and distribution of toxins, as well as the variation of the frequency of STX-group analogues which resulted from the biotransformation processes produced in the visceral and non-visceral tissues of the species
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Summary
Harmful algal blooms (HABs) are natural events that occur worldwide, which lead to significant economic, social, health, and tourism consequences, but due to their temporal variation in magnitude, the precise cost incurred by the affected countries is difficult to estimate [1,2]. In some species, these blooms are associated with the production of toxins which have different harmful effects on the ecosystem [3,4,5]. Around 100 species associated with HAB toxin production have been identified in the sea, where the saxitoxin-group (STX-group)-producing species have the highest prevalence and incidence worldwide [6,7]. This group of toxins is produced by marine dinoflagellates of the genera Alexandrium, Pyrodinium and Gymnodinium [8,9]
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