Dr. Urzua-Osorio, Angel

Alexandrium catenella, one of the most common harmful microalgae observed in southern Chile, produces paralytic shellfish toxins, which can affect many organisms throughout the trophic chain. This research evaluated how paralytic shellfish toxins affected the principal bioenergetic constituents and fatty acids composition of the carnivorous snail Chorus giganteus. Snails were separated into a “toxic” group that was fed the toxic clam Mulinia edulis (which was previously fed A. catenella), and a “non-toxic” group, fed non-toxic clams. Both groups were kept under these conditions for 63 days. Our results indicated no difference in the ingestion rate of toxic versus non-toxic snails; however, a higher protein level was identified in toxic snails. The total lipid content proved to be no different in toxic versus non-toxic snails; although, an effect of the toxic diet on the fatty acid profile of C. giganteus was observed. High levels of essential polyunsaturated fatty acids, especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in toxic snails, were identified. Our results suggest that exposure to paralytic shellfish toxins, through diet, may cause changes in the biochemical composition of C. giganteus, which may have a subsequent impact on its energetic physiology.

Changes in environmental conditions play an important role in essential biological processes such as reproduction, which is partially driven by an organism’s diet. Here, we evaluate spatio-temporal variations in the bioenergetic reserves (lipids and fatty acids) of the fishery resource Concholepas concholepas (Loco), a prominent benthic carnivorous gastropod. We used data from summer (January) and winter (July) from two coastal localities that shown contrasting environmental conditions in central Chile (Quintay and Las Cruces). The results indicate that there is a correlation between the fatty acid profiles and the interactions between seasonality and locality. This was particularly evident among the fatty acid concentrations of docosahexaenoic (DHA, C22:6n-3), eicosapentaenoic (EPA, C20:5n-3) and arachidonic (ARA, C20:4n-6) acids, which were high in winter, in both localities. Contrastingly, palmitic (C16:0) and stearic (C18:0) acids were present among all comparisons at stable concentrations. These findings suggest an influence of environmental conditions on the availability and quality of the prey of C. concholepas, in both localities. Moreover, the high concentration of essential fatty acids during winter, could suggest an adaptive physiological response, to ensure reproductive success. This knowledge is indispensable to improve regulatory measures for the extraction periods of marine resources, towards a more sustainable fishery, in the Humboldt Current System.