Dr. Urzua-Osorio, Angel

The fishery resource Concholepas concholepas is a key species in the benthic marine ecosystems of the Southeastern Pacific Ocean. In the present study, the spatio-temporal changes in the biochemical parameters were evaluated for adult individuals of C. concholepas. They were sampled in summer and winter under upwelling and Non-upwelling conditions in two Management and Exploitation Areas for Benthic Resources of Valparaíso, Chile. The results indicated that the variation in the biochemical parameters is explained to a greater extent by the season. For example, in both upwelling and Nonupwelling conditions, we found a higher content of total lipids, proteins, glucose, and energy in winter than summer. Temporal variations can be explained by the reproductive process after summer season, in which the egg spawning require a greater energy reserves to be perform. Nonetheless, differences in the nutritional status of preys along seasons of the year, can also influence on these results. In fact, these variations in the biochemical parameters of C. concholepas may be indicative of an adaptive seasonal physiological response to the environment for maintaining an optimal energy budget year-round. Altogether, this knowledge will contribute to the Management and Exploitation Areas for Benthic Resources, improving regulatory measures during the annual period of captures and landings of C. concholepas, favoring a more sustainable fishery in the Southeastern Pacific Ocean within an ecosystem approach.

Upwelling systems deliver nutrient-rich water into coastal ecosystems, influencing primary productivity and potentially altering seaweed-herbivore interactions. Upwelling bottom-up effects on distinct trophic levels are wellknown. However, their influence on seaweed biomolecules and on algae-herbivore interactions and growth are less known. The aim of this study was threefold: i) to compare physical-chemical characteristics and nutrient levels in the water of upwelling (U) and downwelling (DU) zones, ii) to quantify their influence on the content of protein and carbohydrates in seaweed tissues of representative U and DU locations, and iii) to experimentally assess their effect on the feeding behavior and growth of a prominent intertidal herbivore, the sea urchin Loxechinus albus. Waters from U zones showed lower temperatures and pH, and higher phosphate concentrations than those from downwelling zones. Similarly, the tissue of seaweeds from a U location had significantly more proteins and carbohydrates than those from a DU location. The origin location of the sea urchins had a significant influence on consumption and growth rates: in general, those coming from a site with U conditions consumed and grew more than those coming from DU conditions. The quality of the algae was a significant factor on consumption rates, although in the case of preference trials, this factor interacted with sea urchin origin location. Our results show that the availability and quality of the food in upwelling zones has an influence on herbivore-seaweed direct interactions. However, these interactions and the growth of the sea urchins were also related to the coastal site and conditions from which the sea urchins came from. These results are relevant considering the expected impact of climate change on the world's oceans, and the importance of U zones as thermal (cold water) refuges for marine ectotherms.

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.