Browsing by Author "Lardies, Marco A."

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    Biomechanical Characterization of Scallop Shells Exposed to Ocean Acidification and Warming
    (2022) Abarca-Ortega, Aldo; Munoz-Moya, Estefano; Pacheco Alarcon, Matias; Garcia-Herrera, Claudio M.; Celentano, Diego J.; Lagos, Nelson A.; Lardies, Marco A.
    Increased carbon dioxide levels (CO2) in the atmosphere triggered a cascade of physical and chemical changes in the ocean surface. Marine organisms producing carbonate shells are regarded as vulnerable to these physical (warming), and chemical (acidification) changes occurring in the oceans. In the last decade, the aquaculture production of the bivalve scallop Argopecten purpuratus (AP) showed declined trends along the Chilean coast. These negative trends have been ascribed to ecophysiological and biomineralization constraints in shell carbonate production. This work experimentally characterizes the biomechanical response of AP scallop shells subjected to climate change scenarios (acidification and warming) via quasi-static tensile and bending tests. The experimental results indicate the adaptation of mechanical properties to hostile growth scenarios in terms of temperature and water acidification. In addition, the mechanical response of the AP subjected to control climate conditions was analyzed with finite element simulations including an anisotropic elastic constitutive model for a two-fold purpose: Firstly, to calibrate the material model parameters using the tensile test curves in two mutually perpendicular directions (representative of the mechanical behavior of the material). Secondly, to validate this characterization procedure in predicting the material's behavior in two mechanical tests.
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    Genetic variation for plasticity in physiological and life-history traits among populations of an invasive species, the terrestrial isopod Porcellio laevis
    (2008) Lardies, Marco A.; Bozinovic, Francisco
    Background: Evolutionary interpretations of life-history as well as physiological patterns require distinction between genotypic variations and environmentally induced phenotypic variation.
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    Intraspecific biogeographic pattern breakage in the snapping shrimp Betaeus emarginatus caused by coastal copper mine tailings
    (2008) Lardies, Marco A.; Medina, Matias H.; Correa, Juan A.
    Environmental gradients are common in nature, and geographically widespread species must cope with environmental differences between habitats. Environmental differences produce bio-geographic patterns that can involve morphological, physiological, and life-history traits. The Bergmann's rule has been described as one of these ecological and evolutionary patterns, predicting an increase in body size towards colder climates. Human-induced polluting events could impair the performance and/or fitness of exposed individuals and populations. Thus, we hypothesized that species undergoing exposure to pollutants will show a breakage of the natural biogeographical variation of their fitness-related life-history traits. In northern Chile, copper mine tailings have been dumped continuously for more than 60 yr. Because the snapping shrimp Betaeus emarginatus is commonly found in intertidal pools near this dumping site, it was used as a study model. This shrimp has a pelagic larva and a wide distribution along the Chilean coast. Different life-history traits were studied in 5 populations over a range of 19 degrees of latitude along the Chilean coast. Population mean values for female body mass, egg volume, and reproductive output were positively correlated with latitude. In contrast, egg number was negatively correlated with latitude and positively correlated with temperature. Shrimps from the dumping site showed life-history trait values significantly lower than the range observed in areas with no copper enrichment, breaking the biogeographical patterns predicted by the Bergmann's rule. Such studies emphasize the need for integrating different concepts of organism and population ecology and life-history theory in the assessment of anthropogenic pollution.
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    Ocean acidification alters anti-predator responses in a competitive dominant intertidal mussel
    (2022) Jahnsen-Guzman, Nicole; Lagos, Nelson A.; Quijon, Pedro A.; Manriquez, Patricio H.; Lardies, Marco A.; Fernandez, Carolina; Reyes, Miguel; Zapata, Javier; Roberto Garcia-Huidobro, M.; Labra, Fabio A.; Duarte, Cristian
    Widespread intertidal mussels are exposed to a variety of natural and anthropogenic stressors. Even so, our understanding of the combined influence of stressors such as predation risk and ocean acidification (OA) on these species remains limited. This study examined the response of the purple mussel (Perumytilus purpuratus), a species distributed along Pacific southeastern rocky shores, to the effects of predation risk and OA. Using a laboratory 2 x 2 cross design, purple mussels were either devoid or exposed to predator cues from the muricid snail Acanthina monodon, while simultaneously exposing them to current (500 ppm) or projected OA conditions (1500 ppm). The response of purple mussels to these factors was assessed using growth, calcification, clearance, and metabolic rates, in addition to byssus production. After 60 d, the presence of predator cues reduced mussel growth in width and length, and in the latter case, OA enhanced this response making the effects of predator cues more severe. Calcification rates were driven by the interaction between the two stressors, whereas clearance rates increased only in response to OA, likely explaining some of the growth results. Mussel byssus production also increased with pCO(2) but interacted with predation risk: in the absence of predator cues, byssus production increased with OA. These results suggest that projected levels of OA may alter and in some cases prevail over the natural response of purple mussels to predation risk. Considering the role played by this mussel as a dominant competitor and ecosystem engineer in rocky shores, these results have community-wide implications.
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    Physiological responses of juvenile Chilean scallops (Argopecten purpuratus) to isolated and combined environmental drivers of coastal upwelling
    (2019) Ramajo, Laura; Fernandez, Carolina; Nunez, Yolanda; Caballero, Paz; Lardies, Marco A.; Josefina Poupin, Maria
    Coastal biota is exposed to continuous environmental variability as a consequence of natural and anthropogenic processes. Responding to heterogeneous conditions requires the presence of physiological strategies to cope with the environment. Ecosystems influenced by upwelling endure naturally cold, acidic and hypoxic conditions, nevertheless they sustain major fisheries worldwide. This suggests that species inhabiting upwelling habitats possess physiological adaptations to handle high environmental variability. Here, we assessed the impact of the main upwelling drivers (temperature, pH and oxygen) in isolation and combined on eco-physiological responses of Chilean scallop Argopecten purpuratus. A. purpuratus responded to hypoxia by increasing their metabolic performance to maintain growth and calcification. Calcification was only affected by pH and increased under acidic conditions. Further, A. purpuratus juveniles prioritized calcification at the expense of growth under upwelling conditions. Increasing temperature had a significant impact by enhancing the physiological performance of A. purpuratus juveniles independently of oxygen and pH conditions, but this was associated with earlier and higher mortalities. Our results suggest that A. purpuratus is acclimated to short-term colder, acidic and hypoxic conditions, and provide important information of how this species responds to the heterogeneous environment of upwelling, which is significantly relevant in the climatic context of upwelling intensification.
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    The effect of diet quality on physiological and life-history traits in the harvestman Pachylus paesslerik
    (PERGAMON-ELSEVIER SCIENCE LTD, 2007) Naya, Daniel E.; Lardies, Marco A.; Bozinovic, Francisco
    The balance between energy acquisition and expenditure is critical to the survival and reproductive success of animals. Here we investigate the long-term effects of diet quality on physiological and life-history flexibility in the harvestman, Pachylus paessleri. We used cow meal as a protein-rich diet and potatoes as a carbohydrate-rich diet in order to reproduce two extreme conditions regarding food quality in harvestmen natural habitat. As proxy variables of the energy expenditure process, we quantified standard metabolic rate (maintenance), changes in body mass (somatic condition), and fecundity (reproduction). We found that animals consuming the protein-rich diet were able to increase both their body condition and fecundity. However, the increment in these two life-history traits was correlated with higher maintenance costs. In contrast, the carbohydrate-rich diet did not provide enough specific nutrients for reproductive events, although it may have allowed animals to survive for a long time. Thus, according to the quality of the diet available in the environment, harvestman females can adopt different life-history strategies correlated with phenotypic adjustments at anatomical and physiological levels. In the Mediterranean region, spatial and temporal changes in food quality are typical, so greater phenotypic flexibility is expected to cope with this kind of environmental variation. (c) 2006 Elsevier Ltd. All rights reserved.