Browsing by Author "Lagos, Nelson A."

Now showing 1 - 9 of 9
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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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    Ecosystem processes, management and human dimension of tectonically-influenced wetlands along the coast of central and southern Chile
    (2019) Lagos, Nelson A.; Labra, Fabio A.; Jaramillo, Eduardo; Marin, Andres; Miguel Farina, JosE; Camano, Andres
    A Workshop on Coastal Wetlands of Chile was held at Universidad Austral de Chile (Valdivia. november 2017). It was discussed the impact of earthquakes and tsunamis along this coast and their implication for wetlands. These events produce major modifications associated with variable rates of resilience. Emphasis was placed on social dimensions of such disturbances considering their impact on ecosystem services. Societal resilience must be included within the scales of wetland recovery, and incorporated in conservation and management strategies.
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    Effects of predation risk on survival, behaviour and morphological traits of small juveniles of Concholepas concholepas (loco)
    (2013) Manriquez, Patricio H.; Elisa Jara, Maria; Opitz, Tania; Carlos Castilla, Juan; Lagos, Nelson A.
    In marine systems, water-borne chemical cues may induce anti-predator responses that influence not only performance and survival of the prey, but also population dynamics and species interaction. The early life stages of marine species with complex life-cycles settle into unpredictable habitats, and therefore may be expected to exploit reliable chemical cues emanating from both prey and predators in order to promote plastic responses to the local conditions. We compared the behavioural responses, survival and growth of early ontogenetic stages of Con cholepas concholepas exposed to the risk of predation by natural predators that commonly co-occur with it in the intertidal: the crabs Homalaspis plana and Acanthocyclus hassleri and the asteroid Heliaster helianthus. Y-maze experiments indicated that C. concholepas use water-borne cues both to detect prey and deploy strong anti-predator behaviour. Our results indicate lower survival rates of small specimens of C. concholepas when they were maintained in the direct presence of predators rather than under control conditions. Similar results and growth inhibition were found with C. concholepas exposed to seawater in which the predators had been maintained. Quantification of feeding activity and shell thickness in response to predation risk indicated lower prey consumption and thicker shells when C. concholepas were exposed to crab odours compared to control conditions. Our results suggest that this behavioural receptiveness to water-borne cues may be responsible, in part, for the early plasticity of species with complex life-cycles such C. concholepas under natural conditions, facilitating predator avoidance and thus enhancing survival.
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    Experimental transplants of the large kelp Lessonia nigrescens (Phaeophyceae) in high-energy wave exposed rocky intertidal habitats of northern Chile
    (2006) Correa, Juan A.; Lagos, Nelson A.; Medina, Matias H.; Castilla, Juan C.; Cerda, Mauricio; Ramirez, Marco; Martinez, Enrique; Faugeron, Sylvain; Andrade, Santiago; Pinto, Raquel; Contreras, Loretto
    Potential for addressing ecological and physiological issues becomes severely limited when the organisms required to experimentally test specific hypotheses are absent from the study areas. This report describes a simple and inexpensive device for re-planting kelps into the lower intertidal zone of wave-swept rocky habitats, using Lessonia nigrescens Bory as a model organism. The device allows a wide range of plant sizes to be anchored by the holdfast. Transplanted kelps regenerated, re-attached to the substratum and overgrew the transplanting device. These results confirm the feasibility of using this technique to tackle a variety of highly relevant questions involving ecological, physiological, conservation, restoration and management issues. (c) 2006 Elsevier B.V. All rights reserved.
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    Geographic variation in trace-element signatures in the statoliths of near-hatch larvae and recruits of Concholepas concholepas (loco)
    (2012) Manriquez, Patricio H.; Galaz, Sylvana P.; Opitz, Tania; Hamilton, Scott; Paradis, George; Warner, Robert R.; Carlos Castilla, Juan; Labra, Fabio A.; Lagos, Nelson A.
    Spatial variation of trace elements in calcified structures (otoliths, statoliths, and shells) has been used to track the movements of individuals among habitats, and connectivity between marine populations. In the present study, we used laser ablation-inductively coupled plasma mass spectrometry to quantify the concentrations of trace elements in statoliths of prehatch larvae and recruits of the gastropod Concholepas concholepas from 3 regions in Chile. We also examined spatial variation in chemical signatures deposited during larval life and at the time of settlement in intertidal habitats. We found significant differences between 3 geographic regions in the trace element concentrations recorded in natal statoliths of near-hatch larvae and in natal core and edge areas of recruit statoliths. Discriminant function analysis indicates that natal signatures of near-hatch larvae and the cores and edges of recruit statoliths show spatial segregation among regions. High levels of reclassification success of larvae to the origin region suggest potential for assigning recruits to the corresponding matching region. Concentrations of trace elements in the natal cores of recruit statoliths fell relatively close but did not overlap with the discriminant space occupied by larvae, and at regional scales the pattern of geographic variation of recruit statoliths resembles that of larval statoliths. This suggests population grouping and little population interchange at this regional scale. Assessing population stocks and connectivity of this species at smaller scales along the Chilean coast will only be possible with more finely structured sampling and a better understanding of temporal variation in the chemical environment.
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    Morphological, physiological and behavioral responses of an intertidal snail, Acanthina monodon (Pallas), to projected ocean acidification and cooling water conditions in upwelling ecosystems
    (2022) Duarte, Cristian; Jahnsen-Guzman, Nicole; Quijon, Pedro A.; Manriquez, Patricio H.; Lardies, Marco A.; Fernandez, Carolina; Reyes, Miguel; Zapata, Javier; Garcia-Huidobro, M. Roberto; Lagos, Nelson A.
    Ocean acidification (OA) is expected to rise towards the end of the 21st century altering the life history traits in marine organisms. Upwelling systems will not escape OA, but unlike other areas of the ocean, cooling effects are expected to intensify in these systems. Regardless, studies evaluating the combined effects of OA and cooling remain scarce. We addressed this gap using a mesocosm system, where we exposed juveniles of the intertidal muricid snail Acanthina monodon to current and projected pCO(2) (500 vs. 1500 ppm) and temperature (15 vs. 10 degrees C) from the southeast Pacific upwelling system. After 9 weeks of experimental exposure to those conditions, we conducted three estimations of growth (wet weight, shell length and shell peristomal length), in addition to measuring calcification, metabolic and feeding rates and the ability of these organisms to return to the normal upright position after being overturned (self-righting). Growth, feeding and calcification rates increased in projected cooling conditions (10 degrees C) but were unaffected by pCO(2) or the interaction between pCO(2) and temperature. Instead, metabolic rates were driven by pCO(2), but a significant interaction with temperature suggests that in cooler conditions, metabolic rates will increase when associated with high pCO(2) levels. Snail self-righting times were not affected across treatments. These results suggest that colder temperatures projected for this area would drive this species growth, feeding and calcification, and consequently, some of its population biology and productivity. However, the snails may need to compensate for the increase in metabolic rates under the effects of ocean acidification. Although A. monodon ability to adjust to individual or combined stressors will likely account for some of the changes described here, our results point to a complex dynamic to take place in intertidal habitats associated with upwelling systems.
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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 and histopathological impacts of increased carbon dioxide and temperature on the scallops Argopecten purpuratus cultured under upwelling influences in northern Chile
    (2017) Lardies Carrasco, Marco Antonio; Benitez, Samanta; Osores, Sebastian; Vargas, Cristian A.; Duarte, Cristián; Lohrmann, Karin B.; Lagos, Nelson A.
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    Upper environmental pCO2 drives sensitivity to ocean acidification in marine invertebrates
    (2022) Vargas, Cristian A.; Cuevas, L. Antonio; Broitman, Bernardo R.; San Martin, Valeska A.; Lagos, Nelson A.; Gaitan-Espitia, Juan Diego; Dupont, Sam
    The authors link the effects of pCO(2) on marine invertebrates to the localized pCO(2) conditions of their coastal habitats. They show that responses depend on the deviation from the locally experienced upper pCO(2) level, highlighting the importance of small-scale variability and adaptation.