Browsing by Author "Andrade, Santiago "
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- ItemCadmium-Copper Antagonism in Seaweeds Inhabiting Coastal Areas Affected by Copper Mine Waste Disposals(2006) Andrade, Santiago ; Medina, Matías H.; Moffett, James W. ; Correa M., Juan A.
- ItemCHANGES IN BACTERIAL COMMUNITY STRUCTURE ASSOCIATED WITH COASTAL COPPER ENRICHMENT(SOC ENVIRONMENTAL TOXICOLOGY & CHEMISTRY-SETAC, 2008) Moran, Ana C.; Hengst, Martha B.; De la Iglesia, Rodrigo; Andrade, Santiago; Correa, Juan A.; Gonzalez, BernardoMarine bacterial communities isolated from the water column, sediment, the rock surface, and the green seaweed Ulva compressa were studied in an intertidal ecosystem. The study area included a coastal zone chronically affected by copper mine waste disposals. Bacterial community composition was analyzed by terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes, and multivariate analyses of T-RFLP data sets were used for comparisons. Results showed that diversity and richness indexes were not able to detect differences among compartments. However, comparisons within the same compartment clearly showed that copper enrichment was associated with changes in the composition of the bacterial communities and revealed that the magnitude of the effect depends on the compartment being considered. In this context, communities from sediments appeared as the most affected by copper enrichment. The present study also demonstrated that intertidal bacterial communities were dominated by Gammaproteobacteria, Firmicutes, and Actinobacteria and the changes in these communities were mainly due to changes in their relative abundances.
- ItemComposition dynamics of epilithic intertidal bacterial communities exposed to high copper levels(2012) Iglesia Cabezas, Rodrigo Alonso de la; Valenzuela Heredia, Daniel; Andrade, Santiago; Correa Maldonado, Juan Alberto; Bernardo González
- ItemDistribution of Dissolved Species and Suspended Particulate Copper in An Intertidal Ecosystem Affected by Copper Mine Tailings in Northern Chile(2006) Andrade, Santiago ; Moffett, James; Correa M., Juan A.
- ItemEffects of copper on early developmental stages of Lessonia nigrescens Bory (Phaeophyceae)(2007) Contreras, Loretto; Medina, Matias H.; Andrade, Santiago; Oppliger, Valeria; Correa, Juan A.Copper effects on the early developmental gametophytic and sporophytic stages of the kelp Lessonia nigrescens were tested in gradients of increasing concentrations of ASV-Iabile copper. The results demonstrated a high sensitivity to copper of all life-history stages of the alga, where even the lowest tested concentration affected spore release as well as their subsequent settlement. More significant, concentrations higher than 7.87 mu g L-1 totally interrupted the development of the spores after they settle. This effect led to a failure in the formation of male and female ametophytes and, as a consequence, to a complete disruption of the normal life cycle of the kelp. Thus, we suggest that the absence of L. nigrescens from copper-enriched environments results from the high sensitivity of its early life cycle stages, which limits growth and maturation of the gametophytic microscopic phase and, as a consequence, prevents development of the macroscopic sporophytic phase. (c) 2006 Elsevier Ltd. All rights reserved.
- ItemEukaryotic picophytoplankton community response to copper enrichment in a metal-perturbed coastal environment(2015) Henríquez Castillo, Carlos Andrés; Rodríguez Marconi, Susana; Rubio, Francisca; Trefault Carrillo, Nicole Natalie; Andrade, Santiago; De la Iglesia Cabezas, Rodrigo Alonso
- ItemExperimental 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, LorettoPotential 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.
- ItemHeavy metals in molted fur of the southern elephant seal Mirounga leonina(2007) Andrade, Santiago; Carlini, Alejandro R.; Vodopivez, Cristian; Poljak, Sebastian
- ItemKinetics of copper accumulation in Lessonia nigrescens (Phaeophyceae) under conditions of environmental oxidative stress(2006) Andrade, Santiago; Contreras, Loretto; Moffett, James W.; Correa, Juan A.Juvenile individuals of the brown kelp Lessonia nigrescens were exposed to a coastal environment chronically impacted by copper mine wastes and currently displaying more than 250 nM of total dissolved copper. The kinetic of copper accumulation in the intra and extracellular compartments was determined and correlated to the oxidative burst resulting from copper-mediated oxidative stress. Accumulation involved an initial adsorption onto the outer cell wall followed by a slower uptake into the cells. A linear pattern of copper uptake over time was found during the first 52 h of exposure, and a steady state was reached at 76 h. The resulting oxidative stress was found to be inefficiently attenuated, and the intracellular level of copper remained sufficiently high to determine a persistently higher than normal level of reactive oxygen species (ROS). Thus, our results strongly suggest that, in L. nigrescens, copper needs to reach an intracellular threshold before oxidative burst develops. Furthermore, it was found that the high ROS levels generated by copper accumulation within the cells persists after the oxidative burst has ceased, suggesting a limited capacity of the algal tissue to buffer the increases of ROS caused by the environmental copper levels. (c) 2006 Elsevier B.V. All rights reserved.
- ItemKinetics of Copper Accumulation in Lessonia Nigrescens (Phaeophyceae) Under Conditions of Environmental Oxidative Stress(2006) Andrade, Santiago ; Contreras, Loretto; Moffett, James W.; Correa M., Juan A.
- ItemSeasonality of hydrographic variables in a coastal lagoon: Mar Chiquita, Argentina(2006) Marcovecchio, Jorge; Freije, Hugo; De Marco, Silvia; Gavio, Andrea; Ferrer, Laura; Andrade, Santiago; Beltrame, Ornela; Asteasuain, Raul1. The concentration and distribution of several hydrographical variables from Mar Chiquita coastal lagoon, Argentina, were measured monthly over a year in order to quantify their seasonal variations. Temperature, salinity, inorganic nutrient concentrations (nitrate, nitrite, phosphate, silicate) in the water column, and photosynthetic pigments (chlorophyll a and phaeopigments) in suspended particulate matter (SPM), were measured using internationally standardized analytical methods.
- ItemThe effect of organic ligands exuded by intertidal seaweeds on copper complexation(2010) Andrade, Santiago ; Pulido Subercaseaux, María Jesús; Correa M., Juan A.