Browsing by Author "Correa, J. A."

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    Invasion of Codium fragile ssp tomentosoides in northern Chile
    (2006) Neill, P. E.; Alcalde, O.; Faugeron, S.; Navarrete, S. A.; Correa, J. A.
    Invasive species are key components of the burgeoning global change in ecological communities. The green alga Codium fragile ssp. tomentosoides (Chlorophyta) is a recognized invader in marine ecosystems around the world, with described ecological effects ranging from minor changes in native species abundance to major changes in community structure, as well as negative economic effects on aquaculture species. The objective of this work is to provide an assessment of the extension of the C. fragile invasion along the coast of Chile, and characterize the pattern of temporal fluctuations in abundance, and potential economic effects of this algal invader in a Gracilaria chilensis farm in northern Chile. In 2005 we recorded C. fragile at 34 of 123 sites sampled along the Chilean coast, with over half of the invaded sites occurring between 26 degrees and 30 degrees S latitude. At 12 sites C. fragile was present only on artificial substrata, suggesting that artificial structures may act as corridors for the dispersal of this alga into subtidal or intertidal habitats where it is otherwise not able to survive. At one site (Calderilla Bay) C. fragile has reached high levels of abundance within G. chilensis farms. At this site we observed marked seasonality in the monthly C. fragile abundance index, with greater C. fragile abundances in summer and fall months, associated with higher sea surface temperatures (SST). In addition, we report a significant long-term trend of increasing C. fragile abundances over the 5 years of observations in the plantation. If the distribution of C fragile in Chile is largely determined by SST, we expect faster spread of northern populations towards the north. Weedy species had a negative effect on the farmed species, G. chilensis. During the 4 months in which algae wet weights were measured, the estimated C fragile biomass averaged 22.9 kg m(-2), compared with an estimated average of 18.5 kg m(-2) of the harvested red alga, G. chilensis. In addition, we recorded a negative effect of C. fragile abundances on the Catch Per Unit Effort (CPUE) of G. chilensis with a significant upper limit to CPUE at the 94th quantile. Since weedy species generate a great loss of time and money in G. chilensis farms, it is likely that without intervention, the costs associated with the C. fragile invasion threaten the persistence of G. chilensis farms in northern Chile. Stakeholders should implement preventative measures to stop C. fragile spread from focal points. (c) 2006 Elsevier B.V. All rights reserved.
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    Novel polymerase chain reaction primers for the specific detection of bacterial copper P-type ATPases gene sequences in environmental isolates and metagenomic DNA
    (WILEY, 2010) De la Iglesia, R.; Valenzuela Heredia, D.; Pavissich, J. P.; Freyhoffer, S.; Andrade, S.; Correa, J. A.; Gonzalez, B.
    Aims:
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    O father where art thou? Paternity analyses in a natural population of the haploid-diploid seaweed Chondrus crispus
    (2015) Krueger-Hadfield, S. A.; Roze, D.; Correa, J. A.; Destombe, C.; Valero, M.
    The link between life history traits and mating systems in diploid organisms has been extensively addressed in the literature, whereas the degree of selfing and/or inbreeding in natural populations of haploid-diploid organisms, in which haploid gametophytes alternate with diploid sporophytes, has been rarely measured. Dioecy has often been used as a proxy for the mating system in these organisms. Yet, dioecy does not prevent the fusion of gametes from male and female gametophytes originating from the same sporophyte. This is likely a common occurrence when spores from the same parent are dispersed in clumps and recruit together. This pattern of clumped spore dispersal has been hypothesized to explain significant heterozygote deficiency in the dioecious haploid-diploid seaweed Chondrus crispus. Fronds and cystocarps (structures in which zygotes are mitotically amplified) were sampled in two 25 m(2) plots located within a high and a low intertidal zone and genotyped at 5 polymorphic microsatellite loci in order to explore the mating system directly using paternity analyses. Multiple males sired cystocarps on each female, but only one of the 423 paternal genotypes corresponded to a field-sampled gametophyte. Nevertheless, larger kinship coefficients were detected between males siring cystocarps on the same female in comparison with males in the entire population, confirming restricted spermatial and clumped spore dispersal. Such dispersal mechanisms may be a mode of reproductive assurance due to nonmotile gametes associated with putatively reduced effects of inbreeding depression because of the free-living haploid stage in C. crispus.
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    Physiological plasticity of Dictyota kunthii (Phaeophyceae) to copper excess
    (2014) Sordet, C.; Contreras-Porcia, L.; Lovazzano, C.; Goulitquer, S.; Andrade, S.; Potin, P.; Correa, J. A.
    The brown alga Dictyota kunthii is one of the dominant species in the coastal areas of northern Chile affected by copper enrichment due to accumulated mining wastes. To assess its physiological plasticity in handling copper-mediated oxidative stress, 4-days copper exposure (ca. 100 mu g/L) experiments were conducted with individuals from a copper impacted area and compared with the responses of plants from a non-impacted site. Several biochemical parameters were then evaluated and compared between populations. Results showed that individuals from the copper-impacted population normally displayed higher levels of copper content and antioxidant enzymes activity (catalase (CAT), ascorbate peroxidase (AP), dehydroascorbate reductase (DHAR), glutathione peroxidase (GP) and peroxiredoxins (PRX)). After copper exposure, antioxidant enzyme activity increased significantly in plants from the two selected sites. In addition, we found that copper-mediated oxidative stress was associated with a reduction of glutathione reductase (GR) activity. Moreover, metabolic profiling of extracellular metabolites from both populations showed a significant change after plants were exposed to copper excess in comparison with controls, strongly suggesting a copper-induced release of metabolites. The copper-binding capacity of those exudates was determined by anodic stripping voltammetry (ASV) and revealed an increased ligand capacity of the medium with plants exposed to copper excess. Results indicated that D. kunthii, regardless their origin, counteracts copper excess by various mechanisms, including metal accumulation, activation of CAT, AP, DHAR, GP and PRX, and an induced release of Cu binding compounds. Thus, plasticity in copper tolerance in D. kunthii seems constitutive, and the occurrence of a copper-tolerant ecotype seems unlikely. (C) 2014 Elsevier B.V. All rights reserved.