Post-doctoral fellow in Dalhousie University, Canada working on dinoflagellates macromolecular content. Address: Quito, Provincia de Pichincha, Ecuador
Elemental and macromolecular composition of three species of Chloropicophyceae grown under non-li... more Elemental and macromolecular composition of three species of Chloropicophyceae grown under non-limiting (t=0) and nitrogen starvation conditions(t>0). To achieve N-starvation, cultures in balanced growth (t=0) were transferred into N-free media and monitor over time.<br>For more details see Ebenezer et al (2021) doi 10.1002/lno.12013<br>
Data on C:N:P of lab-cultured marine dinoflagellates were identified by searching in the ISI Web ... more Data on C:N:P of lab-cultured marine dinoflagellates were identified by searching in the ISI Web of Science using keywords such as elemental composition, elemental stoichiometry, elemental ratios, C:N, C:P or C:N combined with the word dinoflagellate. These studies and suitable studies cited within these sources were evaluated for data collection. Experimental conditions were recorded along with the elemental composition data including culturing methods, the media used, culture temperature and salinity. Cell volume and growth rate data were collected when available. Species were then assigned the following traits: 1. thecate or athecate; 2. non-toxic or the potential to produce C-rich or N-rich toxins; and 3. small, medium or large cell volume.
espanolA pesar de la deforestacion y el rapido crecimiento de la poblacion en Esmeraldas (norte d... more espanolA pesar de la deforestacion y el rapido crecimiento de la poblacion en Esmeraldas (norte de Ecuador), no hay informacion del impacto de estos cambios en los rios de la costa. El Teaone es un rio de orden 5 situado en el norte de Ecuador que nace en las montanas Mache-Chindul y confluye con el rio Esmeradas cerca de su desembocadura. El rio atraviesa un paisaje rural que incluye pastos, plantaciones forestales y algunos remanentes de bosques humedos. En este trabajo, hemos estudiado los indicadores del uso del suelo en la cuenca (porcentaje de usos agricolas y de bosque y la densidad de vias de comunicacion y viviendas), la geomorfologia (composicion del lecho fluvial y la densidad y origen de las acumulaciones de madera), la quimi-ca del agua (pH, turbidez, conductividad, oxigeno y las concentraciones de nitrato, nitrito y ortofosfato) y las diatomeas y macroinvertebrados bentonicos a lo largo del rio. La cuenca del rio Teaone se encuentra muy modificada y los usos agricolas ...
The genus of benthic dinoflagellates Ostreopsis is of particular interest because some species ne... more The genus of benthic dinoflagellates Ostreopsis is of particular interest because some species negatively impact human health and coastal marine ecosystems. Ostreopsis populations from a remote area, such as the Galapagos Marine Reserve with its unique biodiversity, can provide significant data. Samples of epibionthic dinoflagellates were collected from two islands (Santa Cruz and Santa Fe) in 2017. Species of the genera Gambierdiscus, Amphidinium, Coolia and Ostreopsis were found. Ostreopsis strains were isolated to characterize their morphology, molecular biology and toxicity. Three different morphotypes of Ostreopsis based on dorsoventral and width diameters (n=369) were distinguished. The small cell morphotype was dominant in ten samples, with abundances of up to 33405 cells g-1 fresh weight of macroalgae. A total of 16 strains were isolated from field samples with subsequent polymerase chain reaction amplifications of rDNA, 5.8S rDNA and internal transcribed space regions; 13 ...
Dinoflagellates are amongst the most abundant and diverse groups of plankton in surface waters an... more Dinoflagellates are amongst the most abundant and diverse groups of plankton in surface waters and contribute to food web productivity and C:N:P biogeochemistry. Here we analyse the C:N:P of marine, autotrophic, planktonic dinoflagellates compiled from culture data from the scientific literature and test if dinoflagellate C:N:P differs from the Redfield ratio, and whether variability in C:N:P is associated with three traits: cell size, wall structure and toxin production. We find the average C:N:P of dinoflagellates is 90:12:1; higher in C:N, and lower in C:P and N:P than the canonical Redfield ratio. In aggregate the three traits examined here account for between 20–31% while taxonomic order accounts for between 37–38% of the variance in C:N:P. Smaller-sized and thecate taxa are higher in C:N, C:P and N:P than larger-size and athecate taxa. Species known to be able to produce C-rich toxins tend to be higher in C:P and N:P while species known to be able to produce N-rich toxins are ...
An expansion of the distribution of Ostreopsis cf. ovata, a dinoflagellate which produces palytox... more An expansion of the distribution of Ostreopsis cf. ovata, a dinoflagellate which produces palytoxin-like compounds, has been reported in recent years. Economical and social interests are affected by blooms, as they are responsible for respiratory and skin problems in humans and may cause damage to marine organisms. In order to identify the most influential environmental factors that trigger proliferations of O. cf. ovata in the area of the adjacent shallow rocky coast of the Ebro Delta (NW Mediterranean Sea) a three-year survey was performed on the metaphytic microalgae community growing on the macrophytes Jania rubens and Corallina elongata. Small-size diatoms were more abundant than dinoflagellates; O. cf. ovata was identified as the only species present from the genus. Seawater temperature was the primary driver defining the ecological niche of O. cf. ovata. Freshwater and groundwater fluxes were more pronounced in southern than in northern sites, which may have resulted in a distinct O. cf. ovata spatial distribution, with the highest records of abundance and more frequent blooms in the north. In consequence, negative correlations between the abundance of O. cf. ovata and nitrate concentrations and significant positive correlation with salinity were observed. The temporal pattern of O. cf. ovata dynamics from mid-July to early-November is probably due to the fact that this species is observed only above a certain threshold temperature of seawater. Metaphytic cells of O. cf. ovata were smaller in the northern site than in the south, possibly as a result of an increase in cell division, coinciding with higher abundance, and this could be an indicator of favorable conditions. Toxicity in planktonic cells was negatively correlated with cell abundance in the water column, achieving maximum concentrations of 25pg. PLTX eqcell(-1).
ABSTRACT The toxic epi-benthic dinoflagellate Ostreopsis is distributed worldwide in coral reef e... more ABSTRACT The toxic epi-benthic dinoflagellate Ostreopsis is distributed worldwide in coral reef ecosystems and temperate regions. There are nine species described to date based on morphological features. Some of them have been proved to be producers of palytoxin-like compounds, representing a threat to coastal marine organisms and human health. The taxonomy of the genus is currently under revision due to morphological similarities among species. The present study aims to provide additional information on morphology, 5.8S and ITS data and toxin content from thirty three strains isolated along the west coast of Reunion Island, in the Indian Ocean. Two morphotypes, non overlapping in size, were distinguishable: the small morphotype (DV = 53.5 ± 6.9 µm; W = 37.7 ± 5.6 µm) with a typical tear-drop shape and the large morphotype (DV = 103.9 ± 5.1 µm; W = 85.3 ± 6.9 µm) with a rounded shape. Phylogenetic analysis revealed the presence of three genotypes. Within the small morphotype, two different species were identifided, O. cf. ovata and a cryptic species not previously characterized. The larger cells constituted a genetically homogeneous clade. Nucleotide divergence between this species and the one qualified by Sato et al., 2011 of Ostreopsis sp. 5 was relatively low (p &lt; 0.088) and those two strains are likely to be the same species. Haemolytic analysis resulted in no palytoxin-like activity in any of the three species.
Blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the Mediterranean Sea,... more Blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the Mediterranean Sea, since this species produces a wide range of palytoxin-like compounds listed among the most potent marine toxins. This study focused on two analogs of palytoxin found in cultures of six strains of O. cf. ovata isolated from the south of Catalonia (NW Mediterranean Sea). In addition to some already known ovatoxins, our strains produced two minor compounds, ovatoxin-g and the so far called putative palytoxin, whose structures had not been elucidated before. Insufficient quantity of these compounds impeded a full nuclear magnetic resonance (NMR)-based structural elucidation; thus, we studied their structure in crude algal extracts through liquid chromatography-electrospray ionization high-resolution mass spectrometry(n) (LC-ESI-HRMS(n)) in positive ion mode. Under the used MS conditions, the molecules underwent fragmentation at many sites of their backbone and a large number of diagnostic f...
Elemental and macromolecular composition of three species of Chloropicophyceae grown under non-li... more Elemental and macromolecular composition of three species of Chloropicophyceae grown under non-limiting (t=0) and nitrogen starvation conditions(t>0). To achieve N-starvation, cultures in balanced growth (t=0) were transferred into N-free media and monitor over time.<br>For more details see Ebenezer et al (2021) doi 10.1002/lno.12013<br>
Data on C:N:P of lab-cultured marine dinoflagellates were identified by searching in the ISI Web ... more Data on C:N:P of lab-cultured marine dinoflagellates were identified by searching in the ISI Web of Science using keywords such as elemental composition, elemental stoichiometry, elemental ratios, C:N, C:P or C:N combined with the word dinoflagellate. These studies and suitable studies cited within these sources were evaluated for data collection. Experimental conditions were recorded along with the elemental composition data including culturing methods, the media used, culture temperature and salinity. Cell volume and growth rate data were collected when available. Species were then assigned the following traits: 1. thecate or athecate; 2. non-toxic or the potential to produce C-rich or N-rich toxins; and 3. small, medium or large cell volume.
espanolA pesar de la deforestacion y el rapido crecimiento de la poblacion en Esmeraldas (norte d... more espanolA pesar de la deforestacion y el rapido crecimiento de la poblacion en Esmeraldas (norte de Ecuador), no hay informacion del impacto de estos cambios en los rios de la costa. El Teaone es un rio de orden 5 situado en el norte de Ecuador que nace en las montanas Mache-Chindul y confluye con el rio Esmeradas cerca de su desembocadura. El rio atraviesa un paisaje rural que incluye pastos, plantaciones forestales y algunos remanentes de bosques humedos. En este trabajo, hemos estudiado los indicadores del uso del suelo en la cuenca (porcentaje de usos agricolas y de bosque y la densidad de vias de comunicacion y viviendas), la geomorfologia (composicion del lecho fluvial y la densidad y origen de las acumulaciones de madera), la quimi-ca del agua (pH, turbidez, conductividad, oxigeno y las concentraciones de nitrato, nitrito y ortofosfato) y las diatomeas y macroinvertebrados bentonicos a lo largo del rio. La cuenca del rio Teaone se encuentra muy modificada y los usos agricolas ...
The genus of benthic dinoflagellates Ostreopsis is of particular interest because some species ne... more The genus of benthic dinoflagellates Ostreopsis is of particular interest because some species negatively impact human health and coastal marine ecosystems. Ostreopsis populations from a remote area, such as the Galapagos Marine Reserve with its unique biodiversity, can provide significant data. Samples of epibionthic dinoflagellates were collected from two islands (Santa Cruz and Santa Fe) in 2017. Species of the genera Gambierdiscus, Amphidinium, Coolia and Ostreopsis were found. Ostreopsis strains were isolated to characterize their morphology, molecular biology and toxicity. Three different morphotypes of Ostreopsis based on dorsoventral and width diameters (n=369) were distinguished. The small cell morphotype was dominant in ten samples, with abundances of up to 33405 cells g-1 fresh weight of macroalgae. A total of 16 strains were isolated from field samples with subsequent polymerase chain reaction amplifications of rDNA, 5.8S rDNA and internal transcribed space regions; 13 ...
Dinoflagellates are amongst the most abundant and diverse groups of plankton in surface waters an... more Dinoflagellates are amongst the most abundant and diverse groups of plankton in surface waters and contribute to food web productivity and C:N:P biogeochemistry. Here we analyse the C:N:P of marine, autotrophic, planktonic dinoflagellates compiled from culture data from the scientific literature and test if dinoflagellate C:N:P differs from the Redfield ratio, and whether variability in C:N:P is associated with three traits: cell size, wall structure and toxin production. We find the average C:N:P of dinoflagellates is 90:12:1; higher in C:N, and lower in C:P and N:P than the canonical Redfield ratio. In aggregate the three traits examined here account for between 20–31% while taxonomic order accounts for between 37–38% of the variance in C:N:P. Smaller-sized and thecate taxa are higher in C:N, C:P and N:P than larger-size and athecate taxa. Species known to be able to produce C-rich toxins tend to be higher in C:P and N:P while species known to be able to produce N-rich toxins are ...
An expansion of the distribution of Ostreopsis cf. ovata, a dinoflagellate which produces palytox... more An expansion of the distribution of Ostreopsis cf. ovata, a dinoflagellate which produces palytoxin-like compounds, has been reported in recent years. Economical and social interests are affected by blooms, as they are responsible for respiratory and skin problems in humans and may cause damage to marine organisms. In order to identify the most influential environmental factors that trigger proliferations of O. cf. ovata in the area of the adjacent shallow rocky coast of the Ebro Delta (NW Mediterranean Sea) a three-year survey was performed on the metaphytic microalgae community growing on the macrophytes Jania rubens and Corallina elongata. Small-size diatoms were more abundant than dinoflagellates; O. cf. ovata was identified as the only species present from the genus. Seawater temperature was the primary driver defining the ecological niche of O. cf. ovata. Freshwater and groundwater fluxes were more pronounced in southern than in northern sites, which may have resulted in a distinct O. cf. ovata spatial distribution, with the highest records of abundance and more frequent blooms in the north. In consequence, negative correlations between the abundance of O. cf. ovata and nitrate concentrations and significant positive correlation with salinity were observed. The temporal pattern of O. cf. ovata dynamics from mid-July to early-November is probably due to the fact that this species is observed only above a certain threshold temperature of seawater. Metaphytic cells of O. cf. ovata were smaller in the northern site than in the south, possibly as a result of an increase in cell division, coinciding with higher abundance, and this could be an indicator of favorable conditions. Toxicity in planktonic cells was negatively correlated with cell abundance in the water column, achieving maximum concentrations of 25pg. PLTX eqcell(-1).
ABSTRACT The toxic epi-benthic dinoflagellate Ostreopsis is distributed worldwide in coral reef e... more ABSTRACT The toxic epi-benthic dinoflagellate Ostreopsis is distributed worldwide in coral reef ecosystems and temperate regions. There are nine species described to date based on morphological features. Some of them have been proved to be producers of palytoxin-like compounds, representing a threat to coastal marine organisms and human health. The taxonomy of the genus is currently under revision due to morphological similarities among species. The present study aims to provide additional information on morphology, 5.8S and ITS data and toxin content from thirty three strains isolated along the west coast of Reunion Island, in the Indian Ocean. Two morphotypes, non overlapping in size, were distinguishable: the small morphotype (DV = 53.5 ± 6.9 µm; W = 37.7 ± 5.6 µm) with a typical tear-drop shape and the large morphotype (DV = 103.9 ± 5.1 µm; W = 85.3 ± 6.9 µm) with a rounded shape. Phylogenetic analysis revealed the presence of three genotypes. Within the small morphotype, two different species were identifided, O. cf. ovata and a cryptic species not previously characterized. The larger cells constituted a genetically homogeneous clade. Nucleotide divergence between this species and the one qualified by Sato et al., 2011 of Ostreopsis sp. 5 was relatively low (p &lt; 0.088) and those two strains are likely to be the same species. Haemolytic analysis resulted in no palytoxin-like activity in any of the three species.
Blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the Mediterranean Sea,... more Blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the Mediterranean Sea, since this species produces a wide range of palytoxin-like compounds listed among the most potent marine toxins. This study focused on two analogs of palytoxin found in cultures of six strains of O. cf. ovata isolated from the south of Catalonia (NW Mediterranean Sea). In addition to some already known ovatoxins, our strains produced two minor compounds, ovatoxin-g and the so far called putative palytoxin, whose structures had not been elucidated before. Insufficient quantity of these compounds impeded a full nuclear magnetic resonance (NMR)-based structural elucidation; thus, we studied their structure in crude algal extracts through liquid chromatography-electrospray ionization high-resolution mass spectrometry(n) (LC-ESI-HRMS(n)) in positive ion mode. Under the used MS conditions, the molecules underwent fragmentation at many sites of their backbone and a large number of diagnostic f...
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