Francisco Hernández-Sandoval - Academia.edu (original) (raw)

Papers by Francisco Hernández-Sandoval

Environmental conditions are described during a bloom of Cochlodinium polykrikoides that occurred... more Environmental conditions are described during a bloom of Cochlodinium polykrikoides that occurred between September 12 th and November 9 th 2012, in Ensenada de La Paz, Gulf of California. At the beginning of the bloom, the number of cells, chlorophyll a, and peridinin was 6.2 x10 2 cells mL-1 , 10.1 mg m-3 , and 3.5 mg m-3 , respectively; 8.6 x 10 3 cells mL-1 , 121.2 mg m-3 and 40.2 mg m-3 in their maximum intensity; and 5 cells mL-1 , 1.02 mg m-3 of chlorophyll a, and 0.03 mg m-3 of peridinin, at the end of the bloom period. Thermal interval fluctuated between 30.3 and 31.3 °C; salinity varied from 35.2 to 36.8; dissolved O 2 ranged from 4.8 to 10.8 mL L-1 ; saturation percentage was > 200. The values of nitrate, phosphate, and the N:P ratio at the initiation of the bloom were 1.8, 0.9 (μM) and 2.8, during the maximum intensity they were 8.5, 3.4 (μM), and 2.9. At the end of the bloom they were 5.3, 0.6 (μM) and 9.0. Prevailing winds were from the NNE (0.4-5.0 m s-1), and a precipitation of 68 mm was registered previous to the bloom event. As winds diminished < 1.3 m s-1 on to SSE direction, the blooming got more intense. According to this information, we concluded that the NNE winds and continental runoff caused by rain fertilized Ensenada de La Paz waters, created conditions to support growth and survival of C. polykrikoides. Mortality of marine organisms was not observed during this event.

Toxins, Sep 3, 2022

, Morphology and Viability of Gymnodinium catenatum Associated with Allelopathy of Chattonella ma... more , Morphology and Viability of Gymnodinium catenatum Associated with Allelopathy of Chattonella marina var. marina and Gymnodinium impudicum.

Toxicon, Aug 1, 2021

Paralytic shellfish toxin (PST) content in the dinoflagellate Gymnodinium catenatum changes with ... more Paralytic shellfish toxin (PST) content in the dinoflagellate Gymnodinium catenatum changes with culture age, with a higher toxin concentration in the logarithmic phase that decreases when the culture ages. The gene copy number (GCN) of domains sxtA1 and sxtA4 was higher in the lag and stationary phase, and lag phase, respectively. No relationship was found between the GCN of the domains sxtA4 and sxtA1 with the PST content in G. catenatum.

Infectious disorders drug targets, Aug 1, 2013

Revista De Biologia Tropical, Oct 24, 2012

Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable conseq... more Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88µM DIN, 0.78µM PO 4 and 24.34µM SiO 2) were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x10 7 cells/L). Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC) in local oysters (1525.8µg STXeq/100g), and in phytoplankton (10.9pg STXeq/cells) samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells), most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas

Geofísica Internacional

Los cambios en las condiciones físico-químicas y los pigmentos fitoplanctónicos, en Bahía Concepc... more Los cambios en las condiciones físico-químicas y los pigmentos fitoplanctónicos, en Bahía Concepción, Golfo de California, se analizan para el periodo 1997 a 1999 con el objetivo de observar el efecto de El Niño 1997-1998 en esta bahía. Tres diferencias notables en los parámetros medidos ocurrieron durante 1998: Temperaturas mayores en la columna de agua, un retrazo de 2-3 meses en el inicio del período de la estratificación y concentraciones menores de nutrientes (nitratos y fosfatos) y peridinina. Estos datos sugieren la presencia de Agua Ecuatorial Superficial (altas temperaturas y baja concentración de nutrientes) con un efecto negativo en la proliferación de dinoflagelados. Se discuten las posibles causas de la baja en la concentración de los dinoflagelados.doi: sin doi

Toxins

In September and November 2016, eight marine sampling sites along the coast of the southeastern G... more In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and hydrophilic toxins. Water temperature, salinity, hydrogen potential, dissolved oxygen saturation, inorganic nutrients and phytoplankton abundance were also determined. Two samples filtered through glass fiber filters were used for the extraction and analysis of paralytic shellfish toxins (PSTs) by lateral flow immunochromatography (IFL), HPLC with post-column oxidation and fluorescent detection (FLD) and UHPLC coupled to tandem mass spectrometry (UHPLC-MS/MS). Elevated nutrient contents were associated with the sites of rainwater discharge or those near anthropogenic activities. A predominance of the dinoflagellate Pyrodinium bahamense was found with abundances of up to 104 cells L−1. Identification of the dinoflagellate was corroborated by light and scanning electron microscopy. Samples for toxins were positive by IFL, and ...

CICIMAR Oceánides, 2008

Blooms of the ciliate Myrionecta rubra are quite common in Bahía de La Paz. In June and July 2005... more Blooms of the ciliate Myrionecta rubra are quite common in Bahía de La Paz. In June and July 2005 two blooms of this species were sampled to determine abundance, plankton biomass, nutrients, dissolved oxygen, and temperature. During the bloom in June, surface temperature ranged from 19.0 °C to 19.6 °C and dissolved oxygen from 4.2 mg l-1 to 4.7 mg l-1. During the second bloom, surface temperature as 24.2 °C and dissolved oxygen was 6.7 mg l-1. At 25 m depth, conditions were 20.0 °C and 3.5 mg l-1, respectively. At the surface, nutrients were low, except for ammonium (1.14 µM – 2.27 µM). High densities of M. rubra (2.14 × 106 cells l-1), chlorophyll a (55.6 µg l-1), chlorophyll c (6.0 µg l-1), and alloxanthin (8.1 µg l-1) were recorded. This last pigment is characteristic of the cryptophyte group, suggesting an association of the ciliate with this algal group. Winds from the southeast varied from 3 to 4.5 m s-1 in June and 1.7 to 4.8 m s-1 in July. The presence of this bloom under lo...

Revista de biologia tropical, 2004

Along the Mexican coast, harmful algae blooms (HAB) have become more frequent, and therefore, the... more Along the Mexican coast, harmful algae blooms (HAB) have become more frequent, and therefore, there is an urgent need to establish monitoring programs to avoid the undesired consequences of HAB in human and natural ecosystems. In this work, we analyzed the pigment signatures and the species composition from phytoplankton samples to evaluate the utility of the specific pigment "fingerprints" in HAB monitoring programs. Vertical profiles from a coastal lagoon and temporal samples of a red tide occurring in a shrimp-culture pond and in a coastal zone were taken into consideration. Between 76% and 84% of dinoflagellate and diatom cell density was explained by their specific signature variation, in both vertical and temporal samples. Only the variation of zeaxanthin and the cyanobacteria Anabaena sp. showed a poor relationship, probably from difficulties in counting other cyanobacteria present in the samples examined with the microscopic method. These results suggest that inclu...

Hidrobiologica, 2015

Una inusual muerte masiva de peces sucedio durante un florecimiento de diatomeas ocurrido del 10 ... more Una inusual muerte masiva de peces sucedio durante un florecimiento de diatomeas ocurrido del 10 de junio al 3 de julio en la Bahia de La Paz, Golfo de California. Los organismos dominantes fueron Pseudo-nitzschia spp. (2.4 x 106 cels L-1), Thalassiosira eccentrica (2.3 x 106 cels L-1) y Chaetoceros spp. (9.65 x 105 cels L-1). Se identificaron tres especies toxicas: una pertenece al complejo P. pseudodelicatissima, P. fraudulenta y P. pungens. La fucoxantina, con un pico de 9.3 μg L-1, fue el pigmento dominante durante el florecimiento. La temperatura superficial del mar en el transcurso del evento drasticamente se incremento de 19.0 °C a 27.0 °C, con valores de nitrogeno inorganico de 1.0 ± 0.6 μM y Si(OH)4 de 15.5 ± 8.0 μM. El contenido de acido domoico determinado por HPLC-UV fue bajo tanto en muestras de red con un rango de 24.0 a 52.0 ng por filtro como en tejido de almeja chocolata Megapitaria squalida (0.55 μg g-1) y almeja blanca Dosinia ponderosa (0.06 μg g-1). El analisis ...

Algal Research, 2021

Abstract This study assessed the early effects of riboflavin and lumichrome produced by the bacte... more Abstract This study assessed the early effects of riboflavin and lumichrome produced by the bacterium Azospirillum brasilense on mitigating the stress of salinity on the growth and metabolic status of Chlorella sorokiniana. C. sorokiniana was grown in a synthetic growth medium (SGM) at three salt levels (0%, 1.5%, and 3% NaCl) and under four treatments: (1) C. sorokiniana growing alone; (2) C. sorokiniana co-cultured with A. brasilense; (3) C. sorokiniana supplemented with synthetic riboflavin; and (4) C. sorokiniana supplemented with lumichrome, mimicking the riboflavin and lumichrome concentrations naturally produced by A. brasilense. Cell density, total carbohydrates, total and neutral lipids, chlorophyll a and b, and carotenoids contents, proline accumulation, and activity of superoxide dismutase (SOD) were analyzed. Increasing salinity affected the growth rate, cell size, and cell density of C. sorokiniana, induced proline accumulation, and made the total-lipid concentration higher than the carbohydrate concentration. The neutral lipids, chlorophylls, and SOD showed higher values at 1.5% NaCl. Riboflavin and lumichrome showed significant effects on the analyzed variables. Lumichrome at 1.5% salinity induced an early but transient growth response, making carbohydrate production higher than the total lipid production. By contrast, riboflavin enhanced SOD activity and reduced proline accumulation at all the salinity levels. Longer incubation times resulted in effects similar to those of lumichrome in the analyzed metabolites, thus suggesting the conversion of riboflavin into lumichrome. The microalga−bacteria co-cultures at all salinity levels exhibited growth promotion, with consistent effects at the different incubation times and superior magnitude to that presented by lumichrome or riboflavin alone, showing an alleviating effect of the saline stress through osmoregulation with increased carbohydrate concentration and antioxidant activity, but not with increased proline or total lipid concentration. These findings suggest that Azospirillum brasilense can be used as an alternative to mitigate saline stress effects in microalgae cultured in low-salinity waters.

Algal Research, 2019

This study is dedicated to the memory of Prof. Yoav Bashan (1951-2018), leading figure in the fie... more This study is dedicated to the memory of Prof. Yoav Bashan (1951-2018), leading figure in the field of Plant Growth-Promoting Bacteria (PGPB) for environmental purposes, and founder of Bashan Institute of Science, USA. Prof. Bashan passed away during the edition of the manuscript.

Frontiers in Marine Science, 2019

and Fernández-Herrera LJ (2019) The State of Knowledge of Harmful Algal Blooms of Margalefidinium... more and Fernández-Herrera LJ (2019) The State of Knowledge of Harmful Algal Blooms of Margalefidinium polykrikoides (a.k.a. Cochlodinium polykrikoides) in Latin America.

Journal of Marine Biology, 2019

In the exploration of the hydrothermal system of the Guaymas Basin (GB) between 27° 00′ 35′′ and ... more In the exploration of the hydrothermal system of the Guaymas Basin (GB) between 27° 00′ 35′′ and 27° 00′ 50′′ N and 111° 24′ 15′′ and 111° 24′ 40′′ W in the Gulf of California, carried out on the R/V Atlantis and of the DSRV/Alvin in October 2008, four cores of surface sediments were obtained to analyse photosynthetic pigments at two locations with contrasting extreme conditions: Oil Town and Great Pagoda. We identified nine pigments: Chlorophyll-a, Phaeophytin-a, Phaeophorbide-a, Pyropheophytin-a (degradation Chlorophyll-a products), β-Carotene, Alloxanthin, Zeaxanthin, Diadinoxanthin, and Prasinoxanthin (carotenoids). The maximum pigment concentration was registered in the Great Pagoda (10,309 ng/g) and the minimum in Oil Town (918 ng/g). It is demonstrated that photosynthetic pigment profiles in surface sediments depend on the heterogeneity of the extreme conditions of each site caused mainly by temperature and bacterial substrates. Therefore, there were significant differences (...

Frontiers in Marine Science, 2019

In this review we summarize the current state of knowledge regarding taxonomy, bloom dynamics, to... more In this review we summarize the current state of knowledge regarding taxonomy, bloom dynamics, toxicity, autoecology, and trophic interactions, of saxitoxin producing dinoflagellates in this region. The dinoflagellates Gymnodinium catenatum, Pyrodinium bahamense and several species of Alexandrium are saxitoxin producers, and have been responsible of paralytic shellfish poisoning in different regions of Latin America, causing intoxications and important fisheries losses. The species distribution differ; most harmful algal blooms of G. catenatum are from the northern region, however this species has also been reported in central and southern regions. Blooms of P. bahamense are mostly reported in North and Central America, while blooms of Alexandrium species are more common in South America, however this genus is widely spread in Latin America. Species and regional differences are contrasted, with the aim to contribute to future guidelines for an international scientific approach for research and monitoring activities that are needed to increase our understanding of paralytic toxin producing dinoflagellates in this region.

Esta revisión da a conocer el estado de conocimiento de los estudios de Florecimientos Algales No... more Esta revisión da a conocer el estado de conocimiento de los estudios de Florecimientos Algales Nocivos (FAN) en el ámbito marino en México, con el objeto de evaluar la manera de optimizar los recursos destinados para el estudio de FAN en nuestro país, identificando líneas no abordadas y proponiendo mejoras en las actividades de monitoreo y de investigación que puedan aumentar nuestro conocimiento sobre la complejidad de FAN en nuestras costas. Se realizó una búsqueda bibliográfica de 1940 a 2011 consultando bases de datos, reuniones académicas y libros especializados. El número de investigadores e instituciones involucrados con el estudio de FAN se ha incrementado significativamente en las últimas décadas, lo cual se ve reflejado en el número y calidad de las publicaciones. Sin embargo, la mayoría de los programas y actividades de investigación están basados en muestreos puntuales y programas de investigación a corto plazo, enfocándose a pocas especies de FAN. Actualmente, varias líneas de investigación relacionadas con los FAN se han abordado pobremente o no se han considerado como son los estudios sobre quistes, alelopatía, transportación de especies por aguas de lastre, efecto del cambio climático, utilización de imágenes de satélite, uso de herramientas moleculares, análisis socioeconómicos y estrategias de mitigación, entre otros. Este análisis muestra que ha habido un avance significativo en el estudio de FAN en México, si bien la manera de abordar su estudio ha sido individualizada y dispersa. Se obtendría un mayor avance si se coordinaran los esfuerzos entre los diversos investigadores e instituciones para optimizar los recursos disponibles para el estudio de los FAN.

Hidrobiológica: [revista del Departamento de Hidrobiología]

Food Additives & Contaminants: Part A, 2015

The paralytic shellfish toxin (PST) profiles of Gymnodinium catenatum Graham have been reported f... more The paralytic shellfish toxin (PST) profiles of Gymnodinium catenatum Graham have been reported for several strains from the Pacific coast of Mexico cultured under different laboratory conditions, as well as from natural populations. Up to 15 saxitoxin analogues occurred and the quantity of each toxin depended on the growth phase and culture conditions. Previous analysis of toxin profiles of G. catenatum isolated from Mexico have been based on post-column oxidation liquid chromatography with fluorescence detection (LC-FLD), a method prone to artefacts and non-specificity, leading to misinterpretation of toxin composition. We describe, for the first time, the complete toxin profile for several G. catenatum strains from diverse locations of the Pacific coast of Mexico. The new results confirmed previous reports on the dominance of the less potent sulfocarbamoyl toxins (C1/2); significant differences, however, in the composition (e.g., absence of saxitoxin, gonyautoxin 2/3 and neosaxitoxin) were revealed in our confirmatory analysis. The LC-MS/MS analyses also indicated at least seven putative benzoyl toxin analogues and provided support for their existence. This new toxin profile shows a high similarity (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 80%) to the profiles reported from several regions around the world, suggesting low genetic variability among global populations.

Ciencias Marinas, 2013

Temperature and nutrient concentrations were measured during a mixed bloom of Noctiluca scintilla... more Temperature and nutrient concentrations were measured during a mixed bloom of Noctiluca scintillans and Gymnodinium catenatum in La Paz Bay, Gulf of California. Under laboratory conditions, we offered three concentrations of G. catenatum (312, 625, or 1015 cells mL–1) to 0.53 N. scintillans cells mL–1 to study predation rates. Experiments were carried out with 750 mL of culture during a fiveday period. Sea surface temperature clearly showed a transitional period from colder to warmer water during the bloom. Field and laboratory data showed that N. scintillans fed on G. catenatum. During the trial, more than 70% of N. scintillans cells contained G. catenatum cells in their vacuoles. Ingestion rates varied; the highest ranged from 30 to 40 G. catenatum cells h–1 in each N. scintillans cell. A clear relation to the concentration of the diet was not evident. Low values of 1 to 3 G. catenatum cells h–1 in each N. scintillans cell were typical at the end of the trial. Noctiluca scintillan...

Environmental conditions are described during a bloom of Cochlodinium polykrikoides that occurred... more Environmental conditions are described during a bloom of Cochlodinium polykrikoides that occurred between September 12 th and November 9 th 2012, in Ensenada de La Paz, Gulf of California. At the beginning of the bloom, the number of cells, chlorophyll a, and peridinin was 6.2 x10 2 cells mL-1 , 10.1 mg m-3 , and 3.5 mg m-3 , respectively; 8.6 x 10 3 cells mL-1 , 121.2 mg m-3 and 40.2 mg m-3 in their maximum intensity; and 5 cells mL-1 , 1.02 mg m-3 of chlorophyll a, and 0.03 mg m-3 of peridinin, at the end of the bloom period. Thermal interval fluctuated between 30.3 and 31.3 °C; salinity varied from 35.2 to 36.8; dissolved O 2 ranged from 4.8 to 10.8 mL L-1 ; saturation percentage was > 200. The values of nitrate, phosphate, and the N:P ratio at the initiation of the bloom were 1.8, 0.9 (μM) and 2.8, during the maximum intensity they were 8.5, 3.4 (μM), and 2.9. At the end of the bloom they were 5.3, 0.6 (μM) and 9.0. Prevailing winds were from the NNE (0.4-5.0 m s-1), and a precipitation of 68 mm was registered previous to the bloom event. As winds diminished < 1.3 m s-1 on to SSE direction, the blooming got more intense. According to this information, we concluded that the NNE winds and continental runoff caused by rain fertilized Ensenada de La Paz waters, created conditions to support growth and survival of C. polykrikoides. Mortality of marine organisms was not observed during this event.

Toxins, Sep 3, 2022

, Morphology and Viability of Gymnodinium catenatum Associated with Allelopathy of Chattonella ma... more , Morphology and Viability of Gymnodinium catenatum Associated with Allelopathy of Chattonella marina var. marina and Gymnodinium impudicum.

Toxicon, Aug 1, 2021

Paralytic shellfish toxin (PST) content in the dinoflagellate Gymnodinium catenatum changes with ... more Paralytic shellfish toxin (PST) content in the dinoflagellate Gymnodinium catenatum changes with culture age, with a higher toxin concentration in the logarithmic phase that decreases when the culture ages. The gene copy number (GCN) of domains sxtA1 and sxtA4 was higher in the lag and stationary phase, and lag phase, respectively. No relationship was found between the GCN of the domains sxtA4 and sxtA1 with the PST content in G. catenatum.

Infectious disorders drug targets, Aug 1, 2013

Revista De Biologia Tropical, Oct 24, 2012

Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable conseq... more Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88µM DIN, 0.78µM PO 4 and 24.34µM SiO 2) were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x10 7 cells/L). Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC) in local oysters (1525.8µg STXeq/100g), and in phytoplankton (10.9pg STXeq/cells) samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells), most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas

Geofísica Internacional

Los cambios en las condiciones físico-químicas y los pigmentos fitoplanctónicos, en Bahía Concepc... more Los cambios en las condiciones físico-químicas y los pigmentos fitoplanctónicos, en Bahía Concepción, Golfo de California, se analizan para el periodo 1997 a 1999 con el objetivo de observar el efecto de El Niño 1997-1998 en esta bahía. Tres diferencias notables en los parámetros medidos ocurrieron durante 1998: Temperaturas mayores en la columna de agua, un retrazo de 2-3 meses en el inicio del período de la estratificación y concentraciones menores de nutrientes (nitratos y fosfatos) y peridinina. Estos datos sugieren la presencia de Agua Ecuatorial Superficial (altas temperaturas y baja concentración de nutrientes) con un efecto negativo en la proliferación de dinoflagelados. Se discuten las posibles causas de la baja en la concentración de los dinoflagelados.doi: sin doi

Toxins

In September and November 2016, eight marine sampling sites along the coast of the southeastern G... more In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and hydrophilic toxins. Water temperature, salinity, hydrogen potential, dissolved oxygen saturation, inorganic nutrients and phytoplankton abundance were also determined. Two samples filtered through glass fiber filters were used for the extraction and analysis of paralytic shellfish toxins (PSTs) by lateral flow immunochromatography (IFL), HPLC with post-column oxidation and fluorescent detection (FLD) and UHPLC coupled to tandem mass spectrometry (UHPLC-MS/MS). Elevated nutrient contents were associated with the sites of rainwater discharge or those near anthropogenic activities. A predominance of the dinoflagellate Pyrodinium bahamense was found with abundances of up to 104 cells L−1. Identification of the dinoflagellate was corroborated by light and scanning electron microscopy. Samples for toxins were positive by IFL, and ...

CICIMAR Oceánides, 2008

Blooms of the ciliate Myrionecta rubra are quite common in Bahía de La Paz. In June and July 2005... more Blooms of the ciliate Myrionecta rubra are quite common in Bahía de La Paz. In June and July 2005 two blooms of this species were sampled to determine abundance, plankton biomass, nutrients, dissolved oxygen, and temperature. During the bloom in June, surface temperature ranged from 19.0 °C to 19.6 °C and dissolved oxygen from 4.2 mg l-1 to 4.7 mg l-1. During the second bloom, surface temperature as 24.2 °C and dissolved oxygen was 6.7 mg l-1. At 25 m depth, conditions were 20.0 °C and 3.5 mg l-1, respectively. At the surface, nutrients were low, except for ammonium (1.14 µM – 2.27 µM). High densities of M. rubra (2.14 × 106 cells l-1), chlorophyll a (55.6 µg l-1), chlorophyll c (6.0 µg l-1), and alloxanthin (8.1 µg l-1) were recorded. This last pigment is characteristic of the cryptophyte group, suggesting an association of the ciliate with this algal group. Winds from the southeast varied from 3 to 4.5 m s-1 in June and 1.7 to 4.8 m s-1 in July. The presence of this bloom under lo...

Revista de biologia tropical, 2004

Along the Mexican coast, harmful algae blooms (HAB) have become more frequent, and therefore, the... more Along the Mexican coast, harmful algae blooms (HAB) have become more frequent, and therefore, there is an urgent need to establish monitoring programs to avoid the undesired consequences of HAB in human and natural ecosystems. In this work, we analyzed the pigment signatures and the species composition from phytoplankton samples to evaluate the utility of the specific pigment "fingerprints" in HAB monitoring programs. Vertical profiles from a coastal lagoon and temporal samples of a red tide occurring in a shrimp-culture pond and in a coastal zone were taken into consideration. Between 76% and 84% of dinoflagellate and diatom cell density was explained by their specific signature variation, in both vertical and temporal samples. Only the variation of zeaxanthin and the cyanobacteria Anabaena sp. showed a poor relationship, probably from difficulties in counting other cyanobacteria present in the samples examined with the microscopic method. These results suggest that inclu...

Hidrobiologica, 2015

Una inusual muerte masiva de peces sucedio durante un florecimiento de diatomeas ocurrido del 10 ... more Una inusual muerte masiva de peces sucedio durante un florecimiento de diatomeas ocurrido del 10 de junio al 3 de julio en la Bahia de La Paz, Golfo de California. Los organismos dominantes fueron Pseudo-nitzschia spp. (2.4 x 106 cels L-1), Thalassiosira eccentrica (2.3 x 106 cels L-1) y Chaetoceros spp. (9.65 x 105 cels L-1). Se identificaron tres especies toxicas: una pertenece al complejo P. pseudodelicatissima, P. fraudulenta y P. pungens. La fucoxantina, con un pico de 9.3 μg L-1, fue el pigmento dominante durante el florecimiento. La temperatura superficial del mar en el transcurso del evento drasticamente se incremento de 19.0 °C a 27.0 °C, con valores de nitrogeno inorganico de 1.0 ± 0.6 μM y Si(OH)4 de 15.5 ± 8.0 μM. El contenido de acido domoico determinado por HPLC-UV fue bajo tanto en muestras de red con un rango de 24.0 a 52.0 ng por filtro como en tejido de almeja chocolata Megapitaria squalida (0.55 μg g-1) y almeja blanca Dosinia ponderosa (0.06 μg g-1). El analisis ...

Algal Research, 2021

Abstract This study assessed the early effects of riboflavin and lumichrome produced by the bacte... more Abstract This study assessed the early effects of riboflavin and lumichrome produced by the bacterium Azospirillum brasilense on mitigating the stress of salinity on the growth and metabolic status of Chlorella sorokiniana. C. sorokiniana was grown in a synthetic growth medium (SGM) at three salt levels (0%, 1.5%, and 3% NaCl) and under four treatments: (1) C. sorokiniana growing alone; (2) C. sorokiniana co-cultured with A. brasilense; (3) C. sorokiniana supplemented with synthetic riboflavin; and (4) C. sorokiniana supplemented with lumichrome, mimicking the riboflavin and lumichrome concentrations naturally produced by A. brasilense. Cell density, total carbohydrates, total and neutral lipids, chlorophyll a and b, and carotenoids contents, proline accumulation, and activity of superoxide dismutase (SOD) were analyzed. Increasing salinity affected the growth rate, cell size, and cell density of C. sorokiniana, induced proline accumulation, and made the total-lipid concentration higher than the carbohydrate concentration. The neutral lipids, chlorophylls, and SOD showed higher values at 1.5% NaCl. Riboflavin and lumichrome showed significant effects on the analyzed variables. Lumichrome at 1.5% salinity induced an early but transient growth response, making carbohydrate production higher than the total lipid production. By contrast, riboflavin enhanced SOD activity and reduced proline accumulation at all the salinity levels. Longer incubation times resulted in effects similar to those of lumichrome in the analyzed metabolites, thus suggesting the conversion of riboflavin into lumichrome. The microalga−bacteria co-cultures at all salinity levels exhibited growth promotion, with consistent effects at the different incubation times and superior magnitude to that presented by lumichrome or riboflavin alone, showing an alleviating effect of the saline stress through osmoregulation with increased carbohydrate concentration and antioxidant activity, but not with increased proline or total lipid concentration. These findings suggest that Azospirillum brasilense can be used as an alternative to mitigate saline stress effects in microalgae cultured in low-salinity waters.

Algal Research, 2019

This study is dedicated to the memory of Prof. Yoav Bashan (1951-2018), leading figure in the fie... more This study is dedicated to the memory of Prof. Yoav Bashan (1951-2018), leading figure in the field of Plant Growth-Promoting Bacteria (PGPB) for environmental purposes, and founder of Bashan Institute of Science, USA. Prof. Bashan passed away during the edition of the manuscript.

Frontiers in Marine Science, 2019

and Fernández-Herrera LJ (2019) The State of Knowledge of Harmful Algal Blooms of Margalefidinium... more and Fernández-Herrera LJ (2019) The State of Knowledge of Harmful Algal Blooms of Margalefidinium polykrikoides (a.k.a. Cochlodinium polykrikoides) in Latin America.

Journal of Marine Biology, 2019

In the exploration of the hydrothermal system of the Guaymas Basin (GB) between 27° 00′ 35′′ and ... more In the exploration of the hydrothermal system of the Guaymas Basin (GB) between 27° 00′ 35′′ and 27° 00′ 50′′ N and 111° 24′ 15′′ and 111° 24′ 40′′ W in the Gulf of California, carried out on the R/V Atlantis and of the DSRV/Alvin in October 2008, four cores of surface sediments were obtained to analyse photosynthetic pigments at two locations with contrasting extreme conditions: Oil Town and Great Pagoda. We identified nine pigments: Chlorophyll-a, Phaeophytin-a, Phaeophorbide-a, Pyropheophytin-a (degradation Chlorophyll-a products), β-Carotene, Alloxanthin, Zeaxanthin, Diadinoxanthin, and Prasinoxanthin (carotenoids). The maximum pigment concentration was registered in the Great Pagoda (10,309 ng/g) and the minimum in Oil Town (918 ng/g). It is demonstrated that photosynthetic pigment profiles in surface sediments depend on the heterogeneity of the extreme conditions of each site caused mainly by temperature and bacterial substrates. Therefore, there were significant differences (...

Frontiers in Marine Science, 2019

In this review we summarize the current state of knowledge regarding taxonomy, bloom dynamics, to... more In this review we summarize the current state of knowledge regarding taxonomy, bloom dynamics, toxicity, autoecology, and trophic interactions, of saxitoxin producing dinoflagellates in this region. The dinoflagellates Gymnodinium catenatum, Pyrodinium bahamense and several species of Alexandrium are saxitoxin producers, and have been responsible of paralytic shellfish poisoning in different regions of Latin America, causing intoxications and important fisheries losses. The species distribution differ; most harmful algal blooms of G. catenatum are from the northern region, however this species has also been reported in central and southern regions. Blooms of P. bahamense are mostly reported in North and Central America, while blooms of Alexandrium species are more common in South America, however this genus is widely spread in Latin America. Species and regional differences are contrasted, with the aim to contribute to future guidelines for an international scientific approach for research and monitoring activities that are needed to increase our understanding of paralytic toxin producing dinoflagellates in this region.

Esta revisión da a conocer el estado de conocimiento de los estudios de Florecimientos Algales No... more Esta revisión da a conocer el estado de conocimiento de los estudios de Florecimientos Algales Nocivos (FAN) en el ámbito marino en México, con el objeto de evaluar la manera de optimizar los recursos destinados para el estudio de FAN en nuestro país, identificando líneas no abordadas y proponiendo mejoras en las actividades de monitoreo y de investigación que puedan aumentar nuestro conocimiento sobre la complejidad de FAN en nuestras costas. Se realizó una búsqueda bibliográfica de 1940 a 2011 consultando bases de datos, reuniones académicas y libros especializados. El número de investigadores e instituciones involucrados con el estudio de FAN se ha incrementado significativamente en las últimas décadas, lo cual se ve reflejado en el número y calidad de las publicaciones. Sin embargo, la mayoría de los programas y actividades de investigación están basados en muestreos puntuales y programas de investigación a corto plazo, enfocándose a pocas especies de FAN. Actualmente, varias líneas de investigación relacionadas con los FAN se han abordado pobremente o no se han considerado como son los estudios sobre quistes, alelopatía, transportación de especies por aguas de lastre, efecto del cambio climático, utilización de imágenes de satélite, uso de herramientas moleculares, análisis socioeconómicos y estrategias de mitigación, entre otros. Este análisis muestra que ha habido un avance significativo en el estudio de FAN en México, si bien la manera de abordar su estudio ha sido individualizada y dispersa. Se obtendría un mayor avance si se coordinaran los esfuerzos entre los diversos investigadores e instituciones para optimizar los recursos disponibles para el estudio de los FAN.

Hidrobiológica: [revista del Departamento de Hidrobiología]

Food Additives & Contaminants: Part A, 2015

The paralytic shellfish toxin (PST) profiles of Gymnodinium catenatum Graham have been reported f... more The paralytic shellfish toxin (PST) profiles of Gymnodinium catenatum Graham have been reported for several strains from the Pacific coast of Mexico cultured under different laboratory conditions, as well as from natural populations. Up to 15 saxitoxin analogues occurred and the quantity of each toxin depended on the growth phase and culture conditions. Previous analysis of toxin profiles of G. catenatum isolated from Mexico have been based on post-column oxidation liquid chromatography with fluorescence detection (LC-FLD), a method prone to artefacts and non-specificity, leading to misinterpretation of toxin composition. We describe, for the first time, the complete toxin profile for several G. catenatum strains from diverse locations of the Pacific coast of Mexico. The new results confirmed previous reports on the dominance of the less potent sulfocarbamoyl toxins (C1/2); significant differences, however, in the composition (e.g., absence of saxitoxin, gonyautoxin 2/3 and neosaxitoxin) were revealed in our confirmatory analysis. The LC-MS/MS analyses also indicated at least seven putative benzoyl toxin analogues and provided support for their existence. This new toxin profile shows a high similarity (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 80%) to the profiles reported from several regions around the world, suggesting low genetic variability among global populations.

Ciencias Marinas, 2013

Temperature and nutrient concentrations were measured during a mixed bloom of Noctiluca scintilla... more Temperature and nutrient concentrations were measured during a mixed bloom of Noctiluca scintillans and Gymnodinium catenatum in La Paz Bay, Gulf of California. Under laboratory conditions, we offered three concentrations of G. catenatum (312, 625, or 1015 cells mL–1) to 0.53 N. scintillans cells mL–1 to study predation rates. Experiments were carried out with 750 mL of culture during a fiveday period. Sea surface temperature clearly showed a transitional period from colder to warmer water during the bloom. Field and laboratory data showed that N. scintillans fed on G. catenatum. During the trial, more than 70% of N. scintillans cells contained G. catenatum cells in their vacuoles. Ingestion rates varied; the highest ranged from 30 to 40 G. catenatum cells h–1 in each N. scintillans cell. A clear relation to the concentration of the diet was not evident. Low values of 1 to 3 G. catenatum cells h–1 in each N. scintillans cell were typical at the end of the trial. Noctiluca scintillan...