Riqueza y distribución de las diatomeas epilíticas indicadoras de contaminación en el río Angulo afluente del río Lerma, México

Background. The Angulo River has been subject to environmental deterioration as a result of agriculture practices and industrial discharges to its tributary. Goal. Determine the species of diatoms that indicate contamination and their distribution in the Angulo river, a tributary of the Lerma river. Methods. Twelve sites including 2 springs were selected during the low-water and post-rain periods of 2005. The samples were obtained by scraping the rocks to separate the attached diatoms. These were cleaned by oxidizing the sample with hydrochloric acid and hydrogen peroxide; permanent preparations were made with Naphrax® resin, for review with light microscopy. Results. 50 taxa belonging to 20 genera were identified, of which 5 species belong to central forms and 45 to pennate species. The taxa present in both periods were Achnanthidium minutissimum, Amphora pediculus, Luticola geoppertiana, Nitzschia amphibia, Nitzschia dissipata var. dissi- pata, Pleurosira laevis, Staurosira pinnata and Ulnaria ulna. The temperature, pH, dissolved oxygen and total dissolved solids in the Angulo river presented spatial variations and with it the species records. Conclusions. Representative taxa of eutrophic and non-eutrophic environments were found throughout the tributary, such as Nitzschia palea and Amphora pediculus, respectively. This study has provided relevant information re- garding the presence and distribution of diatom species that can be used as bioindicators of environmental conditions. specific.Antecedentes. El río Ángulo ha estado expuesto a un deterioro ambiental como consecuencia de las descargas industriales a su afluente. Objetivo. Determinar las especies de diatomeas indicadoras de contaminación y su distribución en el río Angulo afluente del río Lerma. Métodos. Se seleccionaron 12 sitios incluyendo 2 manantiales durante los periodos de estiaje y post lluvias del año 2005. Las muestras se obtuvieron raspando las rocas para separar las diatomeas adheridas. Estas se limpiaron oxidando la muestra con ácido clorhídrico y peróxido de hidrógeno; se elaboraron preparaciones permanentes con la resina Naphrax®, para su revisión con microscopia óptica. Resultados. Se identificaron 50 taxones pertenecientes a 20 géneros de los cuales 5 especies pertenecen a formas centrales y 45 a las pennadas. Los taxones espresentes en ambos periodos fueron Achnanthidium minutissimum, Amphora pediculus, Luticola geoppertiana, Nitzschia amphibia, Nitzs- chia dissipata var. dissipata, Pleurosira laevis, Staurosira pinnata y Ulnaria ulna. La temperatura, pH, oxígeno disuelto y sólidos disueltos totales en el río Angulo presentaron variaciones espaciales y con ello los registros de las especies. Conclusiones. A lo largo del afluente, se encontraron taxones representativos de ambientes eutrofizados y no eutrofizados como Nitzschia palea y Amphora pediculus. Este estudio aporta información relevante en cuanto a la presencia y distribución de especies de diatomeas que pueden ser utilizadas como bioindicadores de condiciones ambientes específicos

Diatomeas epilíticas como indicadores de la calidad del agua en la cuenca alta del río Lerma, México

The upper Lerma River is the most economically important basin of Mexico because it is the region where 80 % of the commercial activity of the country takes place, with 3500 industries, 750,000 Ha of irrigated land and 14 cities with populations over 100,000 inhabitants. Despite this relevance, little or no waste water treatment is done in the basin, which results in high contamination levels. The present paper deals with the taxonomy and ecology of epilithic diatoms collected at 11 sites in the basin in the dry and post-rainy seasons of the 2003-2005 period. This is the first study in an environmental direction of the diatoms of the upper Lerma River basin and the information generated will be used to propose, in the short-term, a Lerma River diatom index (IDL), supporting water quality monitoring programs. 178 taxa were recognized, of which 112 taxa (63%) were cosmopolitan or widely distributed. The genera with most species were Nitzschia (34), Navicula (19), Gomphonema (15), and Pinnularia (11). The dominant species in the studied locations and study period were Eolimna subminuscula (Manguin) Moser, Lange-Bertalot et Metzeltin, Gomphonema parvulum (Kützing) Kützing, Navicula veneta Kützing, Nitzschia capitellata Hustedt, N. sublinearis Hustedt, N. umbonata (Ehrenberg) Lange-Bertalot and Sellaphora pupula (Kützing) Mereschkowsky, which are characterized as tolerant to α-mesosaprobic to polysaprobic conditions, and to high nitrogen content. Trends in distribution of diatom species in the sampling sites were explained by variations in environmental parameters such as depth, conductivity, pH, temperature, and total dissolved solids.La cuenca alta del río Lerma es la más importante de México desde el punto de vista económico, ya que en ella ocurren el 80 % de las actividades comerciales del país, con 3500 industrias diversas, 750,000 hectáreas de tierras de riego y 14 ciudades con poblaciones de más de 100,000 habitantes. El escaso o nulo tratamiento de las aguas residuales, trae como consecuencia una elevada contaminación. Este trabajo abordó el estudio taxonómico y ecológico de diatomeas epilíticas colectadas en 11 localidades de ésta cuenca, entre los años 2003-2005. Se trata del primer estudio con una orientación ambiental que se realiza sobre diatomeas de la cuenca alta de este río, y la información generada permitirá proponer en el corto plazo un índice diatomológico para el Río Lerma (IDL), que posibilite emprender programas de monitoreo de la calidad del agua. Se reconocieron 178 especies, de las cuales 112 taxones (63 %) fueron de amplia distribución. Los géneros con mayor número de especies fueron Nitzschia (34), Navicula (19), Gomphonema (15) y Pinnularia (11). Las especies dominantes en las localidades de estudio y en las épocas de recolecta fueron Eolimna subminuscula (Manguin) Moser, Lange-Bertalot et Metzeltin, Gomphonema parvulum (Kützing) Kützing, Navicula veneta Kützing, Nitzschia capitellata Hustedt, N. sublinearis Hustedt, N. umbonata (Ehrenberg) Lange-Bertalot y Sellaphora pupula (Kützing) Mereschkowsky, que se caracterizan por ser tolerantes a condiciones α-mesosapróbicas a polisapróbicas con alto contenido de nitrógeno. La distribución de las especies de diatomeas fueron explicadas por las variaciones en parámetros como profundidad, conductividad, pH, temperatura y sólidos disueltos totales.Fil: Garcia Segura, Virginia. Universidad Michoacana de San Nicolas de Hidalgo; MéxicoFil: Cantoral Uriza, Enrique A.. Universidad Nacional Autonoma de Mexico. Facultad de Ciencias; MéxicoFil: Israde, Isabel. Universidad Michoacana de San Nicolas de Hidalgo; MéxicoFil: Maidana, Nora Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Diatomeas epilíticas como indicadores de la calidad del agua en la cuenca alta del río Lerma, México

The upper Lerma River is the most economically important basin of Mexico because it is the region where 80 % of the commercial activity of the country takes place, with 3500 industries, 750,000 Ha of irrigated land and 14 cities with populations over 100,000 inhabitants. Despite this relevance, little or no waste water treatment is done in the basin, which results in high contamination levels. The present paper deals with the taxonomy and ecology of epilithic diatoms collected at 11 sites in the basin in the dry and post-rainy seasons of the 2003-2005 period. This is the first study in an environmental direction of the diatoms of the upper Lerma River basin and the information generated will be used to propose, in the short-term, a Lerma River diatom index (IDL), supporting water quality monitoring programs. 178 taxa were recognized, of which 112 taxa (63%) were cosmopolitan or widely distributed. The genera with most species were Nitzschia (34), Navicula (19), Gomphonema (15), and Pinnularia (11). The dominant species in the studied locations and study period were Eolimna subminuscula (Manguin) Moser, Lange-Bertalot et Metzeltin, Gomphonema parvulum (Kützing) Kützing, Navicula veneta Kützing, Nitzschia capitellata Hustedt, N. sublinearis Hustedt, N. umbonata (Ehrenberg) Lange-Bertalot and Sellaphora pupula (Kützing) Mereschkowsky, which are characterized as tolerant to α-mesosaprobic to polysaprobic conditions, and to high nitrogen content. Trends in distribution of diatom species in the sampling sites were explained by variations in environmental parameters such as depth, conductivity, pH, temperature, and total dissolved solids.La cuenca alta del río Lerma es la más importante de México desde el punto de vista económico, ya que en ella ocurren el 80 % de las actividades comerciales del país, con 3500 industrias diversas, 750,000 hectáreas de tierras de riego y 14 ciudades con poblaciones de más de 100,000 habitantes. El escaso o nulo tratamiento de las aguas residuales, trae como consecuencia una elevada contaminación. Este trabajo abordó el estudio taxonómico y ecológico de diatomeas epilíticas colectadas en 11 localidades de ésta cuenca, entre los años 2003-2005. Se trata del primer estudio con una orientación ambiental que se realiza sobre diatomeas de la cuenca alta de este río, y la información generada permitirá proponer en el corto plazo un índice diatomológico para el Río Lerma (IDL), que posibilite emprender programas de monitoreo de la calidad del agua. Se reconocieron 178 especies, de las cuales 112 taxones (63 %) fueron de amplia distribución. Los géneros con mayor número de especies fueron Nitzschia (34), Navicula (19), Gomphonema (15) y Pinnularia (11). Las especies dominantes en las localidades de estudio y en las épocas de recolecta fueron Eolimna subminuscula (Manguin) Moser, Lange-Bertalot et Metzeltin, Gomphonema parvulum (Kützing) Kützing, Navicula veneta Kützing, Nitzschia capitellata Hustedt, N. sublinearis Hustedt, N. umbonata (Ehrenberg) Lange-Bertalot y Sellaphora pupula (Kützing) Mereschkowsky, que se caracterizan por ser tolerantes a condiciones α-mesosapróbicas a polisapróbicas con alto contenido de nitrógeno. La distribución de las especies de diatomeas fueron explicadas por las variaciones en parámetros como profundidad, conductividad, pH, temperatura y sólidos disueltos totales.Fil: Garcia Segura, Virginia. Universidad Michoacana de San Nicolas de Hidalgo; MéxicoFil: Cantoral Uriza, Enrique A.. Universidad Nacional Autonoma de Mexico. Facultad de Ciencias; MéxicoFil: Israde, Isabel. Universidad Michoacana de San Nicolas de Hidalgo; MéxicoFil: Maidana, Nora Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Diatomeas perifíticas del lago de Pátzcuaro, Michoacán, México

Background. Lake Pátzcuaro has been exposed in the recent past to environmental deterioration with increasing eutrophication as a result of deforestation, indiscriminate use of agrochemicals, overfishing, unplanned urban growth, and sewage dumping. Goals. In order to contribute to the phycofloristic inventory of the Lake, we present the taxonomic description of the periphytic diatoms found, including morphometric information, meristic data, figures, as well as ecological and distributional notes. Methods. Sampling was carried out in four sites during two periods: after the rainy season (October 2004) and the dry season (May 2005); samples were gathered by scraping rooted and floating vegetation. Diatoms ´ thecae were cleared with hydrochloric acid and hydrogen peroxide; permanent slides were made with Naphrax® resin and analyzed through optic microscopy. Results. A total of 83 periphytic diatom species were recorded, including eight varieties and one form; 20 species (24%) represent the first records for Mexico and 57 (68.6%) are new to the study area. Sixty-two species (74.7%) have cosmopolitan distribution and six (7.2%) have tropical affinity. Species richness was slightly higher after the rainy season (October 2004) with a total of 69 taxa, compared to 65 species recorded during the dry season (May 2005). Among the sampling sites, the island of Janitzio had the highest diatom diversity (46 taxa during the dry season). Conclusions. Deterioration of Lake Pátzcuaro in the previous decades has taken a toll on the health ofits ecological system. Diatoms identified in this study indicate a clear tendency of eutrophication of the waterbody.Antecedentes. El Lago de Pátzcuaro ha estado expuesto en el pasado reciente a deterioro ambiental con incrementos en su eutroficación, como resultado de la deforestación, uso indiscriminado de agroquímicos, pesca excesiva, desarrollo urbano no planificado y la descarga de aguas negras. Objetivos. Con la finalidad de contribuir con el inventario ficoflorístico del lago, se presenta la descripción taxonómica de las diatomeas perifíticas encontradas, incluyendo datos morfométricosy merísticos, figuras, así como anotaciones ecológicas y de distribución. Métodos. Los muestreos se realizaron en cuatro sitios durante dos periodos distintos: postlluvias y estiaje (secas) durante octubre 2004 y mayo 2005. Las muestras se obtuvieron raspando la vegetación flotante y arraigada. Los frústulos de las diatomeas se limpiaron oxidando la muestra con ácido clorhídrico y peróxido de hidrógeno; se elaboraron preparaciones permanentes con la resina Naphrax®, que fueron analizadas con microscopía óptica. Resultados. Un total de 83 especies de diatomeas perifíticas fueron determinadas,incluyendo ocho variedades y una forma; 20 especies (24%) constituyen los primeros registros para México y 57 (68.6%) para el área de estudio. 62 especies (74.7%) son de distribución cosmopolita y seis (7.2%) de afinidad tropical. La riqueza de especies fue ligeramente mayor en la época de poslluvias (octubre 2004) con 69 taxones en total y 65 durante el estiaje (mayo 2005). Entre los sitios de muestreo, Janitzio presentó la mayor diversidad de diatomeas, con 46 taxones durante el estiaje. Conclusiones. El deterioro del lago de Pátzcuaro en las últimas décadas ha repercutido en la salud del ecosistema. Las diatomeas identificadas en este estudio, evidencian una clara tendencia a la eutrofización del cuerpo de agua

Epilithic diatoms (Bacillariophyceae) as indicators of water quality in the Upper Lerma River, Mexico

The upper Lerma River is the most economically important basin of Mexico because it is the region where 80 % of the commercial activity of the country takes place, with 3500 industries, 750,000 Ha of irrigated land and 14 cities with populations over 100,000 inhabitants. Despite this relevance, little or no waste water treatment is done in the basin, which results in high contamination levels. The present paper deals with the taxonomy and ecology of epilithic diatoms collected at 11 sites in the basin in the dry and post-rainy seasons of the 2003-2005 period. This is the first study in an environmental direction of the diatoms of the upper Lerma River basin and the information generated will be used to propose, in the short-term, a Lerma River diatom index (IDL), supporting water quality monitoring programs. 178 taxa were recognized, of which 112 taxa (63%) were cosmopolitan or widely distributed. The genera with most species were Nitzschia (34), Navicula (19), Gomphonema (15), and Pinnularia (11). The dominant species in the studied locations and study period were Eolimna subminuscula (Manguin) Moser, Lange-Bertalot et Metzeltin, Gomphonema parvulum (Kützing) Kützing, Navicula veneta Kützing, Nitzschia capitellata Hustedt, N. sublinearis Hustedt, N. umbonata (Ehrenberg) Lange-Bertalot and Sellaphora pupula (Kützing) Mereschkowsky, which are characterized as tolerant to ?-me­so­saprobic to polysaprobic conditions, and to high nitrogen content. Trends in distribution of diatom species in the sampling sites were explained by variations in environmental parameters such as depth, conductivity, pH, temperature, and total dissolved solids

The Younger Dryas black mat from Ojo de Agua, a geoarchaeologicalsite in Northeastern Zacatecas, Mexico

New explorations in the desert of northeastern Zacatecas, in central-northern Mexico, revealed dozens ofarchaeological and geoarchaeological sites. One of them, Ojo de Agua, contains the remains of a Pleis-tocene spring-fed hydrographic system located at the southeastern end of a large elongated endorheicbasin. The locality yielded a particularly dark, highly organic stratigraphic layer commonly known in theAmericas as Black Mat (BM), exposed on the natural profiles of a creek, but not associated with culturalmaterials. Several radiocarbon assessments confirmed the formation of the Ojo de Agua Black Mat duringthe Younger Dryas chronozone, with ten calibrated results clustering between 12,700e12,100 cal BP. Thismulti-proxy study confirmed the peculiarity of the deposit and found similarities and differences withother contexts of Younger Dryas age. The Ojo de Agua Black Mat (stratum C2) is far richer in charcoalspecks than the related strata, but lacks phytoliths, diatoms or ostracods. No further biological remainswere found in it, except for intrusive capillary roots. Clearly water-lain in a shallow pond, the stratumqualifies as a clayey silt with an acidic-to-neutral pH. Rich in heavy metals and with high contents oftitanium, the Ojo de Agua Black Mat yielded significant indicators of intense wildfires during the YoungerDryas, but produced no carbon spherules or nanodiamonds supposedly linked to the impact theory

Early Holocene ritual complexity in South America: the archaeological record of Lapa do Santo (east-central Brazil)

Early Archaic human skeletal remains found in a burial context in Lapa do Santo in eastcentral Brazil provide a rare glimpse into the lives of hunter-gatherer communities in South America, including their rituals for dealing with the dead. These included the reduction of the body by means of mutilation, defleshing, tooth removal, exposure to fire and possibly cannibalism, followed by the secondary burial of the remains according to strict rules. In a later period, pits were filled with disarticulated bones of a single individual without signs of body manipulation, demonstrating that the region was inhabited by dynamic groups in constant transformation over a period of centuries

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago. 2. Lake, Marine, and Terrestrial Sediments

Part 1 of this study investigated evidence of biomass burning in global ice records, and here we continue to test the hypothesis that an impact event at the Younger Dryas boundary (YDB) caused an anomalously intense episode of biomass burning at ∼12.8 ka on a multicontinental scale (North and South America, Europe, and Asia). Quantitative analyses of charcoal and soot records from 152 lakes, marine cores, and terrestrial sequences reveal a major peak in biomass burning at the Younger Dryas (YD) onset that appears to be the highest during the latest Quaternary. For the Cretaceous-Tertiary boundary (K-Pg) impact event, concentrations of soot were previously utilized to estimate the global amount of biomass burned, and similar measurements suggest that wildfires at the YD onset rapidly consumed ∼10 million km2 of Earth’s surface, or ∼9% of Earth’s biomass, considerably more than for the K-Pg impact. Bayesian analyses and age regressions demonstrate that ages for YDB peaks in charcoal and soot across four continents are synchronous with the ages of an abundance peak in platinum in the Greenland Ice Sheet Project 2 (GISP2) ice core and of the YDB impact event (12,835–12,735 cal BP). Thus, existing evidence indicates that the YDB impact event caused an anomalously large episode of biomass burning, resulting in extensive atmospheric soot/dust loading that triggered an “impact winter.” This, in turn, triggered abrupt YD cooling and other climate changes, reinforced by climatic feedback mechanisms, including Arctic sea ice expansion, rerouting of North American continental runoff, and subsequent ocean circulation changes

Variaciones del Pleistoceno en la fase lacustre de la localidad de San Bartolo Lanzados (Atlacomulco, México), evaluadas mediante estratigrafía de diatomeas

En el graben de Acambay se tiene la depresión lacustre de San Bartolo Lanzados, cuya evolución sedimentaria se desarrolla en el Pleistoceno donde existió un medio profundo con la intervención de episodios tanto volcánicos como tectónicos. Se estudió una columna estratigráfica de 10 metros, la cual se dividió en tres zonas. La primera y la tercera fueron muy estables y la segunda bastante inestable. Para la primera y tercera fases existieron condiciones de profundidad, por lo que destacaron las especies planctónicas de diatomeas y para la segunda fase se registró una dominancia de las especies perifíticas. Se registraron cenizas con edades de 1.20 ± 0.13 M.a., relacionadas con la edad de equinos, camélidos y proboscidios intercalados