Distribution of diatoms in central city of Beijing / 法医学杂志

OBJECTIVE@#To explore the quantity and distribution of diatoms in main rivers and lakes in Xicheng, Dongcheng, Chaoyang, Haidian, Fengtai and Shijingshan Districts of the city of Beijing.@*METHODS@#Water samples were examined through the method of disorganizing, which were collected from 16 rivers and lakes in the central city of Beijing in September and October 2011. Diatom species and proportions of water samples were analyzed using DotSlide microscope station.@*RESULTS@#A total of 10 species of diatoms were detected. Cyclotella, Synedra and Melosira etc. were found to be the dominant species via quantitative analysis. Significant differences were observed for diatom species and proportions among the different rivers and lakes. Melosira was found to be the dominant species in the Chang River; Synedra, in the Zhuan River, the Kunyu River and the Taoranting Park; Cyclotella, in the East Moat River, the Ba River, the Liangshui River and the Yongding River; and Navicula, in the Liangma River; Nitzschia, in the diversion canal of the Yongding River.@*CONCLUSION@#The features of distribution of diatoms in the central city of Beijing are outlined. The morphological and relative constituent ratio database of diatoms are established in central city of Beijing.

Estudio comparativo de la estructura del bacterioplancton en aguas del Mar Argentino mediante el método de pirosecuenciación 454 tag / A comparative study of bacterioplankton structure in Argentinian Sea waters by the 454 - tag pyrosequencing method

El presente estudio brinda la primera información sobre diversidad y abundancia de las comunidades microbianas en dos ambientes del Mar Argentino obtenida mediante la técnica de pirosecuenciación tag ribosomal 454. Dentro del dominio Bacteria, se observaron más de 4 600 secuencias únicas a partir de 36 188 amplicones de tags y se identificaron 280 filotipos. Además, se detectaron cerca de 2 700 secuencias únicas a partir de más de 47 700 tags pertenecientes al dominio Archaea, lo que definió sólo 5 filotipos diferentes. La distancia de Jaccard presentó valores de 0,6 para bacterias y de 0,2 para arqueas, esto indica mayor diferencia entre las bacterias en los dos sitios. En el ambiente marino los filotipos más dominantes fueron Bacteroidetes Flavobacteriaceae, Proteobacteria Gammaproteobacteria, Proteobacteria Rhodobacteraceae y Proteobacteria Rickettsiales SAR11, mientras que en el estuario predominaron Pseudoalteromonadaceae Pseudoalteromonas, Proteobacteria Gammaproteobacteria, Proteobacteria Shewanella y Proteobacteria Rickettsiales SAR11. Los 2 filotipos de arqueas encontrados en mayor proporción fueron Archaea Euryarchaeota y Archaea Crenarchaeota. Las secuencias tag más numerosas representaron taxa caracterizados previamente, aunque también se halló un elevado número de filotipos de gran diversidad y de baja abundancia, que forman parte de la denominada "biosfera rara", aún no explorada, que pueden tener un papel ecológico crucial.

The present study provides the first information about diversity and abundance of microbial communities in two environments of the Argentinian Sea by the 454 - tag pyrosequencing technique. We observed more than 4,600 unique bacterial sequences from 36,188 tag amplicons, forming 280 phylotypes. In addition, nearly 2,700 unique sequences from more than 47,700 tags identified as Archaea, defined only 5 different phylotypes. The Jaccard distance (0.6 for Bacteria and 0.2 for Archaea) indicated higher differences among Bacteria rather than among Archaea in both studied sites. The dominant phylotypes in marine environment were Bacteroidetes Flavobacteriaceae, Proteobacteria Gammaproteobacteria, Proteobacteria Rhodobacteraceae and Proteobacteria Rickettsiales SAR11; and Pseudoalteromonadaceae Pseudoalteromonas, Proteobacteria Gammaproteobacteria, Proteobacteria Shewanella, Proteobacteria Rickettsiales SAR11 in the estuary sampling site. Archaea Euryarchaeota and Archaea Crenarchaeota were the major archaeal phylotypes found. The most abundant tag sequences included previously characterized taxa, although we also retrieved a large number of highly diverse, low-abundant phylotypes which constitute a largely unexplored "rare" biosphere. These microorganisms could have a crucial ecological role.

La marea roja causada por el dinoflagelado Alexandrium tamarense en la costa Pacífica colombiana (2001) / The red tide caused by the dinoflagellate Alexandrium tamarense in the Colombian Pacific coast (2001)

El 26 de marzo de 2001 se registró por primera vez en las aguas del Pacífico colombiano, en el área de la Ensenada de Tumaco, la aparición de una marea roja producida por la especie Alexandrium tamarense con valores que superaron las 7.5 x 106 céls l-1 , la marea se mantuvo hacia la región oceánica, derivando en sentido sur-norte por efecto de las corrientes, hasta ser vista por ultima vez cerca a la Isla Gorgona, casi tres semanas después. Un año mas tarde, en marzo de 2002, una segunda proliferación, conformada por la misma especie, se reportó cerca de Cabo Corrientes con una concentración de 1.6 x 106 céls l -1 . Ambos casos estuvieron relacionados con la presencia de bajas temperaturas en la superficie del mar y no estuvieron asociadas con fenómenos de intoxicación y mortalidad

From April 26th to May 15th 2001, a large algae bloom was observed off Tumaco Bay on the Pacific coast of Colombia. This was the first harmful algae bloom (HAB) reported in the region, and reached Gorgona Island, about 120 km north. Ayear later, starting March 2002, an offshore HAB developed from Cabo Corrientes North to Solano Bay. The typical abundance during the blooms reached 7.5 x 106 cells l-1 for the 2001 event and 1.6 x 106 cells l-1 for the 2002 event. During both events, low temperature and high salinity were recorded. Typical measurements in the area are 27-27.5°C and 30-31.5 psu. Values observed during the two events were 24-24.6°C and 33-34 psu; 3°C below normal and more than 2.5 psu above average values. These conditions are indicative of local upwelling processes at the time of the events. On both occasions, cells corresponding to the Alexandrium catenella/fundeyense/tamarense complex represented 99-100% of the biomass. It was difficult to differentiate the cells from A. catenella, but the presence of short chains of only 4 cells (single cells represented most of the biomass) was suggestive of A. tamarense. Shape, dimensions, and detailed structure of the apical pore complex, first apical plate, posterior sulcal plate, and position of the ventral pore on plate 1’ of cells were consistent with the description of A. tamarense, which has not been reported in the tropical East Pacific. The Control Center of Pacific Contamination of the Maritime General Direction of the Colombian Navy has been monitoring the area since 1994 without finding this species or HABs. This leads us to consider the two events as caused by recently introduced species, where local upwelling processes favor permanent and cyclic HABs. However, during these two events, there were no reports of effects on marine biota or of human poisoning, probably because the blooms occurred some distance offshore and far from exploited shellfish beds