Hidrobiológica (E-Journal)
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Antibiotic resistance of neustonic and planktonic fecal coliform bacteria isolated from two water basins differing in the level of pollution
Get PDFAntibiotic resistance of fecal coliform bacteria isolated from the surface microlayer and the subsurface layer of a polluted pond and a non-polluted lake was studied. On the basis of the conducted studies it was stated that the isolated fecal coliform bacteria from both aquatic basins showed various resistance to tested antibiotics. Enteric bacteria were the most resistant to ampicillin, clindmycin, novobiocin, penicillin and the most sensitive to amikacin, gentamycin, neomycin and oxytetracycline. Fecal coliform bacteria inhabiting the pond showed similar resistance to the majority of tested antibiotics than coliform bacteria isolated from the lake. The multiple antibiotic resistance (MAR) index value for fecal coliform bacteria was higher in the pond than the lake. Only in a downtown pond fecal coliform bacteria isolated from the subsurface water were more resistant to tested antibiotics than those inhabiting the surface microlayer. The antibiotic resistance level of the bacteria depended on the chemical structure of antibiotics
Estudios sobre el manejo e incubación de huevos del pargo flamenco Lutjanus guttatus (Pisces, Lutjanidae)
Get PDFEgg handling and incubation are short but important procedures in juvenile fish production technologies. To determine appropriate practices for egg handling and incubation in the spotted rose snapper Lutjanus guttatus (Steindachner, 1969), three experiments were carried out in 100-L fiberglass conical cylinder tanks. Eggs were incubated with and without water flow (30% volume/h), at two densities (250 eggs/L and 1000 eggs/L), and with and without formaldehyde 10-ppm prophylactic treatment for 1-h prior to incubation. Total hatching and larvae survival percentages were not significantly different between the treatments with and without water flow, while results for larvae survival at hatching time and 48 h post-hatch stage were significantly better without water flow. For incubation at two different densities, all examined performance indexes were significantly better at the lower density, except for larvae survival at 48 h after hatching. The eggs with and without prophylactic treatment were not significantly different in all analyzed survival indexes at hatching time and 48 h post-hatch. Total length was significantly different in all treatments at hatching time and 48 h post-hatch, except in the incubation without water flow. The longest larvae were obtained in the experiment with prophylactic treatment.La manipulación y la incubación de huevos de peces son procedimientos simples pero importantes en las tecnologías de producción de juveniles. Para determinar prácticas apropiadas de manejo y de incubación de los huevos del pargo flamenco Lutjanus guttatus (Steindachner, 1869), se realizaron tres experimentos en tanques cilindro-cónicos de fibra de vidrio de 100 L. Los huevos fueron incubados con y sin flujo de agua (30%/h), a dos densidades (250 huevos/L y 1000 huevos/L) y con o sin tratamiento profiláctico de formalina 10 ppm por una hora previo a la incubación. Los porcentajes de eclosión total y larvas vivas normales (larvas viables) al momento de la eclosión no fueron diferentes significativamente entre los tratamientos con flujo y sin flujo. Mientras que los porcentajes de larvas viables al momento de la eclosión y a las 48 h post-eclosión mostraron significativamente mejores resultados en el tratamiento sin flujo de agua. En la incubación a dos densidades todos los índices analizados fueron significativamente mejores en la densidad de 250 huevos/L, excepto en larvas viables a las 48 h post-eclosión. Los huevos con y sin tratamiento profiláctico, no presentaron diferencias significativas para todas las variables de supervivencia al momento de la eclosión y a las 48 h post-eclosión. La longitud total de larvas fue diferente significativamente entre cada uno de los tratamientos al momento de la eclosión y a las 48 h, excepto en la incubación sin flujo de agua. Las larvas de mayor tamaño se obtuvieron en el experimento con sobre tratamiento profiláctico
Modelación numérica de la hidrodinámica, del oxígeno disuelto y la demanda bioquímica de oxígeno en sistemas con vegetación
Get PDFThis work deals with the implementation of a numerical model to simulate hydrodynamics and transport of pollutants in flows where submerged vegetation is present. The model is based on the Shallow-Water Equations to calculate the mean velocities, emphasizing calculations of the shear stress produced by both the vegetation and turbulence. The Advection-Diffusion-Reaction Equation is used to calculate the transport of the Biochemical Oxygen Demand and the Dissolved Oxygen. The main objective is to simulate the transport of these substances and the pollution filtering and reaereation functions of plants in water bodies such as wetlands. In the obtained velocity fields, the change of the behavior due to the restriction imposed by the vegetation can be seen. The BOD and DO concentrations are influenced by the residence time and the reaereation from the atmospheric exchange and plants breathing. As a conclusion, the model represents very precisely the behavior of dissolved substances transport in flows with presence of vegetation and can be applied to different ecosystems, being capable to predict the path and fate of pollution.El presente trabajo trata sobre la implementación de un modelo numérico para simular la hidrodinámica y el transporte de contaminantes en sistemas donde existe vegetación, tanto sumergida como emergente. Dicho modelo se basa en las ecuaciones de aguas someras para el cálculo de las velocidades del flujo, haciendo énfasis en la evaluación del esfuerzo cortante de arrastre de las plantas y en la turbulencia; así como en la ecuación de advección-difusión-reacción para la simulación del transporte de sustancias disueltas. En este trabajo se presenta el cálculo del transporte de la Demanda Bioquímica de Oxígeno y del Oxígeno Disuelto. El objetivo principal es reproducir las funciones de filtrado de contaminación y reaereación que cumplen las plantas en cuerpos de agua, como los humedales. En los resultados obtenidos del campo de velocidades se aprecia el cambio de comportamiento por la restricción al flujo que impone la vegetación. Las concentraciones de DBO y OD varían debido al tiempo de residencia y a la reaereación producida por el intercambio atmosférico y la respiración de las plantas. Se concluye que el modelo representa de manera óptima el comportamiento del transporte de sustancias disueltas en flujos con presencia de vegetación y que se puede aplicar a la gran variedad de ecosistemas, siendo capaz de predecir la ruta y destino de la contaminació
Genetic damage in Goodea atripinnis (Goodeidae) and persistent organic-compounds in both Chapala and Sayula Lakes, in Mexico
Get PDFPOPs are a group of chemicals with genotoxic capacity, found as contaminants in many water bodies. Given the high chemical pollution of Chapala Lake (including POPs), consumption of this water poses a genotoxic risk for people in the Guadalajara metropolitan area. Concentrations of POPs were quantified in water from Chapala Lake, Sayula Lake and in the liver of Goodea atripinnis on two seasons of the year: the dry and rainy seasons of 2006. Chromatographic analysis of the water showed very low concentrations of POPs and variations from one season to another. The increase of methoxychlor, 2,4 D and DDT is notable, indicating that they are dragged into the water bodies during the rainy season. POPs were detected in the liver of fish from both lakes; however, 2,4 D in the liver of fish from Chapala (0.02 ppm) is 10 times as concentrated as in Sayula (0.002 ppm). The evaluation of genetic damage by alkaline comet assay in hepatocytes during the dry season showed significant genetic damage (p < 0.01) in fish from the two reservoirs, probably due to 2,4 D. In the rainy season there was a significant difference (p < 0.01) in the case of Sayula but not for Chapala. Genetic damage in Sayula can be attributed to other substances with a mutagenic capacity different to that of POPs
Intercalibración de las pruebas con Daphnia magna y Pseudokirchneriella subcapitata en México: herramientas potenciales para el monitoreo ambiental
Get PDFIn Mexico, as in other developing countries, the knowledge about pollution status and its effects in local ecosystems has been developed following specific research goals that make use of different methodologies. Since there are information gaps in this topic, it is important to promote the broad use of standardized ecotoxicity protocols as regulatory tools to establish comprehensive environmental protection measures. From this perspective, the goal of this study was to demonstrate, through intercalibration exercises, with previous capacity homologation workshops, the potential of Daphnia magna and Pseudokirchneriella subcapitata (known before as Selenastrum capricornutum) protocols, to generate analytically reliable results in laboratories with little experience in this field. This will allow the promotion of bio-analytical tools in Mexico for environmental monitoring, which will favor the integral evaluation of pollution in water bodies. The results of the laboratories internal calibration exercises demonstrated that in a short term it is possible to achieve an acceptable analytical repeatability and an adequate performance of the protocols, which sustains the idea that these protocols are good environmental monitoring tools, even in countries where today there are very few qualified human resources and laboratories fit for this purpose.En México, como en otros países en desarrollo, el conocimiento sobre el grado de contaminación y sus efectos en los ecosistemas locales se ha generado siguiendo objetivos de investigación específicos que emplean metodologías de distinta naturaleza. Dado que aún existen vacíos de información en el tema, es importante impulsar el uso generalizado de pruebas ecotoxicológicas que empleen protocolos estandarizados y que sirvan como herramientas regulatorias para establecer medidas integrales de protección al ambiente. Por lo anterior, el presente estudio tuvo como objetivo demostrar, a través de ejercicios de intercalibración, previo desarrollo de talleres de homologación de capacidades, el potencial de los protocolos de ensayo con Daphina magna y Pseudokirchneriella subcapitata (antes Selenastrum capricornutum) para generar resultados confiables en laboratorios con poca experiencia en este campo. Esto permitirá impulsar el empleo de herramientas bioanalíticas en México para el monitoreo ambiental, las cuales favorecen la evaluación integral de los problemas de contaminación en los cuerpos de agua. Los resultados de los ejercicios de calibración interna de los laboratorios demostraron que en un corto plazo es posible lograr una repetibilidad aceptable en las pruebas y un desempeño adecuado de los protocolos, lo cual apoya la idea de que estos protocolos son pertinentes para su empleo en programas de monitoreo ambiental, aún en países donde actualmente se cuenta con pocos recursos humanos capacitados y laboratorios aptos para tal fin
Parches del zooplancton asociados con dos florecimientos algales nocivos en Bahía de Banderas
Get PDFRoutine samplings of the Bahia de Banderas plankton communities allowed to detect two Mirionecta rubra y Pseudonitzschia sp red tides events during 2011. In order to identify the most representative zooplankton populations associated with the first event, fourteen standard zooplankton tows were made, including two replicates in the reddest waters. Tows were made with a standard net of 40 cm mouth diameter, and 335 µ mesh size. The highest zooplankton abundance was not recorded in the most colored waters. On the contrary, a sample collected in the most colored waters during the second event revealed a high zooplankton abundance of 5 million ind/m³, which is an unusual density value for the epipelagic zooplankton in the Mexican Pacific. This abundance was at least three orders of magnitude higher than those recorded in other epipelagic zooplankton patches in the Pacific Ocean coastalzone. The zooplankton community structure of both events was dominated by the calanoid copepod Acartia tonsa. Red tide events persisted locally until the end of April, when stranded globe fish were detected on the beach. The sequence of these events appears to be associated with the occurrence of upwellings previously reported in the Cabo Corrientes area.Muestreos rutinarios del plancton de Bahía de Banderas permitieron detectar dos eventos de Mirionecta rubra y Pseudo-nitzschia sp durante 2011. Para identificar las poblaciones de zooplancton más representativas asociadas con el primer evento, se recolectaron catorce unidades de muestras a lo largo de la zona costera, incluyendo dos réplicas sobre la mancha. Los arrastres se hicieron con una red estándar de 40 cm de diámetro de boca y malla de 335 µ. Las máximas abundancias de zooplancton no se registraron en la zona de mayor coloración. De manera contrastante, la recolección de una muestra de agua durante el segundo evento hizo evidente una elevada abundancia de zooplancton que alcanzó un valor de 5 millones de ind/m3 , un valor inusual en zooplancton epipelágico del Pacifico mexicano. Esta abundancia fue al menos tres órdenes de magnitud más alta que las registradas en otros parches reportados en diversas zonas costeras del Océano Pacifico. La estructura del zooplancton de ambos eventos fue dominada por el copépodo Acartia tonsa. Eventos intermitentes persistieron localmente hasta finales de abril, cuando se detectó el varamiento de peces globo en las playas. La secuencia de estos eventos parece estar asociada con la ocurrencia de surgencias previamente reportadas en la región de Cabo Corrientes
Distribución y abundancia de las larvas de peces en el sistema lagunar de Bahía Magdalena-Almejas, Baja California Sur, México
No full textThe present paper reports the specific composition and distribution of fish larvae, in order to know the community structure, and seasonal variability, related to the sea surface temperature and zooplankton biomass distributions at Magdalena-Almejas lagoon system, B. C. S. Sampling was carried out during winter-spring and summer-autumn 1989. The taxonomic analysis allowed the identification of 42 taxa belonging to 24 families of fishes. Larvae of Quietula y-cauda were dominant (61.01%) of the total abundance, followed by Gerreidae (15.5%) and Sardinops sagax (9.94%). Analysis of the assemblages defined two groups stations that identify different environmental persistent conditions throughout the year. One group with lagooner features and characterized by resident tax like gobies, blennies and flatfish larvae, in coincidence with highest zooplankton biomass. The other group located at the main access mouth to Magdalena Bay with oceanic influence was characterized mainly by small pelagic fish larvae asociated with lowest temperature and zooplankton biomass. Sucession of species was observed in both groups stations throughout the year, as a result of seasonal sea surfce temperature changes and the habitat in wich the adults spawn.En este estudio se presenta la riqueza de especies y distribución de la abundancia de las larvas de peces que serán utilizados para analizar la estructura de la comunidad y cambios estacionales asociados a la temperatura y distribución de la biomasa zooplánctica en el sistema lagunar Bahía Magdalena-Almejas, B. C. S. Los muestreos se llevaron a cabo durante el invierno-primavera y verano-otoño de 1989. El análisis taxonómico permitió la identificación de 42 formas específicas que pertenecen a 24 familias de peces. Las larvas de Quietula y cauda fueron dominantes con el 61.01% de la abundancia total de larvas, seguidas por Gerreidae (15.55%) y Sardinops sagax (9.94%). El análisis de agrupamientos definió la existencia de dos grupos principales de estaciones que identifican a dos ambientes diferentes que persisten a lo largo del año. Uno propiamente lagunar caracterizado por larvas de góbidos, blénidos y peces planos en coincidencia con núcleos de lata densidad de zooplancton, y el otro ubicadoo en la boca principal de acceso con influencia oceánica, que fue caracterizado por larvas de pelágicos menores principalmente, asociado con valores d menor temperatura y biomasa zooplánctica. En ambos grupos de estaciones se refleja una sensación de especies a lo largo del año, como resultado de los cambios estacionales de la temperatura superficial y la preferencia del habitat del desove de las especies
Descarte y captura incidental de la flota atunera mexicana menor de 363 tm de capacidad de acarreo en 1996
No full textDue to the importance of fishing in a responsible manner, following FAO's Code of Conduct for Responsaible Fishing, there is the need to estimate the incidental catch and discard of all fisheries worldwide. The fishing logbooks of the mexican tunaboats with less than 363 metric tons of carrying capacity were analyzed to estimate the level of tuna discards and incidental catches during 1996. Due to the absence of scientific observers aboard, direct and indirect methods were used. The tun discard estimate varied fro 190 to 230 metric tons, and the incidental catch estimate from 146 to 262 metric tons of different species or group os species. The discard estimate represents approximately 1.3 to 1.6% of total catch, and the incidental catch estimate about 1.0 to 1.8%. These levels are low compared to worldwide and other tun fisheries discard and incidental catch estimates, but the damage they cause to the populations affected are subject to further population dynamic studies.Debido a la importancia de realizar actividades pesqueras responsables, de acuerdo al Código de Conducta para l Pesca Responsable de la FAO, es de gran necesidad el contar con estimaciones de la captura incidental y descartes en todas las pesquerías a nivel mundial. En el presnte trabajo se aalizaron bitácoras de pesca de embarcaciones atuneras mexicanas menores de 363 tm de capacidad de acarreo para obtener una estimación del nivel de descarte de atunes y captura incidental en 1996. Debido a la ausencia de observadores científicos a bordo, se utilizaron métodos directos e indirectos para las estimaciones. Se estimó un descarte de atunes con un intervalo de 190 a 230 toneladas métricas, y captura incidental con un intervalo de 146 a 262 toneladas métricas de diferentes especies o grupos de especies. El descarte representa entre el 1.3 y 1.6% de la captura total, y la captura incidental entre el 1.0 y 1.8%. Estos niveles resultan bajos comparados con los niveles mundiales y con los de otras pesquerías de túnidos, pero el daño que causan a las poblaciones está sujeto a estudios futuros sobre la dinámica poblacional de cada especie descartada o capturada incidentalmente
Pathogenic vibrios in the oyster Crassostrea virginica in the lagoon system of Mandinga, Veracruz, Mexico
Get PDFOyster consumption has been associated to the transmission of pathogenic bacteria, including those from the genus Vibrio. The objective of this investigation was to determine the concentrations of Vibrio parahaemolyticus and V. alginolyticus in Crassostrea virginica from the lagoon system of Mandinga, Veracruz, and their relationships with salinity and water temperature. Only the periods of greater production and consumption of oysters were examined: the dry and rainy seasons during 2008. Four sampling sites were selected, from which three samples were collected per site per season, resulting in a total of 24 samples. Each sample consisted of 30 oysters of commercial size that were subsequently analyzed using serial dilution. Biochemical analysis of the resulting bacterial colonies revealed concentrations of V. parahaemolyticus and V. alginolyticus ranged from < 3 to 150 MPN/g. A positive correlation was observed between temperature and the concentration of V. parahaemolyticus (r = 0.69, p < 0.05), while the correlation with salinity was negative (r = -0.68, p < 0.05). No significant correlations between the concentration of V. alginolyticus and water temperature and salinity were observed for the rainy season. The main contribution of this paper is to establish safe areas and periods for oyster extraction
Phylogenetic relationships among five marine Catfish species (Pisces: Ariidae) from Mexico
Get PDFThe systematics of the marine catfish of the family Ariidae is controversial because at the present time the number of species and genera in the family, or their relationships, remain uncertain. Phylogenetic relationships among five representative species of marine catfish of the family Ariidae from both the Pacific and the Atlantic coasts of Mexico were assessed by the analysis of the variability in 21 alloenzymatic loci, and by the comparison of the electrophoretic patterns of whole muscle proteins. Interspecific genetic divergence levels obtained by both electrophoretic methods showed a clear separation among the genera Cathorops, Bagre and Ariopsis, as well as in the studied species of Cathorops and Ariopsis, with Bagre marinus showing a greater genetic similarity with the Ariopsis group. Finally, our results contribute to the definition of the presence of this species in the coasts of the Gulf of Mexic