Hidrobiológica (E-Journal)
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Análisis funcional comparativo de fitobacterias productoras de ácido indolacético aisladas de plantas Lemna gibba de la zona chinampera de Xochimilco, México
Get PDFBackground. Bacteria endophytes, harmless symbiotic organisms that promote plant growth and development, have been considered useful tools for ecosystem restauration. Goals. The present study characterized bacteria endophytes isolated from Lemna gibba plants (collected in the chinampera area of Xochimilco canals over two seasons) according to the amount of indole acetic acid production. Methods. Twelve phytobacteria species were found; eight in plants collected through the drought season belonging to the genera Achromobacter, Bacillus, Deinococcus, Enterococcus, and four in plants collected during the rainy season of the genus Serratia. Results. According to their indole acetic acid production, four of the phytobacteria isolated from plants collected in the dry season were characterized as low producers and four as high producers. All the organisms obtained from plants gathered during the rainy season were classified as high producers. Conclusions. The presence of endophytic bacteria producing large amounts of indole acetic acid in Lemna gibba plants suggests that these organisms could promote plant development and act as potential bioinoculants.Antecedentes. Los endófitos bacterianos que habitan dentro de las plantas sin causar daño y promueven su crecimiento y desarrollo se han considerado herramientas útiles para la restauración de los ecosistemas. Objetivos. En el presente estudio se caracterizaron fitobacterias endófitas aisladas de plantas de Lemna gibba, colectadas en la zona chinampera de los canales de Xochimilco en dos temporadas, con base en la comparación de su producción de ácido indolacético. Métodos. Se evaluaron 12 fitobacterias en total; ocho aisladas de las plantas L. gibba colectadas en la temporada de sequía pertenecientes a los géneros Achromobacter, Bacillus, Deinococcus, Enterococcus, Pseudomonas y Rahnella. Las variedades restantes (pertenecientes al género Serratia) se obtuvieron de plantas colectadas en la temporada de lluvias. Resultados. De acuerdo con la producción de ácido indolacético, de las fitobacterias colectadas en la temporada de sequía, cuatro se clasificaron como bajas productoras y cuatro como altas productoras. Por otra parte, todos los organismos que se recolectaron en la temporada de lluvias se clasificaron como altos productores. Conclusiones. La presencia de fitobacterias endófitas altas productoras de ácido indolacético en Lemna gibba sugiere que son promotoras potenciales del desarrollo de dichas plantas y también que actúan como bioinoculantes potenciales
The relationship between the massive nesting of the olive ridley sea turtle (Lepidochelys olivacea) and the local physical environment at La Escobilla, Oaxaca, Mexico, during 2005
Get PDFBackground. Sea turtles of the genus Lepidochelys exhibit a complex and synchronous mass-nesting behavior termed arribada. Goals. This paper analyzes the local physical environment during the arribada events that occurred in 2005 at La Escobilla, Oaxaca, Mexico. Methods. Daily night patrols were conducted from May to November 2005, along the nesting zone. Daily records for air temperature and rainfall were obtained from the automatic weather station by the Comisión Nacional del Agua. Sea surface temperature and salinity fields were obtained from the Hybrid Coordinate Ocean Model (HYCOM), and surface ocean currents were obtained from the Asia-Pacific Data Research Center. Results. The analyses showed five arribada events during the period. A common feature was the presence of eddies and strong currents at the beginning of each arribada. A correlation of statistical significance was observed between the abundance of the arribada and the current speed (R = 0.93, R2 = 0.86, p = 0.04). The correlation with salinity showed values of R = 0.55, R2 = 0.31, p = 0.32, whereas correlation with rainfall was R = 0.53, R2 = 0.28, p = 0.14. A weak correlation was observed with air temperature (R = 0.35, R2 = 0.12, p = 0.59) and with sea surface temperature (R = 0.23, R2 = 0.05, p = 0.66). Conclusions. Although sea turtles are strong swimmers, the proximity to favorable oceanic currents generated by eddies might be related to the beginning of the arribada, considering that this current might provide energy savings and accumulatechemical compounds and food in the water column
Topography and coral community of the Sisal Reefs, Campeche Bank, Yucatán, México
Get PDFThe Campeche Bank, Gulf of Mexico, is a region with abundant coral reef ecosystems that havent been studied despite providing goods and services to some human communities. This work presents the topography, coral community and conspicuous reef associated fauna of three reefs of this region: Sisal, Madagascar and Serpiente. Three-D models of reef topography were derived using a GPS-echo-sounder coupled with geostatistical methods. The coral community was assessed through composition, richness, density and size of the colonies. The size of the Sisal Reefs was bigger than other Gulf of Mexico reefs. Hard coral colonies presented an average diameter of 9 cm and an average density of 9 colonies/m2 , whereas octocoral colonies averaged 11 cm in height and presented an average density of 24 colonies/m2 . We found 18 hard coral and 14 octocoral species, all of them distributed in the Atlantic Ocean; however, this work is the first to report Carijoa riseii and Phyllangia americana for the Mexican reefs of the Gulf of Mexico. The conspicuous fauna consisted in species with aquaculture potential (e.g. Octopus maya, Panulirus argus, Periclimenes pedersoni) and conservation priority (i.e. Eretmochelys imbricata). This study shows that these reefs are important centers of marine life and provides a baseline for future research
Bioenergética de juveniles de langosta de quelas rojas, Cherax quadricarinatus, alimentados con dos dietas artificiales
Get PDFThe metabolic response of juvenile Australian red claw lobster, Cherax quadricarinatus, fed two artificial diets (Rangen with 35% protein and Cherax1 with 32% protein of vegetable substrate), acclimated to the preferred temperature of 28 ° C, was evaluated in a dynamic respirometer, measuring oxygen consumption and ammonia excretion during fasting and feeding. Survival and growth were also determined. The energy consumed by juveniles in the food (C) was (mean ± s): 3614.1 ± 591.3 and 1967 ± 493.8 (J day-1 g-1 ) with Cherax1 and Rangen respectively. Energy eliminated in the feces (F) equivalent to 42.6 Joules by organisms that were fed Cherax1 represented a low energy loss in the percentage distribution, with a higher metabolic efficiency compared to the diet Rangen. The highest percentage of protein supplied through the food was channeled to growth, for all treatments, in which lobsters used a mixture of lipid-protein as the main energy substrate to meet their metabolic requirements. There was no difference in survival, but the juveniles fed Cherax1 had a higher specific growth rate and a 2.2 times higher weight gain than those fed with Rangen. The results show that the experimental diet Cherax1, formulated with plant products, can be considered as a high quality, efficient feed for this species, and that it is a good potential replacement for various commercial diets.Se evaluó la respuesta metabólica de juveniles de langosta australiana de quelas rojas, Cherax quadricarinatus, alimentados con dos dietas artificiales (Rangen con 35% de proteína y Cherax1 con 32% de proteína de sustrato vegetal), aclimatados a la temperatura preferida de 28 ºC en un respirómetro dinámico, midiendo el consumo de oxígeno y la excreción amoniacal durante el ayuno y la alimentación, y determinándose además la mortalidad y el crecimiento. La energía consumida por los juveniles en el alimento (C) fue de (3614.1 ± 591.3 y de 1967 ± 493.8 (J día-1 g-1 ) con Cherax1 y Rangen respectivamente. La energía eliminada en las heces (F) en los organismos que se alimentaron con Cherax1, equivalente a 42.6 Joules, representó una baja pérdida de energía en la distribución porcentual, presentando una mayor eficiencia metabólica en comparación con la dieta Rangen. El mayor porcentaje de la proteína suministrada a través del alimento ingerido fue canalizado hacia el crecimiento, ya que en los diferentes tratamientos los organismos utilizaron una mezcla de lípidos-proteínas como el principal sustrato energético para cubrir sus requerimientos metabólicos. No se encontraron diferencias en la mortalidad, pero los juveniles alimentados con Cherax1 presentaron un mejor índice de rendimiento, una mayor tasa de crecimiento específica y un incremento en peso 2.2 veces mayor. Los resultados obtenidos demuestran que la dieta experimental Cherax1 puede ser considerada como un alimento de buena calidad y eficiencia para esta especie, por lo que puede sustituir diversas dietas comerciales
Further remarks on the role of pro-thrombolites in the origin of coastal lagoons for Northwestern Mexico
Get PDFAlong the margins of coastal lagoons in Baja California Sur, Mexico, cyanobacteria-dominated communities form thick mats that eventually generate consolidated mud platforms or pro-thrombolites (unlithified thrombolites). Pro-thrombolite platforms grow seaward and form spits that alter water flow and promote sand deposition that develop into barriers, thus influencing coastal geomorphology, promoting lagoon formation. In this paper we provide evidences on the role of pro-thrombolites in the generation of coastal lagoons that includes different regions of NW Mexico where pro-thrombolite and/or thrombolithic platforms are common. In Bahía Magdalena, desiccating microbial mats are dominated by Microcoleus chthonoplastes Thuret ex Gomont and their remaining empty sheats occur together with lithified structures (thrombolites) cemented with micrite, considered of biotic origin. Previously proposed as a lacunar process, it is now suggested that pro-thrombolithic development leading to coastal lagoon formation actually occurs in non-lacunar environments with similar hidrological conditions. Likewise, this process is further enhanced once the coastal lagoon has been formed. We also suggest that the establishment of mangrove forests is indeed preceded by the formation of prothrombolithic platforms that provide a stabilized substrate for these plants in tropical and subtropical coastal lagoons
Ríos de la reserva de la biosfera El Triunfo, un diagnóstico para su restauración ecológica
Get PDFIn recent years the rivers in El Triunfo Biosphere Reserve (REBITRI) and its influence area have increased their riverbanks in width because of high precipitation events, resulting in economic and human losses in the states of Chiapas and Tabasco. The objective of the present work was to identify, characterize, and diagnose five river sections to assess their ecological status inside of this natural area. Multicriterion analysis was performed to define the sampling rivers sections; to quantify its changes and dynamism, were characterized geomorphological and hydrologically, and the GIS analysis was complete through an aerial photos comparison to obtain composition and configuration index of each riparian landscape patch. The results indicate that the response of these rivers sections is mainly influenced by lack of tree cover on slopes. Plant cover is essential to retain and absorb much water as product of the surface runoff on the slopes. Therefore, the hydrological restoration projects must consider the tree cover reestablishment to balance erosion and sediment process relationship.En los últimos años los ríos en la Reserva de la Biosfera El Triunfo (REBITRI) y su área de influencia, han incrementado su cauce a causa de eventos de alta precipitación, produciendo pérdidas humanas y económicas en los estados de Chiapas y Tabasco. El objetivo del presente trabajo fue identificar, caracterizar y diagnosticar el estado ecológico de cinco tramos de ríos dentro de esta área natural. Se realizó un análisis multicriterio para definir los tramos de muestreo; para cuantificar sus cambios y dinamismo, se caracterizaron geomorfológica e hidrológicamente y se completó el análisis SIG a través del trazado en planta de cada tramo para obtener índices de composición y configuración de cada componente del paisaje ripario. Los resultados indican que la respuesta de los ríos está mediada por la falta de cobertura vegetal arbórea, imprescindible como obstáculo para retener y absorber mayor cantidad de agua producto de la escorrentía superficial en las laderas de influencia de los segmentos de ríos analizados. Por lo tanto, los proyectos de restauración hidrológica deben considerar el restablecimiento de la cobertura vegetal para equilibrar la relación de los procesos de erosión y sedimentación
Toxic effects of Pseudanabaena tenuis (Cyanobacteria) on the cladocerans Daphnia magna and Ceriodaphnia dubia
Get PDFSome cyanobacteria can produce toxins that affect the aquatic biota and represent a human health risk. The cyanobacterium Pseudanabaena tenuis was isolated from the Valle de Bravo dam, and cultured in the laboratory under controlled conditions. We determined the acute toxic effects and performed a chronic (consumption) test in the cladocerans Daphnia magna (a reference test organism) and Ceriodaphnia dubia (a cosmopolitan species). To determine acute toxicity, three exposure ways were assayed: a) cell-free culture medium, b) crude cell extracts of the cyanobacterium after lysing, and c) aqueous extracts of P. tenuis phycobiliproteins. On the other hand, both cladocerans were fed P. tenuis, assessing the effects on survival and reproduction. For comparison, a control culture of both cladocerans was fed the green microalga Pseudokirchneriella subcapitata. Exposure to the cell-free culture medium did not produce any mortality in either cladoceran, but the aqueous and crude extracts generated acute toxicity. D. magna and C. dubia were negatively affected when fed P. tenuis, since their survival, total progeny, average number of neonates per clutch, and the number of clutches decreased. C. dubia was more sensitive than D. magna, both in the acute toxicity tests and to the effects of P. tenuis consumption. Although most of the blooms around the world are dominated by cyanobacteria of the genus Microcystis, attention should be given to other species, such as P. tenuis, because, frequently, it is not recognized that smaller cyanobacteria could exceed the larger species in terms of biomass, and produce noxious biological effect
The effect of protein and energy levels in diet on the antioxidant activity of juvenile redclaw Cherax quadricarinatus (von Martens, 1868)
Get PDFThis study determined the influence of dietary crude protein and energy levels on growth, survival, and antioxidant response of superoxide dismutase (SOD) in juvenile redclaw Cherax quadricarinatus. Six practical diets containing three crude protein (CP) levels (28, 35, and 40%) and two energy levels (~18 and 20 kJ·g1) were tested. The control group was fed a commercial shrimp diet. The highest SOD activity (34.8 U·mg1 protein) occurred in the diet with 35% CP and 18 kJ · g1. Soluble protein in tissue of redclaw fed 28 and 35% CP increased, compared to the control. The best mean final weight (9.23 g), weight gain (788%), and the lowest feed conversion ratio (1.3) occurred with the 35% CP diet. We conclude that a dietary CP content of 35% and 18 kJ · g1 is recommended for production and best immune responses in redclaw