Hidrobiológica (E-Journal)
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El género Porphyra (Bangiaceae, Rhodophyta) en la costa del Pacífico de México. IV. Porphyra pendula E.Y. Dawson
Get PDFThe occurrence and seasonality of Porphyra pendula E.Y. Dawson (Bangiaceae, Rhodophyta) in its macroscopic phase, is reported for the Pacific coast of Mexico, based on sampling conducted during November 2002 to May 2003, and specimens housed in national and foreign herbaria. We describe in detail the vegetative and reproductive structure of the thallus, as well as its habitat and geographic distribution of the species. The specimens of P. pendula from Isla Carmen, Los Planes and Calerita, represent newly reported populations from the Gulf of California. Based on data obtained from herbarium specimens and observations of a population in Calerita, Baja California Sur, we concluded that P. pendula, in its macroscopic phase, is a seasonal species occurring from January to March (winter to the beginning of spring).Se registra la presencia y estacionalidad de la fase macroscópica de Porphyra pendula E.Y. Dawson (Bangiaceae, Rhodophyta) para la costa del Pacífico de México, con base en material recolectado durante el periodo de noviembre del 2002 a mayo del 2003 y un análisis de ejemplares depositados en herbarios nacionales y extranjeros. Se describen en forma detallada los caracteres morfo-anatómicos y estructuras reproductoras de los talos; así como su hábitat y distribución geográfica. Los especímenes de P. pendula de Isla Carmen, Los Planes y Calerita representan poblaciones nuevas de ésta especie en el Golfo de California. Considerando la revisión de especimenes de herbario y el seguimiento de una población en Calerita, Baja California Sur, se determinó que la estacionalidad de P. pendula en su fase macroscópica es de enero a marzo (invierno-principios de primavera)
Cambio estacional de clorofila a en la Bahía de La Paz, B.C.S., México
No full textFrom april 1993 to march 1995 hourly wind data, intensity and direction, were analyzed. Monthly sampling of temperature, Secchi disc depth and chlorophyll a were carried out on 5 stations transect across the Bahía de La Paz at surface, 10 and 25 meters depth. Southward winds were dominant during october to march and northward the rest of the year. The highest temperatures were registered from July to October with temperatures between 28 and 32ºC, and the lowest from January to march, with values in the range of 20 and 22ºC. Maximum Secchi depths (14-24 m) was observed during July trough November and minimum during January to June (6-15 m). Chlorophyll a concentration showed a inverse relationship with temperature and water transparency. The lowest integrated chlorophyll a calues (<10 mg m-2 ) were found at warm season as a result probably of a strong water column stratification and slow vertical transport of dissolved and particulate materials from deep layers. Maximum values (142.8 mg m-2 ) during cold season were associated with water column mixing processes and nutrient availability inthe euphotic zone.En el período abril de 1993 a marzo de 1995 se analizaron datos diarios de intensidad y dirección del viento, datos mensuales de temperatura hasta 25 metros, profundidad del disco de Secchi y la concetración de clorofila a, en superficie, 10 y 25 metros, en 5 estaciones ubicadas en la Bahía de La Paz. Los vientos presentaron una componente norte durante los mese de octubre a marzo y vientos dominantes del sur de abril a septiembre. Las temperaturas más altas ocurrieron durante julio-octubre entre 28 y 32ºC y las menores se registraron de enero a marzo entre 20 y 22ºC. Las mayores transparencias se observaron durante los mese de julio a noviembre, con valores entre 14 y 24 m; y las menores ocurrieron generalemente de enero a junio con profundidades entre 6 y 15 m. La clorofila a presentó un comportamiento estacional inverso a la temperaatura y a la transparencia del agua. Las menores concentraciones de clorofila a integrada (<10 mg m-2 ) ocurrieron en los meses más cálidos probablemente como resultado de la fuerte estratificación de la columna de agua, que no permite el transporte de material de al capa profunda a la capa superficial. Los mayores valores de clorofila a integrada (142.8 mg m-2 ) se presentan en la época fría asociados con los procesos de mezcla de la columna de agua y probablemente con la disponibilidad de nutrientes en la zona eufótica
Fitotoxicidad del herbicida Roundup® Max sobre la especie no blanco Lemna gibba en estudios de campo y laboratorio
Get PDFThe use of the herbicide formulate Roundup® in transgenic crops of the Pampa´s plains of Argentina has extensively increased, though there is scarce information on its impact on non-target vascular plants from agro-ecosystem related surface waters. Within this frame, the sensitivity of the macrophyte Lemna gibba L. to Roundup® Max was studied in standardized laboratory conditions and field experiments. In the laboratory, phytotoxic effects were assessed on the growth rate (GR) and total chlorophyll content (TCC). The GR was affected at 1 mg/L and TCC at 7.5 mg/L as active ingredient. Effects varied along testing time: toxicity was higher at low concentrations at the beginning, but diminishing during exposure, while at higher concentrations toxicity increments during testing. Also, a reduction of frond and root growth was detected. Field experiments with caged plants placed close to field crops showed an inhibition of 35.5 % in biomass production (dry weight) and 75.5 % in TCC when a dose of 1 kg/ha was applied. Although, in a second dose, only an inhibition effect on TCC of 53.9 % was detected. The assessment of the herbicide drift did not show an influence of this exposure route on the plants for the studied scenery. The lowest glyphosate concentration producing an effect in the laboratory is in agreement with the detected levels of the herbicide in the water body associated with effects in field experiments.La Argentina ha incrementado ampliamente la superficie de cultivos transgénicos resistentes al glifosato, siendo el Roundup®Max uno de los formulados comerciales de mayor uso. Considerando el impacto que las prácticas agrícolas ocasionan sobre ambientes acuáticos vecinos a agroecosistemas, es importante estudiar la sensibilidad de especies no blanco a los productos utilizados en las mismas. Se evaluó la respuesta de la macrófita Lemna gibba L. al Roundup®Max en ensayos estandarizados de laboratorio y a campo. La fitotoxicidad del formulado en el laboratorio se evaluó sobre la tasa de multiplicación (TM) y el contenido de clorofila (CTC). La TM se inhibió a partir de 1 mg/L de principio activo (p.a.) y el CTC a 7.5 mg p.a./L, observándose además reducción en el crecimiento foliar y radical. Los efectos variaron a lo largo del ensayo: a bajas concentraciones la toxicidad inicial es mayor, disminuyendo a lo largo de la exposición, mientras que a concentraciones mayores la toxicidad se incrementa con el tiempo de ensayo. En dos estudios a campo en limnocorrales localizados en un arroyo adyacente a un cultivo, se observó que la aplicación de Roundup®Max (1 kg/ha) en el cultivo, inhibió significativamente la producción de biomasa seca (35.5 %) y el CTC (75.5 %), en una primer aplicación, y solamente el CTC (53.9 %), en la segunda aplicación. El impacto por deriva, no mostró efectos en el escenario estudiado. Los niveles de glifosato esperados y medidos en el arroyo donde se emplazaron los limnocorrales, produjeron fitotoxicidad significativa en L. gibba en ensayos de laboratorio
Evaluación del riesgo por consumir moluscos contaminados con cadmio, cromo y plomo
Get PDFPectinids accumulate metals at higher levels in comparison to other mollusks. This constitutes a possible risk for people that consume them since it has been detected that concentrations of cadmium, chromium and lead in these organisms exceed the maximum limit established by the Mexican NOM (Norma Oficial Mexicana 031-SSA1993). The objective of this work was to determine the concentrations of those metals in tissues of Catarine clams and to evaluate the possible risk that implicates their consumption calculating the minimal secure ration (per day). Samples were collected during the summer and winter seasons of 1998, 1999 and 2000, from the mollusk farm of UABCS (Universidad Autónoma de Baja California Sur, México). The quantification of the elements was carried out by means of atomic absorption technique in flame. The average concentrations of Cd, Cr and Pb ± SD (standard deviation) registered in the scallops ranged from 1.76 ± 1.23, 0.288 ± 0.228 to 3.34 ± 1.09 µg/g (d.w., dry weight), respectively. The season and year that showed the highest concentrations was during the summer (July 1998). The safety portions of scallops (g) calculated for children, women and men (per day) and weight of consumers were: For children of 18 and 30 kg, portions of 1.50 and 2.50 g (w.w., wet weight); for women of 50, 60 and 70 kg, portions of 97.09, 116.50 and 135.92 g (w.w.), respectively. For men of 70, 80, 90 and 100 kg, 135.92, 155.33, 174.75 and 194.17 g (w.w.) of clams. The consumption of higher rations might imply a health risk.Los pectínidos concentran metales en sus tejidos, en niveles superiores en comparación con otros moluscos. Lo cual constituye un posible riesgo para las personas que los consumen, ya que se han detectado concentraciones de cadmio (Cd), cromo (Cr) y plomo (Pb) en estos organismos que rebasan los límites establecidos en la Norma Oficial Mexicana (NOM 031-SSA1993) para consumo de mariscos frescos, congelados y refrigerados. En este trabajo se determinó la variación en el contenido de éstos metales en la almeja Catarina y se evaluó el posible riesgo que implica su consumo calculando la ración mínima segura por día. Se recolectaron muestras de organismos en verano e invierno, durante 1998, 1999 y 2000, del Vivero de cultivo de la Universidad Autónoma de Baja California Sur, (UABCS). La cuantificación de elementos se realizó mediante la técnica de absorción atómica en flama. Las concentraciones promedio ± DE (desviación estándar) de Cd, Cr y Pb registradas en las muestras de almejas fueron de 1.76 ± 1.23, 0.28 ± 0.23 y 3.34 ± 1.09 µg/g (p.s., peso seco) respectivamente. La estación y el año en que se registraron las concentraciones más altas fue en verano (julio) de 1998. Las raciones seguras de consumo de almejas calculadas (g) por día y peso del consumidor (kg) fueron: Para niños de 18 y 30 kg, porciones de 1.50 y 2.50 g (p.h., peso húmedo) de moluscos. Para mujeres de 50, 60 y 70 kg, valores de 97.09, 116.50 y 135.92 g (p.h.), respectivamente. Para hombres de 70, 80, 90 y 100 kg, raciones de 135.92, 155.33, 174.75 y 194.17 g (p.h.) de almejas respectivamente. El consumo de raciones superiores podría implicar un riesgo a la salud
Larvas de moluscos gasterópodos del sur de Quintana Roo, México.
Get PDFIn their first development stages, gastropod presents a planktonic larval phase where their proto-shell suffers morphological transformations. Depending on each species, the shell has forms and different types of ornamentation that turn out to be an important taxonomic character for its identification. In this work, plankton gastropod larvae recollected in 1996-1998 at Bahia de la Ascension, Punta Gavilan, Banco Chinchorro and Hol-Chan Marine Reserve in Belize are described and illustrated; samples were collected using plankton nets and a submersible pump. A total of 31 species were found that grouped in three orders, 18 families and 20 genus. The family Cerithidae was the best represented with three genus and seven species, Naticidae had two genus and four species, while Epitoniidae had one genus and three species. Species with higher presence and distribution were Rissoina sp.1, Natica sp. and Limacina sp.En sus primeras etapas de desarrollo, los caracoles gasterópodos presentan una fase larval plánctica donde su protoconcha sufre transformaciones morfológicas. Dependiendo de cada especie, la concha tiene formas variadas y diferentes tipos de ornamentación que resultan ser un carácter taxonómico importante para su identificación. En este trabajo se describen e ilustran las larvas de gasterópodos recolectadas en muestras de zooplancton en 1996- 1998 en Bahía Ascensión, Punta Gavilán, Banco Chinchorro y la Reserva de la Biosfera de Hol-chan en Belice, para la recolección de las muestras, se utilizaron redes de plancton y mediante bombeo. Se encontraron 31 especies que se agruparon en tres órdenes, 18 familias y 20 géneros. La familia Cerithidae fue la mejor representada con tres géneros y siete especies, Naticidae tuvo dos géneros y cuatro especies, en tanto que Epitoniidae tuvo un género y tres especies. Las especies con mayor presencia y distribución fueron Rissoina sp.1, Natica sp. y Limacina sp
Structure of the mitochondrial control region and flanking tRNA genes of Mugil cephalus
Get PDFWe cloned and sequenced the mitochondrial (mt) control region (CR) and flanking transfer RNA genes (T, P, and F) of the striped mullet, Mugil cephalus and designed species-specific primers to amplify the entire CR in specimens from the Pacific (Hawaii), the Gulf of Mexico, and the Atlantic. We verified the absence of heteroplasmy and nuclear mtDNA duplications of this region in the organisms sampled, finding an extraordinary level of sequence divergence (mean 38-75% Tamura & Nei distance- ) between fish from both Oceans, including Japan. The CR of the mullet was variable in length (845-930 bp) and contained structural elements in common with other CRs, including a central conserved segment flanked by hypervariable regions and smaller conserved sequence blocks. Termination associated sequences, however, were not found. The CR of the striped mullet was rich in AT (~67%) and poor in GC
Habitat Segregation among Trophic Morphs of the Cuatro Ciénegas Cichlid (Herichthys minckleyi
Get PDFHerichthys minckleyi is an endangered, trophically polymorphic cichlid endemic to the Cuatro Ciénegas basin of Coahuila, Mexico. A molariform morph has stout pharyngeal teeth whereas a papilliform morph has numerous fine pharyngeal teeth. Individuals with intermediate pharyngeal dentition also exist, as does yet another morph, called piscivore. Previous studies indicated that morphs utilize different food sources, thus suggesting morph-specific spatial segregation, since food resource availability is spatially heterogeneous. We present data from an observational study of all morphs (but focusing on the three most common, normal-bodied ones molariform, papilliform and intermediate) in a single spring pool, Poza Mojarral Oeste. We analyzed morph distribution in relation to habitat types, and document morph-specific differences in feeding behavior. Spatio-temporal habitat partitioning was also investigated. Habitat use by molariform, papilliform, and intermediate morphs was found to be non-random. Morphs differed in habitat use, albeit with considerable overlap. Strong segregation among morphs was not detected in any season or time of day, but habitat use patterns varied seasonally within each morph and were consistently different among morphs. All morphs behave basically as feeding generalists. This endangered species may prove more difficult to manage than other, non-polymorphic species. It is clearly important to manage not only for the maintenance of the species, but also for maintenance of its different morphs, which our study indicates may each require different mixes of habitat types. We thus hypothesize that any changes in habitat heterogeneity will lead to altered proportions of the different morphs of the species
Composition and spatio-temporal variation of the fish community in the Chacmochuch Lagoon system, Quintana Roo, Mexico
Get PDFThe composition, distribution and abundance of fishes were determined in the Chacmochuch Lagoon System, a natural protected area located on the north coast of Quintana Roo. Monthly diurnal sampling was carried out at 10 sampling stations in March, June and September, 2002. During each field trip, bottom type, submerged and surrounding vegetation, salinity, temperature, dissolved oxygen and other variables were measured. Distribution and abundance of fishes were examined by means of a principal component analysis. Fifty species were recorded; Gerres cinereus, Floridichthys polyommus, Eugerres plumieri, Harengula jaguana, Sphyraena barracuda, and Archosargus rhomboidalis were dominant, and no significant difference in species composition was found between seasons. Apart from a single site where turbidity and nutrient concentration were particularly high, the other sites could be classified mainly according to salinity. Fish composition changed along this gradient
Temporal variability in the abundance of the bay anchovy Anchoa mitchilli (Valenciennes, 1848) eggs and spawning biomass in Pueblo Viejo Lagoon, Veracruz, Mexico
No full textThe spawning of Anchoa mitchilli is analyzed and its adult biomass is estimated in Pueblo Viejo Lagoon, Veracruz, Mexico. Samples were collected at 19 stations in October and December of 1992, in March, April, June and August of 1993, using a zooplankton net with a 505 µm mesh size and a 50 cm mouth to which a flowmeter was fixed. The spawning of A. mitchilli was analyzed with respect to the abundance of eggs in the lagoon (number of eggs/m3), and the adult biomass was calculated through the annual production of eggs. A total of 51,348 eggs was obtained of which 50,205 (97.7%) corresponded to A. mitchilli. This is a species that spawns inside the lagoon throughout the year, except during the rains (July-October), with a peak (96.8%) in March-April in temperatures of 19-20ºC and salinities of 14-21 psu. Temperature (15-32ºC) was observed to be one of the main factprs that determine the spawning period, whereas salinity inhibits spawning below 10 psu. A. mitchilli biomass in Pueblo Viejo Lagoon was 793 metric tons and 5.7 g/m3. A latitudinal gradient from north to south is evident for the biomass of this species, and this is determined by an increase inthe diversity towards the tropical regions and the resulting decrease in the biomass of the species, down to the southern limit of its distribution in the Peninsula of Yucatan, Mexico
Estudio de la ultraestructura de la espermatogénesis de Anadara tuberculosa (Sowerbi 1833) (Mollusca: Pelecipoda:Arcidae)
Get PDFAnadara tuberculosa is a bivalve mollusk of the Arcidae family. This species is found at the Pacific coast, from Laguna de Ballenas (Baja California, Mexico) to Peru. Different types of germ cells have been described at the light microscopic level; however, up to date, no ultrastructural studies of these cells have been performed. The aim of the present work was to determine the main ultrastructural features of the germinal cells, and consequently to contribute on a better taxonomic characterization of different species of the Arcidae family. Spermatogonia were characterized by a large spherical and centrally localized nucleus. Heterochromatin was randomly scattered as dense granules throughout the nucleoplasm. Mitochondria were abundant, and vacuoles were seen dispersed in the cytoplasm. Primary spermatocytes had a more condensed chromatin. The number of mitochondria was lower than in spermatogonia. Secondary spermatocytes had nuclei with chromatin placed peripherically with dense granular projections to the center. Nucleus/cytoplasm ratio was lower as compared to the above mentioned cell types. Spermatids showed two stages of differentiation. At the first stage, chromatin was completely condensed with mitochondria increased in size and migrated to the basal pole of the cell. At the second stage, a centriole was seen localized between the mitochondria and acrosome. Spermatozoids showed a pyramidal acrosome and the centriole was placed intermixed with the typical five mitochondria, specific for this specie. Based in our ultrastructural data, we propose the following for this specie: 1) spermatozoids are of the primitive type 2) centriole is present up from the stage of spermatid and not at earlier stages as reported in other species and 3) five mitochondria with pyramidal acrosome are typical characteristic of this specie.Anadara tuberculosa bivalvo de la familia Arcidae, se distribuye ampliamente en las Costas del Pacífico, desde la Laguna de Ballenas (Baja California), hasta Perú. Las células germinales han sido descritas en microscopia óptica pero no su ultraestructura, por lo que el objetivo de este trabajo es describir las principales diferencias entre dichas células, así como la forma del acrosoma el cual puede contribuir como una característica más para la ubicación taxonómica de las especies de esta familia. Se encontró que las espermatogonias tienen un núcleo grande y esférico en posición central con la presencia de gránulos de heterocromatina esparcidos en el nucleoplasma, el retículo endoplasmático rugoso es escaso y está localizado hacia la periferia del núcleo, las mitocondrias son abundantes, y las vacuolas están dispersas en el citoplasma; en los espermatocitos primarios la heterocromatina está más condensada, las mitocondrias disminuyen en número con respecto a las espermatogonias; los espermatocitos secundarios presentan la heterocromatina distribuida hacia la periferia nuclear con proyecciones hasta el centro del núcleo, la cantidad de citoplasma disminuye con respecto a los tipos celulares anteriores. Las espermátidas presentan dos etapas de diferenciación, en la primera la cromatina esta completamente condensada, las mitocondrias se incrementan en tamaño y migran al polo basal, en la segunda se observa el centríolo localizado entre las mitocondrias y el acrosoma. En los espermatozoides el acrosoma es de forma piramidal y el centríolo se encuentra entre las cinco mitocondrias características para esta especie. Los resultados muestran que 1) Los espermatozoides son de tipo primitivo 2) El centríolo se observa a partir de la fase de espermátida y no en etapas tempranas como en otras especies 3) Se encuentra como característica específica de especie la presencia de cinco mitocondrias y acrosoma de forma piramidal