Ciencias Marinas Research Papers - Academia.edu (original) (raw)

The Antillean manatee (Trichechus manatus manatus) is considered endangered in Mexico. Local extinctions have been documented in the northern Gulf of Mexico, and the only remaining population with a northern distribution is found in the... more

The Antillean manatee (Trichechus manatus manatus) is considered endangered in Mexico. Local extinctions have been documented in the northern Gulf of Mexico, and the only remaining population with a northern distribution is found in the Alvarado Lagoon System (ALS). The objective of this study was to determine manatee distribution in ALS. The system covers an area of 267,010 ha and includes hundreds of lagoons, floodable areas, and dozens of rivers. To detect manatees, systematic line transects were done in a boat 7.6 m in length, totaling 332.6 h of search effort with an average of 7.38 h d–1 in 45 surveys. There was a total of 13 manatee sightings: seven direct sightings, five with hydrophones, and one with a side-scan sonar. For each record the geographical coordinates were taken and integrated in a geographical information system to analyze their distribution. Manatee distribution was not uniform throughout the study area. Manatees were sighted in very specific areas of ALS cons...

A description is given of the purification of B–phycoerythrin (B–PE) from the red microalga Rhodosorus marinus. Initially, phycobiliproteins were released from the microalgal cells by manual cellular fragmentation and sonication. B–PE was... more

A description is given of the purification of B–phycoerythrin (B–PE) from the red microalga Rhodosorus marinus. Initially, phycobiliproteins were released from the microalgal cells by manual cellular fragmentation and sonication. B–PE was extracted with ammonium sulfate precipitation, and purified by anionic and size exclusion chromatography. Its purity was tested using indexes and sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Spectroscopic characterization of B–PE was performed by UV–visible spectroscopy, fluorescence spectroscopy, and circular dichroism. Rhodosorus marinus showed three types of phycobiliproteins: phycoerythrin, phycocyanin, and allophycocyanin. The purified B–PE showed a purity ratio (A545/A280) of 4.8, characteristic peaks at 540 and 562 nm with a shoulder at 498 nm, fluorescence emission maximum at 578 nm, and a secondary structure almost stable with pH changes. B–PE was found to be the predominant pigment in R. marinus and this red microalga could ...

The purpose of this work was to characterize the phytoplankton community of San Quintín Bay using pigment concentrations from HPLC and the CHEMTAX program, so that small cells (< 5 µm) would not be excluded. On 23–24 April 2001, a 24-h... more

The purpose of this work was to characterize the phytoplankton community of San Quintín Bay using pigment concentrations from HPLC and the CHEMTAX program, so that small cells (< 5 µm) would not be excluded. On 23–24 April 2001, a 24-h time series was generated, sampling surface water every hour. Samples were also taken from six localities throughout the bay. There was a significant contribution of seven phytoplankton groups. Those that contributed the most to total chlorophyll a were cryptophytes, cyanobacteria, bacilliarophytes and chlorophytes. In general, pigment concentrations were higher in the mouth region and decreased towards the internal extremes. This is the first report of the presence of the pigment divinyl chlorophyll a in San Quintín Bay, which firmly suggests the presence of Prochlorococcus sp. This group contributed up to 40% of the total chlorophyll a. Other cyanobacteria contributed up to 13% of the total chlorophyll a. These percentages are indicative of a ver...

Recibido en agosto de 1991; aceptado en noviembre de 1992 RESUMEN Se presentan los resultados del estudio de las algas marinas bentónicas de Bahía Concepción, en aguas del Golfo de California, B.C.S. La lista florística se acompaña de... more

Recibido en agosto de 1991; aceptado en noviembre de 1992 RESUMEN Se presentan los resultados del estudio de las algas marinas bentónicas de Bahía Concepción, en aguas del Golfo de California, B.C.S. La lista florística se acompaña de datos sobre las especies presentes en el área de estudio, su estado reproductivo, el nivel de marea, tipo de costa, sustrato y epifitismo. Se identificaron 63 especies de Rhodophyta, 22 de Phaeophyta y 18 de Chlorophyta. Se discute la presencia de las especies en relación con luz, temperatura y tipo de sustrato. Las especies de Rhodophyta dominaron en términos de diversidad. La ficoflora de Bahía Concepción es tropical y más diversa en primavera. ABSTRACT Results are presented of a study on the algae from the waters of Bahía Concepción, B.C.S., in the Gulf of California. The floristic list includes data on the species found, the state of reproduction, tidal levels, type of coast, substrate and epiphytism. Sixty-three species of Rhodophyta, 22 species o...

To understand their migratory environmental history and habitat use in Mexican waters, 31 striped mullet Mugil cephalus and 40 white mullet M. curema (family Mugilidae) were collected from three habitats (Tamiahua Lagoon, and Cazones and... more

To understand their migratory environmental history and habitat use in Mexican waters, 31 striped mullet Mugil cephalus and 40 white mullet M. curema (family Mugilidae) were collected from three habitats (Tamiahua Lagoon, and Cazones and Tecolutla estuaries, Veracruz) in the western Gulf of Mexico. Sr:Ca ratios in otoliths of mullets were measured from the primordium to the otolith edge with an electron probe microanalyzer. Mullets were aged by counting the otolith annuli. The patterns in mullet otolith Sr:Ca ratio differed among habitats and between species, indicating that habitat use and migratory behavior differed between species. Variability in otolith Sr:Ca ratios was consistent with that of the environment inhabited by the mullets. They showed a more diverse euryhaline preference than the simple catadromous behavior expected. The Sr:Ca ratios in the core region of the otolith indicated that mullets can spawn in both offshore waters and nearshore brackish waters, or that spawn...

En los últimos años el interés por la zona marina y marino-costera se ha ampliado y profundizado, sin embargo, aún somos pocos quienes desarrollamos nuestra labor investigativa en el territorio marítimo ecuatoriano. Esta situación está... more

El éxito del reclutamiento de los recursos marinos, en especial de los de importancia comercial como la anchoveta peruana Engraulis ringens, está basado en la continua evaluación y toma de criterios de manejo pesquero. La estimación de la... more

El éxito del reclutamiento de los recursos marinos, en especial de los de importancia comercial como la anchoveta peruana Engraulis ringens, está basado en la continua evaluación y toma de criterios de manejo pesquero. La estimación de la producción potencial de huevos (PPH) es una herramienta valiosa que, a diferencia de los índices reproductivos, cuantifica el desove incrementando la probabilidad de una mejor predicción del reclutamiento. Para el periodo 2000–2008 las hembras desovantes >14.0 cm de longitud total fueron las que tuvieron una mayor PPH, con 60% del total anual, aunque las hembras de 12.0–14.0 cm tuvieron una participación más importante debido a su mayor cantidad numérica durante los periodos de máxima actividad desovante. Durante los periodos de máximo desove se obtuvo 68% de la PPH total anual, donde cada grupo da talla aportó aproximadamente 50% de la puesta, mientras que durante el periodo de menor actividad fueron las hembras >14.0 cm las que mantuvieron ...

Fin whales (Balaenoptera physalus) are observed year-round in the Ballenas Channel and Bahía de los Ángeles region, Gulf of California, where their main food item is the euphausiid Nyctiphanes simplex. This investigation was designed... more

Fin whales (Balaenoptera physalus) are observed year-round in the Ballenas Channel and Bahía de los Ángeles region, Gulf of California, where their main food item is the euphausiid Nyctiphanes simplex. This investigation was designed under the hypothesis that the spatial and temporal occurrence of whales and euphausiids coincides. The aim was to establish the geographic, seasonal, and interanual changes in the abundance of the fin whale and its main prey in the region during 2003 and 2004. Four field trips were carried out per year. Surveys to search for whales and carry out horizontal surface tows were conducted from small boats. Fin whales and euphausiids were mainly observed off the coast of Baja California and in the southern Ballenas Channel. Their abundance varied significantly from one season to another in both years. The highest relative abundance of whales occurred in July (warm season), followed by June (cold–warm transition period) and March–April (cold season), and the l...

Relative batch fecundity, spawning frequency, size at 50% maturity, sex ratio, and egg production were estimated for the Bonaerense and Patagonian Engraulis anchoita stocks. Samples were collected during 19 research surveys carried out... more

Relative batch fecundity, spawning frequency, size at 50% maturity, sex ratio, and egg production were estimated for the Bonaerense and Patagonian Engraulis anchoita stocks. Samples were collected during 19 research surveys carried out over the main spawning seasons and areas of both groups from 1993 to 2008. Reproductive potential between stocks was compared by analyzing the length–class structure and considering environmental variations. Daily egg production varied between 0.2 × 107 and 7.3 × 107 oocytes and the mean annual value was higher for the Bonaerense than the Patagonian stock (2.9 × 107 and 0.54 × 107 oocytes, respectively; P < 0.019). In both stocks, larger size classes produced more oocytes than smaller and more abundant females. No correlation was observed between egg production and adult biomass and between egg production and age–1 recruits. Length at first maturity was lower for the Bonaerense than the Patagonian stock (100.3 and 119.8 mm total length, respectivel...

Recibido en septiembre de 1991; aceptado en enero de 1992 RESUMEN Con el fin de observar el efecto de la energía cinética turbulenta (TKE) sobre la distribución espacial de la clorofila a, se analizaron cuatro variaciones espaciales (dos... more

Recibido en septiembre de 1991; aceptado en enero de 1992 RESUMEN Con el fin de observar el efecto de la energía cinética turbulenta (TKE) sobre la distribución espacial de la clorofila a, se analizaron cuatro variaciones espaciales (dos en flujo y dos en reflujo de marea) los días 15 y 16 de abril de 1989, en Puerto Don Juan. Se realizaron observaciones de deriva de boyas y altura de marea, y se tomaron muestras de agua superficial en 20 estaciones, para determinar la concentración de clorofila a en cada variación. Se deduce un patrón para las condiciones de reflujo, el cual muestra una relación directa entre la pendiente suave del fondo y las altas concentracionesde clorofilaa. En las condiciones de flujo la relación es inversa. Dadas las observaciones, se sugiere que la mayor concentración de la clorofila a se debe a un simple proceso mecánico de acumulación en las zonas que por características morfológicas propias atenúan la TKE. Es decir, la velocidad de transporte del fitoplan...

La producción primaria diaria del fitoplancton fue estimada en la estación serial del programa CaTS (Caribbean Time-Series Station, 17° 36’N, 67° 00’0) mediante incubaciones en un fotosintetrón usando radiocarbono, 14C. Generamos curvas... more

La producción primaria diaria del fitoplancton fue estimada en la estación serial del programa CaTS (Caribbean Time-Series Station, 17° 36’N, 67° 00’0) mediante incubaciones en un fotosintetrón usando radiocarbono, 14C. Generamos curvas de irradianza contra la tasa de fotosíntesis (curvas P-E) para obtener los parámetros fotosintéticos: alfaB, betaB, y PBs.
Determinamos el valor de la constante de atenuación vertical, Kd (PAR), y la profundidad de la capa fótica mediante perfiles de irradianza descendente en la banda de los 400-700 nm, Ed
(PAR,z). Se registró la fluorescencia de la clorofila-a in situ para generar un perfil vertical de la biomasa de fitoplancton distribuida en la columna de agua. La irradianza PAR en la superficie del mar, Ed (PAR,0), fue modelada mediante estimados de la cubierta de nubes tele detectada
por satélites (International Satellite Cloud Cover Project). Modelamos la propagación vertical de la irradianza incidente en superficie utilizando el coeficiente de atenuación vertical de la luz difusa, Kd(PAR,z). Se integró numéricamente el perfil de la tasa de fotosíntesis hasta una profundidad de 200 m, limitando la integración a las horas de luz disponibles para fotosíntesis.
La producción integrada (PP) osciló entre 62 y 943 mg C m-2 d-1. La producción anual es alrededor de 171 g C m-2 año-1. La trayectoria anual de PP muestra una distribución con
valores elevados en: marzo-abril, julio y octubre. Esta estacionalidad coincide con la observada en la serie de tiempo de clorofila-a tele detectada por SeaWiFS en una banda entre los 15.6-17.6° N. El aumento en la producción primaria en marzo-abril esta asociado a la mayor disponibilidad de luz al fitoplancton profundo, a la influencia de aguas dispersas del Río Amazonas y a la presencia de fitoplancton con parámetros fotosintéticos favorables. El máximo de octubre se explica por la influencia del Río Orinoco pero el máximo de julio no parece estar asociado a influencia de los ríos. La estación CaTS muestra oscilaciones mayores en PP que no se observan en otras estaciones oligotróficas como BaTS y HOT.

Conspicuous sedimentary deposits forming well-structured and prominent submarine dunes are found on the coast of Yucatan (Mexico), close to the ports of Dzilam de Bravo, San Felipe, and El Cuyo. The objective of this study was to evaluate... more

Conspicuous sedimentary deposits forming well-structured and prominent submarine dunes are found on the coast of Yucatan (Mexico), close to the ports of Dzilam de Bravo, San Felipe, and El Cuyo. The objective of this study was to evaluate the morphological and sedimentological features of these submarine dunes. Sub-bottom seismologic profiles were obtained and standardized sedimentological analyses were performed on sediment samples collected at the three study sites. Both the height and wavelength of dunes were different between the three sites, mean heights ranging from 0.84 to 2.28 m and mean wavelengths from 98 to 330 m. Most of the dunes showed a well-marked asymmetry, which is related to the direction of their movements. Their granulometric composition was dominated by medium, moderately well-sorted sand. This study provides bases for future systematic monitoring of these peculiar ecosystems, including information to be considered for the evaluation of their ecological role in...

Oceanographic conditions in the Pacific waters off Baja California are described for the period 2002â??2003. Anomalies in the temperature-salinity relationships were observed from October 2002 to April 2003, with a clear contribution of... more

Oceanographic conditions in the Pacific waters off Baja California are described for the period 2002â??2003. Anomalies in the temperature-salinity relationships were observed from October 2002 to April 2003, with a clear contribution of low salinity and low temperature subarctic ...