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Estructura de la comunidad bentónica (infaunal) en el delta del Río Colorado, México
Villarreal Chávez,Guillermo; Melecio Carmona Cedillo,Carlos;
Revista de Biología Tropical , 1999,
Abstract: the benthic community structure of the colorado river delta, mexico, was studied by digging cores in six points along a line perpendicular to the coastline. three communities were found. the external community is influenced by human activities, but the community indexes are similar to others reported in the literature for equivalent areas. the middle community has the highest density and biomass in the area, apparently because of bioturbation created by the crab uca princeps. the internal community is poor in density and biomass, possibly because of the instability caused by erosion related to the tide flux.
Estructura de la comunidad bentónica (infaunal) en el delta del Río Colorado, México
Guillermo Villarreal Chávez,Carlos Melecio Carmona Cedillo
Revista de Biología Tropical , 1999,
Abstract: The benthic community structure of the Colorado River delta, Mexico, was studied by digging cores in six points along a line perpendicular to the coastline. Three communities were found. The external community is influenced by human activities, but the community indexes are similar to others reported in the literature for equivalent areas. The middle community has the highest density and biomass in the area, apparently because of bioturbation created by the crab Uca princeps. The internal community is poor in density and biomass, possibly because of the instability caused by erosion related to the tide flux.
Stratigraphy and structure of the Altar basin of NW Sonora: Implications for the history of the Colorado River delta and the Salton trough
Pacheco, Martín;Martín-Barajas, Arturo;Elders, Wilfred;Espinosa-Carde?a, Juan Manuel;Helenes, Javier;Segura, Alberto;
Revista mexicana de ciencias geológicas , 2006,
Abstract: the altar basin in northwestern sonora, mexico, is a subsidiary basin forming a now inactive part of the colorado river delta. its sedimentary record illustrates how the delta prograded in the last 4-5 ma overa late miocene, structurally distinct, marine basin at the northern end of the gulf of california. our interpretation of outcrop data, and data from seven exploratory wells, six analog seismic lines of petróleos mexicanos (pemex), and magnetic and gravity surveys from various sources indicates the existence of three sedimentary sequences, a, b, and c, which can be correlated at regional scale and have a thickness >5 km at the basin depocenter. the lower sedimentary sequence a is a shale unit representing open marine conditions (outer neritic). it grades into a thick sequence of interstratified mudstone, siltstone, and sandstone (sequence b), which grades in turn into poorly consolidated sand (sequence c). extensive outcrops of a sandy, cut and fill succession exposed along the coast of sonora are consistent with sequences b and c being the sub-aqueous and the sub-aereal parts of the delta, respectively. a contact at the base of the sequence a, where pre-marine continental deposits are missing, and where the marine sequence overlies crystalline basement, is interpreted as tectonic transport along a top-to-the-norihwest detachment fault. the altar basin became inactive as result of the westward shift in the locus of tectonic activity from the altar fault to the cerro prieto fault, coupled with realignments in the course of the colorado river during pleistocene time.
Isotopic Variations of Oxygen (δ18O) in Benthic Foraminifera under Antiestuarine Conditions in the Colorado River Delta  [PDF]
Miguel A. Santa Rosa-del Río, Ismael Yarbuh, Rigoberto Guardado-France, Ronald M. Spelz, Raúl Herrera-Gutiérrez, Karla Mejia-Pi?a, Miguel Agustín Tellez-Duarte, Luis Antonio Cupul-Maga?a
Open Journal of Geology (OJG) , 2018, DOI: 10.4236/ojg.2018.82007
Abstract: Benthic foraminifera are excellent environmental indicators; CaCO3 test records the isotopic concentration of their surroundings and can be used to analyze environmental changes that occur during a certain time period. Stable isotopes, particularly those of oxygen (δ18O), are useful for interpreting ancient environments, given that they are used as “proxy” environmental variables (temperature and salinity). In this study, we provide ranges of isotopic variation in benthic foraminifera communities from the Colorado River delta. Four sampling campaigns were conducted in one year (2009-2010) in the adjacent subtidal zone of Baja California. Four transects with a total of sixteen sample station were drawn perpendicular to the coastline. Here, we recorded the following in situ: sand-type, salinity, and temperature. In the laboratory, 300 individuals per sample were separated, and sub-samples were taken for isotopic analysis. Data was processed using the software’s R 2.12.2, PAST 1.81 and Arc Map 9.3. Forty species were identified in the dead assemblages (Thanatocoenosis), whereas thirteen species were found in the living assemblages (Biocoenosis). The most abundant species in both communities belong to the genera Ammonia and Cribroelphidium. In the living assemblages, isotopic variation 2.15% to 5.94% within a temperature interval of 11°C, indicated antiestuarine conditions. In the dead assemblages, isotopic composition 3.04 to 0.74 served as a sign of estuarine conditions prior to damming.
Caracteristicas y evolucion del delta del Rio Colorado "colú-leuvú", Provincia de Buenos Aires, República Argentina Characteristics and evolution of the Colorado River Delta (Colu-Leuvu): Buenos Aires. Argentina
Luis A Spalletti,Federico I Isla
Revista de la Asociación Argentina de Sedimentología , 2003,
Abstract: Se analizan las características de la planicie y el frente del delta del río Colorado. Sobre la base del mapeo de diversos ambientes de depositación a partir de las imágenes satelitales Landsat 7 ETM 226-087 y 226-088, se establece la influencia de los procesos fluviales y cuencales en el desarrollo del delta del Colorado. La evolución de la arquitectura deltaica y de los rasgos costeros es relacionada con cambios relativos en el nivel del mar. El río Colorado se extiende desde los Andes hasta el Atlántico constituyendo el límite entre la Patagonia y la Pampa arenosa. Nace de la confluencia de los ríos andinos Barrancas y Grande y después de recorrer unos 900 km desemboca en el mar que flanquea el margen pasivo de la placa sudamericana, constituyendo una extensa planicie deltaica.En el área de influencia de la desembocadura del río Colorado se han distinguido tres lóbulos no operativos de gran dimensión en comparación con el lóbulo actual. El lóbulo 1 es el más antiguo y su planicie deltaica con sistemas fluviales multicanales de baja sinuosidad muestra procesos de reiterada incisión. Este lóbulo se relaciona con el inicio de un período de deglaciación, con posición baja del nivel del mar y sobrealimentación fluvial, tanto de carga traccional como de descarga. El lóbulo 2 aparece fuertemente degradado y se ubica en el área de influencia de Bahía Blanca; el sistema de alimentación fluvial se encuentra prácticamente abandonado, y la planicie deltaica está en estado de destrucción por acción mareal. El lóbulo 3 se habría formado durante un sostenido ascenso eustático, posiblemente asignable al estadío isotópico del oxígeno 5e (120.000 a os AP), en condiciones de menor gradiente, con un sistema multicanal de alta sinuosidad. El estado de máxima transgresión produjo singulares efectos destructivos mareales y de olas sobre la superficie de los lóbulos 1, 2 y 3. Posteriormente, sobre la superficie del lóbulo 3, se acumularon cordones litorales alineados en sentido N-S que corresponden a posiciones más elevadas del nivel del mar en relación con la situación actual (transgresión holocena entre 4000 y 3700 a os AP) y reflejan la existencia de sucesivos fenómenos destructivos cuencales (con dominio de oleaje) en el área de influencia de las respectivas planicies deltaicas. Durante los tiempos recientes la desembocadura del río Colorado se desarrolla en una situación general de alto nivel del mar; no obstante, el sistema es regresivo en cuanto a que sus distintos brazos distributarios atraviesan las citadas barreras litorales correspondientes a un nivel del mar supe
Caracteristicas y evolucion del delta del Rio Colorado "colú-leuvú", Provincia de Buenos Aires, República Argentina
Spalletti,Luis A; Isla,Federico I;
Revista de la Asociaci?3n Argentina de Sedimentolog?-a , 2003,
Abstract: the colorado river delta was morphologically analyzed, considering both the deltaic plain and the prodelta areas. by the mean of the landsat 7 etm images 226- 087 and 226-088, different depositional environments were surveyed recognizing the processes involved in their evolution. the delta architecture and present coastal features were particularly assigned to relative sea level changes. the colorado river runs from the andes to the atlantic ocean limiting the patagonia to the south and the sandy pampa to the north. it initiates from the confluence of the barrancas and grande rivers, ending as an extended deltaic plain after a distance of 900 km. within the deltaic plain, significant amount of fine sand is supplied by two aeolian corridors (ombucta and mayor buratovich) that originated from the colorado river valley. at the coast between bahía blanca and bahía anegada, three non-operative extended lobes were recognized. the formation of lobe 1 deltaic plain was assigned to a sea level lower than present, and related to a higher fluvial sediment supply. lobe 2 is strongly eroded comprising the area close to bahía blanca. the original fluvial valley that discharged into this lobe is today mostly abandoned, and the area is subject to tidal reworking. lobe 3 would have deposited during a sea level highstand, possibly related to the sangamonian interglacial (oxygen isotope stage 5e; about 120,000 years bp). during this highstand, low-gradient conditions explained a multichannel fluvial system of high sinuosity, and the erosion dominated by tidal and wave processes. in lobes 1 and 3, constructive and destructive phases are related to glacioeustatic sea-level changes and coeval tectonic uplift. the different availability of sediments between lobes 1 and 3 could be assigned to the interval when the desaguadero system became isolated from the colorado basin. more recently, and attached to lobe 3, coastal ridges composed mostly of gravel, and oriented north to south, indicate
Historic and Current Distributions of River Otters (Lontra canadensis) and (Lontra longicaudis) in the Río Grande or Río Bravo del Norte Drainage of Colorado and New Mexico, USA and of Chihuahua, Mexico and Adjacent Areas  [PDF]
Paul Polechla,Eduardo Carrillo-Rubio
IUCN Otter Specialist Group Bulletin , 2009,
Abstract: The Río Grande drainage is an important and imperiled wetland of the US/Mexican border arid lands. There is a desire to restore otter populations in this river by interested parties. In order to follow IUCN guidelines for restoration, biologists need learn more fully the situation prior to implementation of restoration management. A prerequisite for proper restoration conservation is to know the organism’s taxonomy (i.e., what taxa or species and subspecies one is dealing with), distribution, and relative abundance. The historic and current distribution of the Nearctic otter (Lontra canadensis) and Neotropical otter (L. longicaudis) in the borderlands of US and Mexico are reviewed in this paper. The evidence indicates that otters were native to the Río Grande valley and has been recorded in the languages and customs of Native Americans such as the Pueblo people prior to European settlement of the area. The first Spanish documents we were able to find whereby otters were recorded, date to the middle 16th century. Otters during historical times were probably more numerous than previously thought and one of the first wildlife laws in the borderlands revolved around a moratorium on trapping the otter and beaver. Presently, populations of otters occur in 1) the Río San Pedro of Chihuahua, a tributary of the Río Conchos entering the Río Grande from the southeast, 2) the upper Río Grande near the Colorado/New Mexico border, and 3) the middle Pecos River in southeastern New Mexico entering the Río Grande from the west. These observations are corroborated by multiple observations by competent observers and in the case of the first population, otter photos and sign. These populations are centered on areas with macro-habitats characterized by a river flowing through 1) deep canyons, or 2) ancillary wetlands. Considerable more detailed survey work is needed to determine the full extent of the distribution of otters in the Río Grande drainage. A genetic study is critically needed to determine the true taxonomic affiliation of these recently discovered populations. A moratorium on translocations should be put in place for the Río Grande to conserve the native populations already existing.
Temporal and geographic evidence for evolution of Sin Nombre virus using molecular analyses of viral RNA from Colorado, New Mexico and Montana
William C Black, Jeffrey B Doty, Mark T Hughes, Barry J Beaty, Charles H Calisher
Virology Journal , 2009, DOI: 10.1186/1743-422x-6-102
Abstract: Portions of the Sin Nombre virus small (S) and medium (M) RNA segments were amplified by RT-PCR from kidney, lung, liver and spleen of seropositive peromyscine rodents, principally deer mice, collected in Colorado, New Mexico and Montana from 1995 to 2007. Both a 142 nucleotide (nt) amplicon of the M segment, encoding a portion of the G2 transmembrane glycoprotein, and a 751 nt amplicon of the S segment, encoding part of the nucleocapsid protein, were cloned and sequenced from 19 deer mice and from one brush mouse (P. boylii), S RNA but not M RNA from one deer mouse, and M RNA but not S RNA from another deer mouse.Two of 20 viruses were found to be reassortants. Within virus sequences from different rodents, the average rate of synonymous substitutions among all pair-wise comparisons (πs) was 0.378 in the M segment and 0.312 in the S segment sequences. The replacement substitution rate (πa) was 7.0 × 10-4 in the M segment and 17.3 × 10-4 in the S segment sequences. The low πa relative to πs suggests strong purifying selection and this was confirmed by a Fu and Li analysis. The absolute rate of molecular evolution of the M segment was 6.76 × 10-3 substitutions/site/year. The absolute age of the M segment tree was estimated to be 37 years. In the S segment the rate of molecular evolution was 1.93 × 10-3 substitutions/site/year and the absolute age of the tree was 106 years. Assuming that mice were infected with a single Sin Nombre virus genotype, phylogenetic analyses revealed that 10% (2/20) of viruses were reassortants, similar to the 14% (6/43) found in a previous report.Age estimates from both segments suggest that Sin Nombre virus has evolved within the past 37–106 years. The rates of evolutionary changes reported here suggest that Sin Nombre virus M and S segment reassortment occurs frequently in nature.When Sin Nombre virus (SNV; family Bunyaviridae, genus Hantavirus), the causative agent of the then newly recognized hantavirus pulmonary syndrome in humans, was
Composición Isotópica del Agua Subterránea y su Relación con la Salinidad en el Valle de San Luis Río Colorado en Sonora, México Isotopic composition of groundwater and its relationship with salinity in the Valley of San Luis Rio Colorado Sonora Mexico  [cached]
Lorenzo Valenzuela,Jorge Ramírez-Hernández,Ramón B Palomares
Información Tecnológica , 2013,
Abstract: En este trabajo, se analiza la composición isotópica del acuífero del Valle de San Luis Río Colorado en Sonora en conjunto con la concentración de cloruros del agua para determinar el origen del agua del subsuelo y establecer las causas del aumento de salinidad que se ha observado en el agua de riego. La mineralización del acuífero ha provocado un deterioro en la calidad del agua de esta agua. Se encontró que la composición isotópica deja ver un fraccionamiento como consecuencia de la evaporación rápida y la mezcla de aguas antiguas, infiltradas antes de la construcción del sistema de presas, con aguas recientes del Río Colorado, sometidas a un proceso de evaporación en los vasos de éstas. El análisis isotópico permitió establecer que el agua de los canales de riego más mineralizada aún no está presente en el acuífero. In this work, the isotopic composition and chloride concentration of San Luis Rio Colorado, Sonora, in Mexico were used to determine the origin of groundwater and to establish the salinity increase that has been observed in the irrigation water. The aquifer mineralization has provoked deterioration of this water. The isotopic composition showed a fractioning due to the sudden evaporation and the mixing of water percolated before the dam system, constructed upstream, with water infiltrated to the aquifer after evaporation in the reservoirs, these water types are known as old and recent, respectively. Unlike what it could be expected, the isotopic composition determined that mineralized water from irrigation channels is not yet present in the aquifer.
Evaluación del impacto socioeconómico de la Reserva de la Biosfera Alto Golfo de California y Delta del Río Colorado en la actividad pesquera ribere?a de San Felipe, Baja California, México
Vázquez León, Carlos Israel;Fermán Almada, José Luis;
Región y sociedad , 2010,
Abstract: since 1993, mexican coastal communities such as puerto pe?asco and golfo de santa clara in sonora, and san felipe in baja california have been connected by the upper gulf of california and colorado river delta (rbagc) biosphere reserve. this reserve was created to preserve and protect several endemic species, among them the vaquita marina (phocoenasinus), a marine mammal, and a fish known as totoaba (totoaba macdonaldii).the present article reviews and analyzes the social and economic impact of the reserve on small scale fishers in san felipe in baja california, considering that the reserve is an institutional arrangement designed for environmental and ecological protection as well as fishing regulation.the analysis focuses on the socioeconomic impact of the reserve's creation on fishing in san felipe in 1994 and 2002. the main conclusion is that social and economic factors should be considered when designing evaluation and efficiency indicators in order to obtain a successful reserve.
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