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6047 results, page 1 of 10

The effect of aquatic plant abundance on shell crushing resistance in a freshwater snail

FRANCISCO JAVIER GARCIA DE LEON (2012)

"Most of the shell material in snails is composed of calcium carbonate but the organic shell matrix determines the properties of calcium carbonate crystals. It has been shown that the deposition of calcium carbonate is affected by the ingestion of organic compounds. We hypothesize that organic compounds not synthesized by the snails are important for shell strength and must be obtained from the diet. We tested this idea indirectly by evaluating whether the abundance of the organic matter that snails eat is related to the strength of their shells. We measured shell crushing resistance in the snail Mexipyrgus churinceanus and the abundance of the most common aquatic macrophyte, the water lily Nymphaea ampla, in ten bodies of water in the valley of Cuatro Cienegas, Mexico. We used stable isotopes to test the assumption that these snails feed on water lily organic matter. We also measured other factors that can affect crushing resistance, such as the density of crushing predators, snail density, water pH, and the concentration of calcium and phosphorus in the water. The isotope analysis suggested that snails assimilate water lily organic matter that is metabolized by sediment bacteria. The variable that best explained the variation in crushing resistance found among sites was the local abundance of water lilies. We propose that the local amount of water lily organic matter provides organic compounds important in shell biomineralization, thus determining crushing resistance. Hence, we propose that a third trophic level could be important in the coevolution of snail defensive traits and predatory structures."

Article

Mexipyrgus churinceanus, Nymphaea ampla, freshwater snail, Cuatro Ciénegas, Mexico BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA ANIMAL (ZOOLOGÍA) DESARROLLO ANIMAL

Modelo econométrico de la demanda del agua de los acuíferos Valle de Cuatro Ciénegas y Valle El Hundido.

GILDARDO PEREZ MIRELES (2015)

Tesis (Maestría en Ciencias, especialista en Economía).- Colegio de Postgraduados, 2015.

La expansión agrícola y pecuaria ha originado un incremento en la demanda de agua en Cuatro Ciénegas, Coahuila. La presión por el uso del agua pone en peligro de destrucción los cauces y pozas naturales, así como las diferentes especies endémicas presentes en la región. Para determinar la relación, de la demanda de agua y su precio se estimó un modelo de ecuaciones simultáneas compuesto de tres funciones de demanda (pecuario, agrícola y doméstico) y cuatro identidades. Se utilizaron datos anuales con series históricas de 1993-2013. Los resultados muestran que la demanda precio del agua es inelástica en los tres sectores, con elasticidades de -0.045 para el sector agrícola de riego, -0.160 para el sector pecuario y -0.034 para el doméstico. Los resultados indican que el consumo del agua en el doméstico es insensible a cambio en el precio, los interesados sobre el uso y consumo del agua y las políticas que tratan de diseñar e implementar que deben considerar el aumento de los precios en los sectores. Una disminución de 1% sobre el consumo de agua en los tres sectores agrícola, pecuario y residencial podría lograrse mediante un aumento en el precio del agua en 22.2, 6.3 y 29.4%, respectivamente. Debido a la importancia de Cuatro Ciénegas en la preservación de pozas y especies, que convierten al valle un laboratorio natural, se recomienda disminuir el consumo de agua en aquel sector con un menor valor de uso como es el sector agrícola. _______________ ECONOMETRIC MODEL OF THE WATER DEMAND FROM AQUIFERS FROM “CUATRO CIENEGAS” AND “HUNDIDO” VALLEYS. ABSTRACT: The agricultural and livestock expansion has caused an increase in the water demand in Cuatro Ciénegas, Coahuila. The pressure due to the use of water puts riverbeds and natural pools at risk, as well as the different endemic species in the region. To determine the ratio of water demand and its price a model of simultaneous equations composed of three demand functions (livestock, agricultural and domestic) and four identities are estimated. Annual data with historical series from 1993 to 2013 was used in order to calculate elasticities. The results of the equation show that the demand of water regarding the change in prices is inelastic, showing elasticities of -0.045 for the irrigation agricultural sector, -0.160 for the livestock sector, and -0.034 for the domestic sector. The results indicate that water consumption in the agricultural and domestic sectors is imperceptible towards changes in prices. People interested in the use and consumption, and in the policies intended to be designed and implemented, should consider the increase in prices sectors. A decrease of 1% on water consumption in the three agricultural, livestock and residential sectors could be achieved by increasing the price of water to 22.22, 6.25, and 29.41%, respectively. Due to the importance of Cuatro Ciénegas regarding the natural pools and species conservation, which turns the valley into a natural laboratory, it is recommended to reduce water consumption in that sector, which owns a less-value use just like the agricultural sector.

Master thesis

Cuatro Ciénegas Demanda de agua Elasticidades Sector agrícola, pecuario y doméstico Modelo ecuaciones simultáneas Water demand Elasticities Agricultural, livestock, and domestic sectors Simultaneous equations models Economía Maestría CIENCIAS SOCIALES CIENCIAS ECONÓMICAS ECONOMETRÍA MODELOS ECONOMÉTRICOS

Phylogeography and conservation genetics of a distinct lineage of sunfish in the Cuatro Ciénegas Valley of Mexico

FRANCISCO JAVIER GARCIA DE LEON (2013)

"The valley of Cuatro Ciénegas, an aquatic oasis located in the Mexican Chihuahuan Desert, exhibits the highest level of endemism in North America and is a Mexican National Protected Area. However, little is known about the evolutionary distinctiveness of several vertebrate species present in the Cuatro Ciénegas valley. We conducted a phylogeographic study using mitochondrial haplotypes from the centrarchid fish Lepomis megalotis to determine if the populations found within the valley were evolutionarily distinct from populations outside the valley. We also examined if there was evidence of unique haplotypes of this sunfish within the valley. Genetic divergence of L. megalotis suggests populations within the valley are evolutionarily unique when compared to L. megalotis outside the valley. Significant mitochondrial sequence divergence was also discovered between L. megalotis populations on either side of the Sierra de San Marcos that bisects the valley. Our results reinforce previous studies that suggest the organisms occupying aquatic habitats not only within Cuatro Ciénegas but also in each of the two lobes of the valley generally deserve independent consideration during management decisions."

Article

Sunfish, phylogeography, conservation genetics, Cuatro Ciénegas, Mexico BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA GENÉTICA GENÉTICA DE POBLACIONES

Description of Eucyclops tziscao sp. n., E. angeli sp. n., and a new record of E. festivus Lindberg, 1955 (Cyclopoida, Cyclopidae, Eucyclopinae) in Chiapas, Mexico.

MARTHA ANGELICA GUTIERREZ AGUIRRE NANCY FABIOLA MERCADO SALAS ADRIAN CERVANTES MARTINEZ (2013)

"Two new species of the freshwater cyclopoid genera Eucyclops are described, Eucyclops tziscao sp. n. and E. angeli sp. n. Both species belong to the serrulatus-group defined by morphological features such as: the presence of distal spinules or hair-like setae (groups N1 and N2) on frontal surface of antennal basis; the fourth leg coxa with a strong inner spine that bears dense setules on inner side, yet proximally naked (large gap) on outer side; and a 12-segmented antennule with smooth hyaline membrane on the three distalmost segments. Eucyclops tziscao sp. n. is morphologically similar to E. bondi and E. conrowae but differs from these species in having a unique combination of characters, including a caudal ramus 4.05±0.25 times as long as wide, lateral seta of Enp3P4 modified as a strong, sclerotized blunt seta, coxal spine of fourth leg with inner spinule-like setules distally, and sixth leg of males bearing a strong and long inner spine 2.3 times longer than median seta. Eucyclops angeli sp. n. can be distinguished by an unique combination of morphological features: the short caudal ramus; the long spine on the sixth antennular segment of A1; the presence of one additional group of spinules (N12’) on the caudal surface of A2; the presence of long setae in females, or short spinules in males on the lateral margin of fourth prosomite; the strong ornamentation of the intercoxal sclerite of P4, specially group I modified as long denticles; the distal modified setae of Exp3P3 and Exp3P4 in females and males; and the short lateral seta of P5. Finally, we report on a new record of E. festivus in México, and add data on morphology of the species. "

Article

Copepoda Description Freshwater Free-living Neotropical BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA ANIMAL (ZOOLOGÍA)

Recent increase in the distribution of the snail kite (Rostrhamus sociabilis) along the central Pacific Coast of Mexico

SALVADOR HERNANDEZ VAZQUEZ RICARDO RODRIGUEZ ESTRELLA FRANCISCO ARTURO RAMIREZ ORTEGA (2013)

"New records of the snail kite (Rostrhamus sociabilis) are presented for the central Pacific Coast of Mexico. From April 2010 to August 2011, weekly or biweekly surveys were made through several wetlands of coastal Jalisco and Colima. We recorded 32 snail kites from October 2010 to August 2011. The recordings were in 8 wetlands. In all wetlands there was only 1 individual, except in the lagoons El Aguacate (June 2010) and El Tule (August 2012), where we recorded 3 and 5 individuals, respectively. Although we did not find any nests, we believe reproduction of snail kites is currently occurring because of the observed adult behavior (carrying small branches in its feet) and the records of juveniles during the month of February to July, a time corresponding to the breeding season of the species in Florida. Our records expand the distribution of the snail kite in Mexico as much as 900 km northwest of the previously published distribution of the species.

"Presentamos nuevas observaciones del gavilán caracolero (Rostrhamus sociabilis) para la costa del Pacífico central mexicano. De abril de 2010 a agosto de 2011 se realizaron visitas semanales o quincenales a varios humedales costeros de Jalisco y Colima. Se observaron 32 individuos entre octubre del 2010 y agosto del 2011 en 8 humedales. En todos los humedales se registró sólo 1 individuo, excepto en las lagunas El Aguacate (junio de 2011) y El Tule (agosto de 2012), donde se observaron 3 y 5 individuos, respectivamente. Aunque no se han registraron nidos, consideramos que es probable que la reproducción del gavilán caracolero está ocurriendo actualmente en la región debido a la conducta observada de algunos adultos (p. ej. llevando ramas pequeñas en sus patas) y a la presencia de los juveniles durante los meses de febrero a julio, tiempo en el que ocurre la anidación de la especie en Florida. Nuestras observaciones incrementan la distribución del gavilán caracolero en México a cerca de 900 km al noroeste de su distribución registrada previamente."

Article

snail kite, Rosthramus sociabilis, Jalisco and Colima, México gavilán caracolero BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA ANIMAL (ZOOLOGÍA) ECOLOGÍA ANIMAL

Respuesta fitosíntesis-irradianza del nanoplancton de dos ecosistemas acuáticos urbanos

MARIA DEL ROSARIO CRUZ MUÑOZ MARIA AMPARO MARTINEZ ARROYO (1999)

Four series of experiments on the phytoplankton smaller than 20llm (nannoplankton) were performed during 1997 in two urban aquatic ecosystems: Lake Chapultepec and Lake Xochimilco, in Mexico City. The goal was to learn the nannoplankton photosynthetic capacities by means of laboratory experiments where photosynIhesis- irradiance (P-I) curves were constructed using an integrated system with a polarographic electrode and light and temperature control. Experimental data were fitted to exponential models. The maximum photosynthesis rates (Pmax) ranged from 0.28 to 3.96 µmol 02 mg Chl a-1 h-1 in Chapultepec Lake and from 0.07 and 2. 99 µmol 02 mg Chl a-1 h-1 in Xochimilco Lake samples. The highest production in Chapultepec occurred in the rainy season while in Xochimilco it was in the dry season. Saturation irradiance (Ik) varied from 18 to 295 µEm-2 s-1. The highest photosynthesis rates occurred when some Cyanobacteria genera were dominant (Microcystis spp. and Oscillatoria spp. in both lakes and Merismopedia spp. and Anabaenopsis sp. for Xochimilco Lake). Biomass expressed as chlorophyll a concentration had its maximum values in the rainy season, 220.9 mg m-3 in Chapultepec and 136. 2 mg m-3 in Xochimilco.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Freshwater phytoplanklon nannoplankton photosynthesis urban lakes

Respuesta fitosíntesis-irradianza del nanoplancton de dos ecosistemas acuáticos urbanos

MARIA DEL ROSARIO CRUZ MUÑOZ MARIA AMPARO MARTINEZ ARROYO (1999)

Four series of experiments on the phytoplankton smaller than 20llm (nannoplankton) were performed during 1997 in two urban aquatic ecosystems: Lake Chapultepec and Lake Xochimilco, in Mexico City. The goal was to learn the nannoplankton photosynthetic capacities by means of laboratory experiments where photosynIhesis- irradiance (P-I) curves were constructed using an integrated system with a polarographic electrode and light and temperature control. Experimental data were fitted to exponential models. The maximum photosynthesis rates (Pmax) ranged from 0.28 to 3.96 µmol 02 mg Chl a-1 h-1 in Chapultepec Lake and from 0.07 and 2. 99 µmol 02 mg Chl a-1 h-1 in Xochimilco Lake samples. The highest production in Chapultepec occurred in the rainy season while in Xochimilco it was in the dry season. Saturation irradiance (Ik) varied from 18 to 295 µEm-2 s-1. The highest photosynthesis rates occurred when some Cyanobacteria genera were dominant (Microcystis spp. and Oscillatoria spp. in both lakes and Merismopedia spp. and Anabaenopsis sp. for Xochimilco Lake). Biomass expressed as chlorophyll a concentration had its maximum values in the rainy season, 220.9 mg m-3 in Chapultepec and 136. 2 mg m-3 in Xochimilco.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Freshwater phytoplanklon nannoplankton photosynthesis urban lakes

Morphological alterations in the freshwater rotifer Brachionus calyciflorus Pallas 1766 (Rotifera: Monogononta) caused by vinclozolin chronic exposure

JESUS ALVARADO FLORES ROBERTO RICO MARTINEZ ARACELI ADABACHE ORTIZ MARCELO SILVA BRIANO (2015)

Vinclozolin (VZ) is a dicarboximide fungicide widely used on fruits, vegetables and wines, effective against fungi plagues. In this study we characterized the effects of VZ using a 4-day reproductive chronic assay with the freshwater rotifer Brachionus calyciflorus. The assay included observations of several features of asexual and sexual reproduction. Our results indicate that VZ: (a) increased asexual and sexual reproduction, (b) caused severe abnormality in females and (c) these abnormalities were inherited by sexual and asexual reproduction. At 1.2 mg/L three abnormal females were found out of 457 total females (0.66 %). This low percentage is consistent and reproducible according to further analysis, where we increased the number of replicates and total females exposed to 1.2 mg/L of VZ, and found 18 abnormal females out of 2868 total females (0.63 % abnormality). Interestingly, abnormal females found at 5.6 mg/L VZ exposure, were able to show mating behavior. Our results suggest that VZ behaves as a strong endocrine disruptor whose effects show the characteristic inverted-U-shape exposure concentration response curve regarding the intrinsic population increase and the percentage of abnormalities as endpoints.

Article

ABNORMAL ROTIFERS ENDOCRINE DISRUPTION ENDOCRINE DISRUPTION FRESHWATER INVERTEBRATES FUNGICIDE TRANSGENERATIONAL EFFECTS BIOLOGÍA Y QUÍMICA

Morphological alterations in the freshwater rotifer Brachionus calyciflorus Pallas 1766 (Rotifera: Monogononta) caused by vinclozolin chronic exposure

JESUS ALVARADO FLORES ROBERTO RICO MARTINEZ ARACELI ADABACHE ORTIZ MARCELO SILVA BRIANO (2015)

Vinclozolin (VZ) is a dicarboximide fungicide widely used on fruits, vegetables and wines, effective against fungi plagues. In this study we characterized the effects of VZ using a 4-day reproductive chronic assay with the freshwater rotifer Brachionus calyciflorus. The assay included observations of several features of asexual and sexual reproduction. Our results indicate that VZ: (a) increased asexual and sexual reproduction, (b) caused severe abnormality in females and (c) these abnormalities were inherited by sexual and asexual reproduction. At 1.2 mg/L three abnormal females were found out of 457 total females (0.66 %). This low percentage is consistent and reproducible according to further analysis, where we increased the number of replicates and total females exposed to 1.2 mg/L of VZ, and found 18 abnormal females out of 2868 total females (0.63 % abnormality). Interestingly, abnormal females found at 5.6 mg/L VZ exposure, were able to show mating behavior. Our results suggest that VZ behaves as a strong endocrine disruptor whose effects show the characteristic inverted-U-shape exposure concentration response curve regarding the intrinsic population increase and the percentage of abnormalities as endpoints.

Article

ABNORMAL ROTIFERS ENDOCRINE DISRUPTION ENDOCRINE DISRUPTION FRESHWATER INVERTEBRATES FUNGICIDE TRANSGENERATIONAL EFFECTS BIOLOGÍA Y QUÍMICA BIOLOGÍA Y QUÍMICA

LISTA SISTEMATICA PRELIMINAR DE LOS PECES DEL ESTADO DE NAYARIT, MEXICO

JOSE TRINIDAD NIETO NAVARRO DEIVIS SAMUEL PALACIOS SALGADO LUIS FERNANDO DEL MORAL FLORES OSCAR IRAM ZAVALA LEAL (2013)

Nayarit’s fish fauna deserves to be fully documented; therefore, the objective of this manuscript is to present a systematic list of ichthyofauna of Nayarit (Mexico) as the result of an extensive literature review and databases available on the web. 587 species were found. Most records were from species of marine and estuarine affinity, while the freshwater species seem to be poorly represented. The fish fauna reported is diverse; however there is little knowledge about freshwater environments, priority areas for study are located in virtually all of the state. Review of specimens from current collections is recommended, in order to complement the results obtained in this work.

La ictiofauna del estado de Nayarit México ha sido poco estudiada y documentada, así el objetivo del trabajo es presentar el listado de los peces reportados en el estado a partir de una exhaustiva revisión bibliográfica y consulta de bases de datos disponibles en internet. Se encontraron 587 especies reportadas. La mayoría de los registros corresponden a especies de afinidad marina y estuarina, mientras que las dulceacuícolas están escasamente representadas. La ictiofauna reportada es diversa, sin embargo existen un escaso conocimiento de los ambientes dulceacuícolas, las zonas prioritarias para su estudio se ubican en prácticamente todo el estado. Además, se recomienda verificar el material presente en las colecciones, con la finalidad de complementar los resultados obtenidos en este trabajo.

Article

Pacífico Centra peces dulceacuícolas peces marinos biodiversidad Central Pacific freshwater fishes marine fishes biodiversity CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA