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Trujillo-Jimenez P.,Autonomous University of the State of Morelos | Elias Sedeno-Diaz J.,National Polytechnic Institute of Mexico | Lopez-Lopez E.,Laboratorio Of Ictiologia Y Limnologia
Journal of Environmental Biology | Year: 2014

The use of biomarkers for monitoring aquatic environmental quality has gained considerable interest worldwide. The effects of the environmental conditions of Río Champotón, México, in the hotspot of Mesoamerica, were assessed in Astyanax aeneus, a native fish of the tropics of southwestern México. Pollution from agrochemical residues is a major problem in Río Champotón. Three study sites along the freshwater portion of the river were monitored in April, July, and November 2007 and February 2008. This study includes a water quality index, a set of biomarkers (hepatic glycogen levels and lipid peroxidation in liver, gills, and muscle) to assess the integrated biomarker response, and population bioindicators (gonadosomatic and hepatosomatic indices and Fulton's condition factor). Although the water quality index suggested low level of contamination in the Río Champotón, biomarkers indicated that A. aeneus is exposed to stressors that impair biological responses. The integrated biomarker response showed stress periods with higher biomarker response and recovery periods with decreasing biomarker values. The somatic indices did not indicate severe effects at the population level. This study illustrates the usefulness of lipid peroxidation evaluation in the assessment of aquatic health conditions and corroborates the suitability of A. aeneus as a sentinel species. © Triveni Enterprises, Lucknow (India.

Mejia O.,Laboratorio Of Variacion Biologica Y Evolucion | Leon-Romero Y.,Laboratorio Of Variacion Biologica Y Evolucion | Soto-Galera E.,Laboratorio Of Ictiologia Y Limnologia
Mitochondrial DNA | Year: 2012

The PánucoTamesí complex in eastern Mexico is globally recognized as an important ecoregion due to its high level of endemism. In this study, DNA barcodes were generated for 152 individuals of 31 species. Additionally, 170 DNA barcodes for the related species available in the Barcode of Life Database (BOLD) system were included to test the ability of barcoding technique to discriminate between the closely related species. DNA barcoding allowed the discrimination of 79.2% of the analyzed species; poor resolution was observed in four genera in which the levels of resolution ranged from 16.6% in the genus Herichthys to 77.7% in the genus Xiphophorus. The results of this study demonstrate that DNA barcoding is a useful exploratory tool but fails to discriminate between closely related species. © 2012 Informa UK, Ltd.

Trujillo-Jimenez P.,Autonomous University of the State of Morelos | Sedeno-Diaz J.E.,Programa Ambiental | Camargo J.A.,University of Alcala | Lopez-Lopez E.,Laboratorio Of Ictiologia Y Limnologia
Ecological Indicators | Year: 2011

The upper reaches of the Río Champotón in southwestern Mexico are largely unknown to science. This river is sustaining anthropogenic and natural disturbances by deforestation, substitution of natural vegetation, and agricultural non-point source pollution. Furthermore, hurricanes provoke flooding of these areas, exposing the aquatic biota to pollutants. Several approaches were used to assess the effects of environmental conditions along the freshwater portion of the Río Champotón in the native fish Astyanax aeneus and to determine the feasibility of extrapolating responses between levels of organization, and to link spatial and seasonal fish responses with water quality features. A water quality index (WQI) was employed as an indicator of environmental conditions, a set of sub-organismal biomarkers in A. aeneus (lipid peroxidation, glutathione S-transferase, ethoxyresorufin-O- deethylase and lactate dehydrogenase) was monitored to determine the integrated biomarker response (IBR), and somatic indices (individual and population-level responses; gonadosomatic, hepatosomatic, and condition factor) were characterized. Canonical correspondence analysis revealed spatial and seasonal variations in all the approaches. The dry and the wet season (April and July) exhibited low WQI scores, but decreased hardness and conductivity values as well as increased WQI values occurred during the post-hurricane season when crop fields adjacent to the riverbed were inundated. Although the WQI suggested low levels of contamination, the biomarkers did not remain static; wide fluctuations reflected fish exposure to seasonal stressors that provoked impairments in biological responses. All biomarker values were high, mainly in the post-hurricane season (November). The IBR exhibited two peaks that may be related to stress periods (April and November), with decreasing post-stress values suggesting the existence of homeostatic processes in the fish. The somatic indices reflected some seasonal and spatial differences at the population level - the gonadosomatic and hepatosomatic indices peaked in the middle of July and November, respectively - but the condition factor remained constant among sites and study periods. Future studies are needed to explore the link between the fish biomarker responses and possible causal stressors (natural or anthropogenic). © 2011 Elsevier Ltd.

Trujillo-Jimenez P.,Autonomous University of the State of Morelos | Camargo J.A.,University of Alcala | Lopez-Lopez E.,Laboratorio Of Ictiologia Y Limnologia
Revista de Biologia Tropical | Year: 2013

Champotón River is an unknown area within the Mesoamerican hotspot in Southestern México. Reproductive traits and population structure of Astyanax aeneus were analyzed along an environmental gradient of the upper, middle and lower sections of the river, where diverse environmental factors were recorded. For this, nets were cast for 1h at each site and A. aeneus were collected from all sections with sweep nets (5 and 10m long by 5m deep, 0.03m mesh size) and a casting net (0.05m mesh size). At each study site and campaign, a total of 80 specimens (in average) were collected and were fixed in 10% formaldehyde for further analysis. Population structure by size was analyzed for each study site, based on the relative frequencies by standard length classes. The length-weight relationship was determined, and the identification of gonadal developmental stages, reproductive period, size at first sexual maturity, relative fecundity, sex ratio and somatic indexes (gonadosomatic, hepatosomatic and Fulton's condition factor) were also assessed. Seven size classes were found in the upper and middle sections, and nine downstream, with seasonal and spatial pattern in size-class frequency distribution. Size at first maturity was 45.7mm for females and 40.8mm for males. The maximum relative fecundity was recorded at the downstream site and was positively correlated with body weight and standard length. Sex ratio (1.8:1 males: females) differed significantly from expected values (1:1). Gonadosomatic index scores indicated that the reproductive period of this species in the Champotón River was from April to July, during the warm and wet season. Hepatosomatic index was negatively correlated with the Gonadosomatic index, evidencing transfer of energy from the liver towards gamete production. This strategy enabled A. aeneus to maintain robustness during the study period with tiny changes in condition factor. A. aeneus in the Champotón River, as opposed to South American river congeneric species of similar size, shows early sexual maturity, a short reproductive period with high gonadosomatic index values, and high fecundity, a trade-off for the short reproductive period. Spatio-temporal segregation was evident: breeders congregate downstream, while juveniles prefer the upper reaches. This pattern allows A. aenus to be successful in a river with high frequency of hurricanes.

Trujillo-Jimenez P.,Autonomous University of the State of Morelos | Lopez-Lopez E.,Laboratorio Of Ictiologia Y Limnologia | Diaz-Pardo E.,Autonomous University of Queretaro | Camargo J.A.,University of Alcala
Reviews in Fish Biology and Fisheries | Year: 2010

Patterns in spatial and seasonal distribution of fish communities were analyzed in the Río Amacuzac, Mexico, and their relationship to environmental variables and habitat characteristics. The PCA biplot of the study sites and environmental factors showed the first two axes accounting for 52.93% of the variance. The diagram showed the study sites ordination in environmental gradients. The first axis explained variables related to habitat characteristics and temperature (36.30%) and second axis arranged the sites in physicochemical and water quality environmental gradients (conductivity, dissolved oxygen, orthophosphates, ammonium, pH) displaying seasonal variation. Fifteen species were recorded, eight of them are exotic. One new record appeared for the Río Amacuzac: Pterygoplichthys disjunctivus is exotic. Study sites with highest species richness were: 5, 7 and 9 (twelve species each one); while the study sites with low species richness were 1, 2, 3 and 6 (eight species each one). Six of the species were distributed throughout the whole river. Based on the composition of the fish fauna, the study sites form two groups and the analysis of fish species displays three groups according to the Bray-Curtis index. The diagram of the canonical correspondence analysis relates environmental parameters to the abundance of fish species and showed that the first two axes exhibit 78.31% of the explained variance. Species richness had a spatial pattern associated to the introduction of exotic species for ornamental uses. According to the results of the importance value index (IVI), the dominant species were the poecilids Poeciliopsis gracilis and Heterandria bimaculata, small fishes that were introduced in the river. Río Amacuzac has a biotic alteration in the structure of fish communities due to the invasion of exotic species, representing risks to the integrity of the native fish fauna. © 2009 Springer Science+Business Media B.V.

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