The Mexican territory is characterised by few natural lakes which cover an area of 371,000 ha; on... more The Mexican territory is characterised by few natural lakes which cover an area of 371,000 ha; on the other hand Mexico has a large number of impoundmenrs covering 629,000 ha (TAMAYO 1987). These reservoirs were constructed for rhe supply of drinking water, flood control, aquaculture and irrigation, although many of them have several uses. Management of water resources is a priority in Mexico because of water shortages, reservoir pollurion and frequent blue-green algal blooms. Relatively little research work has been done on the comparative limnology of these reservoirs and their woplankton (CHACON 1993). The aim of this paper is to delineate the major features of the regional limnology of ten reservoirs in the Mexican Central Plateau. There is an attempt to relate water chemistry with the distribution of woplankton.
Champotón River is an unknown area within the Mesoamerican hotspot in Southestern México. Reprodu... more 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 1 h at each site and A. aeneus were collected from all sections with sweep nets (5 and 10 m long by 5 m 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, hepatosomat...
Qanats in the aquifer of the Tehuacán Valley (Mexico) represent an ancient way of using groundwat... more Qanats in the aquifer of the Tehuacán Valley (Mexico) represent an ancient way of using groundwater that is still practiced today. They are used mainly for agricultural irrigation. However, anthropogenic activities have jeopardized the use of these aquifers. We analyzed 24 qanats in the Tehuacán Valley to assess water quality. Based on 24 physicochemical variables, a water quality index (WQI) was constructed on a zero-to-100 scale, divided into five water quality classes. A decision-tree analysis was applied to identify the parameters with the highest influence on the WQI, considering the water quality classes as categorical responses and the values of physicochemical variables as drivers of these categories. We produced interpolation maps to identify trends. The relationship between the WQI and the normalized difference indices of vegetation and salinity (NDVI and NDSI, respectively) was analyzed using a ternary diagram. WQI scores showed that 12.5% of the qanats have very good quality; 25%, good quality; and the remaining (62.5%) range from moderate to unacceptable quality. The CHAID classification-tree method correctly explained 83.3% of the categories, with sulfates, alkalinity, conductivity, and nitrates as the main parameters that explain water quality. WQI was inversely related to NDVI and NDSI, showing seasonal differences. Interpolation maps suggest a better water quality in the northern zone of the aquifer.
A number of natural effects and anthropogenic activities are known to significantly alter the int... more A number of natural effects and anthropogenic activities are known to significantly alter the integrity of freshwater bodies. This is a problem that has promoted the development of chemical or biological strategies to identify and quantify the damage in freshwater ecosystems; it is fundamental knowledge that should be followed by preventive or corrective measures. The use of biomonitor organisms belonging to plant and animal phyla for this has proved their usefulness, mainly because of the idea that any change in the ecosystem should be reflected in the selected organism. However, an appropriate biomonitor should possess several essential characteristics to properly carry out its function. Crayfish are a large group of aquatic macroinvertebrates that have shown sensitivity toward a variety of stressors. They are known to respond in various forms, including metabolic, histologic, and genotoxic changes. For the latter, studies have mainly applied the single cell gel electrophoresis (C...
One of the main concerns of current environmental toxicology is the low number of taxa used for s... more One of the main concerns of current environmental toxicology is the low number of taxa used for standard bioassays. Ferns are the second largest group of vascular plants and are important components of numerous plant communities. Fern spores and gametophytes have long been recognized as useful models for plant research, since they constitute a naturally miniaturized and low-cost higher plant model. Mitochondria are the main energy source in eukaryotic cells, and any toxic damage to this organelle will affect the whole organism. The reduction of tetrazolium salts to water-insoluble coloured formazan salts by the NADH reductase complex (EC 1.6.5.3) has been used for more than 50 years as a measure of cell mitochondrial activity and viability in eukaryotic organisms. Here, the reduction of 2, 3, 5-triphenyltetrazolium chloride (TTC) by mitochondria is adapted and optimized to measure fern spore or gametophyte viability. A review of the recent literature using the fern spore bioassay re...
The analysis of functional diversity has shown to be more sensitive to the effects of natural and... more The analysis of functional diversity has shown to be more sensitive to the effects of natural and anthropogenic disturbances on the assemblages of aquatic macroinvertebrates than the classical analyses of structural ecology. However, this ecological analysis perspective has not been fully explored in tropical environments of America. Protected Natural Areas (PNAs) such as biosphere reserves can be a benchmark regarding structural and functional distribution patterns worldwide, so the characterization of the functional space of biological assemblages in these sites is necessary to promote biodiversity conservation efforts. Our work characterized the multidimensional functional space of the macroinvertebrate assemblages from an ecosystemic approach by main currents, involving a total of 15 study sites encompassing different impact and human influence scenarios, which were monitored in two contrasting seasons. We calculated functional diversity indices (dispersion, richness, divergence...
Antecedentes. Los endófitos bacterianos que habitan dentro de las plantas sin causar daño y promu... more Antecedentes. Los endófitos bacterianos que habitan dentro de las plantas sin causar daño y promueven su crecimiento y desarrollo se han considerado herramientas útiles para la restauración de los ecosistemas. Objetivos. En el presente estudio se caracterizaron fitobacterias endófitas aisladas de plantas de Lemna gibba, colectadas en la zona chinampera de los canales de Xochimilco en dos temporadas, con base en la comparación de su producción de ácido indolacético. Métodos. Se evaluaron 12 fitobacterias en total; ocho aisladas de las plantas L. gibba colectadas en la temporada de sequía pertenecientes a los géneros Achromobacter, Bacillus, Deinococcus, Enterococcus, Pseudomonas y Rahnella. Las variedades restantes (pertenecientes al género Serratia) se obtuvieron de plantas colectadas en la temporada de lluvias. Resultados. De acuerdo con la producción de ácido indolacético, de las fitobacterias colectadas en la temporada de sequía, cuatro se clasificaron como bajas productoras y cuatro como altas productoras. Por otra parte, todos los organismos que se recolectaron en la temporada de lluvias se clasificaron como altos productores. Conclusiones. La presencia de fitobacterias endófitas altas productoras de ácido indolacético en Lemna gibba sugiere que son promotoras potenciales del desarrollo de dichas plantas y también que actúan como bioinoculantes potenciales.
In the Mexican Central Plateau (MCP), due to their long history of geologic instability, numerous... more In the Mexican Central Plateau (MCP), due to their long history of geologic instability, numerous fluvial systems that were blocked formed extensive shallow lakes. Environmental conditions of this area have favored the agricultural land use and the settlement of great industrial corridors and cities. Human activities in MCP are largely sustained by intense water use that has led to a high deterioration in the water bodies of this area. We analyze the water quality of two selected shallow lakes of the MCP: Yuriria Lake and Xochimilco Lake and early warning biomarkers of native sentinel species of each lake. Both studied lakes are influenced by the input of complex mixtures of pollutants. We assess water quality index and a set of oxidative stress biomarkers in native endemic species of each lake. Results showed that the input of xenobiotics and changes in the periods of dry and rains in the shallow lakes studied provoke a stronger response in sentinel organisms because dilution effects are minimal in a small water column. Furthermore, resuspension of sediments in shallow lakes can release pollutants to the water column that could exert damage to the health condition of the aquatic biota compromising the survival of endemic sensitive species.
Xenobiotic mixtures in aquatic ecosystems may compromise fish health by inducing oxidative stress... more Xenobiotic mixtures in aquatic ecosystems may compromise fish health by inducing oxidative stress, decreasing resistance, and fostering susceptibility to pathogens such as helminths. Lipid peroxidation (LPO) is one of the most commonly used methods to evaluate oxidative stress. The present study examines the potential correlations between LPO in liver, muscle, and gill and the presence of helminths in Astyanax aeneus from a subtropical river in Mexico. Five helminth species were identified: the trematodes Uvulifer ambloplitis, a subdermal larval parasite, and Clinostomum complanatum, which infected the base of the gills; the nematodes Contracaecum sp. and Spiroxys sp.; and the acanthocephalan Polymorphus sp. The latter 3 species occurred in the posterior half of the intestine. Total helminth abundance was highest in April and July. Helminth species richness increased along a gradient from the headwaters to the middle reaches of the river. An integrated biomarker response for LPO (IBR-LPO) was assessed in the 3 tissues analyzed. IBR-LPO peaked in July. A direct correlation was found between gill and muscle LPO and mean abundance of Clinostomum complanatum, Contracaecum sp., and orthophosphate values, as well as between liver LPO and mean abundance of Polymorphus sp., whereas no relationship was found between LPO and U. ambloplitis or Spiroxys sp. This research revealed an association of both orthophosphate values and the presence or abundance of parasites with oxidative stress levels in A. aeneus, without any causal association, but rather as a result of synergistic processes associated with these variables.
The Tuxpam and Tecolutla rivers in the Gulf of Mexico, are located in the Mesoamerican biodiversi... more The Tuxpam and Tecolutla rivers in the Gulf of Mexico, are located in the Mesoamerican biodiversity hotspot and support different human activities: crude oil extraction, agriculture and livestock, that provoke environmental disturbances. Aquatic mollusks, physicochemical water characteristics and substrate type were examined along the main watercourse of these rivers during three periods of one year: the wet season, dry season, and during the northern winds season, when hurricanes are more frequent. In both rivers, physicochemical water characteristics, types of substratum and mollusk fauna demonstrated environmental gradients and differentiate two river zones: freshwater and estuarine. Differences were also found between the dry season, with higher inorganic salts content, and the wet and northern winds and hurricane seasons, when inorganic and organic nutrient inputs occurred. The mollusk fauna is composed of nine and eleven taxa in the Tecolutla and Tuxpam rivers, respectively. In both rivers, the introduced gastropod Tarebia granifera is the dominant species in the freshwater zone with regard to population density and the area it covers within the ecosystem, followed by the introduced bivalve Corbicula fluminea. Native mollusk species were confined to point-locations and attained very low densities. The gastropod Neritina virginea and the bivalve Brachidontes exustus were dominant in the estuarine zone of both rivers. Mollusk population densities declined during the wet, northern winds and hurricane seasons, while in the dry season both alien species reached higher densities, which could indicate that alien mollusks are removed by effect of climatic events. T. granifera and C. fluminea exhibit traits characteristic of invasive species and pose a risk to native mollusk biodiversity in these rivers.
Mining is one of the main pollution issues worldwide, causing the greatest disturbances to the en... more Mining is one of the main pollution issues worldwide, causing the greatest disturbances to the environment. Industrial and artisanal mining activities are widespread in Mexico, being a major global producer of various metals. This study aimed to assess the ecological impairments resulting from mining activities using the aquatic macroinvertebrates assemblages (MA). A multiple co-inertia analysis (MCOA) was applied to determine the relationships between environmental factors, habitat quality, heavy metals, and aquatic macroinvertebrates in two rivers of the Central Plateau, Mexico. The results revealed three contrasting environmental conditions and different MA. High concentrations of heavy metals, nutrients, and salinity limit the presence of various families of seemingly sensitive macroinvertebrates, these factors were identified as the drivers of structural changes in the MA, showing that not only mining activities, but also agriculture, and villages in the basin, exert negative e...
Lake Xochimilco has been the receiver of untreated domestic wastewater, agricultural run off and ... more Lake Xochimilco has been the receiver of untreated domestic wastewater, agricultural run off and secondary effluent of a treatment facility, thus becoming the receptor of a mixture of pollutants and their metabolites. Major zones in Lake Xochimilco are urban, agricultural and tourist; all of them exert environmental pressure to the Lake, that has been associated with the extinction of two fish species, and the limited presence of another, Girardinichthys viviparous. Early warning biomarkers of G. viviparous were analyzed after its reintroduction to waters of Lake Xochimilco, in order to evaluate the responses of the fish in the case of their repopulation in their ancient habitat. We examine some indicators of the water quality, the level of lipid peroxidation and the acetylcholinesterase activity in brain, gill, liver and muscle of G. viviparous after exposure to waters of each zone of Lake Xochimilco. The results show that the urban area presents an enrichment of ammonium, related ...
The Tehuacán-Cuicatlán Biosphere Reserve, Mexico (TCBR) is the southernmost arid or semi-arid zon... more The Tehuacán-Cuicatlán Biosphere Reserve, Mexico (TCBR) is the southernmost arid or semi-arid zone with the highest biodiversity in North America and is a UNESCO World Heritage site. Two main hydrographic streams cross the TCBR, the Salado River (an endogenous river) and the Grande River (an exogenous river). This study investigated temperature anomalies over the past 40 years. We analyzed potential differences between sub-basins and riparian areas on both streams using various indices, namely the Global Warming Index (GWI), Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), and Normalized Difference Drought Index (NDDI), and analyzed the potential relationship of these indices with climate change. Time series of satellite-based precipitation (June 2000–December 2020) and air temperature (January 1980–December 2020) were analyzed. A set of Landsat 8 OLI TIRS imagery from the driest and wettest months (2013–2020) was used to estimate NDVI, NDWI, ...
The Mexican territory is characterised by few natural lakes which cover an area of 371,000 ha; on... more The Mexican territory is characterised by few natural lakes which cover an area of 371,000 ha; on the other hand Mexico has a large number of impoundmenrs covering 629,000 ha (TAMAYO 1987). These reservoirs were constructed for rhe supply of drinking water, flood control, aquaculture and irrigation, although many of them have several uses. Management of water resources is a priority in Mexico because of water shortages, reservoir pollurion and frequent blue-green algal blooms. Relatively little research work has been done on the comparative limnology of these reservoirs and their woplankton (CHACON 1993). The aim of this paper is to delineate the major features of the regional limnology of ten reservoirs in the Mexican Central Plateau. There is an attempt to relate water chemistry with the distribution of woplankton.
Champotón River is an unknown area within the Mesoamerican hotspot in Southestern México. Reprodu... more 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 1 h at each site and A. aeneus were collected from all sections with sweep nets (5 and 10 m long by 5 m 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, hepatosomat...
Qanats in the aquifer of the Tehuacán Valley (Mexico) represent an ancient way of using groundwat... more Qanats in the aquifer of the Tehuacán Valley (Mexico) represent an ancient way of using groundwater that is still practiced today. They are used mainly for agricultural irrigation. However, anthropogenic activities have jeopardized the use of these aquifers. We analyzed 24 qanats in the Tehuacán Valley to assess water quality. Based on 24 physicochemical variables, a water quality index (WQI) was constructed on a zero-to-100 scale, divided into five water quality classes. A decision-tree analysis was applied to identify the parameters with the highest influence on the WQI, considering the water quality classes as categorical responses and the values of physicochemical variables as drivers of these categories. We produced interpolation maps to identify trends. The relationship between the WQI and the normalized difference indices of vegetation and salinity (NDVI and NDSI, respectively) was analyzed using a ternary diagram. WQI scores showed that 12.5% of the qanats have very good quality; 25%, good quality; and the remaining (62.5%) range from moderate to unacceptable quality. The CHAID classification-tree method correctly explained 83.3% of the categories, with sulfates, alkalinity, conductivity, and nitrates as the main parameters that explain water quality. WQI was inversely related to NDVI and NDSI, showing seasonal differences. Interpolation maps suggest a better water quality in the northern zone of the aquifer.
A number of natural effects and anthropogenic activities are known to significantly alter the int... more A number of natural effects and anthropogenic activities are known to significantly alter the integrity of freshwater bodies. This is a problem that has promoted the development of chemical or biological strategies to identify and quantify the damage in freshwater ecosystems; it is fundamental knowledge that should be followed by preventive or corrective measures. The use of biomonitor organisms belonging to plant and animal phyla for this has proved their usefulness, mainly because of the idea that any change in the ecosystem should be reflected in the selected organism. However, an appropriate biomonitor should possess several essential characteristics to properly carry out its function. Crayfish are a large group of aquatic macroinvertebrates that have shown sensitivity toward a variety of stressors. They are known to respond in various forms, including metabolic, histologic, and genotoxic changes. For the latter, studies have mainly applied the single cell gel electrophoresis (C...
One of the main concerns of current environmental toxicology is the low number of taxa used for s... more One of the main concerns of current environmental toxicology is the low number of taxa used for standard bioassays. Ferns are the second largest group of vascular plants and are important components of numerous plant communities. Fern spores and gametophytes have long been recognized as useful models for plant research, since they constitute a naturally miniaturized and low-cost higher plant model. Mitochondria are the main energy source in eukaryotic cells, and any toxic damage to this organelle will affect the whole organism. The reduction of tetrazolium salts to water-insoluble coloured formazan salts by the NADH reductase complex (EC 1.6.5.3) has been used for more than 50 years as a measure of cell mitochondrial activity and viability in eukaryotic organisms. Here, the reduction of 2, 3, 5-triphenyltetrazolium chloride (TTC) by mitochondria is adapted and optimized to measure fern spore or gametophyte viability. A review of the recent literature using the fern spore bioassay re...
The analysis of functional diversity has shown to be more sensitive to the effects of natural and... more The analysis of functional diversity has shown to be more sensitive to the effects of natural and anthropogenic disturbances on the assemblages of aquatic macroinvertebrates than the classical analyses of structural ecology. However, this ecological analysis perspective has not been fully explored in tropical environments of America. Protected Natural Areas (PNAs) such as biosphere reserves can be a benchmark regarding structural and functional distribution patterns worldwide, so the characterization of the functional space of biological assemblages in these sites is necessary to promote biodiversity conservation efforts. Our work characterized the multidimensional functional space of the macroinvertebrate assemblages from an ecosystemic approach by main currents, involving a total of 15 study sites encompassing different impact and human influence scenarios, which were monitored in two contrasting seasons. We calculated functional diversity indices (dispersion, richness, divergence...
Antecedentes. Los endófitos bacterianos que habitan dentro de las plantas sin causar daño y promu... more Antecedentes. Los endófitos bacterianos que habitan dentro de las plantas sin causar daño y promueven su crecimiento y desarrollo se han considerado herramientas útiles para la restauración de los ecosistemas. Objetivos. En el presente estudio se caracterizaron fitobacterias endófitas aisladas de plantas de Lemna gibba, colectadas en la zona chinampera de los canales de Xochimilco en dos temporadas, con base en la comparación de su producción de ácido indolacético. Métodos. Se evaluaron 12 fitobacterias en total; ocho aisladas de las plantas L. gibba colectadas en la temporada de sequía pertenecientes a los géneros Achromobacter, Bacillus, Deinococcus, Enterococcus, Pseudomonas y Rahnella. Las variedades restantes (pertenecientes al género Serratia) se obtuvieron de plantas colectadas en la temporada de lluvias. Resultados. De acuerdo con la producción de ácido indolacético, de las fitobacterias colectadas en la temporada de sequía, cuatro se clasificaron como bajas productoras y cuatro como altas productoras. Por otra parte, todos los organismos que se recolectaron en la temporada de lluvias se clasificaron como altos productores. Conclusiones. La presencia de fitobacterias endófitas altas productoras de ácido indolacético en Lemna gibba sugiere que son promotoras potenciales del desarrollo de dichas plantas y también que actúan como bioinoculantes potenciales.
In the Mexican Central Plateau (MCP), due to their long history of geologic instability, numerous... more In the Mexican Central Plateau (MCP), due to their long history of geologic instability, numerous fluvial systems that were blocked formed extensive shallow lakes. Environmental conditions of this area have favored the agricultural land use and the settlement of great industrial corridors and cities. Human activities in MCP are largely sustained by intense water use that has led to a high deterioration in the water bodies of this area. We analyze the water quality of two selected shallow lakes of the MCP: Yuriria Lake and Xochimilco Lake and early warning biomarkers of native sentinel species of each lake. Both studied lakes are influenced by the input of complex mixtures of pollutants. We assess water quality index and a set of oxidative stress biomarkers in native endemic species of each lake. Results showed that the input of xenobiotics and changes in the periods of dry and rains in the shallow lakes studied provoke a stronger response in sentinel organisms because dilution effects are minimal in a small water column. Furthermore, resuspension of sediments in shallow lakes can release pollutants to the water column that could exert damage to the health condition of the aquatic biota compromising the survival of endemic sensitive species.
Xenobiotic mixtures in aquatic ecosystems may compromise fish health by inducing oxidative stress... more Xenobiotic mixtures in aquatic ecosystems may compromise fish health by inducing oxidative stress, decreasing resistance, and fostering susceptibility to pathogens such as helminths. Lipid peroxidation (LPO) is one of the most commonly used methods to evaluate oxidative stress. The present study examines the potential correlations between LPO in liver, muscle, and gill and the presence of helminths in Astyanax aeneus from a subtropical river in Mexico. Five helminth species were identified: the trematodes Uvulifer ambloplitis, a subdermal larval parasite, and Clinostomum complanatum, which infected the base of the gills; the nematodes Contracaecum sp. and Spiroxys sp.; and the acanthocephalan Polymorphus sp. The latter 3 species occurred in the posterior half of the intestine. Total helminth abundance was highest in April and July. Helminth species richness increased along a gradient from the headwaters to the middle reaches of the river. An integrated biomarker response for LPO (IBR-LPO) was assessed in the 3 tissues analyzed. IBR-LPO peaked in July. A direct correlation was found between gill and muscle LPO and mean abundance of Clinostomum complanatum, Contracaecum sp., and orthophosphate values, as well as between liver LPO and mean abundance of Polymorphus sp., whereas no relationship was found between LPO and U. ambloplitis or Spiroxys sp. This research revealed an association of both orthophosphate values and the presence or abundance of parasites with oxidative stress levels in A. aeneus, without any causal association, but rather as a result of synergistic processes associated with these variables.
The Tuxpam and Tecolutla rivers in the Gulf of Mexico, are located in the Mesoamerican biodiversi... more The Tuxpam and Tecolutla rivers in the Gulf of Mexico, are located in the Mesoamerican biodiversity hotspot and support different human activities: crude oil extraction, agriculture and livestock, that provoke environmental disturbances. Aquatic mollusks, physicochemical water characteristics and substrate type were examined along the main watercourse of these rivers during three periods of one year: the wet season, dry season, and during the northern winds season, when hurricanes are more frequent. In both rivers, physicochemical water characteristics, types of substratum and mollusk fauna demonstrated environmental gradients and differentiate two river zones: freshwater and estuarine. Differences were also found between the dry season, with higher inorganic salts content, and the wet and northern winds and hurricane seasons, when inorganic and organic nutrient inputs occurred. The mollusk fauna is composed of nine and eleven taxa in the Tecolutla and Tuxpam rivers, respectively. In both rivers, the introduced gastropod Tarebia granifera is the dominant species in the freshwater zone with regard to population density and the area it covers within the ecosystem, followed by the introduced bivalve Corbicula fluminea. Native mollusk species were confined to point-locations and attained very low densities. The gastropod Neritina virginea and the bivalve Brachidontes exustus were dominant in the estuarine zone of both rivers. Mollusk population densities declined during the wet, northern winds and hurricane seasons, while in the dry season both alien species reached higher densities, which could indicate that alien mollusks are removed by effect of climatic events. T. granifera and C. fluminea exhibit traits characteristic of invasive species and pose a risk to native mollusk biodiversity in these rivers.
Mining is one of the main pollution issues worldwide, causing the greatest disturbances to the en... more Mining is one of the main pollution issues worldwide, causing the greatest disturbances to the environment. Industrial and artisanal mining activities are widespread in Mexico, being a major global producer of various metals. This study aimed to assess the ecological impairments resulting from mining activities using the aquatic macroinvertebrates assemblages (MA). A multiple co-inertia analysis (MCOA) was applied to determine the relationships between environmental factors, habitat quality, heavy metals, and aquatic macroinvertebrates in two rivers of the Central Plateau, Mexico. The results revealed three contrasting environmental conditions and different MA. High concentrations of heavy metals, nutrients, and salinity limit the presence of various families of seemingly sensitive macroinvertebrates, these factors were identified as the drivers of structural changes in the MA, showing that not only mining activities, but also agriculture, and villages in the basin, exert negative e...
Lake Xochimilco has been the receiver of untreated domestic wastewater, agricultural run off and ... more Lake Xochimilco has been the receiver of untreated domestic wastewater, agricultural run off and secondary effluent of a treatment facility, thus becoming the receptor of a mixture of pollutants and their metabolites. Major zones in Lake Xochimilco are urban, agricultural and tourist; all of them exert environmental pressure to the Lake, that has been associated with the extinction of two fish species, and the limited presence of another, Girardinichthys viviparous. Early warning biomarkers of G. viviparous were analyzed after its reintroduction to waters of Lake Xochimilco, in order to evaluate the responses of the fish in the case of their repopulation in their ancient habitat. We examine some indicators of the water quality, the level of lipid peroxidation and the acetylcholinesterase activity in brain, gill, liver and muscle of G. viviparous after exposure to waters of each zone of Lake Xochimilco. The results show that the urban area presents an enrichment of ammonium, related ...
The Tehuacán-Cuicatlán Biosphere Reserve, Mexico (TCBR) is the southernmost arid or semi-arid zon... more The Tehuacán-Cuicatlán Biosphere Reserve, Mexico (TCBR) is the southernmost arid or semi-arid zone with the highest biodiversity in North America and is a UNESCO World Heritage site. Two main hydrographic streams cross the TCBR, the Salado River (an endogenous river) and the Grande River (an exogenous river). This study investigated temperature anomalies over the past 40 years. We analyzed potential differences between sub-basins and riparian areas on both streams using various indices, namely the Global Warming Index (GWI), Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), and Normalized Difference Drought Index (NDDI), and analyzed the potential relationship of these indices with climate change. Time series of satellite-based precipitation (June 2000–December 2020) and air temperature (January 1980–December 2020) were analyzed. A set of Landsat 8 OLI TIRS imagery from the driest and wettest months (2013–2020) was used to estimate NDVI, NDWI, ...
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Papers by Eugenia López