The epicontinental aquatic systems are an important component in the global carbon cycle. In order to generate a baseline as whether tropical lakes act as carbon dioxide (CO2) source or sink, we evaluated the gross (GPP) and net (NPP)... more
The epicontinental aquatic systems are an important component in the global carbon cycle. In order to generate a baseline as whether tropical lakes act as carbon dioxide (CO2) source or sink, we evaluated the gross (GPP) and net (NPP) primary production and respiration (R) in the euphotic zone of a deep, oligotrophic, tropical lake. GPP fluctuated between 1,809 and 4,195 mg C m-2 d-1; three peaks were observed throughout the year. These peaks are associated to the three main phytoplankton events of Lake Alchichica: the diatom bloom during the mixing period, the cyanobacteria bloom at the onset of the stratification period and the deep chlorophyll maximum along the stratification. R varied between 87 and 5,966 mg C m-2 d-1. Despite its oligotrophic condition, Lake Alchichica acts as a CO2 sink because it is mostly autotrophic along the year. The annual gross primary production (GPP) exceeds respiration (GPP:R = 4.39 ± 6.84 ) and therefore, the annual NPP was is positive.
Research Interests:
Research Interests:
Research Interests:
... del Carmen CAMACHO MAN ZAN'LLA, Raymundo LOYOLA-ALVAREZ and Elia ROLDAN-REYES I jJboracortode UKjgtdtlkí y Mu1i(ínt4Íi. ... 197(1. Leidy et el, 1983, 1984, Branham and Wehncr 1985), however the results оГ cytogenetic, mutagenic... more
... del Carmen CAMACHO MAN ZAN'LLA, Raymundo LOYOLA-ALVAREZ and Elia ROLDAN-REYES I jJboracortode UKjgtdtlkí y Mu1i(ínt4Íi. ... 197(1. Leidy et el, 1983, 1984, Branham and Wehncr 1985), however the results оГ cytogenetic, mutagenic and teratogenic tests using this ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT RESUMEN El presente estudio tuvo como propósito evaluar si las concentraciones naturales de fósforo y nitrógeno limitaban la biomasa fitoplanctónica en el Lago Alchichica. Se aplicaron tratamientos de enriquecimiento con... more
ABSTRACT RESUMEN El presente estudio tuvo como propósito evaluar si las concentraciones naturales de fósforo y nitrógeno limitaban la biomasa fitoplanctónica en el Lago Alchichica. Se aplicaron tratamientos de enriquecimiento con nitrógeno, fósforo y nitrógeno + fósforo durante las dos etapas características de la hidrodinámica del lago: estratificación y mezcla. Se dio seguimiento al potencial de crecimiento algal mediante la evaluación fluorométrica in vivo de los cambios diarios de la concentración de clorofila a expresados como porcentaje de cambio relativo con respecto al testigo (T). Durante la época de mezcla la respuesta al enriquecimiento fue limitada y la comunidad de fitoplancton no modificó su composición ni abundancia. Contrariamente, durante la época de estratificación la adición de nutrimentos favoreció el crecimiento del fitoplancton modificando su composición y abundancia. Los resultados muestran que el nitrógeno es el nutrimento que principalmente podría limitar el crecimiento algal en el lago Alchichica como ha sido encontrado en otros lagos tropicales, a diferencia de los lagos templados en donde se ha encontrado que el nutriente limitante es el fósforo. La adición de un solo nutrimento produjo sólo un breve incremento en el crecimiento en tanto el otro nutrimento se agotó. Sin embargo, cuando ambos nutrientes fueron añadidos, el crecimiento fue sostenido y se produjo una respuesta importante y detectable.
Research Interests:
Research Interests: Geography, Geology, Humanities, Saline Lake, Mexico, and 5 moreMéxico, Puebla, MEXICO, Chlorophyll a, and Clorofila a
Research Interests:
Mexico is considered a megadiverse country; it is one of the few countries that possess 70% of the vertebrate and vascular plant species worldwide; however, little is known about the diversity of Mexican freshwaters, and it is unknown if... more
Mexico is considered a megadiverse country; it is one of the few countries that possess 70% of the vertebrate and vascular plant species worldwide; however, little is known about the diversity of Mexican freshwaters, and it is unknown if these ecosystems present the same trend of high biodiversity that terrestrial communities show. The present chapter provides an insight on the biodiversity in inland waters of Mexico through first introducing the regionalizations and inventories at different scales that have been done to identify those areas or sites in which important ecological and evolutionary phenomena occur, including biodiversity and endemisms, and, second, compiling the scattered information available on lentic, lotic, and wetland biodiversity of Mexico and illustrating this by particular cases (water bodies and ecosystems) worth mentioning.
Research Interests:
Research Interests: Humanities and Art
Se determino la batimetria y morfometria de seis lagos costeros del estado de Guerrero, al suroeste de Mexico. Con base en los parametros morfometricos relacionados con la productividad lacustre, se aplico una tecnica que permite... more
Se determino la batimetria y morfometria de seis lagos costeros del estado de Guerrero, al suroeste de Mexico. Con base en los parametros morfometricos relacionados con la productividad lacustre, se aplico una tecnica que permite determinar la "Productividad Condicionada Morfometricamente" (MCP). La MCP se define como la productividad que un lago puede desarrollar con base en sus caracteristicas morfometricas. Con el fin de comprobar el funcionamiento de la mencionada tecnica, se compararon los valores de MCP de los lagos con su captura pesquera. En cinco de los lagos la correlacion fue elevada (r = 0.947. a
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
<p>The Usumacinta River is the most extensive tropical fluvial system in North America and the principal river in Mexico and the tenth of North America. Diverse and growing anthropogenic... more
<p>The Usumacinta River is the most extensive tropical fluvial system in North America and the principal river in Mexico and the tenth of North America. Diverse and growing anthropogenic activities (land-use change, agriculture, and urban development) modify water quality. However, to separate natural (e.g., geology) from anthropic factors responsible for this system characteristics, we looked to evaluate geological environment’s influence on the river’s water quality.</p><p>Water and sediment samples were collected along the mainstem and principal tributaries in the rainy and the dry seasons (2017-2018). We analyzed the major ionic composition in water and metals in sediments. We applied inverse and evaporation models (PHREEQC code) to reveal the physicochemical reactions taking place in the river.</p><p>The inverse models in the middle basin in both seasons showed the influence of ion-exchange between Ca and K, dissolution of dolomite, and precipitation of kaolinite and calcite, whereas in the lower basin in the rainy season suggested the chemical composition is controlled by ion-exchange among Ca, Na and K, dissolution of dolomite, halite, plagioclase, and feldspar and precipitation of calcite, gypsum, and kaolinite. In addition, the evaporation models in the dry season in the lower basin demonstrate the dominant process taking place is the precipitation of calcite, dolomite, gypsum, halite, and kaolinite.</p><p>We found that Cr and Ni are the most abundant metals in the sediments along the river. The geological environment in the basin suggests that the volcanic rocks with felsic minerals could be the source of Ni, whereas sedimentary rocks such as shales and clays could be the source of Cr.</p><p>The use of geochemical models in river systems is of great relevance to understanding the presence of major ions concentrations in water and their seasonal and spatial variations, as well the physicochemical processes (i.e., ion-exchange, dissolution, precipitation, redox reactions, and so on) that allow associating or discard the presence of metals.</p>
Research Interests:
Research Interests:
Acoplamiento pelágico-bentónico: respuesta de la zona bentónica profunda a la sedimentación del florecimiento invernal de diatomeas en el lago oligotrófico Alchichica, Puebla, México Pelagic-benthic coupling: deep benthic zone response to winter diatom bloom sinking in oligotrophic Lake Alchichic...more
Research Interests:
Research Interests:
Abstract Most studies of benthic macroinvertebrate communities are from shallow lakes or restricted to the littoral zone of deep, temperate lakes, with just a few dealing with the deep benthos. Furthermore, the deep benthic... more
Abstract Most studies of benthic macroinvertebrate communities are from shallow lakes or restricted to the littoral zone of deep, temperate lakes, with just a few dealing with the deep benthos. Furthermore, the deep benthic macroinvertebrate communities of tropical lakes are almost unknown. The present work describes the benthic macroinvertebrate communities of three tropical, warm monomictic lakes in “Lagunas de Montebello” National Park, Mexico, by describing the differences along the bathymetric profile, from the littoral down to the profound benthos. We studied the benthic macroinvertebrate communities in the two contrasting hydrodynamic periods of the warm monomictic lakes: a) stratification, when the hypolimnion becomes anoxic, and b) mixing, when the water column becomes oxygenated. We expected: 1) a reduction in the benthic macroinvertebrate taxonomic richness, density, and biomass from the littoral to the deep zone, 2) an impoverished benthic macroinvertebrate community while stratified (anoxia) compared to mixing (oxygenated), and 3) depletion in the taxonomic richness, density, and biomass of the profundal benthic macroinvertebrates in the tropical compared to temperate lakes. We found: 1) a decreasing trend in taxonomic richness (6 ± 2–3 ± 1 taxa), density (1868.7 ± 1069.7–349.1 ± 601.8 in. m−2) and biomass (277.8 ± 188.9–85.1 ± 95.6 mg C m−2) from the littoral to the deep zone; chironomids dominated the littoral zone, while oligochaetes dominated the deep zone. 2) Lower density and biomass but not taxonomic richness while stratified (4 ± 3 taxa; 586.2 ± 527.6 in. m−2; 81.6 ± 164.3 mg C m−2) compared to mixing (4 ± 3 taxa; 877.5 ± 1051.4 in. m−2; 190.1 ± 131.1 mg C m−2). 3) lower taxonomic richness and density but not biomass in tropical Montebello oligotrophic lakes (3 ± 3 taxa; 349.1 ± 601.8 in. m−2; 85.1 ± 195.6 mg C m−2) compared to temperate analogous (2–48 taxa; 492−83,189 8 in. m−2; 0.13−201.5 mg m−2). We conclude the early onset and long-lasting hypolimnetic anoxia restrict the benthic macroinvertebrate community radiation and diversification in tropical, oligotrophic, warm monomictic lakes.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
In tropical first‐order streams, the availability of basal resources changes according to tropical seasonality, i.e., dry and rainy seasons, with consequences for the food web structure. However, the seasonal variation in autotrophic and... more
In tropical first‐order streams, the availability of basal resources changes according to tropical seasonality, i.e., dry and rainy seasons, with consequences for the food web structure. However, the seasonal variation in autotrophic and detrital pathways remains unclear. In this study, we aimed to establish whether the dominant pathway of the benthic macroinvertebrate food web in two tropical first‐order streams in the Lacandona rainforest, Mexico, relies on autotrophic or detrital food resources. We evaluated the assimilation of autotrophic and detrital food resources through carbon and nitrogen stable isotope (δ13C and δ15N) analysis. We included the biomass of the macroinvertebrates sustained by the autotrophic and detrital pathways and the food web structure—trophic position, size structure, and degree of omnivory. The biomass sustained by the detrital pathway remained similar throughout the year in both streams. In contrast, the biomass sustained by the autotrophic pathway was higher in the dry season than in the rainy season. The benthic macroinvertebrate food web had four levels, a poorly developed size structure, and an important degree of omnivory in both streams and in both seasons. It is likely that omnivory was a response to high resource variability and a strategy to reduce intraguild competition. Autotrophs had a relatively higher importance than detritus since a much lower algae biomass sustained an equal or higher macroinvertebrate biomass, particularly in the dry season when the biomass of autotrophs increased. Seasonality influenced the macroinvertebrate food web by modifying the food resource availability and transference to higher trophic levels. However, the high frequency of omnivory reduced the seasonal changes in the food web structure. Our results suggest that the autotrophic pathway plays an important role in maintaining the benthic macroinvertebrate food web in tropical streams. The relative importance of autotrophs in the macroinvertebrate food web is associated with seasonality, the rainfall pattern, and its effect on the stream hydrology.
Research Interests:
Research Interests:
Research Interests: Zoology, Environmental Science, Plant Biology, Ecology, Daphnia, and 4 morePlankton, Zooplankton, Copepod, and Latitude
Research Interests:
Research Interests:
<p>Global change has different effects on inland water bodies. In the case of lakes, the water level is a variable frequently affected. Lakes in semi-arid zones are susceptible to climatic and anthropic... more
<p>Global change has different effects on inland water bodies. In the case of lakes, the water level is a variable frequently affected. Lakes in semi-arid zones are susceptible to climatic and anthropic forcing. Understanding how these factors modulate changes in lakes is essential to develop forecasts and generate management and conservation programs. However, lakes evolution under external forcing may differ despite belonging to the same system. The differences highlight the importance of developing particular management plans for each lake. Therefore, it is necessary to understand the factors that modulate these peculiarities. An example in central Mexico is the six maar lakes found in the easternmost basin of the Mexican Plateau, the Serdán Oriental Basin: Alchichica, Quechulac, La Preciosa, Atexcac, Tecuitlapa, and Aljojuca. Groundwater flow is essential in the water balances of these lakes. However, intensive groundwater exploitation for agriculture has occurred since the '80s in this semi-arid basin. Several studies have revealed that these lakes' trophic states, biota, and chemical compositions differ remarkably. Both locals and researchers have noted water-level declines in all lakes in recent decades. Water level evolution also seems to be particular in each lake. Data on the lakes water levels from 1960 to 1992 and subsequent changes are analyzed. We assessed physical (e.g., climatic, geological, hydrogeological, vegetation) and anthropic (land-use changes and groundwater exploitation) factors that could modulate the water level evolution differences. Time series analysis, remote sensing, and statistical methods were applied. This work represents a conceptual framework for further studies oriented to the numerical modeling of the lake system and the exploration of future change scenarios.</p>
Research Interests: Groundwater and Arid
Research Interests:
Well-known by the desert land, strong solar radiation, and cactuses, Mexico includes certainly such extreme arid condition in about two thirds of its territory – the central part and most of the north. A latitude at the world deserts belt... more
Well-known by the desert land, strong solar radiation, and cactuses, Mexico includes certainly such extreme arid condition in about two thirds of its territory – the central part and most of the north. A latitude at the world deserts belt as well as a horn-like contour toward the US border with a mountainous relief in the periphery altogether precludes the passage of humid clouds from the narrow coastal slopes toward the inner enclosed land. In contrast, the south and southeastern regions contain not only exuberant tropical forests and major river courses but also the recurrent threat of hurricanes and floods. Thus, the specific physical and chemical characteristics of surface and groundwater depend, firstly, on the water cycle. As mentioned before, the atmospheric precipitation falls in disproportion over the Mexican territory and eventually drains over the surface relief as runoff to then incorporate into lakes/reservoirs or permeates the soil into the underground for a last long ...
Research Interests:
Research Interests:
Using long-term time series of meteorological and water-column parameters, the dynamics of two lakes separated by about 500 m from each other by a central lava dome, located at 4207 m above sea level in the volcano crater of Nevado de... more
Using long-term time series of meteorological and water-column parameters, the dynamics of two lakes separated by about 500 m from each other by a central lava dome, located at 4207 m above sea level in the volcano crater of Nevado de Toluca, Mexico were explored. Because of the strong wind-forcing previously measured on the volcano slope and the proximity of the lakes, wind-mixing was expected, with similar dynamics in both lakes. However, the meteorological parameters in the crater were significantly different than on the slope of the volcano, due to the dome and the high walls of the crater, which weakened wind speeds, modified wind direction, and reduced exposure to solar radiation by almost 20% in the crater compared to on the volcano slope. The rate and depth of thermal penetration into each lake differed by an order of magnitude, related with differential insolation due to crater wall shading, along with differences in transparency, most likely due to differential algal growth and suspended matter. At times, rapid surface cooling occurred during periods of reduced insolation and calm winds, leading to strong vertical convection and the formation of a characteristic step profile in the water column rather than the predicted wind mixing. These results are important for interdisciplinary studies of these and other alpine lakes and, in particular for biophysical coupling in these unique hydrological systems.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Testate amoebae are bioindicators sensitive to environmental change, which show good preservation in sediments of low pH environments, such as high mountain lakes (LAM). The presence and diversity of testate amoebae were documented in... more
Testate amoebae are bioindicators sensitive to environmental change, which show good preservation in sediments of low pH environments, such as high mountain lakes (LAM). The presence and diversity of testate amoebae were documented in surface sediments and sediment cores, dated with 210Pb, from the only 2 LAMs in Mexico (El Sol and La Luna), which have shown signs of recent human-induced changes. A total of 18 taxa were recorded and the main species observed in both lakes were Difflugia glans “glans” and D. globulosa. Specific richness and Shannon’s diversity index were higher in Lake El Sol than in the smaller, acidic and ultraoligotrophic Lake La Luna. The sediment cores recorded changes, during the last 20 to 25 years, in the composition of the testate amoebae communities (El Sol) and in their dominance (La Luna), as well as increased accumulation rate and concentrations of iron and organic carbon. These are signs of anthropogenic impact on the lakes, which should alert us to imp...
Research Interests:
Research Interests:
<p>The tropical maar Lake Alchichica lays in the high altitude (> 2,000 m a.s.l). The orographic shadow of the Sierra Madre Oriental generates a semiarid climate with a negative water budget (1 to 3) so... more
<p>The tropical maar Lake Alchichica lays in the high altitude (> 2,000 m a.s.l). The orographic shadow of the Sierra Madre Oriental generates a semiarid climate with a negative water budget (1 to 3) so the lake's water balance depends on groundwater. Nonetheless, the decreasing trend of the water level from 1959 on suggests a combined effect of climate change and increasing groundwater extraction (agriculture, urban). Applying geochemical models to explore the interaction between groundwater and surface water allow to identify the geochemical source of the reported increase in sulfate, magnesium, and chloride concentration in the lake water and its relation to climate change and intensive extraction of groundwater. Thirty-five groundwater samples were obtained from wells surrounding Lake Alchichica. Samples were analyzed for major ionic composition and trace elements. We generated a conceptual model of groundwater-surface water interaction and conducted inverse and evaporation geochemical models using the PHREEQC code. Geochemical models explore the water-rock processes between groundwater and geologic materials, understanding the chemical evolution of the groundwater flow system, and understanding the influence of groundwater chemical characteristics in the chemical composition of the lake. This investigation unravels how climate change and intensive groundwater extraction define the way in which: 1) groundwater influences the chemistry of the lake, and 2) to understand the chemical changes that have been reported in the lake.</p>