G. Vilaclara

National Autonomous University of Mexico | UNAM · School of Higher Studies (F.E.S.) Iztacala

Limnology books provide examples from an inland aquatic ecosystem when each topic is presented. However, in only a few cases are the examples given and discussed throughout for a single water body, particularly the interrelationships among the abiotic and biotic components. This article introduces a “textbook” example of the environmental and biolo...

High-mountain lakes (HMLs) are remote, extreme, and sensitive ecosystems recognized as sentinels of global change. Lakes El Sol and La Luna are very close to each other inside the crater of the Nevado de Toluca volcano, but they differ morphometrically and limnologically. This study aimed to identify the seasonal fluctuation of the phytoplankton co...

Detecting determinism and nonlinear properties from empirical time series is highly nontrivial. Traditionally, nonlinear time series analysis is based on an error-prone phase space reconstruction that is only applicable for stationary, largely noise-free data from a low-dimensional system and requires the nontrivial adjustment of various parameters...

Nitrogen and phosphorous loading drives eutrophication of aquatic systems. Lakes and reservoirs are often effective N and P sinks, but the variability of their biogeochemical dynamics is still poorly documented, particularly in tropical systems. To contribute to the extending of information on tropical reservoirs and to increase the insight on the...

Nitrogen and phosphorous loading drives eutrophication of aquatic systems. Lakes and reservoirs are often effective N and P sinks, but information is needed on the variability of their biogeochemical dynamics, especially for tropical systems. A long-term N and P mass balance (2003-2018) in a small tropical eutrophic reservoir lake, Valle de Bravo (...

The present long-term (1993–2013) study was aimed at identifying the effects of global change on the environmental characteristics and the plankton community of the tropical, high-altitude Lake Alchichica, Puebla, Mexico. We found no statistically significant increasing trend in air temperature, but an increase from 2002 to 2013, and interannual va...

Describing the biological diversity of Lake Alchichica is a task that reflects the historical path of ecology and systematics in the last 80 years. We discuss how the perception of the species richness and endemicity levels in each ecosystem depends not only on natural processes but also on human factors. This chapter presents the most comprehensiv...

Serdán-Oriental is an endorheic basin with scarce surface runoff. Groundwater plays an essential role in the water balance and the chemistry of the existing water bodies, including Lake Alchichica. The principal aquifer is mainly composed of pyroclastic materials with high hydraulic conductivity. Groundwater flows from the recharge zones in the bas...

The phytoplankton in Lake Alchichica show a relatively low species richness with divergent roles in the food web depending on their size. Picophytoplankton (APP <2–3 μm) are essential in the lake microbial loop, due to their outstanding abundance. In contrast, the nano- (2–3 to 20 μm) and microphytoplankton (>20 μm) show lower densities than APP bu...

The protozoan assemblage of Lake Alchichica is composed of euryhaline species, which reflects the hyposaline nature of the lake. In this, microaerophilic and anaerobic species are biomass-dominating components. They occupy resource-rich niches during the prolonged period of stratification. The relevance of protozoa in the microbial food webs has be...

Physical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing events. Such is the case in tropical Valle de Bravo (VB) reservoir lake, where strong diurnal winds drive int...

Euplotes euryhalinus and Spritostomum teres contrasting feeding behaviour

Physical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing events. Such is the case in tropical Valle de Bravo (VB) lake, where strong diurnal winds drive internal wave...

Physical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing events. Such is the case in tropical Valle de Bravo (VB) lake, where strong diurnal winds drive internal wave...

Physical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves (IW) can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing (BM) events. Such is the case in tropical Valle de Bravo (VB) lake, where strong diurnal winds drive IW,...

Due to their dimensions, small and shallow water bodies are more sensitive to changes in nutrient load, water flow, and human management. The four water bodies studied are small (area <0.01 km2), constantly supplied by a non-anthropogenic source of nutrients, and these water bodies present different trophic states: mesotrophic, eutrophic, and hyper...

Alchichica is a warm-monomictic, oligotrophic lake that, differing from other oligotrophic aquatic ecosystems, its phytoplankton biomass is dominated by large size (>2 μm) organisms. As a result of its higher weight and lower predation pressure by zooplankton, the phytoplankton is mostly exported below the thermocline towards the bottom of the lake...

Las aguas continentales constituyen un recurso de importancia estratégica para las naciones, por lo que resulta esencial conocerlas a detalle: su abundancia, distribución, función, problemáticas, vulnerabilidad y capacidad de recuperación o resiliencia. La generación y el análisis oportuno de esta información permitirán planear las estrategias de a...

To understand the responses of phytoplankton to water level fluctuations (WLFs) in tropical conditions at high altitude, limnological monitoring was performed monthly in Valle de Bravo (VB) reservoir, a waterbody affected by relatively strong WLFs due to water scarcity in central Mexico during 2008–2009. The thermal behaviour of the reservoir was w...

Crater lakes are sensitive to natural and anthropogenic environmental changes and it is important to define and understand their current status in order to evaluate past changes related to climate variability and future ones associated with modern global change. We sampled lake waters, surface sediments and sediment trap samples (dry vs wet season)...

Geochemical, mineralogical and microbiological data from four freshwater streams in central region of Mexico indicate the importance of Blennothrix ganeshii mats (Cyanobacteria, Oscillatoriales) in promoting the formation of calcium carbonate crystals. The streams were characterized by alkaline waters and relative physicochemical stability during t...

García. 2013. Calcification of the filamentous cyanobacterium Blennothrix ganeshii in calcareous tropical streams of central Mexico region. Hidrobiológica 23 (1): 17-27. ABSTRACT Geochemical, mineralogical and microbiological data from four freshwater streams in central region of Mexico indicate the importance of Blennothrix ganeshii mats (Cyanobac...

We analyzed a laminated sedimentary sequence, box core C-2 (30.5 cm length); it was recovered in the eastern part of Pescadero Basin at 670 m depth collected aboard of the R/V "El Puma". Pescadero Basin is one of a series of deep tectonically active basins developed in the Gulf of California from south to north, which are characterized by their dis...

Geochemical, mineralogical and microbiological data from four freshwater streams in central region of Mexico indicate the importance of Blennothrix ganeshii mats (Cyanobacteria, Oscillatoriales) in promoting the formation of calcium carbonate crystals. The streams were characterized by alkaline waters and relative physicochemical stability during t...

En publicaciones anteriores de NUESTRO LAGO explicamos que en la superficie de nuestro lago el crecimiento de microalgas produce materia orgánica que al hundirse agota el oxígeno en la capa del fondo (2° capítulo, marzo de 2005; número 3) y libera nutrientes de nitrógeno y fósforo que favorecenel crecimiento de nuevas masas de microalgas y bacteria...

Beltrán-Magos, Y, J. Carmona, G. Vilaclara and M. Bojorge-García. 2013. Calcification of the filamentous cyanobacterium Blennothrix ganeshii in calcareous tropical streams of central Mexico region. Hidrobiológica 23 (1): XXX-XXX. ABSTRACT Geochemical, mineralogical and microbiological data from four freshwater streams in central region of Mexico in...

Alchichica is a warm-monomictic, oligotrophic lake whose phytoplanktonic biomass is dominated by large size (average ca. 55 μm) diatoms. The fast sinking phytoplankton leads to silica, and other nutrient exportation out of the productive zone of the lake. The aim of the present study was to identify and measure the sedimentation fluxes of the diato...

The dustfall (DF) and mass sedimentation rate (MSR) in Lake Alchichica, Central Mexico, were studied from June 2006 to June 2008. DF ranged between 0·11–0·93 g m−2 d−1 in the warm and rainy season and 0·54–1·21 g m−2 d−1 in the cold and dry season. MSR varied from 0·52–2·40 g m−2 d−1 in the stratification season to 1·14–5·07 g m−2 d−1 in the circul...

Lake development in geologically active basins is a complex phenomenon as shown by the bed of the Pliocene Tlaxcala paleolake disturbed by volcanic eruptions in central Mexico. A 5-m layered freshwater diatomite outcrop section shows volcanic ashes throughout a bottom Stephanodiscus zone up to a more recent Aulacoseira zone. A 0.5-m transition regi...

Lagunillo del Tejo is a small groundwater-fed sinkhole lake in the karst region of the Iberian Range (central-eastern Spain), which undergoes significant lake level fluctuation in response to rainfall variability. The aim of this study is to understand the record of water level fluctuations in Lagunillo del Tejo over the last two-and-a-half centuri...

During the last decades a number of lacustrine records from Mesoamerica have documented climatic changes and episodes of intense human impact. These records are concentrated in the Maya region and the in high altitude basins of central and eastern Mexico, few studies have been undertaken in western Mexico. We believe that a regional perspective of...

Ramírez-Zierold JA, Merino-Ibarra M, Monroy-Ríos E, Olson M, Castillo FS, Gallegos ME, Vilaclara G. 2010. 2010. Changing water, phosphorus and nitrogen budgets for Valle de Bravo reservoir, water supply for Mexico City Metropolitan Area. Lake Reserv. Manage. 26:23-34.Valle de Bravo reservoir (VB) provides water supply to the Mexico City Metropolita...

Water chemistry of crater lakes, maars and water reservoirs linked to some Mexican volcanoes within and outside the Mexican Volcanic Belt has been determined for several years and examined regarding environmental and volcanic factors. All the analyzed lakes are relatively small with a maximum depth of 65 m, and are located in regions with different...

Valle de Bravo (VB) is a tropical reservoir located (19°21′30″N, 100°11′00″W) in the highlands of Mexico. The reservoir is daily swept by strong (7.4ms−1 mean speed) diurnal (12:00–19:00h) winds that blow along its two main arms. As expected from its fetch (6.9km) and its depth (21.1m mean), the reservoir behaves as a warm monomictic water body. Du...

A ca. 2500 cal. yr record from Santa Maria del Oro (SMO) was studied for its diatoms, ostracodes, magnetic mineralogy, geochemestry, organic matter and carbonate content to document climatic and limnological trends over western Mexico, a site sensitive to the intensity of monsoon circulation and to any latitudinal shifts of the high pressure subtro...

We study density fluctuations from sediments of a paleolake in central Mexico that was subjected to volcanic perturbations by means of computed tomography (CT) measurements on blocks chiselled out of mines at the lake's bed. The mine walls show laminations corresponding to the alternation of low density diatom sediments and high density volcani...

Freshwater Rhodophyta populations from high altitude streams (1,725-2,900 m a.s.l.) in the Mexican Volcanic Belt (MVB), between 18-19° N and 96-100° W, were investigated through the sampling of six stream segments from 1982 to 2006. Three species are documented, Batrachospermum gelatinosum, B. helminthosum and Sirodotia suecica, including their des...

Magnetic and non-magnetic mineral analyses were conducted on a lacustrine sequence from Lago Verde in the tropical coast along the Gulf of Mexico that covers the last 2000 years. The site witnessed the transformation of the environment since the early Olmec societies until forest clearance in the last century. Through these analyses we investigated...

We analyze a sequence of density variations of sedimentary material from an extinct paleolake of the state of Tlaxcala, Mexico, which we previously obtained by means of computer-aided tomography [J. Miranda, A. Oliver, G. Vilaclara, R. Rico-Montiel, V.M. Macias, J.L. Ruvalcava, M.A. Zenteno, Nucl. Instrum. Methods Phys. Res. B 85 (1994) 886]. In th...

Microhabitat was investigated in four populations of B. ganeshii in calcareous tropical streams in central Mexico to determine the distributional patterns and some of their controlling factors, as well as morphometric adaptations to varying conditions on scales of a few centimetres. Morphometric variations and their relation to physical variables (...

Stephanodiscus niagarae is frequently reported from late Pleistocene (>10,000yr BP) sediments in central Mexico, with lower abundances through the Holocene. Its presence in Holocene and modern environments in central Mexico was not well documented until our study, where we report on three populations of S. niagarae, one middle Holocene population w...

The inactive volcano Nevado de Toluca (19 degrees 10'N, 99 degrees 45'W) has an altitude of 4630 m a.s.l. A massive explosion ca. 10,500 years ago left a crater (4200 m a.s.l.) with a central dome. Two shallow (z < 15 m) lakes, El Sol and La Luna, developed as they filled with rainwater and snowmelt. Their waters are relatively cold (T < 12 degrees...

Mineral magnetic and total organic carbon (TOC) measurements were performed on a 10.9 m long core from Zacapu basin, central Mexico. The sequence, dated by AMS 14C, spans the last ca. 52 kyr. Curie temperature measurements, low-temperature susceptibility and low-temperature remanence indicate that the magnetic fraction is characterized by oxidized...

En el centro de México el fenómeno de “El Niño” provoca una reducción en la precipitación. Estas variaciones interanuales en el clima pueden modificar el comportamiento de mezcla-estratificación de los lagos, reflejándose a veces en los sedimentos que se acumulan año con año en sus fondos, sobrepuesto a las tendencias de cambio climático de mayor d...

Guadalupe Dam is a reservoir located into the Metropolitan area of Mexico City, which had been infested with water hyacinth (Eichhornia crassipes) for more than 12 years. In 1993 a management program was conducted in the reservoir. The main activities included the use of aquatic herbicides and mechanical control. The goal of this study was to monit...

Guadalupe Dam is a reservoir located into the Metropolitan area of Mexico City, which had been infested with water hyacinth (Eichhornia crassipes) for more than 12 years. In 1993 a management program was conducted in the reservoir. The main activities included the use of aquatic herbicides and mechanical control. The goal of this study was to monit...

Mexico City is a critica1 example of drinking water supply and pollution, dueto its population of nineteen million within a closed basin, 2300 m above sea level. The increasing urbanization has diminished the rate of aquifer reload, and a large amount of water is brought fiom lower and more distant zones, with increased energetic and ecological cos...

Diatomite samples from paleolake Tlaxcala, in Central Mexico, have been analyzed using proton induced X-ray emission (PIXE), X-ray tomography and X-ray diffraction. Chiseled blocks were scanned with a 0.7 MeV proton beam, 0.1 mm in diameter, in 0.25 mm steps across the sediments. X-ray tomography with the same step sizes was then applied, in order...

Protozoological and physicochemical analyses were performed in a waste stabilization pond at Sto. Tomas Atzingo, a small town near Mexico City, in order to discern the internal dynamics of the pond water through the study of the spatial distribution pattern of flagellates and the parallel water volume distribution pattern of some selected physicoch...

According to an investigation of an anaerobic sewage pond in the State of Mexico we are proposing the change of the saprobic valence and other saprobiological characteristics for three species of mixotrophic Euglena, i.e. E. viridis (O. F. MÜLLER) EHRENBERG, D. agilis H. J. CARTER and E. proxima DANGEARD.

Con base en los resultados de 16 muestreos mensuales de los nutrimentos (fósforo y nitrógeno) y de la clorofila a en el Lago Viejo de Chapultepec en la Ciudad de México, que es un sistema acuático somero recreativo y con algunas caracteristicas de hipertrofia, se evaluó el efecto ejercidc por el dragado de una zona del Lago, medida llevada a cabo p...

Protozoa of nose, mouth, and pharynx of 30 randomly chosen female caries patients at an odontological clinic of the National Autonomous University of Mexico, were surveyed by culture from swabs. Culture tubes of swabs from each patient were observed every other day during 5 weeks. Pathogenic protozoa found included Entamoeba histolytica Schaudinn,...

A survey of pathogenic and free-living amoebae in swimming pool waters of Mexico City was performed. Among the organisms isolated those which have public health importance were Naegleria fowleri Carter and Acanthamoeba castellanii Douglas. Amoebae of the genera Acanthamoeba, Naegleria, and Vahlkampfia were recovered in their cystic stage while thos...