Lake Chapala Research Articles

Recent history of persistent organic pollutants (PAHs, PCBs, PBDEs) in sediments from a large tropical lake.

210Pb-dated sediment cores and surface sediments from Lake Chapala (LC), Mexico, were analyzed to assess the temporal trends in concentrations and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs). Total sediment concentrations of PAHs (95-1,482 ng g-1), PCBs (9-27 ng g-1) and PBDEs (0.2-2.5 ng g-1) were indicative of moderate to intense contamination. The POP concentrations have progressively increased since the 1990s. The light molecular weight PAHs, and the prevalence of PCB congeners with low-chlorination levels (e.g., di- to tri-CB) and low-to medium-brominated (tri- to penta-BDE) PBDEs in most sections of the sediment profiles, suggested that these POPs have most likely reached these sediments by long-range atmospheric transport from distant sources; although the significant presence of heavier PAH, PCB and PBDE congeners in the topmost sediments, indicate that other nearby and local sources (soil erosion from the catchment, urban and industrial wastewaters discharges, as well as navigation) might have also contributed to the recent input of POPs to LC. Taking into account the relevance of LC as regional freshwater supply and commercial fishing ground, the potential risk posed by the organic contaminated sediments to the biota and human population should not be underestimated.

The origin of the recent (2012-2016) seismic activity in the Guadalajara, Jalisco, Mexico, area: A block boundary interaction?

The central part of Jalisco, Mexico, has experienced low-magnitude earthquake sequences and swarms. Although the effects of these earthquakes have been limited to relatively small areas, the earthquakes have caused general alarm among the population and, in some cases, have been catastrophic. These earthquake swarms are significant because they affect the most populous area of the state, including the capital city of Guadalajara. An extraordinary example is an earthquake swarm that started on 8 May 1912 and lasted until September of that year. The region remained seismically quiescent until May 2012, when seismic activity resumed, lasting to the present. We analyze the recent seismic activity, starting with the earthquake of 18 May 2012 (03:07 UT) at the western edge of Lake Chapala and ending with the magnitude 4.2 earthquake on 3 November 2016. Our analysis includes eight earthquakes with magnitudes between 3.5 and 4.8, the revision of hypocenter locations, and the determination of focal mechanism solutions using the inversion of the moment tensor method. When possible, inversion solutions are compared with solutions obtained with the first arrival polarity method. We compare our results for the recent seismicity with the distribution of reported damage associated with historical earthquakes. Our work indicates a N-S trending seismic source zone and an orientation of nodal planes that suggests reactivation of preexisting local faults induced by the interaction of the western border of the Trans-Mexican Volcanic Belt with the eastern border of the Jalisco Block.

Calculating long-term changes in Lake Chapala’s area and water volume using remote sensing and field data

Mexico’s largest freshwater body, Lake Chapala, is the main source of drinking water for over 4-million inhabitants. This study used satellite and field data to obtain annual estimates of Lake Chapala’s area and water volume from 1973 to 2009, as well as water intakes from 1934 to 2013. Twenty-one Landsat images (multispectral scanner system, 2, 5, and 7) for the period of 1973 to 2009 were processed. Gap filling correction was applied to Landsat 7 enhanced thematic mapper plus scan line corrector-off images. Binary water/no-water segmentation was obtained with a Markov random field model using the normalized difference water index. An area-based model was developed to calculate water volume, which used the lake’s area estimated based on the images as well as an exponential function obtained from area-elevation curves. Three of the resulting water/no-water layers were validated against reference points taken from aerial photography. Overall accuracies of 77% to 90% were obtained. A correlation coefficient of 0.9 resulted when comparing the results from using remote sensing to calculate water volume against field measurements. Given the observed reduction in volume, we concluded that it will be difficult to continue to use the lake as the main source of freshwater for the Guadalajara metropolitan area without substantial interventions.

Spatial and temporal variations and modelling of dissolved oxygen concentration in Chapala Lake, Mexico

De la Mora-Orozco, C., Flores-Garnica, J. G., Flores-Lopez, H. E., Rubio-Arias, H. O., Chavez-Duran, A. A., Ochoa-Rivero, J. M., & Garcia-Velasco, J. (enero-febrero, 2018). Variaciones espacio-temporales y modelaje de la concentracion de oxigeno disuelto en el lago de Chapala, Mexico. Tecnologia y Ciencias del Agua , 9 (1), 39-52, DOI: 10.24850/j-tyca-2018-01-03. La disminucion del oxigeno disuelto (OD) en ecosistemas acuaticos alrededor del mundo ha afectado su calidad. El objetivo fue estimar la variacion espacio-temporal del OD en el agua del lago de Chapala, Mexico. Fueron seleccionados 16 sitios ( n = 16) y en cada uno se cuantifico la concentracion de OD in situ a cinco profundidades; en la superficie, y a 1, 2, 3 y 4 m. Las fechas de cuantificacion fueron en septiembre, octubre, diciembre, febrero y junio (1996-1997). La informacion se analizo con la tecnica geoestadistica de Kriging ordinario, cuyo primer resultado son los variogramas. Los resultados indicaron que en diciembre, febrero y junio los niveles de OD fueron superiores a 5 mg l-1; mientras que en octubre, en la parte sureste del lago, se observaron concentraciones inferiores a 3 mg l-1. Los resultados mostraron que fue posible modelar la variacion espacio-temporal de OD tanto a lo largo del lago de Chapala como a diferentes profundidades. Sin embargo, se observo que en algunos casos los variogramas presentaron una tendencia espacial a nivel global, por lo que, en futuros trabajos, se sugiere modelar con base en Kriging universal o utilizando otros modeles de interpolacion.

Mineralogical signatures and sources of recent sediment in a large tropical lake

Two lead-210 (210Pb) dated sediment cores from Chapala Lake were studied to identify the mineral composition of the sediments and to discuss its relation with trace metals. Minerals and trace metals reflected the domain of volcanic rocks (i.e. basalts, rhyolite and andesite) that characterize Chapala Lake and the Lerma River watershed. Redundancy analyses (RDA) were used to identify the sedimentary variables (magnetic susceptibility, organic matter, sand content, and mineral composition) that could be related to elemental composition. Despite the distance between the two cores (7.3km) and hydrodynamic circulation the RDA showed that the main mechanism that controls the input of mineral species, and, therefore, element distributions in the lacustrine sediment of Chapala Lake, is related to the weathering of volcanic rocks in the Lerma-Chapala watershed, the consequent runoff and transport of fine grained catchment materials, and later in-lake processes. These findings highlight the importance of controlling watershed erosion to contribute to the improvement of the environmental quality of the lake.

Prevalence of Albuminuria in Children Living in a Rural Agricultural and Fishing Subsistence Community in Lake Chapala, Mexico.

The occurrence of Chronic Kidney Disease (CKD) of unknown etiology in autochthonous child populations residing along the Lake Chapala lakeshore is endemic (Jalisco, México). The objective of this study was to determine the prevalence of albuminuria in the pediatric population and to measure the glomerular filtration rate in children with two positive albuminuria tests. Urinary albumin was measured in 394 children. Subjects with two or more positive albuminuria test donated blood samples for the determination of serum biomarkers. From a rural community with 565 children under the age of 17 years, 394 (69.7%) participated with first morning urine samples. A total of 180 children were positive (with two or more positive albuminuria tests). The prevalence of albuminuria among the children participating in the study was 45.7%. Of the 180 children with persistent albuminuria, 160 (88.9%) were tested for serum creatinine, urea, and cystatin C. The 68.1% of the children studied, were found in stages 3a and 3b of the Kidney Disease Improving Global Outcomes (KDIGO) classification (mean glomerular filtration rate (GFR) 51.9 and 38.4 mL/min/1.73 m2 respectively). The lowest frequencies were for classifications 1 and 4. None of the subjects was classified as grade 5. The prevalence of albuminuria in children from this rural community is 3–5 times higher than reported in international literature. Regarding GFR, more than 50% of children studied are under 60 mL/min/1.73 m2. It is a priority to find the causes of albuminuria and CKD in this Mexican region.

Conviviendo con la escasez. Cultura y adaptabilidad pesquera en el lago de Chapala

Este artículo examina las respuestas adaptativas de comunidades lacustres ante cambios ambien­tales. En particular se estudian las localidades cercanas al lago de Chapala, el cual se encuentra en riesgo por las oscilaciones en su nivel de agua. Estos cambios implican una reorganización social, en especial para grupos como los pescadores que son directamente dependientes de la integridad lacustre. Utilizando un marco sobre adaptación y adaptabilidad, se contrastan diversas estrategias históricas y actuales para enfrentar la escasez y el estrés lacustre en La Palma, Michoacán. Con ello pretendemos resaltar el lugar social cambiante de la pesca y sus características culturales más influyentes, las cuales han permitido su continuidad.

Aves del Puerto Interior Turístico Jocotepec, en el Lago de Chapala, Jalisco, México

El Lago de Chapala es el más grande de México, es un sitio de interés para la conservación biológica, declarado sitio Ramsar, además de ser reconocido como un Área de Importancia para la Conservación de las Aves (AICA 58). Los humedales de Jalisco son de gran importancia para la conservación de las aves; sin embargo, existen pocos estudios, específicamente sobre las aves del Lago de Chapala. En este estudio realizamos el inventario de la comunidad de aves del Puerto Interior Turístico Jocotepec, un parque urbano de la ribera de Chapala. Realizamos el estudio de abril de 2015 a marzo de 2016. Registramos 100 especies de aves pertenecientes a 14 órdenes y 34 familias. El 69% de las aves son residentes, 30% son visitantes de invierno y 1% transitorias. Así mismo, comparamos la riqueza y composición encontrada con otros estudios realizados en el estado de Jalisco. Resalta la presencia de Rallus longirostris, una especie residente y endémica en el centro-occidente de México que presenta los valores de vulnerabilidad más altos. Destacamos la importancia biológica del parque urbano y sugerimos incrementar el número de estudios sobre las aves del Lago de Chapala.

CO2 Removal from Biogas by Cyanobacterium Leptolyngbya sp. CChF1 Isolated from the Lake Chapala, Mexico: Optimization of the Temperature and Light Intensity.

In the present study, the capacity of the cyanobacterium Leptolyngbya sp. CChF1 to remove CO2 from real and synthetic biogas was evaluated. The identification of the cyanobacterium, isolated from the lake Chapala, was carried out by means of morphological and molecular analyses, while its potential for CO2 removal from biogas streams was evaluated by kinetic experiments and optimized by a central composite design coupled to a response surface methodology. Results demonstrated that Leptolyngbya sp. CChF1 is able to remove CO2 and grow indistinctly in real or synthetic biogas streams, showing tolerance to high concentrations of CO2 and CH4, 25 and 75%, respectively. The characterization of the biomass composition at the end of the kinetic assays revealed that the main accumulated by-products under both biogas streams were lipids, followed by proteins and carbohydrates. Regarding the optimization experiments, light intensity and temperature were the studied variables, while synthetic biogas was the carbon source. Results showed that light intensity was significant for CO2 capture efficiency (p=0.0290), while temperature was significant for biomass production (p=0.0024). The predicted CO2 capture efficiency under optimal conditions (27.1°C and 920lx) was 93.48%. Overall, the results of the present study suggest that Leptolyngbya sp. CChF1 is a suitable candidate for biogas upgrading.

Spectroscopic Study of Sediments from Chapala Lake in Western Mexico

The first 10 cm of sediment from Lake Chapala, Western Mexico are in constant activity related to the exchange and speciation of metal cations. Samples of this sediment were analyzed in electron paramagnetic resonance (EPR) equipment to study the paramagnetic metals. Assays indicated that only Fe3+ was present in a detectable amount. This cation, along with chemical fractions of sediment obtained by sequential extraction, was analyzed by EPR. The analysis supported by infrared data revealed that Fe3+ was present in diluted and concentrated domains. Easily exchangeable iron was retained by carbonyl groups in organic matter. The carbonate fraction and oxides contained iron in concentrated domains. The alumina-silicate fraction (that resisted the sequential extraction digestions) presented diluted domains of iron in the octahedral alumina sheet along with occlusions of concentrated domains. This last inference was obtained by comparing EPR results against the spectrum of iron in synthetic model clay.

Tracking Metal Pollution in Lake Chapala: Concentrations in Water, Sediments, and Fish.

We measured concentrations of selected metals (Al, Ba, Cu, Mn, Hg, Sr, V, and Zn) in water, sediments, and fish from Lake Chapala and a reference site to evaluate potential negative effects on wildlife, particularly fish-eating birds. Fish metal concentrations ranged from 0.05µg/g wet weight (ww) for Al and Cu to 64.70µg/g ww for Sr. There was a positive and significant correlation between fish length and metals particularly for Ba, Cu, Mn, and Zn in Lake Chapala (p<0.05). However, there were no significant correlations between metal concentrations and δ(15)N values in fish indicating no biomagnification through the food web. Overall, metal concentrations in water, sediments, and fish were similar to and in some cases below those reported for Lake Chapala over the last 20years. Also, metal concentrations were below those that could be of concern for negative effects on fish and wildlife of Lake Chapala.

The level variability, thermal structure and currents in Lake Chapala, Mexico

Measurements of temperature, currents and lake level taken in 2005-2014 are analyzed and discussed. Moored measurements of temperature and level in the northern part of the lake reveal the presence of seiches oscillations of the first and second modes, with periods of 5.7 and 2.8 hours, and amplitudes of 15.4 and 2.1 mm. In 2006 four temperature cross-sections were carried out in the study area. The obtained data reveal that in all four seasons of the year the temperatures averaged over the north and south coastal areas differ by 2-3°C. The lake currents were simulated using the HAMSOM 2-D hydrodynamic model both for wet and dry seasons. The model results are in good agreement with the ADCP data. The presence of an anticyclonic gyre, 10-12 km in diameter, in the central part of the lake in both seasons is revealed. In particular, the summer 2014 data provide evidence of the gyre and its impact on the spatial distribution of temperature in the lake.

ESPECIACIÓN DE METALES PESADOS EN SEDIMENTOS DE UN LAGOTROPICAL MEXICANO

Heavy metals speciation of Mexican Lake Chapala sediments was studied using sequential extraction to assess their mobility. Mineralogical con...

Thermal structure and circulation in Lake Chapala, Mexico

&lt;p&gt;This study analyzed and discussed the instrumental measurements of temperature and currents made on January 10, 2007, in Lake Chapala. We received new data on the formation of the thermocline. It is shown that the thermocline of the lake is formed only in the daytime and in a top-heated 0.5-1.0 m layer. The vertical temperature gradient reaches 2.5°C in the first meter, and the spatial average temperature across the lake showed that the northern end of the lake is, on average, 1°C warmer than the southern end. We numerically modelled the currents in the lake for the dry season using the HAMSOM 2D hydrodynamic model. The simulation results are in good agreement with the acoustic Doppler current profiler ADCP measurements. In the dry season, two gyres were found: a cyclonic gyre in the eastern part and an anticyclonic gyre in the western part.&lt;/p&gt;

Modeling common trends of zooplankton, atherinopsid, and barred splitfin time series in a shallow tropical lake

Abstract Dynamic factor analysis was used to discern underlying common trends and the effect of physicochemical variables on time series of zooplankton, fish density, and biomass of barred splitfin (Chapalichthys encaustus) and atherinopsids (Chirostoma spp.) from Lake Chapala, Mexico. Strongly coherent trends were identified for the zooplankton and atherinopsid time series. Weakly coherent trends were detected for the barred splitfin time series.

Detecting causation on Zooplankton, atherinopsid, and barred splitfin time-series in a shallow tropical lake

Abstract We used Multispatial Convergent Cross Mapping analysis to detect causality on monthly differences of zooplankton volume and fish density and biomass time-series of atherinopsids (Chirostoma species) and barred splitfin (Chapalichthys encaustus) from Lake Chapala, Mexico. The dynamics of monthly differences of zooplankton volume were causally influenced by monthly differences in pH. The dynamics of the monthly differences of atherinopsid and barred splitfin density, and atherinopsid biomass, were not causally influenced by monthly differences of any of the measured physicochemical variables. The dynamics of the monthly differences of the barred splitfin biomass were due to monthly differences in water temperature and alkalinity. The dynamics of monthly differences of zooplankton volume did not show any significant causal forcing on the dynamics of monthly differences of density and biomass of atherinopsid and barred splitfin density. The dynamics of monthly differences of atherinopsids showed sign...

Fishing, public policy and the socio-economic conditions of artisanal fishermen of Lake Chapala

Fishing, public policy and the socio-economic conditions of artisanal fishermen of Lake Chapala

Key constraints and problems affecting the inland fishery value chain in central Mexico

Anthropogenic activities have been the major cause of watershed deterioration in many parts of the world, negatively impacting inland fisheries. In Mexico, freshwater fishing represents a source of protein, income, and employment for rural communities; however, in the national fisheries statistics they only account for 3% of the total production, and increases have not taken place since the 1990s. Demand is higher than supply because the national market can only provide 50% of consumption, and these fisheries are currently passing through a complex situation that prevents an increase in production levels and fishers’ incomes. This study examined the main production constraints and problems that prevent production from increasing to satisfy national demand. We considered value chain analysis and fish catch dynamic approaches. Fieldwork was conducted in 2 periods during 2011 and 2012 in 4 riparian communities near Lake Chapala and Lake Yuriria. The methodological approach considered socioeconomic factors and temporal variability of catch volume in both lakes. Results showed that production constraints are the result of watershed and fisheries mismanagement. Catch levels were strongly related to the environmental conditions of the lakes, which have shown instability and decline that affect fishers’ livelihoods. In addition, illegal, unreported, and unregulated (IUU) fishing and the ineffectiveness of institutions to rule the actions of all actors who intervene in the management and use of these resources allow destructive strategies toward the fisheries. Finally, inland fisheries management is not considered part of watershed management policies, resulting in ill-adapted water allocation policies that affect fisheries production levels.

Surface deformation on the west portion of the Chapala lake basin: uncertainties and facts

Abstract. In this study we investigate different aspects of land subsidence and ground failures occurring in the west portion of Chapala lake basin. Currently, surface discontinuities seem to be associated with subsiding bowls. In an effort to understand some of the conditioning factors to surface deformation, two sounding cores from the upper sequence (11 m depth) were extracted for analyzing physical and mechanical properties. The upper subsoil showed a predominant silty composition and several lenses of pumice pyroclastic sand. Despite the relative predominance of fine soil, the subsoil shows mechanical properties with low clay content, variable water content, low plasticity and variable compressibility index, amongst some others. Some of these properties seem to be influenced by the sandy pyroclastic lenses, therefore, a potential source of the ground failure could be heterogeneities in the upper soil.

Chapala half-graben structure inferred. A magnetometric study

Many geologic and tectonic-structural studies refer to the Chapala lake structure in general terms as a graben (or more generally as rift). However, no formal study has addressed its structure. The Chapala Lake is located in a major topographic depression surrounded by broad middle to late Miocene volcanic-capped plateaus. We conducted a magnetic survey comprising five S-N lines crossing the Chapala Lake. One profile comprises a land extension (southwards along roads). Magnetic anomalies obtained are mainly smooth and large scale features associated to the sedimentary infill, local and high amplitude anomalies are due to shallow basaltic and andesitic tilted blocks, and highest amplitudes due to the outcropped basaltic flows of the Los Alacranes and Mezcala islands. The models obtained point to a large structural high located at the central depression portion that separates two structural lows. The structural lows correspond to half-graben type structures. Through the faults delimiting it were emplaced the basaltic flows of the Mezcala and Los Alacranes islands. The presence of half-graben type structures indicates that the crust has been subject to an extensional tectonic.