El estudio se realizó en 13 zonas del litoral peruano del lago Titicaca, durante la época seca, desde junio hasta agosto de 2017. En cada zona se determinó la abundancia relativa y uso de ...microhábitat de Telmatobius culeus. En las zonas de evaluación se utilizó buceo con esnórquel para realizar en cada una tres transectos de 100 m x 2 m, con un total de 38 transectos evaluados. Se registraron 45 individuos en solo seis zonas de evaluación. El mayor número de individuos se encontraron en la zona de Perka Norte, con una abundancia relativa de 10.33 individuos/hora/02 personas a una profundidad de 1.5 m; en siete zonas no se registró ningún individuo. Los individuos fueron encontrados en los siguientes micro hábitats: 17 fueron encontrados sobre la vegetación acuática, 11 en arena combinado con vegetación acuática, 9 en roca combinado con vegetación acuática, 5 en fango combinado con vegetación acuática, 2 en roca y 1 en arena. a la vez se realizó análisis de diferentes parámetros de calidad de agua en cada zona de estudio, como: temperatura, pH, alcalinidad, dureza y oxígeno.
Aquatic ecosystems of the Bolivian Altiplano (∼3800 m a.s.l.) are characterized by extreme hydro-climatic constrains (e.g., high UV-radiations and low oxygen) and are under the pressure of increasing ...anthropogenic activities, unregulated mining, agricultural and urban development. We report here a complete inventory of mercury (Hg) levels and speciation in the water column, atmosphere, sediment and key sentinel organisms (i.e., plankton, fish and birds) of two endorheic Lakes of the same watershed differing with respect to their size, eutrophication and contamination levels. Total Hg (THg) and monomethylmercury (MMHg) concentrations in filtered water and sediment of Lake Titicaca are in the lowest range of reported levels in other large lakes worldwide. Downstream, Hg levels are 3–10 times higher in the shallow eutrophic Lake Uru-Uru than in Lake Titicaca due to high Hg inputs from the surrounding mining region. High percentages of MMHg were found in the filtered and unfiltered water rising up from <1 to ∼50% THg from the oligo/hetero-trophic Lake Titicaca to the eutrophic Lake Uru-Uru. Such high %MMHg is explained by a high in situ MMHg production in relation to the sulfate rich substrate, the low oxygen levels of the water column, and the stabilization of MMHg due to abundant ligands present in these alkaline waters. Differences in MMHg concentrations in water and sediments compartments between Lake Titicaca and Uru-Uru were found to mirror the offset in MMHg levels that also exist in their respective food webs. This suggests that in situ MMHg baseline production is likely the main factor controlling MMHg levels in fish species consumed by the local population. Finally, the increase of anthropogenic pressure in Lake Titicaca may probably enhance eutrophication processes which favor MMHg production and thus accumulation in water and biota.
Box plot presentation with error bars for percentage methylmercury over total mercury for filtered and unfiltered surface waters along the upstream - downstream gradient from Lake Titicaca to Uru-Uru. Vertical bar chart show the median (upper full line) and standard deviation (SD) of each data set (N is the number of samples). Display omitted
•A global inventory of Hg levels and species is done in Lake Titicaca hydrosystem.•Lake Titicaca exhibits low Total Hg and MMHg concentrations in water and sediment.•Lake Uru-Uru exhibits Hg levels 3 to 10 times higher than in Lake Titicaca.•Percentages of MMHg are high in all waters rising up from <1 to ∼50% of THg.•Enhanced in situ MMHg production by eutrophication controls Hg levels in fish.
High in situ MMHg production and accumulation in Lake Titicaca hydrosystem can be enhanced by local eutrophication and controls MMHg levels in fish species.
Cultural eutrophication is the leading cause of water quality degradation worldwide. The traditional monitoring of eutrophication is time-consuming and not integrative in space and time. Here, we ...examined the use of carbon (δ13C) and nitrogen (δ15N) isotopic composition to track the degree of eutrophication in a bay of Lake Titicaca impacted by anthropogenic (urban, industrial and agricultural wastewater) discharges. Our results show increasing δ13C and decreasing δ15N signatures in macrophytes and suspended particulate matter with distance to the wastewater source. In contrast to δ15N and δ13C signatures, in-between aquatic plants distributed along the slope were not only affected by anthropogenic discharges but also by the pathway of carbon uptake, i.e., atmospheric (emerged) vs aquatic (submerged). A binary mixing model elaborated from pristine and anthropogenic isotope end-members allowed the assessment of anthropogenically derived C and N incorporation in macrophytes with distance to the source. Higher anthropogenic contribution was observed during the wet season, attributed to enhanced wastewater discharges and leaching of agricultural areas. For both seasons, eutrophication was however found naturally attenuated within 6 to 8 km from the wastewater source. Here, we confirm that carbon and nitrogen stable isotopes are simple, integrative and time-saving tools to evaluate the degree of eutrophication (seasonally or annually) in anthropogenically impacted aquatic ecosystems.
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•C and N stable isotopes were measured in four compartments of Lake Titicaca.•Anthropogenic discharge affects baseline C and N isotope signatures.•C recycling from soil, anthropogenic and lacustrine sources affect the δ13C signature.•δ15N signatures track anthropogenic contamination independently of plant type.•Decreased anthropogenic contribution in the bay assessed by isotope mixing model.
•Multidisciplinary approach cross-combined to previous geomorphological maps.•Watercourse are associated to pre-Columbian agricultural structures.•Regressive pattern of the Titicaca Lake coastline ...since mid-20th century.•Major alluvial evolution since mid-20th century.•First synthetized geomorphological and geoarchaeological map of the watershed.
The Altiplano and more specifically the Titicaca circum-lake sector have recorded several major landscape transformations. In particular, changes in the lake water level lead to a significant vulnerability and contributed to the development of flexible and diverse agropastoral activities of the pre-Columbian and current populations to climate change. The Tiwanaku River, particularly because of the presence of the pre-Columbian Tiwanaku site, has been the subject of several research studies aimed at characterizing the environment of the archaeological site. Here we propose a new synthesis of the geomorphology of the Tiwanaku River watershed based on an interdisciplinary approach (Historical geography and remote sensing, cross combined with field survey). Our results show that the general organization of the drainage system is influenced by lake level and climatic changes. However several watercourses of the Tiwanaku River might be related to pre-Columbian agricultural or proto-urban structures. Our work allowed to estimate the regressive pattern of the coastline of Lake Titicaca and to identify major changes of the terminal and medium watercourse of the Tiwanaku River over the last 70 years.
Mortalities of up to 60% farmed rainbow trout (Oncorhynchus mykiss) were recorded in six floating cages farms in the Lake Titicaca during the wet season (December to April) of 2018. Fish presented ...uni or bilateral exophthalmia, ocular hemorrhages and melanosis. Necropsy showed severe hemorrhage in swim bladder, brain, liver and muscle, splenomegaly, and gut congestion. Histology revealed retrobulbar hemorrhage with macrophage infiltration, multifocal necrosis in several tissues, meningitis, splenitis, epicarditis, and congestion. After microbiological culture in blood agar, flat and circular colonies with smooth edges and a zone of α-hemolysis were observed. The presence of Weissella ceti was confirmed through biochemical and molecular analysis (16S rRNA gene sequence analysis), without differences between Peruvian isolates. Worldwide, W. ceti isolates from rainbow trout were similar using 16S rRNA gene sequence, however, showed discrepancies between those isolates from different hosts. Finally, Koch's postulate was confirmed with experimental infections using rainbow trouts (~9 cm) infected intraperitoneally (0.1 mL of 104 CFU). After 21 days, clinical signs and lesions similar to the recorded in natural outbreaks were observed, cumulative mortality rate was 90% and bacteria was successfully recovered from both moribund and survivor fish. This is the first report and description of weissellosis caused by Weissella ceti isolated from rainbow trout cultured in Lake Titicaca, Peru and it is the first report of the primary isolation of this bacterium on TSA and TYES media instead of TSAB medium.
•This is the first report of Weissella ceti in Peru.•First report of primary isolate of this bacteria on TSA and TYES media.•Worldwide, W. ceti isolates from rainbow trout are similar using 16S rRNA gene sequence.
Se investigó la variabilidad espacial y temporal de la temperatura superficial del agua LSWT en el lago Titicaca 15°45′00″S - 69°25′00″O, usando imágenes MODIS para el invierno del 2001-2014. ...Utilizamos el producto MOD11A2 de temperatura de la superficie terrestre (LST), que renombraremos como LSWT. Los datos LST de detección remota se obtuvieron del sensor MODIS a bordo del satélite Terra como un compuesto de 8 días, a una resolución espacial de 1 km. Durante el invierno austral junio, julio, y agosto, el producto MOD06L2 cloud fraction, mostró cielo despejado en el sur del Perú. Se analizó la distribución de LSWT por medio de imágenes, series de tiempo, y el coeficiente de variación (Cv). Se consideró dos regiones del Titicaca, Lago Mayor (LM) y Lago Menor (Lm). Se descubrió que el coeficiente de variación de LSWT para la cuenca principal (LM) para el periodo de estudio no mostró cambios significativos (Cv <9 %). El valor promedio de la temperatura superficial de la cuenca principal (LM) encontrado en esta investigación está aproximadamente a 12°C, la cual muestra un incremento notable en el año 2010.
The quality of quinoa flour is greatly determined by its non-starch components, mainly protein and lipids. Dry fractionation has an important impact on the composition and physicochemical properties ...of quinoa flour and grits. Quinoa cv. Titicaca, the most extensively grown in Europe and little studied so far, was used in this work. Hydration, techno-functional, rheological and thermal properties of three quinoa fractions obtained by dry fractionation (fine, medium and coarse) were evaluated and related to their particle size and composition. The medium fraction (~500 μm) was enriched in protein (50%) and lipids (80%) and depleted in starch (30%) with respect to the original grain; while the coarse fraction (~1000 μm) was enriched in starch (7%) and reduced in protein (15%). The fine fraction showed the most similar functional, pasting and rheological properties to the whole grain quinoa flour. The coarse fraction led to the most consistent gels, with the elastic (G′) and viscous (G'') moduli being ten and twenty times higher than those found in the other quinoa fractions and the whole grain flour. The degree of retrogradation as well as the formation of the amylose-lipid complex were markedly affected by the particle size and not so by the composition of each fraction. This work allows to conclude that dry fractionation of quinoa grains is a feasible procedure to tailoring the nutritional profile of the flour and its techno-functional and rheological properties.
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•An efficient dry milling process of quinoa produces nutritional enriched fractions.•Fraction with medium particle size (~500 μm) was enriched in protein and lipids.•The coarse fraction (~1000 μm) led to gels much more consistent.•Amylose-lipid complex formation decreased in the larger particle size fractions.•Amylopectin retrogradation extent increased in the larger particle size fractions.
La quema prescrita de totorales es una práctica frecuente en zonas litorales del lago Titicaca para eliminar biomasa senescente, obtener brotes tiernos y mejorar la calidad nutritiva como forraje. ...Por ello, el objetivo del estudio fue determinar el efecto de estas quemas en el valor nutricional de tallos aéreos de totora, a través de análisis proximales, comparando totorales con y sin quema, en tres períodos fenológicos (rebrote, crecimiento y madurez); para detectar diferencias entre tratamientos se sometieron los datos a Anova con arreglo factorial 2*3 (dos tratamientos y tres épocas) y prueba de Tukey. Según los resultados la materia seca en totorales con quema incrementó significativamente (P<0,05) en relación a totorales sin quema (27,02 % ± 0,61 vs. 21,22 % ± 1,06), alcanzando mayores valores aún durante el rebrote y madurez, similarmente la fibra cruda tuvo un aumento significativo con la quema consecutiva (30,04 % ± 2,81 vs. 28,13 % ± 2,06), con mayores concentraciones durante el crecimiento y madurez; mientras que la proteína cruda disminuyó por efecto del fuego desde el período de crecimiento (7,34 % vs. 10,14 %), aunque con una transitoria superioridad durante el rebrote (9,28 % vs 6,87 %) respecto al totoral sin quema (P<0,05). La quema prescrita consecutiva afectó la calidad forrajera de culmos de totora, disminuyendo los niveles de proteínas, nutrientes de alto valor biológico, pero propiciando incremento en materia seca y fibra, lo que podría repercutir en su adecuada digestibilidad.
Lake Titicaca is home to a unique high-altitude ecosystem that is suffering from increasing anthropogenic pressures. It experienced its first major algal bloom in March–April 2015 that had ...devastating consequences in the southern shallow lake basin. Such events are expected to intensify in the future and call for a more active and quantitative management of the lake and its watershed. In this paper we describe a coupled ecohydrodynamic model to predict the lake’s water quality and, more particularly, the risk of harmful algal blooms. We have coupled a nitrogen-phytoplankton-zooplankton-detritus (NPZD) ecosystem model to the unstructured-mesh 3D hydrodynamic model SLIM. Our high-resolution multi-scale model explicitly represents the exchanges between the two basins composing the lake, through the narrow Strait of Tiquina. This allowed us to study the biophysical processes driving the entire lake over the period of January 2014 to May 2015. The model has been validated against temperature profiles at several locations throughout the lake. It correctly reproduces the seasonal temperature variations that drive the lake stratification and impact the vertical distributions of phytoplankton. Our model was able to replicate the space–time dynamics of the March–April 2015 algal bloom similarly to what was observed on satellite imagery. We believe that our multi-scale ecohydrodynamic model is a promising tool to complement field observations and hence support water management in the lake and its watershed.
•Algal blooms in Lake Titicaca can be predicted with a coupled ecosystem-hydrodynamic model.•Exchanges between both basins are well represented with a multiscale unstructured mesh.•The seasonal variations of the lake biophysical properties are correctly reproduced.•The space–time dynamics of the 2015 algal bloom is validated with satellite imagery.
According to the Peruvian agricultural ministry, the Pacific watersheds where the great cities and intense farming are located only benefit from 1% of the available freshwater in Peru. Hence a ...thorough knowledge of the hydrology of this region is of particular importance. In the paper, analysis of this region and of the two other main Peruvian drainages, the Titicaca and Amazonas are reported. Rainfall and runoff data collected by the Peruvian National Service of Meteorology and Hydrology (SENAMHI) and controlled under the Hydrogeodynamics of the Amazon Basin (HyBAm) project is the basis of this basin-scale study that covers the 1969–2004 period. Beyond the strong contrasting rainfall conditions that differentiate the dry coastal basins and the wet eastern lowlands, details are given about in situ runoff and per basin rainfall distribution in these regions, and about their different altitude–rainfall relationships. Rainfall and runoff variability is strong in the coastal basins at seasonal and inter-annual time scales, and related to extreme El Niño events in the Pacific Ocean. However, rainfall and runoff are more regular in the Andes and Amazonas at the inter-annual time scale. Warm sea-surface temperatures in the northern tropical Atlantic tend to produce drought in the southern Andes basins. Moreover, significant trends and change-points are observed in the runoff data of Amazonas basins where rainfall and runoff decrease, especially after the mid-1980s and during the low-stage season. Almost all the coastal basins show some change in minimum runoff during the last 35 years while no change is observed in rainfall. This means that human activity may have changed runoff in this region of Peru, but this hypothesis deserves more study.Editor Z.W. Kundzewicz; Associate editor Š. BlažkováCitation Lavado C., W.S., Ronchail, J., Labat, D., Espinoza, J.C. and Guyot, J.L., 2012. Basin-scale analysis of rainfall and runoff in Peru (1969–2004): Pacific, Titicaca and Amazonas watersheds. Hydrological Sciences Journal, 57 (4), 625–642.
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