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Aida G. Infante

Bio: Aida G. Infante is an academic researcher from University of Mobile. The author has contributed to research in topics: Chlorophyll a & Phytoplankton. The author has an hindex of 1, co-authored 1 publications receiving 5 citations.

Papers
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TL;DR: In this article, the maximum rate of gross photosynthesis per hour at light saturation was determined within the uppermost 1-meter layer of Lake Valencia, and the highest value was 16,290 mg O 2. m -3. h -1.
Abstract: Lake Valencia is heavily polluted by waste water of domestic, agricultural and industrial origin. The high organic load may have produced important changes in the limnological properties. Cyanobacteria dominated in numbers and biomass (over 90% throughout the year). Chlorophyll-a content averaged 37.7 ± 15 μg. l -1 . Maximum concentrations of 50-80 μg. l -1 were found near the inflows affected by organically polluted affluents. There has been a 50% reduction in the euphotic zone in only 13 years. The maximum rate of gross photosynthesis per hour at light saturation was determined within the uppermost 1-meter layer. The highest value was 16,290 mg O 2 . m -3 . h -1 Lake Valencia is among the most productive lakes in the world, with areal net photosynthesis averaging 7.5 g C. m -2 . d - 1.

5 citations


Cited by
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TL;DR: In this paper, an exceptionally high abundances and diversity of keto-ols, diols and structurally related long-chain n -alkenols and secondary alkanols were detected in sediments from a hypereutrophic, freshwater lake (Lake Valencia, Venezuela).

33 citations

Journal ArticleDOI
TL;DR: Physical and chemical parameters of Pao-Cachinche reservoir (Venezuela) were measured in four stations (S1-S4) during an eighteen months period from September 1997 to February 1999.
Abstract: Physical and chemical parameters of Pao-Cachinche reservoir (Venezuela) were measured in four stations (S1-S4) during an eighteen months period from September 1997 to February 1999. The tributaries of this reservoir introduce high amounts of nutrients from domestic wastewaters and from poultry and pig farms located in the basin. Thermal stratification was well established throughout the study period. Mountainous topography protects the water surface from mechanical action of wind, preventing water mixing. Hypoxic/anoxic conditions prevailed from 6–7 m depth down to the bottom in the limnetic stations. A strong smell of H2S was detected below the 10 m level. The low water transparency (max. 1.5 m) may be mainly attributed to a high biogenic turbidity. Water salinity was low, as the maximum conductivity measured (260 μS cm−1) suggests. The water was alkaline in the upper layers during the day time (pH >8.0), due to the high phytoplanktonic productivity, whereas in deeper layers, where decomposition processes predominate, pH was acidic (close to 6.0). Orthophosphate concentrations were high, reaching maximal concentrations in the deeper part of the reservoir (greater than 800 μg l−1). Total phosphorus exceeded 1000 μg l−1 in the hypolimnion during the dry season. Ammonia was the dominant inorganic nitrogen species, and its values were greater than 4000 μg l−1 in the hypolimnetic layer during the dry season. Nitrates and nitrites were present in relatively low concentrations, except for the Paito stream entrance, where nitrate concentrations remained above 260 μg l−1. Pao–Cachinche reservoir can be considered hypertrophic, according to Salas & Martino’s criteria for tropical warm lakes, and could be classified as meromictic and warm monomictic, according to Lewis tropical lake types.

31 citations

Journal ArticleDOI
TL;DR: Bulk geochemical parameters and organic matter biomarkers in a short, high resolution gravity core (Lake Valencia, Venezuela) were examined to reconstruct anthropogenic impacts on the lake’s conditions, suggesting a primary autochthonous (algae and macrophytes) organic matter origin.

27 citations

Journal ArticleDOI
Abstract: The lipids in a sediment core from Lake Valencia, a hypereutrophic freshwater lake in Venezuela, are examined to understand environmental changes over the last ∼13,000 years. From the latest Pleistocene to the earliest Holocene, total organic carbon (TOC) substantially increased from 2.2 to 10%, while total organic carbon over total nitrogen (TOC/TN) decreased from as high as 34 to as low as 10. Correspondingly, the concentration of terrestrially derived triterpenoids markedly decreased, and the dominant n-alkane shifted from C31 to C23 or C25. During the same period, algal biomarkers such as botryococcenes, dinosterol, isoarborinol, C20 HBIs and 1,15C32 keto-ol markedly increased in abundance. These changes suggested a greater contribution of algal organic matter at the onset of the Holocene, which was concurrent with increasing rainfall and the formation of a permanent lake (Lake Valencia) in the Aragua Valley, Venezuela. The age profile of Paq, a n-alkane based proxy, showed large oscillations (0.20–0.81), reflecting historical variations in source strength of submerged/floating vs. terrestrial/emergent OM inputs. An abrupt increase in tetrahymanol abundance at ∼7,260 cal years BP suggests the establishment of an oxic–anoxic boundary in the lake’s water column. After reaching its maximum abundance at ∼2,100 cal year BP, botryococcenes, a biomarker of Botryococcus braunii, gradually decreased to below the detection limit in the uppermost sediments, while different algal/microbial biomarkers such as diploptene, dinosterol and isoarborinol substantially increased. These different historical profiles of algal/microbial biomarkers reflect different responses of source organisms to environmental changes throughout this period. The δ13C determinations presented exceptionally enriched values for botryococcene isomers (−7.7 to −15.1‰), indicating the utilization of bicarbonate as carbon sources in an extremely productive ecosystem.

23 citations

Journal Article
TL;DR: Ernesto J. Gonzalez et al. as mentioned in this paper, M.Sc., Mencion Botanica, Universidad Central de Venezuela (UCV), Caracas 1041, Venezuela.
Abstract: Ernesto J. Gonzalez. Doctor en Ciencias, Mencion Ecologia, Universidad Central de Venezuela (UCV). Docente Investigador, Laboratorio de Limnologia, Instituto de Biologia Experimental (IBE), UCV. Direccion: IBE-UCV, Apartado 47106, Los Chaguaramos, Caracas 1041, Venezuela. e-mail: ergonza@reacciun.ve Mario Ortaz. Licenciado en Biologia, UCV. Docente Investigador, Laboratorio de Ecologia de Peces, IBE, UCV, Venezuela. Carlos Penaherrera. Tecnico de Proyectos, Laboratorio de Limnologia, IBE, UCV, Venezuela. Maria Leny Matos. M.Sc., Mencion Botanica, UCV. Jefe de Laboratorio, Hidroven, Venezuela. FITOPLANCTON DE UN EMBALSE TROPICAL HIPEREUTROFICO (PAO-CACHINCHE, VENEZUELA): ABUNDANCIA, BIOMASA Y PRODUCCION PRIMARIA

11 citations