Lake inventory and area of the lakes in the Cajas Massif and volume, depth, and watershed area of... more Lake inventory and area of the lakes in the Cajas Massif and volume, depth, and watershed area of a selection of lakes in the Cajas National Park based on a bathymetric survey
The number, size, and shape of lakes are key determinants of the ecological functionality of a la... more The number, size, and shape of lakes are key determinants of the ecological functionality of a lake district. The lake area scaling relationships with lake number and volume enable upscaling biogeochemical processes and spatially considering organisms' metapopulation dynamics. These relationships vary regionally depending on the geomorphological context, particularly in the range of lake area 104 m2 and 50% of the water resources are held in a few ones (∼10) deeper than 18 m. Therefore, midlakes and large lakes are by far more biogeochemically relevant than ponds and shallow lakes in this tropical mountain lake district
Environmental Science and Pollution Research International, 2020
Historical records of trace elements in lake sediments provide source-to-sink information about p... more Historical records of trace elements in lake sediments provide source-to-sink information about potentially toxic pollutants across space and time. We investigated two lakes located at different elevations in the Ecuadorian Andes to understand how trace element fluxes are related to (i) geology, (ii) erosion in the watersheds, and (iii) local point sources and atmospheric loads. In remote Lake Fondococha (4150 m a.s.l.), total Hg fluxes stay constant between ca. 1760 and 1950 and show an approximately 4.4-fold increase between pre-1950 and post-1950 values. The post-1950 increase in fluxes of other trace elements (V, Cr, Co, Ni, Cu, Zn, As, Cd, and Pb) is lower (2.1–3.0-fold) than for Hg. Mostly lithogenic sources and enhanced soil erosion contribute to their post-1950 increase (lithogenic contribution: > 85%, Hg: ~ 58%). Average post-1950 Hg fluxes are approximately 4.3 times higher in peri-urban Lake Llaviucu (3150 m a.s.l.) than in the remote Lake Fondococha. Post-1950 fluxes ...
Lakes located downwind of active volcanoes serve as a natural repository for volcanic ash (tephra... more Lakes located downwind of active volcanoes serve as a natural repository for volcanic ash (tephra) produced during eruptive events. In this study, sediment cores from four lakes in Cajas National Park, southern Ecuador, situated approximately 200 km downwind of active volcanoes in the Northern Andes Volcanic Zone, were analysed to document the regional history of tephra fall extending back around 3,000 a cal BP. The ages of the lacustrine sedimentary sequences were constrained using a total of 20 AMS radiocarbon ages on plant remains. The tephra layers were correlated among the lakes based on their radiocarbon age, elemental composition, colour, and grain morphology. We found five unique tephra layers, each at least 0.2 cm thick, and further constrained their ages by combining the results from two age-depth modelling approaches (clam and rbacon). The tephra layers were deposited 3,034±621, 2,027±41, 1,557±177, 733±112, and 450±70 a cal BP. The ages of all but the youngest tephra lay...
Aim: Lakes in the Ecuadorean Andes span different altitudinal and climatic regions, from inter An... more Aim: Lakes in the Ecuadorean Andes span different altitudinal and climatic regions, from inter Andean plateau to the high-elevation páramo, which differ in their historical evolution in the several centuries since the pioneering Humboldt expeditions. Here, we evaluate temporal and spatial patterns of change in diatom assemblages between historical (palaeolimnological) and modern times. Location: Ecuadorean Andes Methods: We compared historical (pre-1850) and modern (2017) diatom assemblages from 21 lakes and determined the relative role of environmental (water chemistry and climate) and spatial factors (distance-based Moran's eigenvectors maps) on both assemblages using non-metric multidimensional scaling (NMDS) with environmental fitting. In addition, we used redundancy analysis (RDA) with variance partitioning to estimate the historical (measured using downcore assemblage composition) effects on modern diatom assemblages and identified diatom species that contributed most to dissimilarity between the two times. Results: Diatom changes between the two time points were limited across the group of lakes, as indicated by the NMDS ordination. Variance partitioning indicated that modern diatom assemblages were affected by environmental and spatial effects, but with non-significant effects of past diatom species composition. Ordination results showed that variables related to elevation and water chemistry affected both modern and historical diatom assemblages. Diatom species with the best fit on NMDS axes (i.e. >70%) were influenced by elevation and climatic variables. The most distinctive change between the two time periods was the higher relative abundance of planktic diatom species in top-core assemblages of some lakes, but in a highly variable fashion across gradients of increased elevation and water depth. Main conclusions: Landscape palaeolimnological analyses of varied Ecuadorean Andean lakes demonstrate both environmental and spatial controls on diatom metacommunities. The multi-faceted ecological control of the altitudinal gradient on both historic and contemporary diatom assemblages suggests species sorting and dispersal constraints operating at centennial timescale. Although a few individual lakes show substantive change between the 1850s and today, the majority of lakes do not, and the analysis suggests the resilience of lakes at a regional scale. We emphasize the potential of diatom palaeolimnological approaches in biogeography to test
The Science of the total environment, Jan 19, 2017
The temporal profiles of polycyclic aromatic compounds (PACs) in lake sediments reflect past chan... more The temporal profiles of polycyclic aromatic compounds (PACs) in lake sediments reflect past changes in emissions, transport and deposition of these pollutants and, thus, record natural and anthropogenic processes. We document fluxes of PACs [(polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs) and azaarenes (AZAs)] deposited in two tropical high-altitude lakes in the Cajas National Park (Ecuadorian Andes, 2°50'S, 79°10'W). In remote and high elevation Laguna Fondococha (4130m a.s.l.), the temporal fluxes of OPAHs and AZAs were similar to those of PAHs suggesting similar sources. A significant increase of PAC deposition after the 1950s reflects Ecuador's economic development. PAH fluxes were relatively low (∑27PAHs (without retene and perylene): 0.86-11.21ngcm-2yr-1) with a composition pattern typical for long-range atmospheric transport (high 9-fluorenone/fluorene ratios) and biomass burning (30% low molecular weight PAHs). PAHs diagnostic of high temperatu...
Se ha estudiado la composición taxonómica de las comunidades de crustáceos litoral-bentónicos (br... more Se ha estudiado la composición taxonómica de las comunidades de crustáceos litoral-bentónicos (branquiópodos, copépodos y ostrácodos) y macrófitos de las masas de agua lacustre del Parque Nacional Cajas situado en los Andes Australes de Ecuador, con objeto de identificar los taxones más adecuados para ser utilizados como indicadores del estado ecológico de los lagos. De los crustáceos (22 taxones) se diferencian tres grupos. Un primer grupo con taxones de alto valor indicador formado por Branchinecta papillata, Ilyocryptus spinosus, Alonella sp, Pleuroxus sp. Paralona pigra y Alona sp. gr. manueli. Un segundo grupo con taxones de valor indicador medio formado por Alona glabra, Alona guttata, Microcyclops sp. Eucyclops sp. y Paracyclops sp. El tercer grupo estaría formado por taxones de escaso valor indicador, bien por su carácter eurioico y/o cosmopolita o por su rareza. De los macrófitos se han valorado como buenos indicadores del estado ecológico y de conservación de los lagos, los taxones enraizados sumergidos y flotantes para la masa de agua, y los helófitos e higrófitos para los litorales. Palabras clave: Crustáceos, macrófitos, indicadores, calidad ecológica,
• The tropical high-mountain lakes show power-law lake-size distributions truncated at both ends ... more • The tropical high-mountain lakes show power-law lake-size distributions truncated at both ends similar to those found in temperate ranges both deviating from the Earth's general patterns for lakes >1 km 2 • The causes for the power-law deviation differ between the two extremes. The marked relief limits the size of the largest lakes at high altitudes, whereas ponds are more prompt to a complete infilling. • Lake volume scales to lake area according to a larger coefficient that those found for other lake areas of also glacial origin but softer relief.
Lake inventory and area of the lakes in the Cajas Massif and volume, depth, and watershed area of... more Lake inventory and area of the lakes in the Cajas Massif and volume, depth, and watershed area of a selection of lakes in the Cajas National Park based on a bathymetric survey
The number, size, and shape of lakes are key determinants of the ecological functionality of a la... more The number, size, and shape of lakes are key determinants of the ecological functionality of a lake district. The lake area scaling relationships with lake number and volume enable upscaling biogeochemical processes and spatially considering organisms' metapopulation dynamics. These relationships vary regionally depending on the geomorphological context, particularly in the range of lake area 104 m2 and 50% of the water resources are held in a few ones (∼10) deeper than 18 m. Therefore, midlakes and large lakes are by far more biogeochemically relevant than ponds and shallow lakes in this tropical mountain lake district
Environmental Science and Pollution Research International, 2020
Historical records of trace elements in lake sediments provide source-to-sink information about p... more Historical records of trace elements in lake sediments provide source-to-sink information about potentially toxic pollutants across space and time. We investigated two lakes located at different elevations in the Ecuadorian Andes to understand how trace element fluxes are related to (i) geology, (ii) erosion in the watersheds, and (iii) local point sources and atmospheric loads. In remote Lake Fondococha (4150 m a.s.l.), total Hg fluxes stay constant between ca. 1760 and 1950 and show an approximately 4.4-fold increase between pre-1950 and post-1950 values. The post-1950 increase in fluxes of other trace elements (V, Cr, Co, Ni, Cu, Zn, As, Cd, and Pb) is lower (2.1–3.0-fold) than for Hg. Mostly lithogenic sources and enhanced soil erosion contribute to their post-1950 increase (lithogenic contribution: > 85%, Hg: ~ 58%). Average post-1950 Hg fluxes are approximately 4.3 times higher in peri-urban Lake Llaviucu (3150 m a.s.l.) than in the remote Lake Fondococha. Post-1950 fluxes ...
Lakes located downwind of active volcanoes serve as a natural repository for volcanic ash (tephra... more Lakes located downwind of active volcanoes serve as a natural repository for volcanic ash (tephra) produced during eruptive events. In this study, sediment cores from four lakes in Cajas National Park, southern Ecuador, situated approximately 200 km downwind of active volcanoes in the Northern Andes Volcanic Zone, were analysed to document the regional history of tephra fall extending back around 3,000 a cal BP. The ages of the lacustrine sedimentary sequences were constrained using a total of 20 AMS radiocarbon ages on plant remains. The tephra layers were correlated among the lakes based on their radiocarbon age, elemental composition, colour, and grain morphology. We found five unique tephra layers, each at least 0.2 cm thick, and further constrained their ages by combining the results from two age-depth modelling approaches (clam and rbacon). The tephra layers were deposited 3,034±621, 2,027±41, 1,557±177, 733±112, and 450±70 a cal BP. The ages of all but the youngest tephra lay...
Aim: Lakes in the Ecuadorean Andes span different altitudinal and climatic regions, from inter An... more Aim: Lakes in the Ecuadorean Andes span different altitudinal and climatic regions, from inter Andean plateau to the high-elevation páramo, which differ in their historical evolution in the several centuries since the pioneering Humboldt expeditions. Here, we evaluate temporal and spatial patterns of change in diatom assemblages between historical (palaeolimnological) and modern times. Location: Ecuadorean Andes Methods: We compared historical (pre-1850) and modern (2017) diatom assemblages from 21 lakes and determined the relative role of environmental (water chemistry and climate) and spatial factors (distance-based Moran's eigenvectors maps) on both assemblages using non-metric multidimensional scaling (NMDS) with environmental fitting. In addition, we used redundancy analysis (RDA) with variance partitioning to estimate the historical (measured using downcore assemblage composition) effects on modern diatom assemblages and identified diatom species that contributed most to dissimilarity between the two times. Results: Diatom changes between the two time points were limited across the group of lakes, as indicated by the NMDS ordination. Variance partitioning indicated that modern diatom assemblages were affected by environmental and spatial effects, but with non-significant effects of past diatom species composition. Ordination results showed that variables related to elevation and water chemistry affected both modern and historical diatom assemblages. Diatom species with the best fit on NMDS axes (i.e. >70%) were influenced by elevation and climatic variables. The most distinctive change between the two time periods was the higher relative abundance of planktic diatom species in top-core assemblages of some lakes, but in a highly variable fashion across gradients of increased elevation and water depth. Main conclusions: Landscape palaeolimnological analyses of varied Ecuadorean Andean lakes demonstrate both environmental and spatial controls on diatom metacommunities. The multi-faceted ecological control of the altitudinal gradient on both historic and contemporary diatom assemblages suggests species sorting and dispersal constraints operating at centennial timescale. Although a few individual lakes show substantive change between the 1850s and today, the majority of lakes do not, and the analysis suggests the resilience of lakes at a regional scale. We emphasize the potential of diatom palaeolimnological approaches in biogeography to test
The Science of the total environment, Jan 19, 2017
The temporal profiles of polycyclic aromatic compounds (PACs) in lake sediments reflect past chan... more The temporal profiles of polycyclic aromatic compounds (PACs) in lake sediments reflect past changes in emissions, transport and deposition of these pollutants and, thus, record natural and anthropogenic processes. We document fluxes of PACs [(polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs) and azaarenes (AZAs)] deposited in two tropical high-altitude lakes in the Cajas National Park (Ecuadorian Andes, 2°50'S, 79°10'W). In remote and high elevation Laguna Fondococha (4130m a.s.l.), the temporal fluxes of OPAHs and AZAs were similar to those of PAHs suggesting similar sources. A significant increase of PAC deposition after the 1950s reflects Ecuador's economic development. PAH fluxes were relatively low (∑27PAHs (without retene and perylene): 0.86-11.21ngcm-2yr-1) with a composition pattern typical for long-range atmospheric transport (high 9-fluorenone/fluorene ratios) and biomass burning (30% low molecular weight PAHs). PAHs diagnostic of high temperatu...
Se ha estudiado la composición taxonómica de las comunidades de crustáceos litoral-bentónicos (br... more Se ha estudiado la composición taxonómica de las comunidades de crustáceos litoral-bentónicos (branquiópodos, copépodos y ostrácodos) y macrófitos de las masas de agua lacustre del Parque Nacional Cajas situado en los Andes Australes de Ecuador, con objeto de identificar los taxones más adecuados para ser utilizados como indicadores del estado ecológico de los lagos. De los crustáceos (22 taxones) se diferencian tres grupos. Un primer grupo con taxones de alto valor indicador formado por Branchinecta papillata, Ilyocryptus spinosus, Alonella sp, Pleuroxus sp. Paralona pigra y Alona sp. gr. manueli. Un segundo grupo con taxones de valor indicador medio formado por Alona glabra, Alona guttata, Microcyclops sp. Eucyclops sp. y Paracyclops sp. El tercer grupo estaría formado por taxones de escaso valor indicador, bien por su carácter eurioico y/o cosmopolita o por su rareza. De los macrófitos se han valorado como buenos indicadores del estado ecológico y de conservación de los lagos, los taxones enraizados sumergidos y flotantes para la masa de agua, y los helófitos e higrófitos para los litorales. Palabras clave: Crustáceos, macrófitos, indicadores, calidad ecológica,
• The tropical high-mountain lakes show power-law lake-size distributions truncated at both ends ... more • The tropical high-mountain lakes show power-law lake-size distributions truncated at both ends similar to those found in temperate ranges both deviating from the Earth's general patterns for lakes >1 km 2 • The causes for the power-law deviation differ between the two extremes. The marked relief limits the size of the largest lakes at high altitudes, whereas ponds are more prompt to a complete infilling. • Lake volume scales to lake area according to a larger coefficient that those found for other lake areas of also glacial origin but softer relief.
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