Water chemistry variation in tropical high‐mountain lakes on old volcanic bedrocks

Mosquera, Pablo V.; Hampel, Henrietta; Vázquez, Raúl F.; Catalan, Jordi

doi:10.1002/lno.12099

Cited by 9 publications

(17 citation statements)

References 63 publications

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“…Surface air temperatures remain cold throughout the year in the equatorial Andes, yet precipitation is highly variable, characterided by a bimodal regime with wet periods from February to May and October to November, coincident with the thermal regimes of the study lakes. Our results support the recent study by Mosquera (2023) which posits that a warm monomictic regime is the dominant pattern across high mountain tropical lakes of varied morphology, and is in contrast to the long-established paradigm of a polymictic thermal regime, as suggested in earlier studies (Steinitz-Kannan et al, 1983).…”

Section: Temporal Variabilitysupporting

confidence: 93%

“…In mountain lakes, variability in divalent cations is characteristic of the multifactorial alkalinity-pH gradient (Jacobsen & Dangles, 2017). between alkalinity and DOC in our study lakes (Mosquera et al, 2022).…”

mentioning

confidence: 59%

“…The vast majority (>4,000) of lakes in the Cajas Massif are protected within Cajas National Park (CNP). In the lake watersheds, the bedrock consists of a complex layering of volcanic formations from late Eocene to Miocene, where andesites, dacites, rhyolites, tuffs, pyroclastics and ignimbrites are the most abundant (Mosquera et al., 2022). The Cajas Massif soils are of volcanic origin, consisting mainly of non‐allophanic Andosols and Histosols (Crespo et al., 2011), and the land cover consists of páramo ( Stipa and Calamagrostis) (Ramsay & Oxley, 1997) and rocky páramo grassland, with small patches of Polylepis forest, scrub, wetlands, bare rock and eroded land (Mosquera et al., 2022).…”

Section: Methodsmentioning

confidence: 99%

“…) can be released to fuel primary production (Dengg et al, 2023;Mosquera et al, 2022). This could be the case in our lower elevation study lakes, but also in lakes characterised by nutrient-enriched conditions (Leira et al, 2009), physical disturbance (i.e., mixing) or cold waters (Vázquez & Caballero, 2013).…”

mentioning

confidence: 88%

“…Standard methods for water chemical analysis were followed (APHA-AWWA-WEF, 2012). For detailed description of the methods used for analysing the chemical parameters and land-use in the lake watershed see Mosquera et al (2022) and for lake morphological parameters see Mosquera et al (2017). Chl-a was extracted with acetone (90%) and determined by the spectrophotometric method (SM 10200H Chlorophyll).…”

Section: Water Chemistry Physical and Spatial Datasetsmentioning

confidence: 99%

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Planktic diatom responses to spatiotemporal environmental variation in high‐mountain tropical lakes

Luethje,

Mosquera,

Hampel

et al. 2024

Freshwater Biology

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Tropical lakes harbour high levels of biodiversity, but the temporal and spatial variability of biological communities are still inadequately characterised, making it difficult to predict the impact of accelerated rates of environmental change in these regions. Our goal was to identify the spatiotemporal dynamics of the planktic diatom community in the Cajas Massif in the tropical Andes. We analysed seasonal diatom and environmental data over a period of 1 year from 10 lakes located in geologically distinct basins and modelled community–environment relationships using multivariate ordination and variation partitioning techniques. Generalised additive models with a full‐subset information theoretic approach also were used to determine which environmental variables explain single‐species abundance. Although the lakes are monomictic and thus have variable thermal structure across the year, seasonal variability of water chemistry conditions was negligible, and seasonal differences in diatom community composition were small. Across space, diatom community composition was correlated primarily with ionic content (divalent cations and alkalinity), related to bedrock composition, and secondly with lake thermal structure and productivity. The ionic gradient overrode the effect of the thermal structure–productivity gradient at the diatom community level, whereas individual diatom species responded more sensitively to variables related to in‐lake and catchment productivity, including chlorophyll‐a and iron, and the proportion of wetlands in the catchment. Our results indicate that the spatiotemporal variability of Cajas lakes and their diatom communities is the result of multiple intertwined environmental factors. The emergence of the ionic and thermal structure–productivity gradients in a rather small tropical lake district suggests segregation of ecological niches for diatoms that also may be important in other high‐elevation lake regions. Future studies that track tropical Andean lakes under natural and anthropogenically mediated change, both in contemporary times and in palaeoenvironmental reconstructions, would benefit from the modelling approach (community and species levels) developed here.

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Section: Temporal Variabilitysupporting

confidence: 93%

mentioning

confidence: 59%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 88%

Section: Water Chemistry Physical and Spatial Datasetsmentioning

confidence: 99%

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Planktic diatom responses to spatiotemporal environmental variation in high‐mountain tropical lakes

Luethje,

Mosquera,

Hampel

et al. 2024

Freshwater Biology

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Dissolved greenhouse gas (CO2, CH4, and N2O) emissions from highland lakes of the Andes cordillera in Northern Ecuador

Chiriboga,

Bouillon,

Borges

2024

Aquat Sci

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We report, in 15 Ecuadorian mountainous lakes, dissolved concentrations of CO 2 , CH 4 , and N 2 O and a suite of ancillary biogeochemical variables (dissolved inorganic nutrients, oxygen, major cations, dissolved and particulate organic carbon, and the stable isotope composition of dissolved inorganic carbon and water). The sampled lakes were located in the páramos of Salve Facha and Antisana y Mojanda (northern region of Ecuadorian Andes), along an elevational gradient from 2213 to 4361 m above sea level, as well as a gradient of lake surface area (0.003-6.1 km 2 ) and depth (1-74 m). Most lakes were characterized by lower values of the partial pressure of CO 2 (pCO 2 ) (644-2152 ppm) than usually attributed to tropical lakes (~ 1900 ppm). Three lakes influenced by volcanic inputs were characterized by the highest pCO 2 values (3269-10,069 ppm), while two lakes bordered by large cities were characterized by the lowest pCO 2 values (208-254 ppm). Dissolved CH 4 concentrations ranged between 170 and 24,908 nmol/L and were negatively correlated to lake area and depth. N 2 O saturation levels ranged between 64% and 101%. The surface waters were undersaturated in N 2 O with respect to atmospheric equilibrium, probably due to inputs of soil-water with low N 2 O levels owing to denitrification in soils. The data obtained in the sampled highland lakes was combined with published data from lowland lakes (elevation < 500 m, n = 17 for CO 2 and n = 16 for CH 4 ) to derive relations between CO 2 and CH 4 and lake surface area, allowing to compute CO 2 and CH 4 lacustrine emissions at the scale of the Amazon basin using the HydroLAKES spatial data set. The CO 2 and CH 4 emissions from highland lakes (elevation > 500 m) only represented 0.4% and 2% of the total lacustrine emissions at the scale of the Amazon basin, respectively. Total CO 2 and CH 4 emissions from lakes represented a small fraction (8.6%) of total lentic and lotic CO 2 and CH 4 emissions at the scale of the Amazon basin. The lake and river emissions of CH 4 represented ~ 3% of total CH 4 emissions from all compartments of the Amazon basin, mainly attributable to wetlands. KeywordsAmazon River • Ecuador • Mountainous lakes • CO 2 • CH 4 • N 2 O * Alberto V. Borges

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Paleolimnological responses of Ecuadorian páramo lakes to local and regional stressors over the last two millennia

et al. 2023

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Increasing surface air temperatures and human influences (e.g., agriculture, grazing, mining, urbanization, tourism) are altering lakes on the Andean páramo of South America, as illustrated by changes in diatom species composition in sediment cores from the region that span the last ~150 years. Previous studies were limited by their relatively short temporal scales and limited spatial coverage. We analyzed sediment cores from the northern (Laguna Piñan) and southern (Laguna Fondococha) Andean páramos of Ecuador. The deposits span the last two millennia and provide a longer-term perspective on past changes in lake ecological and geochemical dynamics.Both lakes show shifts in dominant diatoms through time. Dominant diatom taxa in Fondococha shifted between two Aulacoseira species, and there was a change in the planktic to benthic ratio, a proxy for open-water versus shallow-water habitats. Both changes are interpreted as evidence of fluctuating lake level. The inferred lake-level changes are corroborated by stratigraphic variations in the concentration of Ti, an erosional proxy, indicating changes in clastic input as a function of wetter or drier conditions. Piñan shows a directional shift in the diatom assemblage over the period of the record, from benthic diatoms tolerant of high dissolved organic carbon (DOC), low pH, and low nutrients, to an assemblage characteristic of lower DOC, higher pH, higher nutrients, and higher lake levels. Shifts in Piñan's diatoms are correlated with tephra layers in the sediment, suggesting that local volcanic ash deposition may have altered both the catchment and lake geochemistry. This is supported by relatively higher δ 13 C values in organic matter associated with tephra layers, which become more negative up-section. Our data suggest that remote lakes in spatially heterogenous montane regions are sentinels of environmental change, and the records from Piñan and Fondococha provide insights into Andean ecosystem responses to past environmental perturbations.

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Water chemistry variation in tropical high‐mountain lakes on old volcanic bedrocks

Cited by 9 publications

References 63 publications

Planktic diatom responses to spatiotemporal environmental variation in high‐mountain tropical lakes

Planktic diatom responses to spatiotemporal environmental variation in high‐mountain tropical lakes

Dissolved greenhouse gas (CO2, CH4, and N2O) emissions from highland lakes of the Andes cordillera in Northern Ecuador

Paleolimnological responses of Ecuadorian páramo lakes to local and regional stressors over the last two millennia

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