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We report, in 15 Ecuadorian mountainous lakes, dissolved concentrations of CO2, CH4, and N2O 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 km2) and depth (1–74 m). Most lakes were characterized by lower values of the partial pressure of CO2 (pCO2) (644–2152 ppm) than usually attributed to tropical lakes (~ 1900 ppm). Three lakes influenced by volcanic inputs were characterized by the highest pCO2 values (3269–10,069 ppm), while two lakes bordered by large cities were characterized by the lowest pCO2 values (208–254 ppm). Dissolved CH4 concentrations ranged between 170 and 24,908 nmol/L and were negatively correlated to lake area and depth. N2O saturation levels ranged between 64% and 101%. The surface waters were undersaturated in N2O with respect to atmospheric equilibrium, probably due to inputs of soil–water with low N2O 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 CO2 and n = 16 for CH4) to derive relations between CO2 and CH4 and lake surface area, allowing to compute CO2 and CH4 lacustrine emissions at the scale of the Amazon basin using the HydroLAKES spatial data set. The CO2 and CH4 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 CO2 and CH4 emissions from lakes represented a small fraction (8.6%) of total lentic and lotic CO2 and CH4 emissions at the scale of the Amazon basin. The lake and river emissions of CH4 represented ~ 3% of total CH4 emissions from all compartments of the Amazon basin, mainly attributable to wetlands. [ABSTRACT FROM AUTHOR]

A number of species of Chydorus Leach, 1816 (Crustacea: Cladocera) need improvements in their taxonomy much more than any other genus within the family Chydoridae Dybowsky & Grochowski, 1894 emend. Frey, 1967, which makes the systematics of the genus still a puzzle that lacks several pieces. Here, we redescribe the African species Chydorus tilhoi Rey & Saint-Jeans, 1969 and compare its morphology with that of Chydorus sphaericus (O.F. Mller, 1776). The two taxa might be easily differentiated because C. tilhoi has a single and relatively large major head pore with a wide rim, labral keel elongated with a large spine, and postabdomen with postanal part elongated, narrowing distally and with denticles near its anal margin, organized in groups. These morphological traits are absent in C. sphaericus. Chydorus tilhoi and C. sphaericus also differ in the morphology of the first (Inner Distal Lobe setae), third (exopodite proportion), and fifth (exopodite shape) limbs. Based on the literature and our observations, the limb morphology of C. tilhoi has important similarities with that of C. breviceps, C. nitidulus and C. dentifer, and their translocation to a new genus seems to be a fundamental piece in the puzzle of Chydorus.