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Lakes are important components in the carbon cycling and threatened by direct and indirect human activities, which ultimately affect metabolic processes. We analyzed the daily dynamics of the air-water CO 2 and O 2 fluxes over nine days in a mesocosm experiment to determine how the inputs of inorganic nutrients (+NUTRI) and allochthonous organic matter (+OM) affected the metabolic processes. The control, representing the original state of the lake, showed low coefficient of variability among the days sampled and a predominant F CO 2 to the atmosphere, but with mean values close to zero (0.2 ± 0.3 mmol m −2  d −1 ). In +NUTRI and +NUTRI+OM treatments mesocosms, the F CO 2 and F O 2 showed similar response, where the F CO 2 was negative during all days (mean −1.8 ± 1.1 and −1.9 ± 1.2 mmol m −2  d −1 , respectively) and F O 2 was initially negative, becoming positive after day 4, and decreasing again after day 6. The +OM treatment intensified the F CO 2 to the atmosphere (mean 0.4 ± 0.9 mmol m −2 d −1 ) with highest values at day 7. The ecosystem in +NUTRI and +NUTRI+OM treatments showed a similar recovery (8 days), while +OM treatment mesocosm was similar to the control conditions. The models showed that nutrients promoted larger overall changes and higher daily variability in both F CO 2 and F O 2 , leading to a CO 2 influx, followed by organic matter addition. In conclusion, this mesocosm experiment showed the fast response of the lakes to even small disturbances (e.g organic matter addition), which can intensify the sink or the source of carbon to the atmosphere and change the role of the lakes in the global carbon cycling. [ABSTRACT FROM AUTHOR]

Carioca Lake is located within the limits of the Rio Doce State Park, in the eastern part of the state of Minas Gerais. This park, one of the largest natural reserves of the Atlantic Rain Forest in Brazil, is a hotspot of tropical biodiversity. The purpose of this study was to update existing information on the bathymetry and morphometric features of the lake, using differential GPS (DGPS) technology for data collection, coupled to a digital echo sounder. The bathymetry was based on the acquisition of 1106 points, where the depths as well as the geographic coordinates were obtained. The new study allowed the refinement of existing primary and secondary morphometric data for this lake.A lagoa Carioca está localizada nos limites do Parque Estadual do Rio Doce (PERD), na região leste do Estado de Minas Gerais. Este parque, uma das maiores reservas naturais da Mata Atlântica no Brasil, é um hotspot da biodiversidade. Este trabalho tem por objetivo elaborar um novo mapeamento batimétrico e descrever as características morfométricas deste ambiente utilizando a tecnologia do GPS diferencial (DGPS) para coleta dos dados de localização geográfica em conjunto com uma ecossonda digital, equipamento para coleta das informações de profundidade. O levantamento batimétrico da lagoa Carioca foi baseado num total de 1106 pontos com profundidade e localização conhecidas, obtidas com precisão submétrica. O novo estudo permitiu o refinamento dos dados morfométricos primários e secundários existentes para este lago.

Carioca Lake is located within the limits of the Rio Doce State Park, in the eastern part of the state of Minas Gerais. This park, one of the largest natural reserves of the Atlantic Rain Forest in Brazil, is a hotspot of tropical biodiversity. The purpose of this study was to update existing information on the bathymetry and morphometric features of the lake, using differential GPS (DGPS) technology for data collection, coupled to a digital echo sounder. The bathymetry was based on the acquisition of 1106 points, where the depths as well as the geographic coordinates were obtained. The new study allowed the refinement of existing primary and secondary morphometric data for this lake.