scholarly journals Chemoautotrophy and anoxygenic photosynthesis within the water column of a large meromictic tropical lake (Lake Kivu, East Africa)

2016 ◽  
Vol 61 (4) ◽  
pp. 1424-1437 ◽  
Author(s):  
Cédric Morana ◽  
Fleur A. E. Roland ◽  
Sean A. Crowe ◽  
Marc Llirós ◽  
Alberto V. Borges ◽  
...  
Keyword(s):  
Water Column ◽  
East Africa ◽  
Tropical Lake ◽  
Anoxygenic Photosynthesis ◽  
Lake Kivu

scholarly journals Missing atmospheric noble gases in a large, tropical lake: The case of Lake Kivu, East-Africa

2020 ◽  
Vol 532 ◽  
pp. 119374
Author(s):  
Fabian Bärenbold ◽  
Martin Schmid ◽  
Matthias S. Brennwald ◽  
Rolf Kipfer
Keyword(s):  
East Africa ◽  
Noble Gases ◽  
Tropical Lake ◽  
Lake Kivu

scholarly journals Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa): insights from a stable isotope study covering an annual cycle

2014 ◽  
Vol 11 (12) ◽  
pp. 17227-17254 ◽  
Author(s):  
C. Morana ◽  
F. Darchambeau ◽  
F. A. E. Roland ◽  
A. V. Borges ◽  
F. Muvundja ◽  
...  
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
East Africa ◽  
Mixed Layer ◽  
Seasonal Variability ◽  
Rainy Season ◽  
Dry Season ◽  
Tropical Lake ◽  
Particulate Nitrogen ◽  
Lake Kivu

Abstract. During this study, we investigated the seasonal variability of the concentration and the stable isotope composition of several inorganic and organic matter reservoirs in the large, oligotrophic and deep tropical Lake Kivu (East Africa). Data were acquired during one year at a fornightly temporal resolution. The δ13C signature of the dissolved inorganic carbon (DIC) increased linearly with time during the rainy season, then suddenly decreased during the dry season due to vertical mixing with δ13C-depleted DIC waters. This pattern reflects the net autotrophic status of the mixed layer of Lake Kivu, contrary to the common observation that oligotrophic aquatic ecosystems tend to be net heterotrophic. The δ13C signature of the particulate organic carbon pool (POC) revealed the presence of a consistently abundant methanotrophic biomass in the oxycline throughout the year. We also noticed a seasonal shift during the dry season toward higher values in the δ15N of particulate nitrogen (PN) in the mixed layer and δ15N-PN was significantly related to the contribution of cyanobacteria to the phytoplankton assemblage, suggesting that rainy season conditions could be more favourable to atmospheric nitrogen-fixing cyanobacteria. Finally, zooplankton were slightly enriched in δ13C compared to the autochtonous POC pool, and the δ15N signature of zooplankton followed well the seasonal variability in δ15N-PN, being consistently 3.0 ± 1.1‰ heavier than the PN pool. Together, δ13C and δ15N analysis suggests that zooplankton directly incorporate algal-derived organic matter in their biomass, and they would rely almost exclusively on this source of organic matter throughout the year in general agreement with the very low allochthonous organic matter inputs from rivers in Lake Kivu.

scholarly journals Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa: insights from a stable isotope study covering an annual cycle

2015 ◽  
Vol 12 (16) ◽  
pp. 4953-4963 ◽  
Author(s):  
C. Morana ◽  
F. Darchambeau ◽  
F. A. E. Roland ◽  
A. V. Borges ◽  
F. Muvundja ◽  
...  
Keyword(s):  
Stable Isotope ◽  
East Africa ◽  
Seasonal Variability ◽  
Rainy Season ◽  
Dissolved Inorganic Carbon ◽  
Dry Season ◽  
Tropical Lake ◽  
Particulate Nitrogen ◽  
Δ13c And Δ15n ◽  
Lake Kivu

Abstract. During this study, we investigated the seasonal variability of the concentration and the stable isotope composition of several inorganic and organic matter (OM) reservoirs in the large, oligotrophic and deep tropical Lake Kivu (East Africa). Data were acquired over 1 year at a fortnightly temporal resolution. The δ13C signature of the dissolved inorganic carbon (DIC) increased linearly with time during the rainy season, then suddenly decreased during the dry season due to vertical mixing with 13C-depleted DIC waters. The δ13C signature of the particulate organic carbon pool (POC) revealed the presence of a consistently abundant methanotrophic biomass in the oxycline throughout the year. We also noticed a seasonal shift during the dry season toward higher values in the δ15N of particulate nitrogen (PN) in the mixed layer and δ15N-PN was significantly related to the contribution of cyanobacteria to the phytoplankton assemblage, suggesting that rainy season conditions could be more favourable to atmospheric nitrogen-fixing cyanobacteria. Finally, zooplankton were slightly enriched in 13C compared to the autochthonous POC pool, and the δ15N signature of zooplankton followed well the seasonal variability in δ15N-PN, consistently 3.0 ± 1.1 ‰ heavier than the PN pool. Together, δ13C and δ15N analysis suggests that zooplankton directly incorporate algal-derived OM in their biomass, and that they rely almost exclusively on this source of OM throughout the year in general agreement with the very low allochthonous OM inputs from rivers in Lake Kivu.

Studies of the hydrobiology of a tropical lake in north-western Queensland. II. Seasonal changes in thermal and dissolved oxygen characteristics

1980 ◽  
Vol 31 (5) ◽  
pp. 589 ◽  
Author(s):  
CM Finlayson ◽  
TP Farrell ◽  
DJ Griffiths
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Environmental Conditions ◽  
Seasonal Changes ◽  
Thermal Stratification ◽  
Oxygen Depletion ◽  
Tropical Lake ◽  
North Western

The stratification characteristics of Lake Moondarra (24�34'S.,139�35'E.), a man-made lake in north- western Queensland, have been studied. Evidence is presented that the lake approximates the warm polymictic type in which no persistent thermal stratification ever develops. During the cooler months, thermal stratification breaks down during the night; in the warmer months, the intense rainstorms prevent the establishment of a persistently stratified water column. The shallowness of the lake relative to its surface areaand the prevailing environmental conditions ensure that extensive periods of oxygen depletion do not develop in the water column. It is concluded that a strong and prolonged period of thermal stratification, with subsequent serious effects of the availability of dissolved oxygen in the deeper layers, would only arise if, in a particular year. there were no significant rainstorms.

Microcrystalline sphalerite in resin globules suspended in Lake Kivu, East Africa

1972 ◽  
Vol 7 (1) ◽  
Author(s):  
E.T. Degens ◽  
H. Okada ◽  
S. Honjo ◽  
J.C. Hathaway
Keyword(s):  
East Africa ◽  
Lake Kivu

scholarly journals Nitrous oxide and methane seasonal variability in the epilimnion of a large tropical meromictic lake (Lake Kivu, East-Africa)

2016 ◽  
Vol 79 (2) ◽  
pp. 209-218 ◽  
Author(s):  
Fleur A. E. Roland ◽  
François Darchambeau ◽  
Cédric Morana ◽  
Alberto V. Borges
Keyword(s):  
Nitrous Oxide ◽  
East Africa ◽  
Seasonal Variability ◽  
Meromictic Lake ◽  
Lake Kivu
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