Are Limnic Eruptions in the CO2–CH4-Rich Gas Reservoir of Lake Kivu (Democratic Republic of the Congo and Rwanda) Possible? Insights from Physico-Chemical and Isotopic Data

Author(s):  
Orlando Vaselli ◽  
Dario Tedesco ◽  
Emilio Cuoco ◽  
Franco Tassi
2010 ◽  
Vol 76 (20) ◽  
pp. 6853-6863 ◽  
Author(s):  
Marc Llir�s ◽  
Frederic Gich ◽  
Anna Plasencia ◽  
Jean-Christophe Auguet ◽  
Fran�ois Darchambeau ◽  
...  

ABSTRACT Four stratified basins in Lake Kivu (Rwanda-Democratic Republic of the Congo) were sampled in March 2007 to investigate the abundance, distribution, and potential biogeochemical role of planktonic archaea. We used fluorescence in situ hybridization with catalyzed-reported deposition microscopic counts (CARD-FISH), denaturing gradient gel electrophoresis (DGGE) fingerprinting, and quantitative PCR (qPCR) of signature genes for ammonia-oxidizing archaea (16S rRNA for marine Crenarchaeota group 1.1a [MCG1] and ammonia monooxygenase subunit A [amoA]). Abundance of archaea ranged from 1 to 4.5% of total DAPI (4′,6-diamidino-2-phenylindole) counts with maximal concentrations at the oxic-anoxic transition zone (∼50-m depth). Phylogenetic analysis of the archaeal planktonic community revealed a higher level of richness of crenarchaeal 16S rRNA gene sequences (21 of the 28 operational taxonomic units [OTUs] identified [75%]) over euryarchaeotal ones (7 OTUs). Sequences affiliated with the kingdom Euryarchaeota were mainly recovered from the anoxic water compartment and mostly grouped into methanogenic lineages (Methanosarcinales and Methanocellales). In turn, crenarchaeal phylotypes were recovered throughout the sampled epipelagic waters (0- to 100-m depth), with clear phylogenetic segregation along the transition from oxic to anoxic water masses. Thus, whereas in the anoxic hypolimnion crenarchaeotal OTUs were mainly assigned to the miscellaneous crenarchaeotic group, the OTUs from the oxic-anoxic transition and above belonged to Crenarchaeota groups 1.1a and 1.1b, two lineages containing most of the ammonia-oxidizing representatives known so far. The concomitant vertical distribution of both nitrite and nitrate maxima and the copy numbers of both MCG1 16S rRNA and amoA genes suggest the potential implication of Crenarchaeota in nitrification processes occurring in the epilimnetic waters of the lake.


2021 ◽  
pp. 1-11
Author(s):  
Michael Tshibangu Mukendi ◽  
Henri Kunzi Mbale ◽  
Pisco Munkolo Menga ◽  
Masens-da-Musa Yung ◽  
Jean Meti Ntumba ◽  
...  

Nowadays, invasive alien species are causing more and more environmental problems in several water bodies around the world, in Africa and in the Democratic Republic of the Congo. In October 2020, a floristic inventory was carried out around three islands of the Congo River (Molondo, Mipongo and Japon) at the Pool Malebo in Kinshasa. The study focused on the identification and behavior of alien species along with associated abiotic factors in the Malebo Pool of the Congo River in Kinkole, Kinshasa. The study used a simple random sampling design to select different sites where samples were collected after a direct observation. We collected invasive species in the middle of the Congo River and to achieve that, we used canoe depending on the location of each site. Recorded species were classified either alien species or invasive alien species according to the status in the study region. The identification of collected species was performed according to APG III. Seeing the way these species invade the environment and how they disturb the ecology of rivers, the physico-chemical characteristics of waters were measured between 8:00 am and 3:00 pm with the appropriate electronic probe for each parameter. For each parameter, the comparison between the sites was carried out using the ANOVA test with XLSTAT 2013 software. The findings show that 19 species have been identified as invasive alien species out of which, four were dominant, namely Echinochloa pyramidalis, Eichhornia crassipes, Salvinia molesta and Pistia stratiotes. Considering the physico-chemical parameters, no significant differences were observed for the temperature (F=0.42 and p=0.66), conductivity (F=1.55 and p=0.25) and turbidity (F=2.28 and p=0.14) for the three sites. While the pH (F=4.98; p=0.026; LSD=0.361), dissolved oxygen (F=12; p=0.001; LSD=3.65) and salinity (F=4.06; p= 0.04; LSD= 1.69) showed significant variation in the three sites. The formation of vegetation groups around these islands in the Congo River at the Pool Malebo in Kinshasa  would also be justified by the influence of these parameters.


2021 ◽  
Author(s):  
Meer T Alam ◽  
Carla Mavian ◽  
Marco Salemi ◽  
Massimiliano S Tagliamonte ◽  
Taylor K Paisie ◽  
...  

Bacteriophage predation of toxigenic Vibrio cholerae O1 (the causative agent of cholera) has been linked with seasonal patterns of disease and with clinical response to infection in humans 1-4. However, we still lack a clear demonstration of how the interplay between bacteria and bacteriophage can influence shifts in strain populations. We analyzed toxigenic V. cholerae O1 isolated from patients in the Great Lakes, a cholera endemic region of the Democratic Republic of the Congo (DRC), between 2013-2017. Bayesian phylogeography shows that all strains derived from the East Africa T10 introduction event5, consistent with establishment of a regional endemic focus, and identified two major lineages, with the most recent correlating to ST515, a cholera cluster previously found in the Lake Kivu and expanding northward6. We also identified a novel ICP1 bacteriophage, genetically distinct from previous ICP1 isolates detected in Asia 7,8, from stool samples of cholera patients. The presence of phages in specific regions of the DRC resulted in the independent emergence, along both internal and external branches of the cholera phylogeny, of distinct mutational pathways in genes of the O1 biosynthetic gene cluster associated with phage resistance. Our data evidence, for the first time, V. cholerae multi-peaked adaptive landscape during outbreaks, and a complex co-evolutionary dynamic linked to presence of predatory phages


Zootaxa ◽  
2011 ◽  
Vol 3011 (1) ◽  
pp. 45 ◽  
Author(s):  
KIRSTIN S. MEYER ◽  
NEIL CUMBERLIDGE

The taxonomy of the freshwater crabs living in the rivers draining from the mountains in the eastern Democratic Republic of the Congo and Rwanda into Lake Kivu is revised. Four species are recognized: Potamonautes perparvus (Rathbun, 1921), P. minor Bott, 1955, P. gonocristatus Bott, 1955, and P. semilunaris Bott, 1955. Updated diagnoses, illustrations, and distribution maps are provided for the species. The four species are compared to each other, and an identification key to all eight species found in Lake Kivu and its drainage basin is included.


Author(s):  
Henri Kunzi Mbale ◽  
Michael Tshibangu Mukendi ◽  
Gédéon Ngiala Bongo ◽  
Anthony Batoba Kikufi ◽  
Félicien Luyeye Lukoki

Aim: To identify invasive aquatic alien plant species found in the Pool Malebo and some rivers in Kinshasa city, their behavior as well as their socio-economic impacts. Study Design: The study used a combination of purposive sampling and simple random sampling in order to select different sites where samples were collected. Place and Duration of Study: This study was carried out in different rivers (Pool Malebo system (Kinkole, Kingabwa), and N'sele, Funa and Lukaya rivers) of Kinshasa city in Democratic Republic of the Congo. The Pool Malebo is located along the Congo River. This was conducted between March and October 2013. Methodology: The collection was performed after a direct observation. The location of collection depended on sites, at Kingabwa and Kinkole, we collected invasive species in the middle of the Congo river and to achieve that, we used canoe. While at N’sele, Lukaya and Funa rivers, samples were collected at the edges. The collection took place in the morning between 7 and 11 am. Recorded species were classified either alien species or invasive alien species according to the status in the study region. The identification of collected species was carried out according to APG III. Seeing the way these species invade the environment and how they disturb the ecology of rivers, the physico-chemical characteristics of waters were measured between 7:00 and 11:00 am with the appropriate electronic probe for each parameter. For each parameter, the comparison between the sites was carried out using the ANOVA test with XLSTAT 2013 software. Results: Out of 151 specimens collected, 35 species have been identified of which 19 species as alien were identified and 4 proved to be invasive alien species, namely: Eichhornia crassipes, Echinochloa pyramidalis, Ludwigia peploides and Pistia stratiotes. These invasive species are used by farmers as livestock feed and also as green manure for different agricultural and farming activities, As to the physico-chemical characteristics, no significant differences were observed for the temperature and the turbidity in various sites while the pH and conductivity, there was a highly significant difference between different sites. The hydrology of these rivers is seriously disturbed due to the presence of these invasive alien species. These species constitute a serious threat in the erosion of aquatic biodiversity in the removal of native species in the formation of floating monospecific dense mats as observed. Conclusion: The invasion of alien species is a consequence of human activities and a concern, which affects all sectors of the society. It constitutes a true challenge for ecologists, economists, social scientists, agricultural engineers, environmentalists and other in order to develop and implement strong risk analysis frameworks and environmental impact assessments.


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