Phytoplankton ecology of Lake Kivu (eastern Africa)

Sarmento, Hugo; Isumbisho, Mwapu; Descy, Jean-Pierre

doi:10.1093/plankt/fbl017

Cited by 108 publications

(130 citation statements)

References 26 publications

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“…Presence of a high percentage of these two phyla in different seasons might be due to the competition between these two phyla for organic matter or dominance of different phytoplankton species in two seasons, as mainly a higher dominance of diatoms was observed in the DS and Cyanobacteria were more dominant in the RS ( Fig. 4; [23]). Besides, Cyanobacteria represent a big fraction of the active microbial community in oxic and illuminated waters (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…It has a surface area of 2370 km 2 , a total volume of 580 km 3 , and a maximum depth of 485 m. Surface waters are considered to be oligotrophic with moderate primary production compared to other African lakes [22,23]. Further details on the hydrology, physicochemistry, and biology of the lake are published elsewhere [22][23][24][25]. In order to study the microbial communities in the water column of Lake Kivu, water samples were collected from the upper 100 m of the water column in the North basin (off Gisenyi; 29.24°E, −1.72°N).…”

Section: Methodsmentioning

confidence: 99%

“…After two 15-min sonication steps separated by an overnight period at 4°C, the extracts were stored in 2-mL amber vials at −25°C. HPLC analysis was performed following the method described in Sarmento et al [23]. Commercial external standards (DHI Lab Products) were used for calibration.…”

Section: Methodsmentioning

confidence: 99%

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Vertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu

et al. 2015

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The microbial community composition in meromictic Lake Kivu, with one of the largest CH 4 reservoirs, was studied using 16S rDNA and ribosomal RNA (rRNA) pyrosequencing during the dry and rainy seasons. Highly abundant taxa were shared in a high percentage between bulk (DNA-based) and active (RNA-based) bacterial communities, whereas a high proportion of rare species was detected only in either an active or bulk community, indicating the existence of a potentially active rare biosphere and the possible underestimation of diversity detected when using only one nucleic acid pool. Most taxa identified as generalists were abundant, and those identified as specialists were more likely to be rare in the bulk community. The overall number of environmental parameters that could explain the variation was higher for abundant taxa in comparison to rare taxa. Clustering analysis based on operational taxonomic units (OTUs at 0.03 cutoff) level revealed significant and systematic microbial community composition shifts with depth. In the oxic zone, Actinobacteria were found highly dominant in the bulk community but not in the metabolically active community. In the oxic-anoxic transition zone, highly abundant potentially active Nitrospira and Methylococcales were observed. The cooccurrence of potentially active sulfur-oxidizing and sulfatereducing bacteria in the anoxic zone may suggest the presence of an active yet cryptic sulfur cycle.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Vertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu

et al. 2015

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“…General physico-chemical characteristics of the lake's water are described elsewhere (e.g. Borges et al, 2011;Descy et al, 2012;Sarmento et al, 2006;Schmid et al, 2005). Limnological observations were made twice a month from March 2002to November 2009.…”

Section: Samplingmentioning

confidence: 99%

“…The assessment of algal abundance from pigment concentrations uses different techniques, involving ratios of marker pigments to chlorophyll a (Chla) (Mackey et al, 1996). As it is based on a fast, automatic and reliable analytical technique, the pigment approach has been largely used in oceanographic studies and monitoring programs (Jeffrey et al, 1997), as well as in large lake studies (Descy et al, 2005;Fietz and Nicklish, 2004;Fietz et al, 2005;Sarmento et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Primary production in a tropical large lake: The role of phytoplankton composition

Darchambeau

Sarmento

Descy

2014

Science of The Total Environment

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• We provide a 7-year dataset of primary production in a tropical great lake.• Specific photosynthetic rate was determined by community composition.• Annual primary production varied between 143 and 278 mg C m − 2 y − 1 .• Pelagic production was highly sensitive to climate variability. Phytoplankton biomass and primary production in tropical large lakes vary at different time scales, from seasons to centuries. We provide a dataset made of 7 consecutive years of phytoplankton biomass and production in Lake Kivu (Eastern Africa). From 2002 to 2008, bi-weekly samplings were performed in a pelagic site in order to quantify phytoplankton composition and biomass, using marker pigments determined by HPLC. Primary production rates were estimated by 96 in situ 14 C incubations. A principal component analysis showed that the main environmental gradient was linked to a seasonal variation of the phytoplankton assemblage, with a clear separation between diatoms during the dry season and cyanobacteria during the rainy season. A rather wide range of the maximum specific photosynthetic rate (P Bm ) was found, ranging between 1.15 and 7.21 g carbon g −1 chlorophyll a h −1 , and was best predicted by a regression model using phytoplankton composition as an explanatory variable. The irradiance at the onset of light saturation (I k ) ranged between 91 and 752 μE m −2 s −1 and was linearly correlated with the mean irradiance in the mixed layer. The inter-annual variability of phytoplankton biomass and production was high, ranging from 53 to 100 mg chlorophyll a m −2 (annual mean) and from 143 to 278 g carbon m −2 y −1 , respectively. The degree of seasonal mixing determined annual production, demonstrating the sensitivity of tropical lakes to climate variability. A review of primary production of other African great lakes allows situating Lake Kivu productivity in the same range as that of lakes Tanganyika and Malawi, even if mean phytoplankton biomass was higher in Lake Kivu. a b s t r a c t a r t i c l e i n f o

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Climatic Variability, Mixing Dynamics, and Ecological Consequences in the African Great Lakes

MacIntyre

2012

Climatic Change and Global Warming of Inland Waters

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Phytoplankton ecology of Lake Kivu (eastern Africa)

Cited by 108 publications

References 26 publications

Vertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu

Vertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu

Primary production in a tropical large lake: The role of phytoplankton composition

Climatic Variability, Mixing Dynamics, and Ecological Consequences in the African Great Lakes

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