Figure 1
Geographical location of the study sites: (a) South America, Argentina and Buenos Aires Province (representative of Pampa Plain), (b) Buenos Aires Province and Río Salado Basin, (c) Salado River with the two shallow lakes sampling. TR: El Triunfo. CH: Chascomús.
Figure 2
Main Spearman rank correlations (r > 0.60) in: (a) clear El Triunfo lake and (b) turbid Chascomús lake (Turb: turbidity, DO: dissolved oxygen, Temp: water temperature, Cond: conductivity, N_NO3 -: nitrate, N_NO2 -: nitrite, TN: total nitrogen, TP: total phosphorus, TSS: total suspended solid, AFDW: ash free dry weigh, aCDOM440: absorbance of chromophoric dissolved organic matter at 440 nm, Alk: alkalinity, Z: water depth, Kd: light attenuation coefficient, PAR: photosynthetically active radiation, I0: incident irradiance, HB: heterotrophic bacteria, Pcy: picocyanobacteria, Peuk: picoeukaryotes, Chl-a: chlorophyll-a, HF: heterotrophic flagellates (2-5 µm, 5-10 µm, > 10 µm), t HF: total HF, Cil: ciliates (10-20 µm), t Cil: total Cil. * p < 0.05, ** p < 0.01, *** p < 0.001).
Figure 3
Mean monthly rainfall (mm) accumulated between 2005 to 2007 and temporal rainfall together to incident photosynthetic active irradiance (I0PAR: W m-2) measured during sampling period.
Figure 4
Temporal variation in chemical and physical parameters measured in the two lakes during sampling period: (a) Water Temperature (Temp: °C), (b) Alkalinity (Alk: mEq L-1), (c) Turbidity (NTU), (d) Total Phosphorous (TP: µg L-1), (e) Total Nitrogen (TN: mg L-1), (f) Water depth (Z: m). TR: El Triunfo. CH: Chascomús. Numbers in parentheses after variable and site name in legends indicate the median value for each site and *** indicate significantly different median after Mann Whitney test (p < 0.001). Grey areas correspond to warm (Spring and Summer) seasons.
Figure 5
Temporal variation of microbial communities measured in the two lakes during sampling period: (a) Heterotrophic bacteria (HB: cells mL-1), (b) Picocyanobacteria (Pcy: cells mL-1), (c) Picoeukaryote (Peuk: cells mL-1), (d) Heterotrophic flagellates (HF: cells mL-1), (e) Ciliates (cells mL-1). TR: El Triunfo. CH: Chascomús. Numbers in parentheses after variable and site name in legends indicate the median value for each site and *** indicate significantly different median after Mann Whitney test (p < 0.001). Grey areas correspond to warm (Spring and Summer) seasons.
Figure 6
Relative seasonal importance of microbial abundances in the two studied lakes. Picoplankton -PP-: Heterotrophic Bacteria -HB-, Picocyanobacteria -Pcy- and Picoeukaryote -Peuk-; Heterotrophic Flagellates -HF-: HF < 2 µm, HF 2-5 µm, HF 5-10 µm and HF > 10 µm and ciliates -Cil- : Ciliates < 10 µm, Ciliates 10-20 µm; Ciliates > 20 µm. (Aut: Autumn, Win: Winter, Spr: Spring, Sum: Summer). TR: El Triunfo. CH: Chascomús. * indicate significant differences after ANOSIM (Table IV).
Figure 7
Biplot of RDA method and venn diagrams showing the variation partitioning performed with the microbial abundance explained by unique and joint effects of extrinsic and intrinsic factors: (a) El Triunfo: extrinsic: I0PAR and rainfall. Intrinsic PP: Temp., Chl-a, Alk; HF: pH, Temp., Chl-a, SRP; Ciliates: Alk, TSS and TP. (b) Chascomús: extrinsic: I0PAR and rainfall. Intrinsic PP: pH, Temp, DO, Cond, Chl-a, TN, SRP; HF: Chl-a, Cond, SRP; Ciliates: AFDW, Alk. Solid black, dashed black arrows and points represents microbial community, environmental factors and sites, respectively; and each arrow points in the direction of the steepest increase of the corresponding values. I0PAR: photosynthetic light intensity, Chl-a: chlorophyll a, Temp: water temperature, TN: total nitrogen, SRP: soluble reactive phosphorous, DO: dissolved oxygen, TP: total phosphorous, Alk: alkalinity, TSS: total solid suspended, AFDW: ash free dry weigh. PP: Picoplankton. HB: Heterotrophic Bacteria, Pcy: Picocyanobacteria, Peuk: Picoeukaryote, HF: Heterotrophic Flagellates, Cil: ciliates ( Autumn 08 -Aut 08-, Winter 08 -Win 08-, Spring 08 -Spr 08- , Summer 09 -Sum 09-, Autumn 09 -Aut 09-).
Figure 3
Mean monthly rainfall (mm) accumulated between 2005 to 2007 and temporal rainfall together to incident photosynthetic active irradiance (I0PAR: W m-2) measured during sampling period.
Figure 4
Temporal variation in chemical and physical parameters measured in the two lakes during sampling period: (a) Water Temperature (Temp: °C), (b) Alkalinity (Alk: mEq L-1), (c) Turbidity (NTU), (d) Total Phosphorous (TP: µg L-1), (e) Total Nitrogen (TN: mg L-1), (f) Water depth (Z: m). TR: El Triunfo. CH: Chascomús. Numbers in parentheses after variable and site name in legends indicate the median value for each site and *** indicate significantly different median after Mann Whitney test (p < 0.001). Grey areas correspond to warm (Spring and Summer) seasons.
Figure 5
Temporal variation of microbial communities measured in the two lakes during sampling period: (a) Heterotrophic bacteria (HB: cells mL-1), (b) Picocyanobacteria (Pcy: cells mL-1), (c) Picoeukaryote (Peuk: cells mL-1), (d) Heterotrophic flagellates (HF: cells mL-1), (e) Ciliates (cells mL-1). TR: El Triunfo. CH: Chascomús. Numbers in parentheses after variable and site name in legends indicate the median value for each site and *** indicate significantly different median after Mann Whitney test (p < 0.001). Grey areas correspond to warm (Spring and Summer) seasons.
Figure 6
Relative seasonal importance of microbial abundances in the two studied lakes. Picoplankton -PP-: Heterotrophic Bacteria -HB-, Picocyanobacteria -Pcy- and Picoeukaryote -Peuk-; Heterotrophic Flagellates -HF-: HF < 2 µm, HF 2-5 µm, HF 5-10 µm and HF > 10 µm and ciliates -Cil- : Ciliates < 10 µm, Ciliates 10-20 µm; Ciliates > 20 µm. (Aut: Autumn, Win: Winter, Spr: Spring, Sum: Summer). TR: El Triunfo. CH: Chascomús. * indicate significant differences after ANOSIM (Table IV).
Figure 7
Biplot of RDA method and venn diagrams showing the variation partitioning performed with the microbial abundance explained by unique and joint effects of extrinsic and intrinsic factors: (a) El Triunfo: extrinsic: I0PAR and rainfall. Intrinsic PP: Temp., Chl-a, Alk; HF: pH, Temp., Chl-a, SRP; Ciliates: Alk, TSS and TP. (b) Chascomús: extrinsic: I0PAR and rainfall. Intrinsic PP: pH, Temp, DO, Cond, Chl-a, TN, SRP; HF: Chl-a, Cond, SRP; Ciliates: AFDW, Alk. Solid black, dashed black arrows and points represents microbial community, environmental factors and sites, respectively; and each arrow points in the direction of the steepest increase of the corresponding values. I0PAR: photosynthetic light intensity, Chl-a: chlorophyll a, Temp: water temperature, TN: total nitrogen, SRP: soluble reactive phosphorous, DO: dissolved oxygen, TP: total phosphorous, Alk: alkalinity, TSS: total solid suspended, AFDW: ash free dry weigh. PP: Picoplankton. HB: Heterotrophic Bacteria, Pcy: Picocyanobacteria, Peuk: Picoeukaryote, HF: Heterotrophic Flagellates, Cil: ciliates ( Autumn 08 -Aut 08-, Winter 08 -Win 08-, Spring 08 -Spr 08- , Summer 09 -Sum 09-, Autumn 09 -Aut 09-).